cosmopolitan/libc/nexgen32e/tinystrcmp.S

52 lines
2.5 KiB
ArmAsm

/*-*- 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
This program is free software; you can redistribute it and/or modify │
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License. │
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of │
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software │
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "libc/macros.h"
/ Compares strings w/ no-clobber greg abi.
/
/ @param rdi is first non-null NUL-terminated string pointer
/ @param rsi is second non-null NUL-terminated string pointer
/ @return rax is <0, 0, or >0 based on uint8_t comparison
/ @clob flags only
/ @asyncsignalsafe
tinystrcmp:
.leafprologue
push %rcx
push %rdx
xor %eax,%eax
xor %edx,%edx
xor %ecx,%ecx
cmp %rdi,%rsi
je 1f
0: movzbl (%rdi,%rcx,1),%eax
movzbl (%rsi,%rcx,1),%edx
test %al,%al
jz 1f
cmp %dl,%al
jne 1f
inc %rcx
jmp 0b
1: sub %edx,%eax
pop %rdx
pop %rcx
.leafepilogue
.endfn tinystrcmp,globl
.source __FILE__