/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│ │vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│ ╞══════════════════════════════════════════════════════════════════════════════╡ │ Copyright 2020 Justine Alexandra Roberts Tunney │ │ │ │ Permission to use, copy, modify, and/or distribute this software for │ │ any purpose with or without fee is hereby granted, provided that the │ │ above copyright notice and this permission notice appear in all copies. │ │ │ │ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │ │ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │ │ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │ │ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │ │ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │ │ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │ │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │ │ PERFORMANCE OF THIS SOFTWARE. │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/macros.h" / Duplicates chrominance samples horizontally, e.g. / / 12345678-------- / → 1122334455667788 / / @param %edi is size of %rsi array in bytes / @param %rsi is char[edi/16][16] output and %rsi==%rdx is OK / @param %rdx is char[edi/16][8] input / @return %rax is %rsi doublechrominance: .leafprologue .profilable shr $1,%edi # backwards algorithm jbe 1f # do nothing if !n || n%2 mov %edi,%ecx shr $4,%ecx shl $4,%ecx 0: cmp %edi,%ecx je 0f dec %edi movzbl (%rdx,%rdi),%eax mov %al,(%rsi,%rdi,2) mov %al,1(%rsi,%rdi,2) jmp 0b 0: sub $8,%edi movq (%rdx,%rdi),%xmm0 punpcklbw %xmm0,%xmm0 movdqu %xmm0,(%rsi,%rdi,2) jnz 0b 1: mov %rsi,%rax .leafepilogue .endfn doublechrominance,globl .source __FILE__