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e16a7d8f3b
`et` means `expandtab`. ```sh rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\) et\(.*\) :vi/vi: \1 xoet\2:vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)noet\(.*\):vi/vi: \1et\2 :vi/' rg 'vi: .* :vi' -l -0 | \ xargs -0 sed -i '' 's/vi: \(.*\)xoet\(.*\):vi/vi: \1noet\2:vi/' ```
87 lines
3.6 KiB
C
87 lines
3.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/assert.h"
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#include "libc/dce.h"
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#include "libc/nexgen32e/x86feature.h"
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/**
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* Returns population count of array.
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*
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* @param a is byte sequence
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* @return number of bits set to one
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* @note 30gbps on Nehalem (Intel 2008+) otherwise 3gbps
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*/
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size_t _countbits(const void *a, size_t n) {
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size_t t;
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unsigned b;
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uint64_t x;
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const char *p, *e;
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t = 0;
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p = a;
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e = p + n;
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if (!IsTiny()) {
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#ifdef __x86_64__
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long Ai, Bi, Ci, Di;
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long Ao, Bo, Co, Do;
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if (X86_HAVE(POPCNT)) {
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while (p + sizeof(long) * 4 <= e) {
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__builtin_memcpy(&Ai, p + 000, sizeof(long));
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__builtin_memcpy(&Bi, p + 010, sizeof(long));
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__builtin_memcpy(&Ci, p + 020, sizeof(long));
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__builtin_memcpy(&Di, p + 030, sizeof(long));
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asm("popcnt\t%1,%0" : "=r"(Ao) : "r"(Ai) : "cc");
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asm("popcnt\t%1,%0" : "=r"(Bo) : "r"(Bi) : "cc");
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asm("popcnt\t%1,%0" : "=r"(Co) : "r"(Ci) : "cc");
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asm("popcnt\t%1,%0" : "=r"(Do) : "r"(Di) : "cc");
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t += Ao + Bo + Co + Do;
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p += sizeof(long) * 4;
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}
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while (p + sizeof(long) <= e) {
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__builtin_memcpy(&Ai, p, 8);
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asm("popcnt\t%1,%0" : "=r"(Ao) : "rm"(Ai) : "cc");
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p += sizeof(long);
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t += Ao;
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}
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} else {
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#endif
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while (p + 8 <= e) {
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__builtin_memcpy(&x, p, 8);
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x = x - ((x >> 1) & 0x5555555555555555);
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x = ((x >> 2) & 0x3333333333333333) + (x & 0x3333333333333333);
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x = (x + (x >> 4)) & 0x0f0f0f0f0f0f0f0f;
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x = (x + (x >> 32)) & 0xffffffff;
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x = x + (x >> 16);
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x = (x + (x >> 8)) & 0x7f;
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t += x;
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p += 8;
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}
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#ifdef __x86_64__
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}
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#endif
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}
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while (p < e) {
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b = *p++ & 255;
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b = b - ((b >> 1) & 0x55);
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b = ((b >> 2) & 0x33) + (b & 0x33);
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b = (b + (b >> 4)) & 15;
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t += b;
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}
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return t;
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}
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