const_ryu/
f2s_intrinsics.rs

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
21use crate::d2s;
22
23pub const FLOAT_POW5_INV_BITCOUNT: i32 = d2s::DOUBLE_POW5_INV_BITCOUNT - 64;
24pub const FLOAT_POW5_BITCOUNT: i32 = d2s::DOUBLE_POW5_BITCOUNT - 64;
25
26#[cfg_attr(feature = "no-panic", inline)]
27const fn pow5factor_32(mut value: u32) -> u32 {
28    let mut count = 0u32;
29    loop {
30        if true {
    if !(value != 0) {
        ::core::panicking::panic("assertion failed: value != 0")
    };
};debug_assert!(value != 0);
31        let q = value / 5;
32        let r = value % 5;
33        if r != 0 {
34            break;
35        }
36        value = q;
37        count += 1;
38    }
39    count
40}
41
42// Returns true if value is divisible by 5^p.
43#[cfg_attr(feature = "no-panic", inline)]
44pub const fn multiple_of_power_of_5_32(value: u32, p: u32) -> bool {
45    pow5factor_32(value) >= p
46}
47
48// Returns true if value is divisible by 2^p.
49#[cfg_attr(feature = "no-panic", inline)]
50pub const fn multiple_of_power_of_2_32(value: u32, p: u32) -> bool {
51    // __builtin_ctz doesn't appear to be faster here.
52    (value & ((1u32 << p) - 1)) == 0
53}
54
55// It seems to be slightly faster to avoid uint128_t here, although the
56// generated code for uint128_t looks slightly nicer.
57#[cfg_attr(feature = "no-panic", inline)]
58#[expect(clippy::legacy_numeric_constants)]
59const fn mul_shift_32(m: u32, factor: u64, shift: i32) -> u32 {
60    if true {
    if !(shift > 32) {
        ::core::panicking::panic("assertion failed: shift > 32")
    };
};debug_assert!(shift > 32);
61
62    // The casts here help MSVC to avoid calls to the __allmul library
63    // function.
64    let factor_lo = factor as u32;
65    let factor_hi = (factor >> 32) as u32;
66    let bits0 = m as u64 * factor_lo as u64;
67    let bits1 = m as u64 * factor_hi as u64;
68
69    let sum = (bits0 >> 32) + bits1;
70    let shifted_sum = sum >> (shift - 32);
71    if true {
    if !(shifted_sum <= u32::max_value() as u64) {
        ::core::panicking::panic("assertion failed: shifted_sum <= u32::max_value() as u64")
    };
};debug_assert!(shifted_sum <= u32::max_value() as u64);
72    shifted_sum as u32
73}
74
75#[cfg_attr(feature = "no-panic", inline)]
76pub const fn mul_pow5_inv_div_pow2(m: u32, q: u32, j: i32) -> u32 {
77    #[cfg(feature = "small")]
78    {
79        // The inverse multipliers are defined as [2^x / 5^y] + 1; the upper 64
80        // bits from the double lookup table are the correct bits for [2^x /
81        // 5^y], so we have to add 1 here. Note that we rely on the fact that
82        // the added 1 that's already stored in the table never overflows into
83        // the upper 64 bits.
84        let pow5 = unsafe { d2s::compute_inv_pow5(q) };
85        mul_shift_32(m, pow5.1 + 1, j)
86    }
87
88    #[cfg(not(feature = "small"))]
89    {
90        if true {
    if !(q < d2s::DOUBLE_POW5_INV_SPLIT.len() as u32) {
        ::core::panicking::panic("assertion failed: q < d2s::DOUBLE_POW5_INV_SPLIT.len() as u32")
    };
};debug_assert!(q < d2s::DOUBLE_POW5_INV_SPLIT.len() as u32);
91        unsafe {
92            mul_shift_32(
93                m,
94                d2s::DOUBLE_POW5_INV_SPLIT.get_unchecked(q as usize).1 + 1,
95                j,
96            )
97        }
98    }
99}
100
101#[cfg_attr(feature = "no-panic", inline)]
102pub const fn mul_pow5_div_pow2(m: u32, i: u32, j: i32) -> u32 {
103    #[cfg(feature = "small")]
104    {
105        let pow5 = unsafe { d2s::compute_pow5(i) };
106        mul_shift_32(m, pow5.1, j)
107    }
108
109    #[cfg(not(feature = "small"))]
110    {
111        if true {
    if !(i < d2s::DOUBLE_POW5_SPLIT.len() as u32) {
        ::core::panicking::panic("assertion failed: i < d2s::DOUBLE_POW5_SPLIT.len() as u32")
    };
};debug_assert!(i < d2s::DOUBLE_POW5_SPLIT.len() as u32);
112        unsafe { mul_shift_32(m, d2s::DOUBLE_POW5_SPLIT.get_unchecked(i as usize).1, j) }
113    }
114}
const_ryu/f2s_intrinsics.rs

const_ryu/
f2s_intrinsics.rs
