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 9ENTRY(bzero) 10 movq %rsi,%rdx 11 12 xorq %rax,%rax /* set fill data to 0 */ 13 14 /* 15 * if the string is too short, it's really not worth the overhead 16 * of aligning to word boundaries, etc. So we jump to a plain 17 * unaligned set. 18 */ 19 cmpq $16,%rdx 20 jb L1 21 22 movq %rdi,%rcx /* compute misalignment */ 23 negq %rcx 24 andq $7,%rcx 25 subq %rcx,%rdx 26 rep /* zero until word aligned */ 27 stosb 28 29 movq %rdx,%rcx /* zero by words */ 30 shrq $3,%rcx 31 andq $7,%rdx 32 rep 33 stosq 34 35L1: movq %rdx,%rcx /* zero remainder by bytes */ 36 rep 37 stosb 38 39 ret 40