| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* $OpenBSD: bzero.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */ |
| 2 | /* |
| 3 | * Written by J.T. Conklin <jtc@netbsd.org>. |
| 4 | * Public domain. |
| 5 | */ |
| 6 | |
| 7 | #include <machine/asm.h> |
| 8 | |
| 9 | ENTRY(bzero) |
| 10 | pushl %edi |
| 11 | movl 8(%esp),%edi |
| 12 | movl 12(%esp),%edx |
| 13 | |
| 14 | cld /* set fill direction forward */ |
| 15 | xorl %eax,%eax /* set fill data to 0 */ |
| 16 | |
| 17 | /* |
| 18 | * if the string is too short, it's really not worth the overhead |
| 19 | * of aligning to word boundries, etc. So we jump to a plain |
| 20 | * unaligned set. |
| 21 | */ |
| 22 | cmpl $16,%edx |
| 23 | jb L1 |
| 24 | |
| 25 | movl %edi,%ecx /* compute misalignment */ |
| 26 | negl %ecx |
| 27 | andl $3,%ecx |
| 28 | subl %ecx,%edx |
| 29 | rep /* zero until word aligned */ |
| 30 | stosb |
| 31 | |
| 32 | movl %edx,%ecx /* zero by words */ |
| 33 | shrl $2,%ecx |
| 34 | andl $3,%edx |
| 35 | rep |
| 36 | stosl |
| 37 | |
| 38 | L1: movl %edx,%ecx /* zero remainder by bytes */ |
| 39 | rep |
| 40 | stosb |
| 41 | |
| 42 | popl %edi |
| 43 | ret |