| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* $OpenBSD: memset.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(memset) |
| 10 | pushl %edi |
| 11 | pushl %ebx |
| 12 | movl 12(%esp),%edi |
| 13 | movzbl 16(%esp),%eax /* unsigned char, zero extend */ |
| 14 | movl 20(%esp),%ecx |
| 15 | pushl %edi /* push address of buffer */ |
| 16 | |
| 17 | cld /* set fill direction forward */ |
| 18 | |
| 19 | /* |
| 20 | * if the string is too short, it's really not worth the overhead |
| 21 | * of aligning to word boundries, etc. So we jump to a plain |
| 22 | * unaligned set. |
| 23 | */ |
| 24 | cmpl $0x0f,%ecx |
| 25 | jle L1 |
| 26 | |
| 27 | movb %al,%ah /* copy char to all bytes in word */ |
| 28 | movl %eax,%edx |
| 29 | sall $16,%eax |
| 30 | orl %edx,%eax |
| 31 | |
| 32 | movl %edi,%edx /* compute misalignment */ |
| 33 | negl %edx |
| 34 | andl $3,%edx |
| 35 | movl %ecx,%ebx |
| 36 | subl %edx,%ebx |
| 37 | |
| 38 | movl %edx,%ecx /* set until word aligned */ |
| 39 | rep |
| 40 | stosb |
| 41 | |
| 42 | movl %ebx,%ecx |
| 43 | shrl $2,%ecx /* set by words */ |
| 44 | rep |
| 45 | stosl |
| 46 | |
| 47 | movl %ebx,%ecx /* set remainder by bytes */ |
| 48 | andl $3,%ecx |
| 49 | L1: rep |
| 50 | stosb |
| 51 | |
| 52 | popl %eax /* pop address of buffer */ |
| 53 | popl %ebx |
| 54 | popl %edi |
| 55 | ret |
| Elliott Hughes | 6719500 | 2013-02-13 15:12:32 -0800 | [diff] [blame] | 56 | END(memset) |
