Import 'ryu' crate version 1.0.5
Bug: 163175424
Test: N/A
Change-Id: I7bda5411adccb26198c53ed1cb41fc6bb08468d7
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
+}