41 lines
2.3 KiB
C
41 lines
2.3 KiB
C
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/*-*- 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/psrad.h"
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/**
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* Divides ints by two power.
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*
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* @note c needs to be a literal, asmconstexpr, or linkconstsym
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* @note arithmetic shift right will sign extend negatives
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* @mayalias
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*/
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void(psrad)(int32_t a[4], const int32_t b[4], unsigned char k) {
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unsigned i, x, m;
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if (k > 31) k = 31;
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for (i = 0; i < 4; ++i) {
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m = 0;
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x = b[i];
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if (x & 0x80000000) m = ~(0xffffffffu >> k);
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x >>= k;
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x |= m;
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a[i] = x;
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}
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}
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