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// Translated from C to Rust. The original C code can be found at
//
// 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
//
// 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
//
// 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 core::ptr;
#[cfg_attr(feature = "no-panic", inline)]
pub fn div5(x: u64) -> u64 {
x / 5
}
#[cfg_attr(feature = "no-panic", inline)]
pub fn div10(x: u64) -> u64 {
x / 10
}
#[cfg_attr(feature = "no-panic", inline)]
pub fn div100(x: u64) -> u64 {
x / 100
}
#[cfg_attr(feature = "no-panic", inline)]
fn pow5_factor(mut value: u64) -> u32 {
let mut count = 0u32;
loop {
debug_assert!(value != 0);
let q = div5(value);
let r = (value as u32).wrapping_sub(5u32.wrapping_mul(q as u32));
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(value: u64, p: u32) -> bool {
// I tried a case distinction on p, but there was no performance difference.
pow5_factor(value) >= p
}
// Returns true if value is divisible by 2^p.
#[cfg_attr(feature = "no-panic", inline)]
pub fn multiple_of_power_of_2(value: u64, p: u32) -> bool {
debug_assert!(value != 0);
debug_assert!(p < 64);
// __builtin_ctzll doesn't appear to be faster here.
(value & ((1u64 << p) - 1)) == 0
}
#[cfg_attr(feature = "no-panic", inline)]
pub fn mul_shift_64(m: u64, mul: &(u64, u64), j: u32) -> u64 {
let b0 = m as u128 * mul.0 as u128;
let b2 = m as u128 * mul.1 as u128;
(((b0 >> 64) + b2) >> (j - 64)) as u64
}
#[cfg_attr(feature = "no-panic", inline)]
pub unsafe fn mul_shift_all_64(
m: u64,
mul: &(u64, u64),
j: u32,
vp: *mut u64,
vm: *mut u64,
mm_shift: u32,
) -> u64 {
ptr::write(vp, mul_shift_64(4 * m + 2, mul, j));
ptr::write(vm, mul_shift_64(4 * m - 1 - mm_shift as u64, mul, j));
mul_shift_64(4 * m, mul, j)
}