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lib/libc/arch/amd64/string/strcmp.S
74 строки
1 KB
mortimer
Add retguard macros for libc.
04 июл 2018, 02:14
04 июл 2018, 02:14
631951a
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/* $OpenBSD: strcmp.S,v 1.8 2018/07/03 23:14:05 mortimer Exp $ */ /* $NetBSD: strcmp.S,v 1.2 2014/03/22 19:16:34 jakllsch Exp $ */ /* * Written by J.T. Conklin <jtc@acorntoolworks.com> * Public domain. */ #include "DEFS.h" ENTRY(strcmp) RETGUARD_SETUP(strcmp, r11) /* * Align s1 to word boundary. * Consider unrolling loop? */ .Ls1align: testb $7,%dil je .Ls1aligned movb (%rdi),%al incq %rdi movb (%rsi),%dl incq %rsi testb %al,%al je .Ldone cmpb %al,%dl je .Ls1align jmp .Ldone /* * Check whether s2 is aligned to a word boundary. If it is, we * can compare by words. Otherwise we have to compare by bytes. */ .Ls1aligned: testb $7,%sil jne .Lbyte_loop movabsq $0x0101010101010101,%r8 subq $8,%rdi movabsq $0x8080808080808080,%r9 subq $8,%rsi _ALIGN_TEXT .Lword_loop: movq 8(%rdi),%rax addq $8,%rdi movq 8(%rsi),%rdx addq $8,%rsi cmpq %rax,%rdx jne .Lbyte_loop subq %r8,%rdx notq %rax andq %rax,%rdx testq %r9,%rdx je .Lword_loop _ALIGN_TEXT .Lbyte_loop: movb (%rdi),%al incq %rdi movb (%rsi),%dl incq %rsi testb %al,%al je .Ldone cmpb %al,%dl je .Lbyte_loop .Ldone: movzbq %al,%rax movzbq %dl,%rdx subq %rdx,%rax RETGUARD_CHECK(strcmp, r11) ret END_STRONG(strcmp)