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 "DEFS.h" 8 9 ENTRY(memset) 10 RETGUARD_SETUP(memset, r10) 11 movq %rsi,%rax 12 andq $0xff,%rax 13 movq %rdx,%rcx 14 movq %rdi,%r11 15 16 cld /* set fill direction forward */ 17 18 /* 19 * if the string is too short, it's really not worth the overhead 20 * of aligning to word boundaries, etc. So we jump to a plain 21 * unaligned set. 22 */ 23 cmpq $0x0f,%rcx 24 jle L1 25 26 movb %al,%ah /* copy char to all bytes in word */ 27 movl %eax,%edx 28 sall $16,%eax 29 orl %edx,%eax 30 31 movl %eax,%edx 32 salq $32,%rax 33 orq %rdx,%rax 34 35 movq %rdi,%rdx /* compute misalignment */ 36 negq %rdx 37 andq $7,%rdx 38 movq %rcx,%r8 39 subq %rdx,%r8 40 41 movq %rdx,%rcx /* set until word aligned */ 42 rep 43 stosb 44 45 movq %r8,%rcx 46 shrq $3,%rcx /* set by words */ 47 rep 48 stosq 49 50 movq %r8,%rcx /* set remainder by bytes */ 51 andq $7,%rcx 52 L1: rep 53 stosb 54 movq %r11,%rax 55 56 RETGUARD_CHECK(memset, r10) 57 ret 58 END_BUILTIN(memset) 59