Annotation of sys/lib/libkern/arch/amd64/memset.S, Revision 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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