Annotation of sys/lib/libkern/arch/amd64/memchr.S, Revision 1.1.1.1
1.1 nbrk 1: /*
2: * Written by J.T. Conklin <jtc@netbsd.org>.
3: * Public domain.
4: * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
5: */
6:
7: #include <machine/asm.h>
8:
9: #if defined(LIBC_SCCS)
10: RCSID("$NetBSD: memchr.S,v 1.1 2001/06/19 00:22:46 fvdl Exp $")
11: #endif
12:
13: ENTRY(memchr)
14: movb %sil,%al /* set character to search for */
15: movq %rdx,%rcx /* set length of search */
16: testq %rcx,%rcx /* test for len == 0 */
17: jz L1
18: cld /* set search forward */
19: repne /* search! */
20: scasb
21: jne L1 /* scan failed, return null */
22: leaq -1(%rdi),%rax /* adjust result of scan */
23: ret
24: L1: xorq %rax,%rax
25: ret
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