1/* 2 * Written by J.T. Conklin <jtc@acorntoolworks.com> 3 * Public domain. 4 */ 5 6#include <machine/asm.h> 7__FBSDID("$FreeBSD$"); 8 9#if 0 10 RCSID("$NetBSD: strcmp.S,v 1.3 2004/07/19 20:04:41 drochner Exp $") 11#endif 12 13ENTRY(strcmp) 14 /* 15 * Align s1 to word boundary. 16 * Consider unrolling loop? 17 */ 18.Ls1align: 19 testb $7,%dil 20 je .Ls1aligned 21 movb (%rdi),%al 22 incq %rdi 23 movb (%rsi),%dl 24 incq %rsi 25 testb %al,%al 26 je .Ldone 27 cmpb %al,%dl 28 je .Ls1align 29 jmp .Ldone 30 31 /* 32 * Check whether s2 is aligned to a word boundary. If it is, we 33 * can compare by words. Otherwise we have to compare by bytes. 34 */ 35.Ls1aligned: 36 testb $7,%sil 37 jne .Lbyte_loop 38 39 movabsq $0x0101010101010101,%r8 40 subq $8,%rdi 41 movabsq $0x8080808080808080,%r9 42 subq $8,%rsi 43 44 .align 4 45.Lword_loop: 46 movq 8(%rdi),%rax 47 addq $8,%rdi 48 movq 8(%rsi),%rdx 49 addq $8,%rsi 50 cmpq %rax,%rdx 51 jne .Lbyte_loop 52 subq %r8,%rdx 53 notq %rax 54 andq %rax,%rdx 55 testq %r9,%rdx 56 je .Lword_loop 57 58 .align 4 59.Lbyte_loop: 60 movb (%rdi),%al 61 incq %rdi 62 movb (%rsi),%dl 63 incq %rsi 64 testb %al,%al 65 je .Ldone 66 cmpb %al,%dl 67 je .Lbyte_loop 68 69.Ldone: 70 movzbq %al,%rax 71 movzbq %dl,%rdx 72 subq %rdx,%rax 73 ret 74END(strcmp) 75 76 .section .note.GNU-stack,"",%progbits 77