Vendor things

third-party/vendor/ryu/src/d2s_intrinsics.rs

@@ -0,0 +1,89 @@
+// 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 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)]
+pub(crate) fn pow5_factor(mut value: u64) -> u32 {
+    const M_INV_5: u64 = 14757395258967641293; // 5 * m_inv_5 = 1 (mod 2^64)
+    const N_DIV_5: u64 = 3689348814741910323; // #{ n | n = 0 (mod 2^64) } = 2^64 / 5
+    let mut count = 0u32;
+    loop {
+        debug_assert!(value != 0);
+        value = value.wrapping_mul(M_INV_5);
+        if value > N_DIV_5 {
+            break;
+        }
+        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)
+}