45 lines
2.5 KiB
C
45 lines
2.5 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/assert.h"
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#include "libc/intrin/palignr.h"
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#include "libc/macros.h"
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/**
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* Overlaps vectors.
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*
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* 𝑖= 0 means 𝑐←𝑎
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* 0<𝑖<16 means 𝑐←𝑎║𝑏
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* 𝑖=16 means 𝑐←𝑏
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* 16<𝑖<32 means 𝑐←𝑏║0
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* 𝑖≥32 means 𝑐←0
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*
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* @param 𝑖 goes faster as constexpr
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* @note not compatible with mmx
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* @see pvalignr()
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* @mayalias
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*/
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void(palignr)(void *c, const void *b, const void *a, unsigned long i) {
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char t[48];
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memcpy(t, a, 16);
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memcpy(t + 16, b, 16);
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memset(t + 32, 0, 16);
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memcpy(c, t + MIN(i, 32), 16);
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}
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