97 lines
5.7 KiB
C
97 lines
5.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/str/internal.h"
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/**
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* Hashes data with hardware acceleration at 10GBps.
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* @note needs Nehalem+ c. 2008 or Bulldozer+ c. 2011
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*/
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optimizespeed uint32_t crc32c$sse42(uint32_t init, const void *data, size_t n) {
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const unsigned char *p = (const unsigned char *)data;
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const unsigned char *pe = (const unsigned char *)data + n;
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uint32_t h = init ^ 0xffffffff;
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if (n >= 16 + 8) {
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while ((uintptr_t)p & 7) asm("crc32b\t%1,%0" : "+r"(h) : "rm"(*p++));
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uint64_t hl = h;
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while (p < pe - 16ul) {
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asm("crc32q\t%1,%0" : "+r"(hl) : "rm"(*(const uint64_t *)p));
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p += 8;
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asm("crc32q\t%1,%0" : "+r"(hl) : "rm"(*(const uint64_t *)p));
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p += 8;
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}
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h = (uint32_t)hl;
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}
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while (p < pe) asm("crc32b\t%1,%0" : "+r"(h) : "rm"(*p++));
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return h ^ 0xffffffff;
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}
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/*
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bench_crc32c$sse42 for #c per n where c ≈ 0.293ns
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N x1 x8 x64 mBps
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------------------------------------------------------------
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1 877.000 43.375 40.359 81
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1 45.000 39.625 40.484 80
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2 34.500 27.562 20.461 159
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3 23.000 16.708 14.245 228
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4 18.250 13.094 11.449 284
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7 10.429 8.339 8.185 397
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8 42.125 8.734 6.850 475
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15 9.400 5.375 4.884 665
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16 7.312 5.070 4.882 666
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31 5.258 2.923 2.680 1213
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32 3.969 2.676 2.562 1269
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63 3.095 1.581 1.428 2276
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64 2.234 1.623 1.478 2199
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127 1.205 0.901 0.900 3610
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128 1.164 0.960 0.915 3552
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255 0.922 0.651 0.618 5260
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256 0.715 0.650 0.609 5341
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511 0.558 0.482 0.477 6819
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512 0.529 0.475 0.469 6932
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1023 0.425 0.400 0.396 8204
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1024 0.417 0.392 0.388 8383
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2047 0.367 0.355 0.353 9199
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2048 0.374 0.366 0.364 8929
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4095 0.351 0.338 0.337 9644
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4096 0.353 0.338 0.338 9624
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8191 0.335 0.338 0.337 9641
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8192 0.335 0.329 0.329 9870
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16383 0.336 0.325 0.325 10011
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16384 0.336 0.326 0.375 8666
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32767 0.329 0.323 0.323 10070
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32768 0.327 0.324 0.323 10062
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65535 0.322 0.322 0.322 10103
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65536 0.321 0.322 0.322 10102
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131071 0.322 0.321 0.321 10125
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131072 0.321 0.321 0.321 10124
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262143 0.322 0.321 0.335 9699
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262144 0.321 0.321 0.321 10134
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524287 0.321 0.321 0.499 6516
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524288 0.321 0.321 0.339 9575
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1048575 0.322 0.321 0.322 10095
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1048576 0.320 1.001 0.323 10048
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2097151 0.325 0.321 0.322 10086
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2097152 0.330 0.320 0.323 10076
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4194303 0.331 0.322 0.321 10128
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4194304 0.332 0.321 0.325 10004
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8388607 0.334 0.332 0.331 9829
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8388608 0.334 0.329 0.327 9934
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*/
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