cosmopolitan/libc/intrin/psadbw.c

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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
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/intrin/psadbw.h"
#include "libc/macros.h"
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/**
* Computes sum of absolute differences.
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*
* @param 𝑎 [w/o] receives sum at first index and rest is zero'd
* @param 𝑏 [r/o] is your first unsigned byte array
* @param 𝑐 [r/o] is your second unsigned byte array
* @mayalias
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*/
void(psadbw)(uint64_t a[2], const uint8_t b[16], const uint8_t c[16]) {
unsigned i, x, y;
for (x = i = 0; i < 8; ++i) x += ABS(b[i] - c[i]);
for (y = 0; i < 16; ++i) y += ABS(b[i] - c[i]);
a[0] = x;
a[1] = y;
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}