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Fold LIBC_BITS into LIBC_INTRIN

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Justine Tunney 2022-08-11 12:13:18 -07:00
parent 625aa365f1
commit 05b8f82371
603 changed files with 1071 additions and 1211 deletions
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31
libc/intrin/bitreverse32.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/bits.h"
#include "libc/intrin/bswap.h"
/**
* Reverses bits in 32-bit word.
*/
uint32_t bitreverse32(uint32_t x) {
x = bswap_32(x);
x = (x & 0xaaaaaaaa) >> 1 | (x & 0x55555555) << 1;
x = (x & 0xcccccccc) >> 2 | (x & 0x33333333) << 2;
x = (x & 0xf0f0f0f0) >> 4 | (x & 0x0f0f0f0f) << 4;
return x;
}