50 lines
2.5 KiB
ArmAsm
50 lines
2.5 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.h"
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/ Creates bit mask of which bytes are the same.
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/
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/ @param %rdi points to bit mask (write-only)
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/ @param %rsi points to first buffer (read-only)
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/ @param %rdx points to second buffer (read-only)
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/ @param %rcx is byte length of both %rsi and %rdx
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/ @return %rax is set to %rdi
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/ @note buffers should be 128-byte aligned
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memeqmask:
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.leafprologue
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xor %eax,%eax
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test %ecx,%ecx
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jz 1f
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shr $3,%ecx
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0: movdqa (%rsi,%rax,8),%xmm0
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movdqa 16(%rsi,%rax,8),%xmm1
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pcmpeqb (%rdx,%rax,8),%xmm0
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pcmpeqb 16(%rdx,%rax,8),%xmm1
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vpmovmskb %xmm0,%r8d
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vpmovmskb %xmm1,%r9d
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mov %r8w,(%rdi,%rax)
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mov %r9w,2(%rdi,%rax)
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add $4,%eax
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cmp %ecx,%eax
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jb 0b
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1: mov %rdi,%rax
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.leafepilogue
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.endfn memeqmask,globl
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.source __FILE__
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