1 | // Translated from C to Rust. The original C code can be found at |
2 | // https://github.com/ulfjack/ryu and carries the following license: |
3 | // |
4 | // Copyright 2018 Ulf Adams |
5 | // |
6 | // The contents of this file may be used under the terms of the Apache License, |
7 | // Version 2.0. |
8 | // |
9 | // (See accompanying file LICENSE-Apache or copy at |
10 | // http://www.apache.org/licenses/LICENSE-2.0) |
11 | // |
12 | // Alternatively, the contents of this file may be used under the terms of |
13 | // the Boost Software License, Version 1.0. |
14 | // (See accompanying file LICENSE-Boost or copy at |
15 | // https://www.boost.org/LICENSE_1_0.txt) |
16 | // |
17 | // Unless required by applicable law or agreed to in writing, this software |
18 | // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
19 | // KIND, either express or implied. |
20 | |
21 | use core::ptr; |
22 | |
23 | #[cfg_attr (feature = "no-panic" , inline)] |
24 | pub fn div5(x: u64) -> u64 { |
25 | x / 5 |
26 | } |
27 | |
28 | #[cfg_attr (feature = "no-panic" , inline)] |
29 | pub fn div10(x: u64) -> u64 { |
30 | x / 10 |
31 | } |
32 | |
33 | #[cfg_attr (feature = "no-panic" , inline)] |
34 | pub fn div100(x: u64) -> u64 { |
35 | x / 100 |
36 | } |
37 | |
38 | #[cfg_attr (feature = "no-panic" , inline)] |
39 | fn pow5_factor(mut value: u64) -> u32 { |
40 | let mut count: u32 = 0u32; |
41 | loop { |
42 | debug_assert!(value != 0); |
43 | let q: u64 = div5(value); |
44 | let r: u32 = (value as u32).wrapping_sub(5u32.wrapping_mul(q as u32)); |
45 | if r != 0 { |
46 | break; |
47 | } |
48 | value = q; |
49 | count += 1; |
50 | } |
51 | count |
52 | } |
53 | |
54 | // Returns true if value is divisible by 5^p. |
55 | #[cfg_attr (feature = "no-panic" , inline)] |
56 | pub fn multiple_of_power_of_5(value: u64, p: u32) -> bool { |
57 | // I tried a case distinction on p, but there was no performance difference. |
58 | pow5_factor(value) >= p |
59 | } |
60 | |
61 | // Returns true if value is divisible by 2^p. |
62 | #[cfg_attr (feature = "no-panic" , inline)] |
63 | pub fn multiple_of_power_of_2(value: u64, p: u32) -> bool { |
64 | debug_assert!(value != 0); |
65 | debug_assert!(p < 64); |
66 | // __builtin_ctzll doesn't appear to be faster here. |
67 | (value & ((1u64 << p) - 1)) == 0 |
68 | } |
69 | |
70 | #[cfg_attr (feature = "no-panic" , inline)] |
71 | pub fn mul_shift_64(m: u64, mul: &(u64, u64), j: u32) -> u64 { |
72 | let b0: u128 = m as u128 * mul.0 as u128; |
73 | let b2: u128 = m as u128 * mul.1 as u128; |
74 | (((b0 >> 64) + b2) >> (j - 64)) as u64 |
75 | } |
76 | |
77 | #[cfg_attr (feature = "no-panic" , inline)] |
78 | pub unsafe fn mul_shift_all_64( |
79 | m: u64, |
80 | mul: &(u64, u64), |
81 | j: u32, |
82 | vp: *mut u64, |
83 | vm: *mut u64, |
84 | mm_shift: u32, |
85 | ) -> u64 { |
86 | ptr::write(dst:vp, src:mul_shift_64(m:4 * m + 2, mul, j)); |
87 | ptr::write(dst:vm, src:mul_shift_64(m:4 * m - 1 - mm_shift as u64, mul, j)); |
88 | mul_shift_64(m:4 * m, mul, j) |
89 | } |
90 | |