| // 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) } |
| } |
| } |