1 /* $OpenBSD: strcat.S,v 1.8 2005/08/07 11:30:38 espie Exp $ */ 2 /* 3 * Written by J.T. Conklin <jtc (at) netbsd.org>. 4 * Public domain. 5 */ 6 7 #include <machine/asm.h> 8 9 #if defined(APIWARN) 10 #APP 11 .section .gnu.warning.strcat 12 .ascii "warning: strcat() is almost always misused, please use strlcat()" 13 #NO_APP 14 #endif 15 16 /* 17 * NOTE: I've unrolled the loop eight times: large enough to make a 18 * significant difference, and small enough not to totally trash the 19 * cache. 20 */ 21 22 ENTRY(strcat) 23 pushl %edi /* save edi */ 24 movl 8(%esp),%edi /* dst address */ 25 movl 12(%esp),%edx /* src address */ 26 pushl %edi /* push destination address */ 27 28 cld /* set search forward */ 29 xorl %eax,%eax /* set search for null terminator */ 30 movl $-1,%ecx /* set search for lots of characters */ 31 repne /* search! */ 32 scasb 33 34 leal -1(%edi),%ecx /* correct dst address */ 35 36 .align 2,0x90 37 L1: movb (%edx),%al /* unroll loop, but not too much */ 38 movb %al,(%ecx) 39 testb %al,%al 40 jz L2 41 movb 1(%edx),%al 42 movb %al,1(%ecx) 43 testb %al,%al 44 jz L2 45 movb 2(%edx),%al 46 movb %al,2(%ecx) 47 testb %al,%al 48 jz L2 49 movb 3(%edx),%al 50 movb %al,3(%ecx) 51 testb %al,%al 52 jz L2 53 movb 4(%edx),%al 54 movb %al,4(%ecx) 55 testb %al,%al 56 jz L2 57 movb 5(%edx),%al 58 movb %al,5(%ecx) 59 testb %al,%al 60 jz L2 61 movb 6(%edx),%al 62 movb %al,6(%ecx) 63 testb %al,%al 64 jz L2 65 movb 7(%edx),%al 66 movb %al,7(%ecx) 67 addl $8,%edx 68 addl $8,%ecx 69 testb %al,%al 70 jnz L1 71 L2: popl %eax /* pop destination address */ 72 popl %edi /* restore edi */ 73 ret 74
