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      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