cosmopolitan/libc/intrin/pavgw.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/pavgw.h"
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#include "libc/str/str.h"
/**
* Averages packed 16-bit unsigned integers w/ rounding.
*
* @param 𝑎 [w/o] receives result
* @param 𝑏 [r/o] supplies first input vector
* @param 𝑐 [r/o] supplies second input vector
* @mayalias
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*/
void(pavgw)(uint16_t a[8], const uint16_t b[8], const uint16_t c[8]) {
unsigned i;
int16_t r[8];
for (i = 0; i < 8; ++i) {
r[i] = (b[i] + c[i] + 1) >> 1;
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}
memcpy(a, r, 16);
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}