2020-06-15 14:18:57 +00:00
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/*-*- mode:asm; 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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│ 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/nexgen32e/x86feature.h"
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#include "libc/dce.h"
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#include "libc/macros.h"
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/ Searches for last instance of byte in memory region.
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/
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/ @param rdi points to data to search
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/ @param esi is treated as unsigned char
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/ @param rdx is byte length of rdi
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/ @return rax is address of last %sil in %rdi, or NULL
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/ @note AVX2 requires Haswell (2014+) or Excavator (2015+)
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/ @asyncsignalsafe
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memrchr:.leafprologue
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.profilable
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#if !IsTiny()
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cmp $32,%rdx
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jb 5f
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testb X86_HAVE(AVX2)+kCpuids(%rip)
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jz 5f
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vmovd %esi,%xmm0
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vpbroadcastb %xmm0,%ymm0
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3: vmovups -32(%rdi,%rdx),%ymm1
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vpcmpeqb %ymm1,%ymm0,%ymm1
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vpmovmskb %ymm1,%eax
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lzcnt %eax,%eax
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mov %eax,%ecx
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sub %rcx,%rdx
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cmp $32,%eax
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jne 5f
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cmp $31,%rdx
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ja 3b
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vzeroupper
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#endif
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5: xor %eax,%eax
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mov %rdx,%rcx
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6: sub $1,%rcx
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jb 9f
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cmp %sil,-1(%rdi,%rdx)
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mov %rcx,%rdx
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jne 6b
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lea (%rdi,%rcx),%rax
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9: .leafepilogue
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.endfn memrchr,globl
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2020-06-16 02:01:28 +00:00
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.source __FILE__
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