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/* MIT License
*
* Copyright (c) 2023 Brad House
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* SPDX-License-Identifier: MIT
*/
#include "ares_setup.h"
#include "ares.h"
#include "ares_private.h"
/* Uses public domain code snippets from
* http://graphics.stanford.edu/~seander/bithacks.html */
static unsigned int ares__round_up_pow2_u32(unsigned int n)
{
/* NOTE: if already a power of 2, will return itself, not the next */
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n++;
return n;
}
static ares_int64_t ares__round_up_pow2_u64(ares_int64_t n)
{
/* NOTE: if already a power of 2, will return itself, not the next */
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n |= n >> 32;
n++;
return n;
}
size_t ares__round_up_pow2(size_t n)
{
if (sizeof(size_t) > 4) {
return (size_t)ares__round_up_pow2_u64((ares_int64_t)n);
}
return (size_t)ares__round_up_pow2_u32((unsigned int)n);
}
size_t ares__log2(size_t n)
{
static const unsigned char tab32[32] = { 0, 1, 28, 2, 29, 14, 24, 3,
30, 22, 20, 15, 25, 17, 4, 8,
31, 27, 13, 23, 21, 19, 16, 7,
26, 12, 18, 6, 11, 5, 10, 9 };
static const unsigned char tab64[64] = {
63, 0, 58, 1, 59, 47, 53, 2, 60, 39, 48, 27, 54, 33, 42, 3,
61, 51, 37, 40, 49, 18, 28, 20, 55, 30, 34, 11, 43, 14, 22, 4,
62, 57, 46, 52, 38, 26, 32, 41, 50, 36, 17, 19, 29, 10, 13, 21,
56, 45, 25, 31, 35, 16, 9, 12, 44, 24, 15, 8, 23, 7, 6, 5
};
if (sizeof(size_t) == 4) {
return tab32[(n * 0x077CB531) >> 27];
}
return tab64[(n * 0x07EDD5E59A4E28C2) >> 58];
}
/* x^y */
size_t ares__pow(size_t x, size_t y)
{
size_t res = 1;
while (y > 0) {
/* If y is odd, multiply x with result */
if (y & 1) {
res = res * x;
}
/* y must be even now */
y = y >> 1; /* y /= 2; */
x = x * x; /* x^2 */
}
return res;
}
size_t ares__count_digits(size_t n)
{
size_t digits;
for (digits = 0; n > 0; digits++) {
n /= 10;
}
if (digits == 0) {
digits = 1;
}
return digits;
}
size_t ares__count_hexdigits(size_t n)
{
size_t digits;
for (digits = 0; n > 0; digits++) {
n /= 16;
}
if (digits == 0) {
digits = 1;
}
return digits;
}
unsigned char ares__count_bits_u8(unsigned char x)
{
/* Implementation obtained from:
* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetTable */
#define B2(n) n, n + 1, n + 1, n + 2
#define B4(n) B2(n), B2(n + 1), B2(n + 1), B2(n + 2)
#define B6(n) B4(n), B4(n + 1), B4(n + 1), B4(n + 2)
static const unsigned char lookup[256] = { B6(0), B6(1), B6(1), B6(2) };
return lookup[x];
}
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