Annotation of sys/lib/libkern/arch/amd64/memset.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: memset.S,v 1.1 2001/06/19 00:22:46 fvdl Exp $")
11: #endif
12:
13: ENTRY(memset)
14: movq %rsi,%rax
15: movq %rdx,%rcx
16: movq %rdi,%r11
17:
18: cld /* set fill direction forward */
19:
20: /*
21: * if the string is too short, it's really not worth the overhead
22: * of aligning to word boundaries, etc. So we jump to a plain
23: * unaligned set.
24: */
25: cmpq $0x0f,%rcx
26: jle L1
27:
28: movb %al,%ah /* copy char to all bytes in word */
29: movl %eax,%edx
30: sall $16,%eax
31: orl %edx,%eax
32:
33: movl %eax,%edx
34: salq $32,%rax
35: orq %rdx,%rax
36:
37: movq %rdi,%rdx /* compute misalignment */
38: negq %rdx
39: andq $7,%rdx
40: movq %rcx,%r8
41: subq %rdx,%r8
42:
43: movq %rdx,%rcx /* set until word aligned */
44: rep
45: stosb
46:
47: movq %r8,%rcx
48: shrq $3,%rcx /* set by words */
49: rep
50: stosq
51:
52: movq %r8,%rcx /* set remainder by bytes */
53: andq $7,%rcx
54: L1: rep
55: stosb
56: movq %r11,%rax
57:
58: ret
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