| /* $OpenBSD: bzero.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */ |
| /* |
| * Written by J.T. Conklin <jtc@netbsd.org>. |
| * Public domain. |
| */ |
| |
| #include <machine/asm.h> |
| |
| ENTRY(bzero) |
| pushl %edi |
| movl 8(%esp),%edi |
| movl 12(%esp),%edx |
| |
| cld /* set fill direction forward */ |
| xorl %eax,%eax /* set fill data to 0 */ |
| |
| /* |
| * if the string is too short, it's really not worth the overhead |
| * of aligning to word boundries, etc. So we jump to a plain |
| * unaligned set. |
| */ |
| cmpl $16,%edx |
| jb L1 |
| |
| movl %edi,%ecx /* compute misalignment */ |
| negl %ecx |
| andl $3,%ecx |
| subl %ecx,%edx |
| rep /* zero until word aligned */ |
| stosb |
| |
| movl %edx,%ecx /* zero by words */ |
| shrl $2,%ecx |
| andl $3,%edx |
| rep |
| stosl |
| |
| L1: movl %edx,%ecx /* zero remainder by bytes */ |
| rep |
| stosb |
| |
| popl %edi |
| ret |
