46 lines
2.6 KiB
C
46 lines
2.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set 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/intrin/mpsadbw.h"
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#include "libc/macros.h"
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#include "libc/str/str.h"
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/**
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* Computes multiple sum of absolute differences.
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*
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* This appears to be intended for video encoding motion estimation. It
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* can be combined with phminposuw. That allows us to search for an int
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* overlapping inside 𝑏 that's nearest to an aligned int in 𝑎.
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*
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* @note goes fast w/ sse4 cf. core c. 2006 cf. bulldozer c. 2011
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* @mayalias
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*/
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void(mpsadbw)(uint16_t c[8], const uint8_t b[16], const uint8_t a[16],
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uint8_t control) {
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unsigned i, j;
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uint16_t r[8];
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for (i = 0; i < 8; ++i) {
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r[i] = 0;
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for (j = 0; j < 4; ++j) {
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r[i] += ABS(b[(control & 4) + i + j] - a[(control & 3) * 4 + j]);
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}
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}
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memcpy(c, r, 16);
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}
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