Import 'ryu' crate version 1.0.5
Bug: 163175424
Test: N/A
Change-Id: I7bda5411adccb26198c53ed1cb41fc6bb08468d7
diff --git a/src/buffer/mod.rs b/src/buffer/mod.rs
new file mode 100644
index 0000000..df21fe0
--- /dev/null
+++ b/src/buffer/mod.rs
@@ -0,0 +1,180 @@
+use crate::raw;
+#[cfg(maybe_uninit)]
+use core::mem::MaybeUninit;
+use core::{mem, slice, str};
+#[cfg(feature = "no-panic")]
+use no_panic::no_panic;
+
+const NAN: &'static str = "NaN";
+const INFINITY: &'static str = "inf";
+const NEG_INFINITY: &'static str = "-inf";
+
+/// Safe API for formatting floating point numbers to text.
+///
+/// ## Example
+///
+/// ```
+/// let mut buffer = ryu::Buffer::new();
+/// let printed = buffer.format_finite(1.234);
+/// assert_eq!(printed, "1.234");
+/// ```
+pub struct Buffer {
+ #[cfg(maybe_uninit)]
+ bytes: [MaybeUninit<u8>; 24],
+ #[cfg(not(maybe_uninit))]
+ bytes: [u8; 24],
+}
+
+impl Buffer {
+ /// This is a cheap operation; you don't need to worry about reusing buffers
+ /// for efficiency.
+ #[inline]
+ #[cfg_attr(feature = "no-panic", no_panic)]
+ pub fn new() -> Self {
+ // assume_init is safe here, since this is an array of MaybeUninit, which does not need
+ // to be initialized.
+ #[cfg(maybe_uninit)]
+ let bytes = [MaybeUninit::<u8>::uninit(); 24];
+ #[cfg(not(maybe_uninit))]
+ let bytes = unsafe { mem::uninitialized() };
+
+ Buffer { bytes: bytes }
+ }
+
+ /// Print a floating point number into this buffer and return a reference to
+ /// its string representation within the buffer.
+ ///
+ /// # Special cases
+ ///
+ /// This function formats NaN as the string "NaN", positive infinity as
+ /// "inf", and negative infinity as "-inf" to match std::fmt.
+ ///
+ /// If your input is known to be finite, you may get better performance by
+ /// calling the `format_finite` method instead of `format` to avoid the
+ /// checks for special cases.
+ #[cfg_attr(feature = "no-panic", inline)]
+ #[cfg_attr(feature = "no-panic", no_panic)]
+ pub fn format<F: Float>(&mut self, f: F) -> &str {
+ if f.is_nonfinite() {
+ f.format_nonfinite()
+ } else {
+ self.format_finite(f)
+ }
+ }
+
+ /// Print a floating point number into this buffer and return a reference to
+ /// its string representation within the buffer.
+ ///
+ /// # Special cases
+ ///
+ /// This function **does not** check for NaN or infinity. If the input
+ /// number is not a finite float, the printed representation will be some
+ /// correctly formatted but unspecified numerical value.
+ ///
+ /// Please check [`is_finite`] yourself before calling this function, or
+ /// check [`is_nan`] and [`is_infinite`] and handle those cases yourself.
+ ///
+ /// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite
+ /// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan
+ /// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_infinite
+ #[inline]
+ #[cfg_attr(feature = "no-panic", no_panic)]
+ pub fn format_finite<F: Float>(&mut self, f: F) -> &str {
+ unsafe {
+ let n = f.write_to_ryu_buffer(self.bytes.as_mut_ptr() as *mut u8);
+ debug_assert!(n <= self.bytes.len());
+ let slice = slice::from_raw_parts(self.bytes.as_ptr() as *const u8, n);
+ str::from_utf8_unchecked(slice)
+ }
+ }
+}
+
+impl Copy for Buffer {}
+
+impl Clone for Buffer {
+ #[inline]
+ fn clone(&self) -> Self {
+ Buffer::new()
+ }
+}
+
+impl Default for Buffer {
+ #[inline]
+ #[cfg_attr(feature = "no-panic", no_panic)]
+ fn default() -> Self {
+ Buffer::new()
+ }
+}
+
+/// A floating point number, f32 or f64, that can be written into a
+/// [`ryu::Buffer`][Buffer].
+///
+/// This trait is sealed and cannot be implemented for types outside of the
+/// `ryu` crate.
+pub trait Float: Sealed {}
+impl Float for f32 {}
+impl Float for f64 {}
+
+pub trait Sealed: Copy {
+ fn is_nonfinite(self) -> bool;
+ fn format_nonfinite(self) -> &'static str;
+ unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize;
+}
+
+impl Sealed for f32 {
+ #[inline]
+ fn is_nonfinite(self) -> bool {
+ const EXP_MASK: u32 = 0x7f800000;
+ let bits = unsafe { mem::transmute::<f32, u32>(self) };
+ bits & EXP_MASK == EXP_MASK
+ }
+
+ #[cold]
+ #[cfg_attr(feature = "no-panic", inline)]
+ fn format_nonfinite(self) -> &'static str {
+ const MANTISSA_MASK: u32 = 0x007fffff;
+ const SIGN_MASK: u32 = 0x80000000;
+ let bits = unsafe { mem::transmute::<f32, u32>(self) };
+ if bits & MANTISSA_MASK != 0 {
+ NAN
+ } else if bits & SIGN_MASK != 0 {
+ NEG_INFINITY
+ } else {
+ INFINITY
+ }
+ }
+
+ #[inline]
+ unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize {
+ raw::format32(self, result)
+ }
+}
+
+impl Sealed for f64 {
+ #[inline]
+ fn is_nonfinite(self) -> bool {
+ const EXP_MASK: u64 = 0x7ff0000000000000;
+ let bits = unsafe { mem::transmute::<f64, u64>(self) };
+ bits & EXP_MASK == EXP_MASK
+ }
+
+ #[cold]
+ #[cfg_attr(feature = "no-panic", inline)]
+ fn format_nonfinite(self) -> &'static str {
+ const MANTISSA_MASK: u64 = 0x000fffffffffffff;
+ const SIGN_MASK: u64 = 0x8000000000000000;
+ let bits = unsafe { mem::transmute::<f64, u64>(self) };
+ if bits & MANTISSA_MASK != 0 {
+ NAN
+ } else if bits & SIGN_MASK != 0 {
+ NEG_INFINITY
+ } else {
+ INFINITY
+ }
+ }
+
+ #[inline]
+ unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize {
+ raw::format64(self, result)
+ }
+}
diff --git a/src/common.rs b/src/common.rs
new file mode 100644
index 0000000..9613036
--- /dev/null
+++ b/src/common.rs
@@ -0,0 +1,95 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+// Returns the number of decimal digits in v, which must not contain more than 9
+// digits.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn decimal_length9(v: u32) -> u32 {
+ // Function precondition: v is not a 10-digit number.
+ // (f2s: 9 digits are sufficient for round-tripping.)
+ debug_assert!(v < 1000000000);
+
+ if v >= 100000000 {
+ 9
+ } else if v >= 10000000 {
+ 8
+ } else if v >= 1000000 {
+ 7
+ } else if v >= 100000 {
+ 6
+ } else if v >= 10000 {
+ 5
+ } else if v >= 1000 {
+ 4
+ } else if v >= 100 {
+ 3
+ } else if v >= 10 {
+ 2
+ } else {
+ 1
+ }
+}
+
+// Returns e == 0 ? 1 : [log_2(5^e)]; requires 0 <= e <= 3528.
+#[cfg_attr(feature = "no-panic", inline)]
+#[allow(dead_code)]
+pub fn log2_pow5(e: i32) -> i32 /* or u32 -> u32 */ {
+ // This approximation works up to the point that the multiplication
+ // overflows at e = 3529. If the multiplication were done in 64 bits, it
+ // would fail at 5^4004 which is just greater than 2^9297.
+ debug_assert!(e >= 0);
+ debug_assert!(e <= 3528);
+ ((e as u32 * 1217359) >> 19) as i32
+}
+
+// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn pow5bits(e: i32) -> i32 /* or u32 -> u32 */ {
+ // This approximation works up to the point that the multiplication
+ // overflows at e = 3529. If the multiplication were done in 64 bits, it
+ // would fail at 5^4004 which is just greater than 2^9297.
+ debug_assert!(e >= 0);
+ debug_assert!(e <= 3528);
+ (((e as u32 * 1217359) >> 19) + 1) as i32
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+#[allow(dead_code)]
+pub fn ceil_log2_pow5(e: i32) -> i32 /* or u32 -> u32 */ {
+ log2_pow5(e) + 1
+}
+
+// Returns floor(log_10(2^e)); requires 0 <= e <= 1650.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn log10_pow2(e: i32) -> u32 /* or u32 -> u32 */ {
+ // The first value this approximation fails for is 2^1651 which is just greater than 10^297.
+ debug_assert!(e >= 0);
+ debug_assert!(e <= 1650);
+ (e as u32 * 78913) >> 18
+}
+
+// Returns floor(log_10(5^e)); requires 0 <= e <= 2620.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn log10_pow5(e: i32) -> u32 /* or u32 -> u32 */ {
+ // The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
+ debug_assert!(e >= 0);
+ debug_assert!(e <= 2620);
+ (e as u32 * 732923) >> 20
+}
diff --git a/src/d2s.rs b/src/d2s.rs
new file mode 100644
index 0000000..862fd5f
--- /dev/null
+++ b/src/d2s.rs
@@ -0,0 +1,344 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use crate::common::*;
+#[cfg(not(feature = "small"))]
+pub use crate::d2s_full_table::*;
+use crate::d2s_intrinsics::*;
+#[cfg(feature = "small")]
+pub use crate::d2s_small_table::*;
+#[cfg(not(maybe_uninit))]
+use core::mem;
+#[cfg(maybe_uninit)]
+use core::mem::MaybeUninit;
+
+pub const DOUBLE_MANTISSA_BITS: u32 = 52;
+pub const DOUBLE_EXPONENT_BITS: u32 = 11;
+pub const DOUBLE_BIAS: i32 = 1023;
+pub const DOUBLE_POW5_INV_BITCOUNT: i32 = 125;
+pub const DOUBLE_POW5_BITCOUNT: i32 = 125;
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn decimal_length17(v: u64) -> u32 {
+ // This is slightly faster than a loop.
+ // The average output length is 16.38 digits, so we check high-to-low.
+ // Function precondition: v is not an 18, 19, or 20-digit number.
+ // (17 digits are sufficient for round-tripping.)
+ debug_assert!(v < 100000000000000000);
+
+ if v >= 10000000000000000 {
+ 17
+ } else if v >= 1000000000000000 {
+ 16
+ } else if v >= 100000000000000 {
+ 15
+ } else if v >= 10000000000000 {
+ 14
+ } else if v >= 1000000000000 {
+ 13
+ } else if v >= 100000000000 {
+ 12
+ } else if v >= 10000000000 {
+ 11
+ } else if v >= 1000000000 {
+ 10
+ } else if v >= 100000000 {
+ 9
+ } else if v >= 10000000 {
+ 8
+ } else if v >= 1000000 {
+ 7
+ } else if v >= 100000 {
+ 6
+ } else if v >= 10000 {
+ 5
+ } else if v >= 1000 {
+ 4
+ } else if v >= 100 {
+ 3
+ } else if v >= 10 {
+ 2
+ } else {
+ 1
+ }
+}
+
+// A floating decimal representing m * 10^e.
+pub struct FloatingDecimal64 {
+ pub mantissa: u64,
+ // Decimal exponent's range is -324 to 308
+ // inclusive, and can fit in i16 if needed.
+ pub exponent: i32,
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn d2d(ieee_mantissa: u64, ieee_exponent: u32) -> FloatingDecimal64 {
+ let (e2, m2) = if ieee_exponent == 0 {
+ (
+ // We subtract 2 so that the bounds computation has 2 additional bits.
+ 1 - DOUBLE_BIAS - DOUBLE_MANTISSA_BITS as i32 - 2,
+ ieee_mantissa,
+ )
+ } else {
+ (
+ ieee_exponent as i32 - DOUBLE_BIAS - DOUBLE_MANTISSA_BITS as i32 - 2,
+ (1u64 << DOUBLE_MANTISSA_BITS) | ieee_mantissa,
+ )
+ };
+ let even = (m2 & 1) == 0;
+ let accept_bounds = even;
+
+ // Step 2: Determine the interval of valid decimal representations.
+ let mv = 4 * m2;
+ // Implicit bool -> int conversion. True is 1, false is 0.
+ let mm_shift = (ieee_mantissa != 0 || ieee_exponent <= 1) as u32;
+ // We would compute mp and mm like this:
+ // uint64_t mp = 4 * m2 + 2;
+ // uint64_t mm = mv - 1 - mm_shift;
+
+ // Step 3: Convert to a decimal power base using 128-bit arithmetic.
+ let mut vr: u64;
+ let mut vp: u64;
+ let mut vm: u64;
+ #[cfg(not(maybe_uninit))]
+ {
+ vp = unsafe { mem::uninitialized() };
+ vm = unsafe { mem::uninitialized() };
+ }
+ #[cfg(maybe_uninit)]
+ let mut vp_uninit: MaybeUninit<u64> = MaybeUninit::uninit();
+ #[cfg(maybe_uninit)]
+ let mut vm_uninit: MaybeUninit<u64> = MaybeUninit::uninit();
+ let e10: i32;
+ let mut vm_is_trailing_zeros = false;
+ let mut vr_is_trailing_zeros = false;
+ if e2 >= 0 {
+ // I tried special-casing q == 0, but there was no effect on performance.
+ // This expression is slightly faster than max(0, log10_pow2(e2) - 1).
+ let q = log10_pow2(e2) - (e2 > 3) as u32;
+ e10 = q as i32;
+ let k = DOUBLE_POW5_INV_BITCOUNT + pow5bits(q as i32) - 1;
+ let i = -e2 + q as i32 + k;
+ vr = unsafe {
+ mul_shift_all_64(
+ m2,
+ #[cfg(feature = "small")]
+ &compute_inv_pow5(q),
+ #[cfg(not(feature = "small"))]
+ {
+ debug_assert!(q < DOUBLE_POW5_INV_SPLIT.len() as u32);
+ DOUBLE_POW5_INV_SPLIT.get_unchecked(q as usize)
+ },
+ i as u32,
+ #[cfg(maybe_uninit)]
+ {
+ vp_uninit.as_mut_ptr()
+ },
+ #[cfg(not(maybe_uninit))]
+ {
+ &mut vp
+ },
+ #[cfg(maybe_uninit)]
+ {
+ vm_uninit.as_mut_ptr()
+ },
+ #[cfg(not(maybe_uninit))]
+ {
+ &mut vm
+ },
+ mm_shift,
+ )
+ };
+ #[cfg(maybe_uninit)]
+ {
+ vp = unsafe { vp_uninit.assume_init() };
+ vm = unsafe { vm_uninit.assume_init() };
+ }
+ if q <= 21 {
+ // This should use q <= 22, but I think 21 is also safe. Smaller values
+ // may still be safe, but it's more difficult to reason about them.
+ // Only one of mp, mv, and mm can be a multiple of 5, if any.
+ let mv_mod5 = (mv as u32).wrapping_sub(5u32.wrapping_mul(div5(mv) as u32));
+ if mv_mod5 == 0 {
+ vr_is_trailing_zeros = multiple_of_power_of_5(mv, q);
+ } else if accept_bounds {
+ // Same as min(e2 + (~mm & 1), pow5_factor(mm)) >= q
+ // <=> e2 + (~mm & 1) >= q && pow5_factor(mm) >= q
+ // <=> true && pow5_factor(mm) >= q, since e2 >= q.
+ vm_is_trailing_zeros = multiple_of_power_of_5(mv - 1 - mm_shift as u64, q);
+ } else {
+ // Same as min(e2 + 1, pow5_factor(mp)) >= q.
+ vp -= multiple_of_power_of_5(mv + 2, q) as u64;
+ }
+ }
+ } else {
+ // This expression is slightly faster than max(0, log10_pow5(-e2) - 1).
+ let q = log10_pow5(-e2) - (-e2 > 1) as u32;
+ e10 = q as i32 + e2;
+ let i = -e2 - q as i32;
+ let k = pow5bits(i) - DOUBLE_POW5_BITCOUNT;
+ let j = q as i32 - k;
+ vr = unsafe {
+ mul_shift_all_64(
+ m2,
+ #[cfg(feature = "small")]
+ &compute_pow5(i as u32),
+ #[cfg(not(feature = "small"))]
+ {
+ debug_assert!(i < DOUBLE_POW5_SPLIT.len() as i32);
+ DOUBLE_POW5_SPLIT.get_unchecked(i as usize)
+ },
+ j as u32,
+ #[cfg(maybe_uninit)]
+ {
+ vp_uninit.as_mut_ptr()
+ },
+ #[cfg(not(maybe_uninit))]
+ {
+ &mut vp
+ },
+ #[cfg(maybe_uninit)]
+ {
+ vm_uninit.as_mut_ptr()
+ },
+ #[cfg(not(maybe_uninit))]
+ {
+ &mut vm
+ },
+ mm_shift,
+ )
+ };
+ #[cfg(maybe_uninit)]
+ {
+ vp = unsafe { vp_uninit.assume_init() };
+ vm = unsafe { vm_uninit.assume_init() };
+ }
+ if q <= 1 {
+ // {vr,vp,vm} is trailing zeros if {mv,mp,mm} has at least q trailing 0 bits.
+ // mv = 4 * m2, so it always has at least two trailing 0 bits.
+ vr_is_trailing_zeros = true;
+ if accept_bounds {
+ // mm = mv - 1 - mm_shift, so it has 1 trailing 0 bit iff mm_shift == 1.
+ vm_is_trailing_zeros = mm_shift == 1;
+ } else {
+ // mp = mv + 2, so it always has at least one trailing 0 bit.
+ vp -= 1;
+ }
+ } else if q < 63 {
+ // TODO(ulfjack): Use a tighter bound here.
+ // We want to know if the full product has at least q trailing zeros.
+ // We need to compute min(p2(mv), p5(mv) - e2) >= q
+ // <=> p2(mv) >= q && p5(mv) - e2 >= q
+ // <=> p2(mv) >= q (because -e2 >= q)
+ vr_is_trailing_zeros = multiple_of_power_of_2(mv, q);
+ }
+ }
+
+ // Step 4: Find the shortest decimal representation in the interval of valid representations.
+ let mut removed = 0i32;
+ let mut last_removed_digit = 0u8;
+ // On average, we remove ~2 digits.
+ let output = if vm_is_trailing_zeros || vr_is_trailing_zeros {
+ // General case, which happens rarely (~0.7%).
+ loop {
+ let vp_div10 = div10(vp);
+ let vm_div10 = div10(vm);
+ if vp_div10 <= vm_div10 {
+ break;
+ }
+ let vm_mod10 = (vm as u32).wrapping_sub(10u32.wrapping_mul(vm_div10 as u32));
+ let vr_div10 = div10(vr);
+ let vr_mod10 = (vr as u32).wrapping_sub(10u32.wrapping_mul(vr_div10 as u32));
+ vm_is_trailing_zeros &= vm_mod10 == 0;
+ vr_is_trailing_zeros &= last_removed_digit == 0;
+ last_removed_digit = vr_mod10 as u8;
+ vr = vr_div10;
+ vp = vp_div10;
+ vm = vm_div10;
+ removed += 1;
+ }
+ if vm_is_trailing_zeros {
+ loop {
+ let vm_div10 = div10(vm);
+ let vm_mod10 = (vm as u32).wrapping_sub(10u32.wrapping_mul(vm_div10 as u32));
+ if vm_mod10 != 0 {
+ break;
+ }
+ let vp_div10 = div10(vp);
+ let vr_div10 = div10(vr);
+ let vr_mod10 = (vr as u32).wrapping_sub(10u32.wrapping_mul(vr_div10 as u32));
+ vr_is_trailing_zeros &= last_removed_digit == 0;
+ last_removed_digit = vr_mod10 as u8;
+ vr = vr_div10;
+ vp = vp_div10;
+ vm = vm_div10;
+ removed += 1;
+ }
+ }
+ if vr_is_trailing_zeros && last_removed_digit == 5 && vr % 2 == 0 {
+ // Round even if the exact number is .....50..0.
+ last_removed_digit = 4;
+ }
+ // We need to take vr + 1 if vr is outside bounds or we need to round up.
+ vr + ((vr == vm && (!accept_bounds || !vm_is_trailing_zeros)) || last_removed_digit >= 5)
+ as u64
+ } else {
+ // Specialized for the common case (~99.3%). Percentages below are relative to this.
+ let mut round_up = false;
+ let vp_div100 = div100(vp);
+ let vm_div100 = div100(vm);
+ // Optimization: remove two digits at a time (~86.2%).
+ if vp_div100 > vm_div100 {
+ let vr_div100 = div100(vr);
+ let vr_mod100 = (vr as u32).wrapping_sub(100u32.wrapping_mul(vr_div100 as u32));
+ round_up = vr_mod100 >= 50;
+ vr = vr_div100;
+ vp = vp_div100;
+ vm = vm_div100;
+ removed += 2;
+ }
+ // Loop iterations below (approximately), without optimization above:
+ // 0: 0.03%, 1: 13.8%, 2: 70.6%, 3: 14.0%, 4: 1.40%, 5: 0.14%, 6+: 0.02%
+ // Loop iterations below (approximately), with optimization above:
+ // 0: 70.6%, 1: 27.8%, 2: 1.40%, 3: 0.14%, 4+: 0.02%
+ loop {
+ let vp_div10 = div10(vp);
+ let vm_div10 = div10(vm);
+ if vp_div10 <= vm_div10 {
+ break;
+ }
+ let vr_div10 = div10(vr);
+ let vr_mod10 = (vr as u32).wrapping_sub(10u32.wrapping_mul(vr_div10 as u32));
+ round_up = vr_mod10 >= 5;
+ vr = vr_div10;
+ vp = vp_div10;
+ vm = vm_div10;
+ removed += 1;
+ }
+ // We need to take vr + 1 if vr is outside bounds or we need to round up.
+ vr + (vr == vm || round_up) as u64
+ };
+ let exp = e10 + removed;
+
+ FloatingDecimal64 {
+ exponent: exp,
+ mantissa: output,
+ }
+}
diff --git a/src/d2s_full_table.rs b/src/d2s_full_table.rs
new file mode 100644
index 0000000..7534ddd
--- /dev/null
+++ b/src/d2s_full_table.rs
@@ -0,0 +1,696 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+const DOUBLE_POW5_INV_TABLE_SIZE: usize = 342;
+const DOUBLE_POW5_TABLE_SIZE: usize = 326;
+
+pub static DOUBLE_POW5_INV_SPLIT: [(u64, u64); DOUBLE_POW5_INV_TABLE_SIZE] = [
+ (1, 2305843009213693952),
+ (11068046444225730970, 1844674407370955161),
+ (5165088340638674453, 1475739525896764129),
+ (7821419487252849886, 1180591620717411303),
+ (8824922364862649494, 1888946593147858085),
+ (7059937891890119595, 1511157274518286468),
+ (13026647942995916322, 1208925819614629174),
+ (9774590264567735146, 1934281311383406679),
+ (11509021026396098440, 1547425049106725343),
+ (16585914450600699399, 1237940039285380274),
+ (15469416676735388068, 1980704062856608439),
+ (16064882156130220778, 1584563250285286751),
+ (9162556910162266299, 1267650600228229401),
+ (7281393426775805432, 2028240960365167042),
+ (16893161185646375315, 1622592768292133633),
+ (2446482504291369283, 1298074214633706907),
+ (7603720821608101175, 2076918743413931051),
+ (2393627842544570617, 1661534994731144841),
+ (16672297533003297786, 1329227995784915872),
+ (11918280793837635165, 2126764793255865396),
+ (5845275820328197809, 1701411834604692317),
+ (15744267100488289217, 1361129467683753853),
+ (3054734472329800808, 2177807148294006166),
+ (17201182836831481939, 1742245718635204932),
+ (6382248639981364905, 1393796574908163946),
+ (2832900194486363201, 2230074519853062314),
+ (5955668970331000884, 1784059615882449851),
+ (1075186361522890384, 1427247692705959881),
+ (12788344622662355584, 2283596308329535809),
+ (13920024512871794791, 1826877046663628647),
+ (3757321980813615186, 1461501637330902918),
+ (10384555214134712795, 1169201309864722334),
+ (5547241898389809503, 1870722095783555735),
+ (4437793518711847602, 1496577676626844588),
+ (10928932444453298728, 1197262141301475670),
+ (17486291911125277965, 1915619426082361072),
+ (6610335899416401726, 1532495540865888858),
+ (12666966349016942027, 1225996432692711086),
+ (12888448528943286597, 1961594292308337738),
+ (17689456452638449924, 1569275433846670190),
+ (14151565162110759939, 1255420347077336152),
+ (7885109000409574610, 2008672555323737844),
+ (9997436015069570011, 1606938044258990275),
+ (7997948812055656009, 1285550435407192220),
+ (12796718099289049614, 2056880696651507552),
+ (2858676849947419045, 1645504557321206042),
+ (13354987924183666206, 1316403645856964833),
+ (17678631863951955605, 2106245833371143733),
+ (3074859046935833515, 1684996666696914987),
+ (13527933681774397782, 1347997333357531989),
+ (10576647446613305481, 2156795733372051183),
+ (15840015586774465031, 1725436586697640946),
+ (8982663654677661702, 1380349269358112757),
+ (18061610662226169046, 2208558830972980411),
+ (10759939715039024913, 1766847064778384329),
+ (12297300586773130254, 1413477651822707463),
+ (15986332124095098083, 2261564242916331941),
+ (9099716884534168143, 1809251394333065553),
+ (14658471137111155161, 1447401115466452442),
+ (4348079280205103483, 1157920892373161954),
+ (14335624477811986218, 1852673427797059126),
+ (7779150767507678651, 1482138742237647301),
+ (2533971799264232598, 1185710993790117841),
+ (15122401323048503126, 1897137590064188545),
+ (12097921058438802501, 1517710072051350836),
+ (5988988032009131678, 1214168057641080669),
+ (16961078480698431330, 1942668892225729070),
+ (13568862784558745064, 1554135113780583256),
+ (7165741412905085728, 1243308091024466605),
+ (11465186260648137165, 1989292945639146568),
+ (16550846638002330379, 1591434356511317254),
+ (16930026125143774626, 1273147485209053803),
+ (4951948911778577463, 2037035976334486086),
+ (272210314680951647, 1629628781067588869),
+ (3907117066486671641, 1303703024854071095),
+ (6251387306378674625, 2085924839766513752),
+ (16069156289328670670, 1668739871813211001),
+ (9165976216721026213, 1334991897450568801),
+ (7286864317269821294, 2135987035920910082),
+ (16897537898041588005, 1708789628736728065),
+ (13518030318433270404, 1367031702989382452),
+ (6871453250525591353, 2187250724783011924),
+ (9186511415162383406, 1749800579826409539),
+ (11038557946871817048, 1399840463861127631),
+ (10282995085511086630, 2239744742177804210),
+ (8226396068408869304, 1791795793742243368),
+ (13959814484210916090, 1433436634993794694),
+ (11267656730511734774, 2293498615990071511),
+ (5324776569667477496, 1834798892792057209),
+ (7949170070475892320, 1467839114233645767),
+ (17427382500606444826, 1174271291386916613),
+ (5747719112518849781, 1878834066219066582),
+ (15666221734240810795, 1503067252975253265),
+ (12532977387392648636, 1202453802380202612),
+ (5295368560860596524, 1923926083808324180),
+ (4236294848688477220, 1539140867046659344),
+ (7078384693692692099, 1231312693637327475),
+ (11325415509908307358, 1970100309819723960),
+ (9060332407926645887, 1576080247855779168),
+ (14626963555825137356, 1260864198284623334),
+ (12335095245094488799, 2017382717255397335),
+ (9868076196075591040, 1613906173804317868),
+ (15273158586344293478, 1291124939043454294),
+ (13369007293925138595, 2065799902469526871),
+ (7005857020398200553, 1652639921975621497),
+ (16672732060544291412, 1322111937580497197),
+ (11918976037903224966, 2115379100128795516),
+ (5845832015580669650, 1692303280103036413),
+ (12055363241948356366, 1353842624082429130),
+ (841837113407818570, 2166148198531886609),
+ (4362818505468165179, 1732918558825509287),
+ (14558301248600263113, 1386334847060407429),
+ (12225235553534690011, 2218135755296651887),
+ (2401490813343931363, 1774508604237321510),
+ (1921192650675145090, 1419606883389857208),
+ (17831303500047873437, 2271371013423771532),
+ (6886345170554478103, 1817096810739017226),
+ (1819727321701672159, 1453677448591213781),
+ (16213177116328979020, 1162941958872971024),
+ (14873036941900635463, 1860707134196753639),
+ (15587778368262418694, 1488565707357402911),
+ (8780873879868024632, 1190852565885922329),
+ (2981351763563108441, 1905364105417475727),
+ (13453127855076217722, 1524291284333980581),
+ (7073153469319063855, 1219433027467184465),
+ (11317045550910502167, 1951092843947495144),
+ (12742985255470312057, 1560874275157996115),
+ (10194388204376249646, 1248699420126396892),
+ (1553625868034358140, 1997919072202235028),
+ (8621598323911307159, 1598335257761788022),
+ (17965325103354776697, 1278668206209430417),
+ (13987124906400001422, 2045869129935088668),
+ (121653480894270168, 1636695303948070935),
+ (97322784715416134, 1309356243158456748),
+ (14913111714512307107, 2094969989053530796),
+ (8241140556867935363, 1675975991242824637),
+ (17660958889720079260, 1340780792994259709),
+ (17189487779326395846, 2145249268790815535),
+ (13751590223461116677, 1716199415032652428),
+ (18379969808252713988, 1372959532026121942),
+ (14650556434236701088, 2196735251241795108),
+ (652398703163629901, 1757388200993436087),
+ (11589965406756634890, 1405910560794748869),
+ (7475898206584884855, 2249456897271598191),
+ (2291369750525997561, 1799565517817278553),
+ (9211793429904618695, 1439652414253822842),
+ (18428218302589300235, 2303443862806116547),
+ (7363877012587619542, 1842755090244893238),
+ (13269799239553916280, 1474204072195914590),
+ (10615839391643133024, 1179363257756731672),
+ (2227947767661371545, 1886981212410770676),
+ (16539753473096738529, 1509584969928616540),
+ (13231802778477390823, 1207667975942893232),
+ (6413489186596184024, 1932268761508629172),
+ (16198837793502678189, 1545815009206903337),
+ (5580372605318321905, 1236652007365522670),
+ (8928596168509315048, 1978643211784836272),
+ (18210923379033183008, 1582914569427869017),
+ (7190041073742725760, 1266331655542295214),
+ (436019273762630246, 2026130648867672343),
+ (7727513048493924843, 1620904519094137874),
+ (9871359253537050198, 1296723615275310299),
+ (4726128361433549347, 2074757784440496479),
+ (7470251503888749801, 1659806227552397183),
+ (13354898832594820487, 1327844982041917746),
+ (13989140502667892133, 2124551971267068394),
+ (14880661216876224029, 1699641577013654715),
+ (11904528973500979224, 1359713261610923772),
+ (4289851098633925465, 2175541218577478036),
+ (18189276137874781665, 1740432974861982428),
+ (3483374466074094362, 1392346379889585943),
+ (1884050330976640656, 2227754207823337509),
+ (5196589079523222848, 1782203366258670007),
+ (15225317707844309248, 1425762693006936005),
+ (5913764258841343181, 2281220308811097609),
+ (8420360221814984868, 1824976247048878087),
+ (17804334621677718864, 1459980997639102469),
+ (17932816512084085415, 1167984798111281975),
+ (10245762345624985047, 1868775676978051161),
+ (4507261061758077715, 1495020541582440929),
+ (7295157664148372495, 1196016433265952743),
+ (7982903447895485668, 1913626293225524389),
+ (10075671573058298858, 1530901034580419511),
+ (4371188443704728763, 1224720827664335609),
+ (14372599139411386667, 1959553324262936974),
+ (15187428126271019657, 1567642659410349579),
+ (15839291315758726049, 1254114127528279663),
+ (3206773216762499739, 2006582604045247462),
+ (13633465017635730761, 1605266083236197969),
+ (14596120828850494932, 1284212866588958375),
+ (4907049252451240275, 2054740586542333401),
+ (236290587219081897, 1643792469233866721),
+ (14946427728742906810, 1315033975387093376),
+ (16535586736504830250, 2104054360619349402),
+ (5849771759720043554, 1683243488495479522),
+ (15747863852001765813, 1346594790796383617),
+ (10439186904235184007, 2154551665274213788),
+ (15730047152871967852, 1723641332219371030),
+ (12584037722297574282, 1378913065775496824),
+ (9066413911450387881, 2206260905240794919),
+ (10942479943902220628, 1765008724192635935),
+ (8753983955121776503, 1412006979354108748),
+ (10317025513452932081, 2259211166966573997),
+ (874922781278525018, 1807368933573259198),
+ (8078635854506640661, 1445895146858607358),
+ (13841606313089133175, 1156716117486885886),
+ (14767872471458792434, 1850745787979017418),
+ (746251532941302978, 1480596630383213935),
+ (597001226353042382, 1184477304306571148),
+ (15712597221132509104, 1895163686890513836),
+ (8880728962164096960, 1516130949512411069),
+ (10793931984473187891, 1212904759609928855),
+ (17270291175157100626, 1940647615375886168),
+ (2748186495899949531, 1552518092300708935),
+ (2198549196719959625, 1242014473840567148),
+ (18275073973719576693, 1987223158144907436),
+ (10930710364233751031, 1589778526515925949),
+ (12433917106128911148, 1271822821212740759),
+ (8826220925580526867, 2034916513940385215),
+ (7060976740464421494, 1627933211152308172),
+ (16716827836597268165, 1302346568921846537),
+ (11989529279587987770, 2083754510274954460),
+ (9591623423670390216, 1667003608219963568),
+ (15051996368420132820, 1333602886575970854),
+ (13015147745246481542, 2133764618521553367),
+ (3033420566713364587, 1707011694817242694),
+ (6116085268112601993, 1365609355853794155),
+ (9785736428980163188, 2184974969366070648),
+ (15207286772667951197, 1747979975492856518),
+ (1097782973908629988, 1398383980394285215),
+ (1756452758253807981, 2237414368630856344),
+ (5094511021344956708, 1789931494904685075),
+ (4075608817075965366, 1431945195923748060),
+ (6520974107321544586, 2291112313477996896),
+ (1527430471115325346, 1832889850782397517),
+ (12289990821117991246, 1466311880625918013),
+ (17210690286378213644, 1173049504500734410),
+ (9090360384495590213, 1876879207201175057),
+ (18340334751822203140, 1501503365760940045),
+ (14672267801457762512, 1201202692608752036),
+ (16096930852848599373, 1921924308174003258),
+ (1809498238053148529, 1537539446539202607),
+ (12515645034668249793, 1230031557231362085),
+ (1578287981759648052, 1968050491570179337),
+ (12330676829633449412, 1574440393256143469),
+ (13553890278448669853, 1259552314604914775),
+ (3239480371808320148, 2015283703367863641),
+ (17348979556414297411, 1612226962694290912),
+ (6500486015647617283, 1289781570155432730),
+ (10400777625036187652, 2063650512248692368),
+ (15699319729512770768, 1650920409798953894),
+ (16248804598352126938, 1320736327839163115),
+ (7551343283653851484, 2113178124542660985),
+ (6041074626923081187, 1690542499634128788),
+ (12211557331022285596, 1352433999707303030),
+ (1091747655926105338, 2163894399531684849),
+ (4562746939482794594, 1731115519625347879),
+ (7339546366328145998, 1384892415700278303),
+ (8053925371383123274, 2215827865120445285),
+ (6443140297106498619, 1772662292096356228),
+ (12533209867169019542, 1418129833677084982),
+ (5295740528502789974, 2269007733883335972),
+ (15304638867027962949, 1815206187106668777),
+ (4865013464138549713, 1452164949685335022),
+ (14960057215536570740, 1161731959748268017),
+ (9178696285890871890, 1858771135597228828),
+ (14721654658196518159, 1487016908477783062),
+ (4398626097073393881, 1189613526782226450),
+ (7037801755317430209, 1903381642851562320),
+ (5630241404253944167, 1522705314281249856),
+ (814844308661245011, 1218164251424999885),
+ (1303750893857992017, 1949062802279999816),
+ (15800395974054034906, 1559250241823999852),
+ (5261619149759407279, 1247400193459199882),
+ (12107939454356961969, 1995840309534719811),
+ (5997002748743659252, 1596672247627775849),
+ (8486951013736837725, 1277337798102220679),
+ (2511075177753209390, 2043740476963553087),
+ (13076906586428298482, 1634992381570842469),
+ (14150874083884549109, 1307993905256673975),
+ (4194654460505726958, 2092790248410678361),
+ (18113118827372222859, 1674232198728542688),
+ (3422448617672047318, 1339385758982834151),
+ (16543964232501006678, 2143017214372534641),
+ (9545822571258895019, 1714413771498027713),
+ (15015355686490936662, 1371531017198422170),
+ (5577825024675947042, 2194449627517475473),
+ (11840957649224578280, 1755559702013980378),
+ (16851463748863483271, 1404447761611184302),
+ (12204946739213931940, 2247116418577894884),
+ (13453306206113055875, 1797693134862315907),
+ (3383947335406624054, 1438154507889852726),
+ (16482362180876329456, 2301047212623764361),
+ (9496540929959153242, 1840837770099011489),
+ (11286581558709232917, 1472670216079209191),
+ (5339916432225476010, 1178136172863367353),
+ (4854517476818851293, 1885017876581387765),
+ (3883613981455081034, 1508014301265110212),
+ (14174937629389795797, 1206411441012088169),
+ (11611853762797942306, 1930258305619341071),
+ (5600134195496443521, 1544206644495472857),
+ (15548153800622885787, 1235365315596378285),
+ (6430302007287065643, 1976584504954205257),
+ (16212288050055383484, 1581267603963364205),
+ (12969830440044306787, 1265014083170691364),
+ (9683682259845159889, 2024022533073106183),
+ (15125643437359948558, 1619218026458484946),
+ (8411165935146048523, 1295374421166787957),
+ (17147214310975587960, 2072599073866860731),
+ (10028422634038560045, 1658079259093488585),
+ (8022738107230848036, 1326463407274790868),
+ (9147032156827446534, 2122341451639665389),
+ (11006974540203867551, 1697873161311732311),
+ (5116230817421183718, 1358298529049385849),
+ (15564666937357714594, 2173277646479017358),
+ (1383687105660440706, 1738622117183213887),
+ (12174996128754083534, 1390897693746571109),
+ (8411947361780802685, 2225436309994513775),
+ (6729557889424642148, 1780349047995611020),
+ (5383646311539713719, 1424279238396488816),
+ (1235136468979721303, 2278846781434382106),
+ (15745504434151418335, 1823077425147505684),
+ (16285752362063044992, 1458461940118004547),
+ (5649904260166615347, 1166769552094403638),
+ (5350498001524674232, 1866831283351045821),
+ (591049586477829062, 1493465026680836657),
+ (11540886113407994219, 1194772021344669325),
+ (18673707743239135, 1911635234151470921),
+ (14772334225162232601, 1529308187321176736),
+ (8128518565387875758, 1223446549856941389),
+ (1937583260394870242, 1957514479771106223),
+ (8928764237799716840, 1566011583816884978),
+ (14521709019723594119, 1252809267053507982),
+ (8477339172590109297, 2004494827285612772),
+ (17849917782297818407, 1603595861828490217),
+ (6901236596354434079, 1282876689462792174),
+ (18420676183650915173, 2052602703140467478),
+ (3668494502695001169, 1642082162512373983),
+ (10313493231639821582, 1313665730009899186),
+ (9122891541139893884, 2101865168015838698),
+ (14677010862395735754, 1681492134412670958),
+ (673562245690857633, 1345193707530136767),
+];
+
+pub static DOUBLE_POW5_SPLIT: [(u64, u64); DOUBLE_POW5_TABLE_SIZE] = [
+ (0, 1152921504606846976),
+ (0, 1441151880758558720),
+ (0, 1801439850948198400),
+ (0, 2251799813685248000),
+ (0, 1407374883553280000),
+ (0, 1759218604441600000),
+ (0, 2199023255552000000),
+ (0, 1374389534720000000),
+ (0, 1717986918400000000),
+ (0, 2147483648000000000),
+ (0, 1342177280000000000),
+ (0, 1677721600000000000),
+ (0, 2097152000000000000),
+ (0, 1310720000000000000),
+ (0, 1638400000000000000),
+ (0, 2048000000000000000),
+ (0, 1280000000000000000),
+ (0, 1600000000000000000),
+ (0, 2000000000000000000),
+ (0, 1250000000000000000),
+ (0, 1562500000000000000),
+ (0, 1953125000000000000),
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diff --git a/src/d2s_intrinsics.rs b/src/d2s_intrinsics.rs
new file mode 100644
index 0000000..918ccab
--- /dev/null
+++ b/src/d2s_intrinsics.rs
@@ -0,0 +1,171 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use core::ptr;
+
+// Returns (lo, hi).
+#[cfg(not(integer128))]
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn umul128(a: u64, b: u64) -> (u64, u64) {
+ let a_lo = a as u32;
+ let a_hi = (a >> 32) as u32;
+ let b_lo = b as u32;
+ let b_hi = (b >> 32) as u32;
+
+ let b00 = a_lo as u64 * b_lo as u64;
+ let b01 = a_lo as u64 * b_hi as u64;
+ let b10 = a_hi as u64 * b_lo as u64;
+ let b11 = a_hi as u64 * b_hi as u64;
+
+ let b00_lo = b00 as u32;
+ let b00_hi = (b00 >> 32) as u32;
+
+ let mid1 = b10 + b00_hi as u64;
+ let mid1_lo = mid1 as u32;
+ let mid1_hi = (mid1 >> 32) as u32;
+
+ let mid2 = b01 + mid1_lo as u64;
+ let mid2_lo = mid2 as u32;
+ let mid2_hi = (mid2 >> 32) as u32;
+
+ let p_hi = b11 + mid1_hi as u64 + mid2_hi as u64;
+ let p_lo = ((mid2_lo as u64) << 32) | b00_lo as u64;
+
+ (p_lo, p_hi)
+}
+
+#[cfg(not(integer128))]
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn shiftright128(lo: u64, hi: u64, dist: u32) -> u64 {
+ // We don't need to handle the case dist >= 64 here (see above).
+ debug_assert!(dist > 0);
+ debug_assert!(dist < 64);
+ (hi << (64 - dist)) | (lo >> dist)
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn div5(x: u64) -> u64 {
+ x / 5
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn div10(x: u64) -> u64 {
+ x / 10
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn div100(x: u64) -> u64 {
+ x / 100
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+fn pow5_factor(mut value: u64) -> u32 {
+ let mut count = 0u32;
+ loop {
+ debug_assert!(value != 0);
+ let q = div5(value);
+ let r = (value as u32).wrapping_sub(5u32.wrapping_mul(q as u32));
+ if r != 0 {
+ break;
+ }
+ value = q;
+ count += 1;
+ }
+ count
+}
+
+// Returns true if value is divisible by 5^p.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn multiple_of_power_of_5(value: u64, p: u32) -> bool {
+ // I tried a case distinction on p, but there was no performance difference.
+ pow5_factor(value) >= p
+}
+
+// Returns true if value is divisible by 2^p.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn multiple_of_power_of_2(value: u64, p: u32) -> bool {
+ debug_assert!(value != 0);
+ debug_assert!(p < 64);
+ // __builtin_ctzll doesn't appear to be faster here.
+ (value & ((1u64 << p) - 1)) == 0
+}
+
+#[cfg(integer128)]
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn mul_shift_64(m: u64, mul: &(u64, u64), j: u32) -> u64 {
+ let b0 = m as u128 * mul.0 as u128;
+ let b2 = m as u128 * mul.1 as u128;
+ (((b0 >> 64) + b2) >> (j - 64)) as u64
+}
+
+#[cfg(integer128)]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn mul_shift_all_64(
+ m: u64,
+ mul: &(u64, u64),
+ j: u32,
+ vp: *mut u64,
+ vm: *mut u64,
+ mm_shift: u32,
+) -> u64 {
+ ptr::write(vp, mul_shift_64(4 * m + 2, mul, j));
+ ptr::write(vm, mul_shift_64(4 * m - 1 - mm_shift as u64, mul, j));
+ mul_shift_64(4 * m, mul, j)
+}
+
+#[cfg(not(integer128))]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn mul_shift_all_64(
+ mut m: u64,
+ mul: &(u64, u64),
+ j: u32,
+ vp: *mut u64,
+ vm: *mut u64,
+ mm_shift: u32,
+) -> u64 {
+ m <<= 1;
+ // m is maximum 55 bits
+ let (lo, tmp) = umul128(m, mul.0);
+ let (mut mid, mut hi) = umul128(m, mul.1);
+ mid = mid.wrapping_add(tmp);
+ hi = hi.wrapping_add((mid < tmp) as u64); // overflow into hi
+
+ let lo2 = lo.wrapping_add(mul.0);
+ let mid2 = mid.wrapping_add(mul.1).wrapping_add((lo2 < lo) as u64);
+ let hi2 = hi.wrapping_add((mid2 < mid) as u64);
+ ptr::write(vp, shiftright128(mid2, hi2, j - 64 - 1));
+
+ if mm_shift == 1 {
+ let lo3 = lo.wrapping_sub(mul.0);
+ let mid3 = mid.wrapping_sub(mul.1).wrapping_sub((lo3 > lo) as u64);
+ let hi3 = hi.wrapping_sub((mid3 > mid) as u64);
+ ptr::write(vm, shiftright128(mid3, hi3, j - 64 - 1));
+ } else {
+ let lo3 = lo + lo;
+ let mid3 = mid.wrapping_add(mid).wrapping_add((lo3 < lo) as u64);
+ let hi3 = hi.wrapping_add(hi).wrapping_add((mid3 < mid) as u64);
+ let lo4 = lo3.wrapping_sub(mul.0);
+ let mid4 = mid3.wrapping_sub(mul.1).wrapping_sub((lo4 > lo3) as u64);
+ let hi4 = hi3.wrapping_sub((mid4 > mid3) as u64);
+ ptr::write(vm, shiftright128(mid4, hi4, j - 64));
+ }
+
+ shiftright128(mid, hi, j - 64 - 1)
+}
diff --git a/src/d2s_small_table.rs b/src/d2s_small_table.rs
new file mode 100644
index 0000000..08519a2
--- /dev/null
+++ b/src/d2s_small_table.rs
@@ -0,0 +1,205 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use crate::common::*;
+#[cfg(not(integer128))]
+use crate::d2s_intrinsics::*;
+
+pub static DOUBLE_POW5_INV_SPLIT2: [(u64, u64); 13] = [
+ (1, 2305843009213693952),
+ (5955668970331000884, 1784059615882449851),
+ (8982663654677661702, 1380349269358112757),
+ (7286864317269821294, 2135987035920910082),
+ (7005857020398200553, 1652639921975621497),
+ (17965325103354776697, 1278668206209430417),
+ (8928596168509315048, 1978643211784836272),
+ (10075671573058298858, 1530901034580419511),
+ (597001226353042382, 1184477304306571148),
+ (1527430471115325346, 1832889850782397517),
+ (12533209867169019542, 1418129833677084982),
+ (5577825024675947042, 2194449627517475473),
+ (11006974540203867551, 1697873161311732311),
+];
+
+pub static POW5_INV_OFFSETS: [u32; 19] = [
+ 0x54544554, 0x04055545, 0x10041000, 0x00400414, 0x40010000, 0x41155555, 0x00000454, 0x00010044,
+ 0x40000000, 0x44000041, 0x50454450, 0x55550054, 0x51655554, 0x40004000, 0x01000001, 0x00010500,
+ 0x51515411, 0x05555554, 0x00000000,
+];
+
+pub static DOUBLE_POW5_SPLIT2: [(u64, u64); 13] = [
+ (0, 1152921504606846976),
+ (0, 1490116119384765625),
+ (1032610780636961552, 1925929944387235853),
+ (7910200175544436838, 1244603055572228341),
+ (16941905809032713930, 1608611746708759036),
+ (13024893955298202172, 2079081953128979843),
+ (6607496772837067824, 1343575221513417750),
+ (17332926989895652603, 1736530273035216783),
+ (13037379183483547984, 2244412773384604712),
+ (1605989338741628675, 1450417759929778918),
+ (9630225068416591280, 1874621017369538693),
+ (665883850346957067, 1211445438634777304),
+ (14931890668723713708, 1565756531257009982),
+];
+
+pub static POW5_OFFSETS: [u32; 21] = [
+ 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x40000000, 0x59695995, 0x55545555, 0x56555515,
+ 0x41150504, 0x40555410, 0x44555145, 0x44504540, 0x45555550, 0x40004000, 0x96440440, 0x55565565,
+ 0x54454045, 0x40154151, 0x55559155, 0x51405555, 0x00000105,
+];
+
+pub static DOUBLE_POW5_TABLE: [u64; 26] = [
+ 1,
+ 5,
+ 25,
+ 125,
+ 625,
+ 3125,
+ 15625,
+ 78125,
+ 390625,
+ 1953125,
+ 9765625,
+ 48828125,
+ 244140625,
+ 1220703125,
+ 6103515625,
+ 30517578125,
+ 152587890625,
+ 762939453125,
+ 3814697265625,
+ 19073486328125,
+ 95367431640625,
+ 476837158203125,
+ 2384185791015625,
+ 11920928955078125,
+ 59604644775390625,
+ 298023223876953125,
+];
+
+// Computes 5^i in the form required by Ryū.
+#[cfg(integer128)]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn compute_pow5(i: u32) -> (u64, u64) {
+ let base = i / DOUBLE_POW5_TABLE.len() as u32;
+ let base2 = base * DOUBLE_POW5_TABLE.len() as u32;
+ let offset = i - base2;
+ debug_assert!(base < DOUBLE_POW5_SPLIT2.len() as u32);
+ let mul = *DOUBLE_POW5_SPLIT2.get_unchecked(base as usize);
+ if offset == 0 {
+ return mul;
+ }
+ debug_assert!(offset < DOUBLE_POW5_TABLE.len() as u32);
+ let m = *DOUBLE_POW5_TABLE.get_unchecked(offset as usize);
+ let b0 = m as u128 * mul.0 as u128;
+ let b2 = m as u128 * mul.1 as u128;
+ let delta = pow5bits(i as i32) - pow5bits(base2 as i32);
+ debug_assert!(base < POW5_OFFSETS.len() as u32);
+ let shifted_sum = (b0 >> delta)
+ + (b2 << (64 - delta))
+ + ((*POW5_OFFSETS.get_unchecked((i / 16) as usize) >> ((i % 16) << 1)) & 3) as u128;
+ (shifted_sum as u64, (shifted_sum >> 64) as u64)
+}
+
+// Computes 5^-i in the form required by Ryū.
+#[cfg(integer128)]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn compute_inv_pow5(i: u32) -> (u64, u64) {
+ let base = (i + DOUBLE_POW5_TABLE.len() as u32 - 1) / DOUBLE_POW5_TABLE.len() as u32;
+ let base2 = base * DOUBLE_POW5_TABLE.len() as u32;
+ let offset = base2 - i;
+ debug_assert!(base < DOUBLE_POW5_INV_SPLIT2.len() as u32);
+ let mul = *DOUBLE_POW5_INV_SPLIT2.get_unchecked(base as usize); // 1/5^base2
+ if offset == 0 {
+ return mul;
+ }
+ debug_assert!(offset < DOUBLE_POW5_TABLE.len() as u32);
+ let m = *DOUBLE_POW5_TABLE.get_unchecked(offset as usize); // 5^offset
+ let b0 = m as u128 * (mul.0 - 1) as u128;
+ let b2 = m as u128 * mul.1 as u128; // 1/5^base2 * 5^offset = 1/5^(base2-offset) = 1/5^i
+ let delta = pow5bits(base2 as i32) - pow5bits(i as i32);
+ debug_assert!(base < POW5_INV_OFFSETS.len() as u32);
+ let shifted_sum = ((b0 >> delta) + (b2 << (64 - delta)))
+ + 1
+ + ((*POW5_INV_OFFSETS.get_unchecked((i / 16) as usize) >> ((i % 16) << 1)) & 3) as u128;
+ (shifted_sum as u64, (shifted_sum >> 64) as u64)
+}
+
+// Computes 5^i in the form required by Ryū, and stores it in the given pointer.
+#[cfg(not(integer128))]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn compute_pow5(i: u32) -> (u64, u64) {
+ let base = i / DOUBLE_POW5_TABLE.len() as u32;
+ let base2 = base * DOUBLE_POW5_TABLE.len() as u32;
+ let offset = i - base2;
+ debug_assert!(base < DOUBLE_POW5_SPLIT2.len() as u32);
+ let mul = *DOUBLE_POW5_SPLIT2.get_unchecked(base as usize);
+ if offset == 0 {
+ return mul;
+ }
+ debug_assert!(offset < DOUBLE_POW5_TABLE.len() as u32);
+ let m = *DOUBLE_POW5_TABLE.get_unchecked(offset as usize);
+ let (low1, mut high1) = umul128(m, mul.1);
+ let (low0, high0) = umul128(m, mul.0);
+ let sum = high0 + low1;
+ if sum < high0 {
+ high1 += 1; // overflow into high1
+ }
+ // high1 | sum | low0
+ let delta = pow5bits(i as i32) - pow5bits(base2 as i32);
+ debug_assert!(base < POW5_OFFSETS.len() as u32);
+ (
+ shiftright128(low0, sum, delta as u32)
+ + ((*POW5_OFFSETS.get_unchecked((i / 16) as usize) >> ((i % 16) << 1)) & 3) as u64,
+ shiftright128(sum, high1, delta as u32),
+ )
+}
+
+// Computes 5^-i in the form required by Ryū, and stores it in the given pointer.
+#[cfg(not(integer128))]
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn compute_inv_pow5(i: u32) -> (u64, u64) {
+ let base = (i + DOUBLE_POW5_TABLE.len() as u32 - 1) / DOUBLE_POW5_TABLE.len() as u32;
+ let base2 = base * DOUBLE_POW5_TABLE.len() as u32;
+ let offset = base2 - i;
+ debug_assert!(base < DOUBLE_POW5_INV_SPLIT2.len() as u32);
+ let mul = *DOUBLE_POW5_INV_SPLIT2.get_unchecked(base as usize); // 1/5^base2
+ if offset == 0 {
+ return mul;
+ }
+ debug_assert!(offset < DOUBLE_POW5_TABLE.len() as u32);
+ let m = *DOUBLE_POW5_TABLE.get_unchecked(offset as usize);
+ let (low1, mut high1) = umul128(m, mul.1);
+ let (low0, high0) = umul128(m, mul.0 - 1);
+ let sum = high0 + low1;
+ if sum < high0 {
+ high1 += 1; // overflow into high1
+ }
+ // high1 | sum | low0
+ let delta = pow5bits(base2 as i32) - pow5bits(i as i32);
+ debug_assert!(base < POW5_INV_OFFSETS.len() as u32);
+ (
+ shiftright128(low0, sum, delta as u32)
+ + 1
+ + ((*POW5_INV_OFFSETS.get_unchecked((i / 16) as usize) >> ((i % 16) << 1)) & 3) as u64,
+ shiftright128(sum, high1, delta as u32),
+ )
+}
diff --git a/src/digit_table.rs b/src/digit_table.rs
new file mode 100644
index 0000000..d871f03
--- /dev/null
+++ b/src/digit_table.rs
@@ -0,0 +1,28 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+// A table of all two-digit numbers. This is used to speed up decimal digit
+// generation by copying pairs of digits into the final output.
+pub static DIGIT_TABLE: [u8; 200] = *b"\
+ 0001020304050607080910111213141516171819\
+ 2021222324252627282930313233343536373839\
+ 4041424344454647484950515253545556575859\
+ 6061626364656667686970717273747576777879\
+ 8081828384858687888990919293949596979899";
diff --git a/src/f2s.rs b/src/f2s.rs
new file mode 100644
index 0000000..eeb457a
--- /dev/null
+++ b/src/f2s.rs
@@ -0,0 +1,176 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use crate::common::*;
+use crate::f2s_intrinsics::*;
+
+pub const FLOAT_MANTISSA_BITS: u32 = 23;
+pub const FLOAT_EXPONENT_BITS: u32 = 8;
+const FLOAT_BIAS: i32 = 127;
+pub use crate::f2s_intrinsics::{FLOAT_POW5_BITCOUNT, FLOAT_POW5_INV_BITCOUNT};
+
+// A floating decimal representing m * 10^e.
+pub struct FloatingDecimal32 {
+ pub mantissa: u32,
+ // Decimal exponent's range is -45 to 38
+ // inclusive, and can fit in i16 if needed.
+ pub exponent: i32,
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn f2d(ieee_mantissa: u32, ieee_exponent: u32) -> FloatingDecimal32 {
+ let (e2, m2) = if ieee_exponent == 0 {
+ (
+ // We subtract 2 so that the bounds computation has 2 additional bits.
+ 1 - FLOAT_BIAS - FLOAT_MANTISSA_BITS as i32 - 2,
+ ieee_mantissa,
+ )
+ } else {
+ (
+ ieee_exponent as i32 - FLOAT_BIAS - FLOAT_MANTISSA_BITS as i32 - 2,
+ (1u32 << FLOAT_MANTISSA_BITS) | ieee_mantissa,
+ )
+ };
+ let even = (m2 & 1) == 0;
+ let accept_bounds = even;
+
+ // Step 2: Determine the interval of valid decimal representations.
+ let mv = 4 * m2;
+ let mp = 4 * m2 + 2;
+ // Implicit bool -> int conversion. True is 1, false is 0.
+ let mm_shift = (ieee_mantissa != 0 || ieee_exponent <= 1) as u32;
+ let mm = 4 * m2 - 1 - mm_shift;
+
+ // Step 3: Convert to a decimal power base using 64-bit arithmetic.
+ let mut vr: u32;
+ let mut vp: u32;
+ let mut vm: u32;
+ let e10: i32;
+ let mut vm_is_trailing_zeros = false;
+ let mut vr_is_trailing_zeros = false;
+ let mut last_removed_digit = 0u8;
+ if e2 >= 0 {
+ let q = log10_pow2(e2);
+ e10 = q as i32;
+ let k = FLOAT_POW5_INV_BITCOUNT + pow5bits(q as i32) - 1;
+ let i = -e2 + q as i32 + k;
+ vr = mul_pow5_inv_div_pow2(mv, q, i);
+ vp = mul_pow5_inv_div_pow2(mp, q, i);
+ vm = mul_pow5_inv_div_pow2(mm, q, i);
+ if q != 0 && (vp - 1) / 10 <= vm / 10 {
+ // We need to know one removed digit even if we are not going to loop below. We could use
+ // q = X - 1 above, except that would require 33 bits for the result, and we've found that
+ // 32-bit arithmetic is faster even on 64-bit machines.
+ let l = FLOAT_POW5_INV_BITCOUNT + pow5bits(q as i32 - 1) - 1;
+ last_removed_digit =
+ (mul_pow5_inv_div_pow2(mv, q - 1, -e2 + q as i32 - 1 + l) % 10) as u8;
+ }
+ if q <= 9 {
+ // The largest power of 5 that fits in 24 bits is 5^10, but q <= 9 seems to be safe as well.
+ // Only one of mp, mv, and mm can be a multiple of 5, if any.
+ if mv % 5 == 0 {
+ vr_is_trailing_zeros = multiple_of_power_of_5_32(mv, q);
+ } else if accept_bounds {
+ vm_is_trailing_zeros = multiple_of_power_of_5_32(mm, q);
+ } else {
+ vp -= multiple_of_power_of_5_32(mp, q) as u32;
+ }
+ }
+ } else {
+ let q = log10_pow5(-e2);
+ e10 = q as i32 + e2;
+ let i = -e2 - q as i32;
+ let k = pow5bits(i) - FLOAT_POW5_BITCOUNT;
+ let mut j = q as i32 - k;
+ vr = mul_pow5_div_pow2(mv, i as u32, j);
+ vp = mul_pow5_div_pow2(mp, i as u32, j);
+ vm = mul_pow5_div_pow2(mm, i as u32, j);
+ if q != 0 && (vp - 1) / 10 <= vm / 10 {
+ j = q as i32 - 1 - (pow5bits(i + 1) - FLOAT_POW5_BITCOUNT);
+ last_removed_digit = (mul_pow5_div_pow2(mv, (i + 1) as u32, j) % 10) as u8;
+ }
+ if q <= 1 {
+ // {vr,vp,vm} is trailing zeros if {mv,mp,mm} has at least q trailing 0 bits.
+ // mv = 4 * m2, so it always has at least two trailing 0 bits.
+ vr_is_trailing_zeros = true;
+ if accept_bounds {
+ // mm = mv - 1 - mm_shift, so it has 1 trailing 0 bit iff mm_shift == 1.
+ vm_is_trailing_zeros = mm_shift == 1;
+ } else {
+ // mp = mv + 2, so it always has at least one trailing 0 bit.
+ vp -= 1;
+ }
+ } else if q < 31 {
+ // TODO(ulfjack): Use a tighter bound here.
+ vr_is_trailing_zeros = multiple_of_power_of_2_32(mv, q - 1);
+ }
+ }
+
+ // Step 4: Find the shortest decimal representation in the interval of valid representations.
+ let mut removed = 0i32;
+ let output = if vm_is_trailing_zeros || vr_is_trailing_zeros {
+ // General case, which happens rarely (~4.0%).
+ while vp / 10 > vm / 10 {
+ vm_is_trailing_zeros &= vm - (vm / 10) * 10 == 0;
+ vr_is_trailing_zeros &= last_removed_digit == 0;
+ last_removed_digit = (vr % 10) as u8;
+ vr /= 10;
+ vp /= 10;
+ vm /= 10;
+ removed += 1;
+ }
+ if vm_is_trailing_zeros {
+ while vm % 10 == 0 {
+ vr_is_trailing_zeros &= last_removed_digit == 0;
+ last_removed_digit = (vr % 10) as u8;
+ vr /= 10;
+ vp /= 10;
+ vm /= 10;
+ removed += 1;
+ }
+ }
+ if vr_is_trailing_zeros && last_removed_digit == 5 && vr % 2 == 0 {
+ // Round even if the exact number is .....50..0.
+ last_removed_digit = 4;
+ }
+ // We need to take vr + 1 if vr is outside bounds or we need to round up.
+ vr + ((vr == vm && (!accept_bounds || !vm_is_trailing_zeros)) || last_removed_digit >= 5)
+ as u32
+ } else {
+ // Specialized for the common case (~96.0%). Percentages below are relative to this.
+ // Loop iterations below (approximately):
+ // 0: 13.6%, 1: 70.7%, 2: 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%
+ while vp / 10 > vm / 10 {
+ last_removed_digit = (vr % 10) as u8;
+ vr /= 10;
+ vp /= 10;
+ vm /= 10;
+ removed += 1;
+ }
+ // We need to take vr + 1 if vr is outside bounds or we need to round up.
+ vr + (vr == vm || last_removed_digit >= 5) as u32
+ };
+ let exp = e10 + removed;
+
+ FloatingDecimal32 {
+ exponent: exp,
+ mantissa: output,
+ }
+}
diff --git a/src/f2s_intrinsics.rs b/src/f2s_intrinsics.rs
new file mode 100644
index 0000000..1a35218
--- /dev/null
+++ b/src/f2s_intrinsics.rs
@@ -0,0 +1,113 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+// (See accompanying file LICENSE-Apache or copy at
+// http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE-Boost or copy at
+// https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use crate::d2s;
+
+pub const FLOAT_POW5_INV_BITCOUNT: i32 = d2s::DOUBLE_POW5_INV_BITCOUNT - 64;
+pub const FLOAT_POW5_BITCOUNT: i32 = d2s::DOUBLE_POW5_BITCOUNT - 64;
+
+#[cfg_attr(feature = "no-panic", inline)]
+fn pow5factor_32(mut value: u32) -> u32 {
+ let mut count = 0u32;
+ loop {
+ debug_assert!(value != 0);
+ let q = value / 5;
+ let r = value % 5;
+ if r != 0 {
+ break;
+ }
+ value = q;
+ count += 1;
+ }
+ count
+}
+
+// Returns true if value is divisible by 5^p.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn multiple_of_power_of_5_32(value: u32, p: u32) -> bool {
+ pow5factor_32(value) >= p
+}
+
+// Returns true if value is divisible by 2^p.
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn multiple_of_power_of_2_32(value: u32, p: u32) -> bool {
+ // __builtin_ctz doesn't appear to be faster here.
+ (value & ((1u32 << p) - 1)) == 0
+}
+
+// It seems to be slightly faster to avoid uint128_t here, although the
+// generated code for uint128_t looks slightly nicer.
+#[cfg_attr(feature = "no-panic", inline)]
+fn mul_shift_32(m: u32, factor: u64, shift: i32) -> u32 {
+ debug_assert!(shift > 32);
+
+ // The casts here help MSVC to avoid calls to the __allmul library
+ // function.
+ let factor_lo = factor as u32;
+ let factor_hi = (factor >> 32) as u32;
+ let bits0 = m as u64 * factor_lo as u64;
+ let bits1 = m as u64 * factor_hi as u64;
+
+ let sum = (bits0 >> 32) + bits1;
+ let shifted_sum = sum >> (shift - 32);
+ debug_assert!(shifted_sum <= u32::max_value() as u64);
+ shifted_sum as u32
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn mul_pow5_inv_div_pow2(m: u32, q: u32, j: i32) -> u32 {
+ #[cfg(feature = "small")]
+ {
+ // The inverse multipliers are defined as [2^x / 5^y] + 1; the upper 64
+ // bits from the double lookup table are the correct bits for [2^x /
+ // 5^y], so we have to add 1 here. Note that we rely on the fact that
+ // the added 1 that's already stored in the table never overflows into
+ // the upper 64 bits.
+ let pow5 = unsafe { d2s::compute_inv_pow5(q) };
+ mul_shift_32(m, pow5.1 + 1, j)
+ }
+
+ #[cfg(not(feature = "small"))]
+ {
+ debug_assert!(q < d2s::DOUBLE_POW5_INV_SPLIT.len() as u32);
+ unsafe {
+ mul_shift_32(
+ m,
+ d2s::DOUBLE_POW5_INV_SPLIT.get_unchecked(q as usize).1 + 1,
+ j,
+ )
+ }
+ }
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn mul_pow5_div_pow2(m: u32, i: u32, j: i32) -> u32 {
+ #[cfg(feature = "small")]
+ {
+ let pow5 = unsafe { d2s::compute_pow5(i) };
+ mul_shift_32(m, pow5.1, j)
+ }
+
+ #[cfg(not(feature = "small"))]
+ {
+ debug_assert!(i < d2s::DOUBLE_POW5_SPLIT.len() as u32);
+ unsafe { mul_shift_32(m, d2s::DOUBLE_POW5_SPLIT.get_unchecked(i as usize).1, j) }
+ }
+}
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..db6ee16
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,117 @@
+//! [![github]](https://github.com/dtolnay/ryu) [![crates-io]](https://crates.io/crates/ryu) [![docs-rs]](https://docs.rs/ryu)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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
+//!
+//! <br>
+//!
+//! Pure Rust implementation of Ryū, an algorithm to quickly convert floating
+//! point numbers to decimal strings.
+//!
+//! The PLDI'18 paper [*Ryū: fast float-to-string conversion*][paper] by Ulf
+//! Adams includes a complete correctness proof of the algorithm. The paper is
+//! available under the creative commons CC-BY-SA license.
+//!
+//! This Rust implementation is a line-by-line port of Ulf Adams' implementation
+//! in C, [https://github.com/ulfjack/ryu][upstream].
+//!
+//! [paper]: https://dl.acm.org/citation.cfm?id=3192369
+//! [upstream]: https://github.com/ulfjack/ryu
+//!
+//! # Example
+//!
+//! ```
+//! fn main() {
+//! let mut buffer = ryu::Buffer::new();
+//! let printed = buffer.format(1.234);
+//! assert_eq!(printed, "1.234");
+//! }
+//! ```
+//!
+//! ## Performance
+//!
+//! You can run upstream's benchmarks with:
+//!
+//! ```console
+//! $ git clone https://github.com/ulfjack/ryu c-ryu
+//! $ cd c-ryu
+//! $ bazel run -c opt //ryu/benchmark
+//! ```
+//!
+//! And the same benchmark against our implementation with:
+//!
+//! ```console
+//! $ git clone https://github.com/dtolnay/ryu rust-ryu
+//! $ cd rust-ryu
+//! $ cargo run --example upstream_benchmark --release
+//! ```
+//!
+//! These benchmarks measure the average time to print a 32-bit float and average
+//! time to print a 64-bit float, where the inputs are distributed as uniform random
+//! bit patterns 32 and 64 bits wide.
+//!
+//! The upstream C code, the unsafe direct Rust port, and the safe pretty Rust API
+//! all perform the same, taking around 21 nanoseconds to format a 32-bit float and
+//! 31 nanoseconds to format a 64-bit float.
+//!
+//! There is also a Rust-specific benchmark comparing this implementation to the
+//! standard library which you can run with:
+//!
+//! ```console
+//! $ cargo bench
+//! ```
+//!
+//! The benchmark shows Ryū approximately 4-10x faster than the standard library
+//! across a range of f32 and f64 inputs. Measurements are in nanoseconds per
+//! iteration; smaller is better.
+//!
+//! | type=f32 | 0.0 | 0.1234 | 2.718281828459045 | f32::MAX |
+//! |:--------:|:----:|:------:|:-----------------:|:--------:|
+//! | RYU | 3ns | 28ns | 23ns | 22ns |
+//! | STD | 40ns | 106ns | 128ns | 110ns |
+//!
+//! | type=f64 | 0.0 | 0.1234 | 2.718281828459045 | f64::MAX |
+//! |:--------:|:----:|:------:|:-----------------:|:--------:|
+//! | RYU | 3ns | 50ns | 35ns | 32ns |
+//! | STD | 39ns | 105ns | 128ns | 202ns |
+//!
+//! ## Formatting
+//!
+//! This library tends to produce more human-readable output than the standard
+//! library's to\_string, which never uses scientific notation. Here are two
+//! examples:
+//!
+//! - *ryu:* 1.23e40, *std:* 12300000000000000000000000000000000000000
+//! - *ryu:* 1.23e-40, *std:* 0.000000000000000000000000000000000000000123
+//!
+//! Both libraries print short decimals such as 0.0000123 without scientific
+//! notation.
+
+#![no_std]
+#![doc(html_root_url = "https://docs.rs/ryu/1.0.5")]
+#![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
+#![cfg_attr(
+ feature = "cargo-clippy",
+ allow(cast_lossless, many_single_char_names, unreadable_literal,)
+)]
+
+mod buffer;
+mod common;
+mod d2s;
+#[cfg(not(feature = "small"))]
+mod d2s_full_table;
+mod d2s_intrinsics;
+#[cfg(feature = "small")]
+mod d2s_small_table;
+mod digit_table;
+mod f2s;
+mod f2s_intrinsics;
+mod pretty;
+
+pub use crate::buffer::{Buffer, Float};
+
+/// Unsafe functions that mirror the API of the C implementation of Ryū.
+pub mod raw {
+ pub use crate::pretty::{format32, format64};
+}
diff --git a/src/parse.rs b/src/parse.rs
new file mode 100644
index 0000000..00f7983
--- /dev/null
+++ b/src/parse.rs
@@ -0,0 +1,19 @@
+use core::fmt::{self, Display};
+
+#[derive(Copy, Clone, Debug)]
+pub enum Error {
+ InputTooShort,
+ InputTooLong,
+ MalformedInput,
+}
+
+impl Display for Error {
+ fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+ let msg = match self {
+ Error::InputTooShort => "input too short",
+ Error::InputTooLong => "input too long",
+ Error::MalformedInput => "malformed input",
+ };
+ formatter.write_str(msg)
+ }
+}
diff --git a/src/pretty/exponent.rs b/src/pretty/exponent.rs
new file mode 100644
index 0000000..84053d5
--- /dev/null
+++ b/src/pretty/exponent.rs
@@ -0,0 +1,48 @@
+use crate::digit_table::*;
+use core::ptr;
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn write_exponent3(mut k: isize, mut result: *mut u8) -> usize {
+ let sign = k < 0;
+ if sign {
+ *result = b'-';
+ result = result.offset(1);
+ k = -k;
+ }
+
+ debug_assert!(k < 1000);
+ if k >= 100 {
+ *result = b'0' + (k / 100) as u8;
+ k %= 100;
+ let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
+ ptr::copy_nonoverlapping(d, result.offset(1), 2);
+ sign as usize + 3
+ } else if k >= 10 {
+ let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
+ ptr::copy_nonoverlapping(d, result, 2);
+ sign as usize + 2
+ } else {
+ *result = b'0' + k as u8;
+ sign as usize + 1
+ }
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn write_exponent2(mut k: isize, mut result: *mut u8) -> usize {
+ let sign = k < 0;
+ if sign {
+ *result = b'-';
+ result = result.offset(1);
+ k = -k;
+ }
+
+ debug_assert!(k < 100);
+ if k >= 10 {
+ let d = DIGIT_TABLE.get_unchecked(k as usize * 2);
+ ptr::copy_nonoverlapping(d, result, 2);
+ sign as usize + 2
+ } else {
+ *result = b'0' + k as u8;
+ sign as usize + 1
+ }
+}
diff --git a/src/pretty/mantissa.rs b/src/pretty/mantissa.rs
new file mode 100644
index 0000000..e5fc202
--- /dev/null
+++ b/src/pretty/mantissa.rs
@@ -0,0 +1,50 @@
+use crate::digit_table::*;
+use core::ptr;
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn write_mantissa_long(mut output: u64, mut result: *mut u8) {
+ if (output >> 32) != 0 {
+ // One expensive 64-bit division.
+ let mut output2 = (output - 100_000_000 * (output / 100_000_000)) as u32;
+ output /= 100_000_000;
+
+ let c = output2 % 10_000;
+ output2 /= 10_000;
+ let d = output2 % 10_000;
+ let c0 = (c % 100) << 1;
+ let c1 = (c / 100) << 1;
+ let d0 = (d % 100) << 1;
+ let d1 = (d / 100) << 1;
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c0 as usize), result.offset(-2), 2);
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c1 as usize), result.offset(-4), 2);
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(d0 as usize), result.offset(-6), 2);
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(d1 as usize), result.offset(-8), 2);
+ result = result.offset(-8);
+ }
+ write_mantissa(output as u32, result);
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub unsafe fn write_mantissa(mut output: u32, mut result: *mut u8) {
+ while output >= 10_000 {
+ let c = (output - 10_000 * (output / 10_000)) as u32;
+ output /= 10_000;
+ let c0 = (c % 100) << 1;
+ let c1 = (c / 100) << 1;
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c0 as usize), result.offset(-2), 2);
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c1 as usize), result.offset(-4), 2);
+ result = result.offset(-4);
+ }
+ if output >= 100 {
+ let c = ((output % 100) << 1) as u32;
+ output /= 100;
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c as usize), result.offset(-2), 2);
+ result = result.offset(-2);
+ }
+ if output >= 10 {
+ let c = (output << 1) as u32;
+ ptr::copy_nonoverlapping(DIGIT_TABLE.get_unchecked(c as usize), result.offset(-2), 2);
+ } else {
+ *result.offset(-1) = b'0' + output as u8;
+ }
+}
diff --git a/src/pretty/mod.rs b/src/pretty/mod.rs
new file mode 100644
index 0000000..a82692d
--- /dev/null
+++ b/src/pretty/mod.rs
@@ -0,0 +1,225 @@
+mod exponent;
+mod mantissa;
+
+use self::exponent::*;
+use self::mantissa::*;
+use crate::common;
+use crate::d2s::{self, *};
+use crate::f2s::*;
+use core::{mem, ptr};
+#[cfg(feature = "no-panic")]
+use no_panic::no_panic;
+
+/// Print f64 to the given buffer and return number of bytes written.
+///
+/// At most 24 bytes will be written.
+///
+/// ## Special cases
+///
+/// This function **does not** check for NaN or infinity. If the input
+/// number is not a finite float, the printed representation will be some
+/// correctly formatted but unspecified numerical value.
+///
+/// Please check [`is_finite`] yourself before calling this function, or
+/// check [`is_nan`] and [`is_infinite`] and handle those cases yourself.
+///
+/// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite
+/// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan
+/// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_infinite
+///
+/// ## Safety
+///
+/// The `result` pointer argument must point to sufficiently many writable bytes
+/// to hold Ryū's representation of `f`.
+///
+/// ## Example
+///
+/// ```
+/// use std::{mem::MaybeUninit, slice, str};
+///
+/// let f = 1.234f64;
+///
+/// unsafe {
+/// let mut buffer = [MaybeUninit::<u8>::uninit(); 24];
+/// let len = ryu::raw::format64(f, buffer.as_mut_ptr() as *mut u8);
+/// let slice = slice::from_raw_parts(buffer.as_ptr() as *const u8, len);
+/// let print = str::from_utf8_unchecked(slice);
+/// assert_eq!(print, "1.234");
+/// }
+/// ```
+#[must_use]
+#[cfg_attr(feature = "no-panic", no_panic)]
+pub unsafe fn format64(f: f64, result: *mut u8) -> usize {
+ let bits = mem::transmute::<f64, u64>(f);
+ let sign = ((bits >> (DOUBLE_MANTISSA_BITS + DOUBLE_EXPONENT_BITS)) & 1) != 0;
+ let ieee_mantissa = bits & ((1u64 << DOUBLE_MANTISSA_BITS) - 1);
+ let ieee_exponent =
+ (bits >> DOUBLE_MANTISSA_BITS) as u32 & ((1u32 << DOUBLE_EXPONENT_BITS) - 1);
+
+ let mut index = 0isize;
+ if sign {
+ *result = b'-';
+ index += 1;
+ }
+
+ if ieee_exponent == 0 && ieee_mantissa == 0 {
+ ptr::copy_nonoverlapping(b"0.0".as_ptr(), result.offset(index), 3);
+ return sign as usize + 3;
+ }
+
+ let v = d2d(ieee_mantissa, ieee_exponent);
+
+ let length = d2s::decimal_length17(v.mantissa) as isize;
+ let k = v.exponent as isize;
+ let kk = length + k; // 10^(kk-1) <= v < 10^kk
+ debug_assert!(k >= -324);
+
+ if 0 <= k && kk <= 16 {
+ // 1234e7 -> 12340000000.0
+ write_mantissa_long(v.mantissa, result.offset(index + length));
+ for i in length..kk {
+ *result.offset(index + i) = b'0';
+ }
+ *result.offset(index + kk) = b'.';
+ *result.offset(index + kk + 1) = b'0';
+ index as usize + kk as usize + 2
+ } else if 0 < kk && kk <= 16 {
+ // 1234e-2 -> 12.34
+ write_mantissa_long(v.mantissa, result.offset(index + length + 1));
+ ptr::copy(result.offset(index + 1), result.offset(index), kk as usize);
+ *result.offset(index + kk) = b'.';
+ index as usize + length as usize + 1
+ } else if -5 < kk && kk <= 0 {
+ // 1234e-6 -> 0.001234
+ *result.offset(index) = b'0';
+ *result.offset(index + 1) = b'.';
+ let offset = 2 - kk;
+ for i in 2..offset {
+ *result.offset(index + i) = b'0';
+ }
+ write_mantissa_long(v.mantissa, result.offset(index + length + offset));
+ index as usize + length as usize + offset as usize
+ } else if length == 1 {
+ // 1e30
+ *result.offset(index) = b'0' + v.mantissa as u8;
+ *result.offset(index + 1) = b'e';
+ index as usize + 2 + write_exponent3(kk - 1, result.offset(index + 2))
+ } else {
+ // 1234e30 -> 1.234e33
+ write_mantissa_long(v.mantissa, result.offset(index + length + 1));
+ *result.offset(index) = *result.offset(index + 1);
+ *result.offset(index + 1) = b'.';
+ *result.offset(index + length + 1) = b'e';
+ index as usize
+ + length as usize
+ + 2
+ + write_exponent3(kk - 1, result.offset(index + length + 2))
+ }
+}
+
+/// Print f32 to the given buffer and return number of bytes written.
+///
+/// At most 16 bytes will be written.
+///
+/// ## Special cases
+///
+/// This function **does not** check for NaN or infinity. If the input
+/// number is not a finite float, the printed representation will be some
+/// correctly formatted but unspecified numerical value.
+///
+/// Please check [`is_finite`] yourself before calling this function, or
+/// check [`is_nan`] and [`is_infinite`] and handle those cases yourself.
+///
+/// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_finite
+/// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_nan
+/// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_infinite
+///
+/// ## Safety
+///
+/// The `result` pointer argument must point to sufficiently many writable bytes
+/// to hold Ryū's representation of `f`.
+///
+/// ## Example
+///
+/// ```
+/// use std::{mem::MaybeUninit, slice, str};
+///
+/// let f = 1.234f32;
+///
+/// unsafe {
+/// let mut buffer = [MaybeUninit::<u8>::uninit(); 16];
+/// let len = ryu::raw::format32(f, buffer.as_mut_ptr() as *mut u8);
+/// let slice = slice::from_raw_parts(buffer.as_ptr() as *const u8, len);
+/// let print = str::from_utf8_unchecked(slice);
+/// assert_eq!(print, "1.234");
+/// }
+/// ```
+#[must_use]
+#[cfg_attr(feature = "no-panic", no_panic)]
+pub unsafe fn format32(f: f32, result: *mut u8) -> usize {
+ let bits = mem::transmute::<f32, u32>(f);
+ let sign = ((bits >> (FLOAT_MANTISSA_BITS + FLOAT_EXPONENT_BITS)) & 1) != 0;
+ let ieee_mantissa = bits & ((1u32 << FLOAT_MANTISSA_BITS) - 1);
+ let ieee_exponent =
+ ((bits >> FLOAT_MANTISSA_BITS) & ((1u32 << FLOAT_EXPONENT_BITS) - 1)) as u32;
+
+ let mut index = 0isize;
+ if sign {
+ *result = b'-';
+ index += 1;
+ }
+
+ if ieee_exponent == 0 && ieee_mantissa == 0 {
+ ptr::copy_nonoverlapping(b"0.0".as_ptr(), result.offset(index), 3);
+ return sign as usize + 3;
+ }
+
+ let v = f2d(ieee_mantissa, ieee_exponent);
+
+ let length = common::decimal_length9(v.mantissa) as isize;
+ let k = v.exponent as isize;
+ let kk = length + k; // 10^(kk-1) <= v < 10^kk
+ debug_assert!(k >= -45);
+
+ if 0 <= k && kk <= 13 {
+ // 1234e7 -> 12340000000.0
+ write_mantissa(v.mantissa, result.offset(index + length));
+ for i in length..kk {
+ *result.offset(index + i) = b'0';
+ }
+ *result.offset(index + kk) = b'.';
+ *result.offset(index + kk + 1) = b'0';
+ index as usize + kk as usize + 2
+ } else if 0 < kk && kk <= 13 {
+ // 1234e-2 -> 12.34
+ write_mantissa(v.mantissa, result.offset(index + length + 1));
+ ptr::copy(result.offset(index + 1), result.offset(index), kk as usize);
+ *result.offset(index + kk) = b'.';
+ index as usize + length as usize + 1
+ } else if -6 < kk && kk <= 0 {
+ // 1234e-6 -> 0.001234
+ *result.offset(index) = b'0';
+ *result.offset(index + 1) = b'.';
+ let offset = 2 - kk;
+ for i in 2..offset {
+ *result.offset(index + i) = b'0';
+ }
+ write_mantissa(v.mantissa, result.offset(index + length + offset));
+ index as usize + length as usize + offset as usize
+ } else if length == 1 {
+ // 1e30
+ *result.offset(index) = b'0' + v.mantissa as u8;
+ *result.offset(index + 1) = b'e';
+ index as usize + 2 + write_exponent2(kk - 1, result.offset(index + 2))
+ } else {
+ // 1234e30 -> 1.234e33
+ write_mantissa(v.mantissa, result.offset(index + length + 1));
+ *result.offset(index) = *result.offset(index + 1);
+ *result.offset(index + 1) = b'.';
+ *result.offset(index + length + 1) = b'e';
+ index as usize
+ + length as usize
+ + 2
+ + write_exponent2(kk - 1, result.offset(index + length + 2))
+ }
+}
diff --git a/src/s2d.rs b/src/s2d.rs
new file mode 100644
index 0000000..3d3808d
--- /dev/null
+++ b/src/s2d.rs
@@ -0,0 +1,216 @@
+use crate::common::*;
+use crate::d2s;
+use crate::d2s_intrinsics::*;
+use crate::parse::Error;
+#[cfg(feature = "no-panic")]
+use no_panic::no_panic;
+
+const DOUBLE_EXPONENT_BIAS: usize = 1023;
+
+fn floor_log2(value: u64) -> u32 {
+ 63_u32.wrapping_sub(value.leading_zeros())
+}
+
+#[cfg_attr(feature = "no-panic", no_panic)]
+pub fn s2d(buffer: &[u8]) -> Result<f64, Error> {
+ let len = buffer.len();
+ if len == 0 {
+ return Err(Error::InputTooShort);
+ }
+
+ let mut m10digits = 0;
+ let mut e10digits = 0;
+ let mut dot_index = len;
+ let mut e_index = len;
+ let mut m10 = 0u64;
+ let mut e10 = 0i32;
+ let mut signed_m = false;
+ let mut signed_e = false;
+
+ let mut i = 0;
+ if unsafe { *buffer.get_unchecked(0) } == b'-' {
+ signed_m = true;
+ i += 1;
+ }
+
+ while let Some(c) = buffer.get(i).copied() {
+ if c == b'.' {
+ if dot_index != len {
+ return Err(Error::MalformedInput);
+ }
+ dot_index = i;
+ i += 1;
+ continue;
+ }
+ if c < b'0' || c > b'9' {
+ break;
+ }
+ if m10digits >= 17 {
+ return Err(Error::InputTooLong);
+ }
+ m10 = 10 * m10 + (c - b'0') as u64;
+ if m10 != 0 {
+ m10digits += 1;
+ }
+ i += 1;
+ }
+
+ if let Some(b'e') | Some(b'E') = buffer.get(i) {
+ e_index = i;
+ i += 1;
+ match buffer.get(i) {
+ Some(b'-') => {
+ signed_e = true;
+ i += 1;
+ }
+ Some(b'+') => i += 1,
+ _ => {}
+ }
+ while let Some(c) = buffer.get(i).copied() {
+ if c < b'0' || c > b'9' {
+ return Err(Error::MalformedInput);
+ }
+ if e10digits > 3 {
+ // TODO: Be more lenient. Return +/-Infinity or +/-0 instead.
+ return Err(Error::InputTooLong);
+ }
+ e10 = 10 * e10 + (c - b'0') as i32;
+ if e10 != 0 {
+ e10digits += 1;
+ }
+ i += 1;
+ }
+ }
+
+ if i < len {
+ return Err(Error::MalformedInput);
+ }
+ if signed_e {
+ e10 = -e10;
+ }
+ e10 -= if dot_index < e_index {
+ (e_index - dot_index - 1) as i32
+ } else {
+ 0
+ };
+ if m10 == 0 {
+ return Ok(if signed_m { -0.0 } else { 0.0 });
+ }
+
+ if m10digits + e10 <= -324 || m10 == 0 {
+ // Number is less than 1e-324, which should be rounded down to 0; return
+ // +/-0.0.
+ let ieee = (signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS);
+ return Ok(f64::from_bits(ieee));
+ }
+ if m10digits + e10 >= 310 {
+ // Number is larger than 1e+309, which should be rounded to +/-Infinity.
+ let ieee = ((signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS))
+ | (0x7ff_u64 << d2s::DOUBLE_MANTISSA_BITS);
+ return Ok(f64::from_bits(ieee));
+ }
+
+ // Convert to binary float m2 * 2^e2, while retaining information about
+ // whether the conversion was exact (trailing_zeros).
+ let e2: i32;
+ let m2: u64;
+ let mut trailing_zeros: bool;
+ if e10 >= 0 {
+ // The length of m * 10^e in bits is:
+ // log2(m10 * 10^e10) = log2(m10) + e10 log2(10) = log2(m10) + e10 + e10 * log2(5)
+ //
+ // We want to compute the DOUBLE_MANTISSA_BITS + 1 top-most bits (+1 for
+ // the implicit leading one in IEEE format). We therefore choose a
+ // binary output exponent of
+ // log2(m10 * 10^e10) - (DOUBLE_MANTISSA_BITS + 1).
+ //
+ // We use floor(log2(5^e10)) so that we get at least this many bits;
+ // better to have an additional bit than to not have enough bits.
+ e2 = floor_log2(m10)
+ .wrapping_add(e10 as u32)
+ .wrapping_add(log2_pow5(e10) as u32)
+ .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS + 1) as i32;
+
+ // We now compute [m10 * 10^e10 / 2^e2] = [m10 * 5^e10 / 2^(e2-e10)].
+ // To that end, we use the DOUBLE_POW5_SPLIT table.
+ let j = e2
+ .wrapping_sub(e10)
+ .wrapping_sub(ceil_log2_pow5(e10))
+ .wrapping_add(d2s::DOUBLE_POW5_BITCOUNT);
+ debug_assert!(j >= 0);
+ debug_assert!(e10 < d2s::DOUBLE_POW5_SPLIT.len() as i32);
+ m2 = mul_shift_64(
+ m10,
+ unsafe { d2s::DOUBLE_POW5_SPLIT.get_unchecked(e10 as usize) },
+ j as u32,
+ );
+
+ // We also compute if the result is exact, i.e.,
+ // [m10 * 10^e10 / 2^e2] == m10 * 10^e10 / 2^e2.
+ // This can only be the case if 2^e2 divides m10 * 10^e10, which in turn
+ // requires that the largest power of 2 that divides m10 + e10 is
+ // greater than e2. If e2 is less than e10, then the result must be
+ // exact. Otherwise we use the existing multiple_of_power_of_2 function.
+ trailing_zeros =
+ e2 < e10 || e2 - e10 < 64 && multiple_of_power_of_2(m10, (e2 - e10) as u32);
+ } else {
+ e2 = floor_log2(m10)
+ .wrapping_add(e10 as u32)
+ .wrapping_sub(ceil_log2_pow5(-e10) as u32)
+ .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS + 1) as i32;
+ let j = e2
+ .wrapping_sub(e10)
+ .wrapping_add(ceil_log2_pow5(-e10))
+ .wrapping_sub(1)
+ .wrapping_add(d2s::DOUBLE_POW5_INV_BITCOUNT);
+ debug_assert!(-e10 < d2s::DOUBLE_POW5_INV_SPLIT.len() as i32);
+ m2 = mul_shift_64(
+ m10,
+ unsafe { d2s::DOUBLE_POW5_INV_SPLIT.get_unchecked(-e10 as usize) },
+ j as u32,
+ );
+ trailing_zeros = multiple_of_power_of_5(m10, -e10 as u32);
+ }
+
+ // Compute the final IEEE exponent.
+ let mut ieee_e2 = i32::max(0, e2 + DOUBLE_EXPONENT_BIAS as i32 + floor_log2(m2) as i32) as u32;
+
+ if ieee_e2 > 0x7fe {
+ // Final IEEE exponent is larger than the maximum representable; return +/-Infinity.
+ let ieee = ((signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS))
+ | (0x7ff_u64 << d2s::DOUBLE_MANTISSA_BITS);
+ return Ok(f64::from_bits(ieee));
+ }
+
+ // We need to figure out how much we need to shift m2. The tricky part is
+ // that we need to take the final IEEE exponent into account, so we need to
+ // reverse the bias and also special-case the value 0.
+ let shift = if ieee_e2 == 0 { 1 } else { ieee_e2 as i32 }
+ .wrapping_sub(e2)
+ .wrapping_sub(DOUBLE_EXPONENT_BIAS as i32)
+ .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS as i32);
+ debug_assert!(shift >= 0);
+
+ // We need to round up if the exact value is more than 0.5 above the value
+ // we computed. That's equivalent to checking if the last removed bit was 1
+ // and either the value was not just trailing zeros or the result would
+ // otherwise be odd.
+ //
+ // We need to update trailing_zeros given that we have the exact output
+ // exponent ieee_e2 now.
+ trailing_zeros &= (m2 & ((1_u64 << (shift - 1)) - 1)) == 0;
+ let last_removed_bit = (m2 >> (shift - 1)) & 1;
+ let round_up = last_removed_bit != 0 && (!trailing_zeros || ((m2 >> shift) & 1) != 0);
+
+ let mut ieee_m2 = (m2 >> shift).wrapping_add(round_up as u64);
+ if ieee_m2 == (1_u64 << (d2s::DOUBLE_MANTISSA_BITS + 1)) {
+ // Due to how the IEEE represents +/-Infinity, we don't need to check
+ // for overflow here.
+ ieee_e2 += 1;
+ }
+ ieee_m2 &= (1_u64 << d2s::DOUBLE_MANTISSA_BITS) - 1;
+ let ieee = ((((signed_m as u64) << d2s::DOUBLE_EXPONENT_BITS) | ieee_e2 as u64)
+ << d2s::DOUBLE_MANTISSA_BITS)
+ | ieee_m2;
+ Ok(f64::from_bits(ieee))
+}
diff --git a/src/s2f.rs b/src/s2f.rs
new file mode 100644
index 0000000..d9e0744
--- /dev/null
+++ b/src/s2f.rs
@@ -0,0 +1,207 @@
+use crate::common::*;
+use crate::f2s;
+use crate::f2s_intrinsics::*;
+use crate::parse::Error;
+#[cfg(feature = "no-panic")]
+use no_panic::no_panic;
+
+const FLOAT_EXPONENT_BIAS: usize = 127;
+
+fn floor_log2(value: u32) -> u32 {
+ 31_u32.wrapping_sub(value.leading_zeros())
+}
+
+#[cfg_attr(feature = "no-panic", no_panic)]
+pub fn s2f(buffer: &[u8]) -> Result<f32, Error> {
+ let len = buffer.len();
+ if len == 0 {
+ return Err(Error::InputTooShort);
+ }
+
+ let mut m10digits = 0;
+ let mut e10digits = 0;
+ let mut dot_index = len;
+ let mut e_index = len;
+ let mut m10 = 0u32;
+ let mut e10 = 0i32;
+ let mut signed_m = false;
+ let mut signed_e = false;
+
+ let mut i = 0;
+ if unsafe { *buffer.get_unchecked(0) } == b'-' {
+ signed_m = true;
+ i += 1;
+ }
+
+ while let Some(c) = buffer.get(i).copied() {
+ if c == b'.' {
+ if dot_index != len {
+ return Err(Error::MalformedInput);
+ }
+ dot_index = i;
+ i += 1;
+ continue;
+ }
+ if c < b'0' || c > b'9' {
+ break;
+ }
+ if m10digits >= 9 {
+ return Err(Error::InputTooLong);
+ }
+ m10 = 10 * m10 + (c - b'0') as u32;
+ if m10 != 0 {
+ m10digits += 1;
+ }
+ i += 1;
+ }
+
+ if let Some(b'e') | Some(b'E') = buffer.get(i) {
+ e_index = i;
+ i += 1;
+ match buffer.get(i) {
+ Some(b'-') => {
+ signed_e = true;
+ i += 1;
+ }
+ Some(b'+') => i += 1,
+ _ => {}
+ }
+ while let Some(c) = buffer.get(i).copied() {
+ if c < b'0' || c > b'9' {
+ return Err(Error::MalformedInput);
+ }
+ if e10digits > 3 {
+ // TODO: Be more lenient. Return +/-Infinity or +/-0 instead.
+ return Err(Error::InputTooLong);
+ }
+ e10 = 10 * e10 + (c - b'0') as i32;
+ if e10 != 0 {
+ e10digits += 1;
+ }
+ i += 1;
+ }
+ }
+
+ if i < len {
+ return Err(Error::MalformedInput);
+ }
+ if signed_e {
+ e10 = -e10;
+ }
+ e10 -= if dot_index < e_index {
+ (e_index - dot_index - 1) as i32
+ } else {
+ 0
+ };
+ if m10 == 0 {
+ return Ok(if signed_m { -0.0 } else { 0.0 });
+ }
+
+ if m10digits + e10 <= -46 || m10 == 0 {
+ // Number is less than 1e-46, which should be rounded down to 0; return
+ // +/-0.0.
+ let ieee = (signed_m as u32) << (f2s::FLOAT_EXPONENT_BITS + f2s::FLOAT_MANTISSA_BITS);
+ return Ok(f32::from_bits(ieee));
+ }
+ if m10digits + e10 >= 40 {
+ // Number is larger than 1e+39, which should be rounded to +/-Infinity.
+ let ieee = ((signed_m as u32) << (f2s::FLOAT_EXPONENT_BITS + f2s::FLOAT_MANTISSA_BITS))
+ | (0xff_u32 << f2s::FLOAT_MANTISSA_BITS);
+ return Ok(f32::from_bits(ieee));
+ }
+
+ // Convert to binary float m2 * 2^e2, while retaining information about
+ // whether the conversion was exact (trailing_zeros).
+ let e2: i32;
+ let m2: u32;
+ let mut trailing_zeros: bool;
+ if e10 >= 0 {
+ // The length of m * 10^e in bits is:
+ // log2(m10 * 10^e10) = log2(m10) + e10 log2(10) = log2(m10) + e10 + e10 * log2(5)
+ //
+ // We want to compute the FLOAT_MANTISSA_BITS + 1 top-most bits (+1 for
+ // the implicit leading one in IEEE format). We therefore choose a
+ // binary output exponent of
+ // log2(m10 * 10^e10) - (FLOAT_MANTISSA_BITS + 1).
+ //
+ // We use floor(log2(5^e10)) so that we get at least this many bits; better to
+ // have an additional bit than to not have enough bits.
+ e2 = floor_log2(m10)
+ .wrapping_add(e10 as u32)
+ .wrapping_add(log2_pow5(e10) as u32)
+ .wrapping_sub(f2s::FLOAT_MANTISSA_BITS + 1) as i32;
+
+ // We now compute [m10 * 10^e10 / 2^e2] = [m10 * 5^e10 / 2^(e2-e10)].
+ // To that end, we use the FLOAT_POW5_SPLIT table.
+ let j = e2
+ .wrapping_sub(e10)
+ .wrapping_sub(ceil_log2_pow5(e10))
+ .wrapping_add(f2s::FLOAT_POW5_BITCOUNT);
+ debug_assert!(j >= 0);
+ m2 = mul_pow5_div_pow2(m10, e10 as u32, j);
+
+ // We also compute if the result is exact, i.e.,
+ // [m10 * 10^e10 / 2^e2] == m10 * 10^e10 / 2^e2.
+ // This can only be the case if 2^e2 divides m10 * 10^e10, which in turn
+ // requires that the largest power of 2 that divides m10 + e10 is
+ // greater than e2. If e2 is less than e10, then the result must be
+ // exact. Otherwise we use the existing multiple_of_power_of_2 function.
+ trailing_zeros =
+ e2 < e10 || e2 - e10 < 32 && multiple_of_power_of_2_32(m10, (e2 - e10) as u32);
+ } else {
+ e2 = floor_log2(m10)
+ .wrapping_add(e10 as u32)
+ .wrapping_sub(ceil_log2_pow5(-e10) as u32)
+ .wrapping_sub(f2s::FLOAT_MANTISSA_BITS + 1) as i32;
+ let j = e2
+ .wrapping_sub(e10)
+ .wrapping_add(ceil_log2_pow5(-e10))
+ .wrapping_sub(1)
+ .wrapping_add(f2s::FLOAT_POW5_INV_BITCOUNT);
+ m2 = mul_pow5_inv_div_pow2(m10, -e10 as u32, j);
+ trailing_zeros = multiple_of_power_of_5_32(m10, -e10 as u32);
+ }
+
+ // Compute the final IEEE exponent.
+ let mut ieee_e2 = i32::max(0, e2 + FLOAT_EXPONENT_BIAS as i32 + floor_log2(m2) as i32) as u32;
+
+ if ieee_e2 > 0xfe {
+ // Final IEEE exponent is larger than the maximum representable; return
+ // +/-Infinity.
+ let ieee = ((signed_m as u32) << (f2s::FLOAT_EXPONENT_BITS + f2s::FLOAT_MANTISSA_BITS))
+ | (0xff_u32 << f2s::FLOAT_MANTISSA_BITS);
+ return Ok(f32::from_bits(ieee));
+ }
+
+ // We need to figure out how much we need to shift m2. The tricky part is
+ // that we need to take the final IEEE exponent into account, so we need to
+ // reverse the bias and also special-case the value 0.
+ let shift = if ieee_e2 == 0 { 1 } else { ieee_e2 as i32 }
+ .wrapping_sub(e2)
+ .wrapping_sub(FLOAT_EXPONENT_BIAS as i32)
+ .wrapping_sub(f2s::FLOAT_MANTISSA_BITS as i32);
+ debug_assert!(shift >= 0);
+
+ // We need to round up if the exact value is more than 0.5 above the value
+ // we computed. That's equivalent to checking if the last removed bit was 1
+ // and either the value was not just trailing zeros or the result would
+ // otherwise be odd.
+ //
+ // We need to update trailing_zeros given that we have the exact output
+ // exponent ieee_e2 now.
+ trailing_zeros &= (m2 & ((1_u32 << (shift - 1)) - 1)) == 0;
+ let last_removed_bit = (m2 >> (shift - 1)) & 1;
+ let round_up = last_removed_bit != 0 && (!trailing_zeros || ((m2 >> shift) & 1) != 0);
+
+ let mut ieee_m2 = (m2 >> shift).wrapping_add(round_up as u32);
+ if ieee_m2 == (1_u32 << (f2s::FLOAT_MANTISSA_BITS + 1)) {
+ // Due to how the IEEE represents +/-Infinity, we don't need to check
+ // for overflow here.
+ ieee_e2 += 1;
+ }
+ ieee_m2 &= (1_u32 << f2s::FLOAT_MANTISSA_BITS) - 1;
+ let ieee = ((((signed_m as u32) << f2s::FLOAT_EXPONENT_BITS) | ieee_e2 as u32)
+ << f2s::FLOAT_MANTISSA_BITS)
+ | ieee_m2;
+ Ok(f32::from_bits(ieee))
+}