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Diffstat (limited to '')
-rw-r--r-- | vendor/ryu/src/f2s_intrinsics.rs | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/vendor/ryu/src/f2s_intrinsics.rs b/vendor/ryu/src/f2s_intrinsics.rs new file mode 100644 index 000000000..1a352189c --- /dev/null +++ b/vendor/ryu/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) } + } +} |