| /* $OpenBSD: memset.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(memset) |
| pushl %edi |
| pushl %ebx |
| movl 12(%esp),%edi |
| movzbl 16(%esp),%eax /* unsigned char, zero extend */ |
| movl 20(%esp),%ecx |
| pushl %edi /* push address of buffer */ |
| |
| cld /* set fill direction forward */ |
| |
| /* |
| * 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 $0x0f,%ecx |
| jle L1 |
| |
| movb %al,%ah /* copy char to all bytes in word */ |
| movl %eax,%edx |
| sall $16,%eax |
| orl %edx,%eax |
| |
| movl %edi,%edx /* compute misalignment */ |
| negl %edx |
| andl $3,%edx |
| movl %ecx,%ebx |
| subl %edx,%ebx |
| |
| movl %edx,%ecx /* set until word aligned */ |
| rep |
| stosb |
| |
| movl %ebx,%ecx |
| shrl $2,%ecx /* set by words */ |
| rep |
| stosl |
| |
| movl %ebx,%ecx /* set remainder by bytes */ |
| andl $3,%ecx |
| L1: rep |
| stosb |
| |
| popl %eax /* pop address of buffer */ |
| popl %ebx |
| popl %edi |
| ret |