Rev 1408 | Details | Compare with Previous | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1627 | serge | 1 | /* memset() Author: Kees J. Bot */ |
| 2 | /* 2 Jan 1994 */ |
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| 1408 | serge | 3 | |
| 1627 | serge | 4 | /* void *memset(void *s, int c, size_t n) */ |
| 5 | /* Set a chunk of memory to the same byte value. */ |
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| 6 | /* */ |
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| 7 | #include "asm.h" |
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| 1408 | serge | 8 | |
| 1627 | serge | 9 | ENTRY(memset) |
| 10 | push %ebp |
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| 11 | movl %esp, %ebp |
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| 12 | push %edi |
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| 13 | movl 8(%ebp), %edi /* The string */ |
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| 14 | movzbl 12(%ebp), %eax /* The fill byte */ |
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| 15 | movl 16(%ebp), %ecx /* Length */ |
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| 16 | cld |
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| 17 | cmpl $16, %ecx |
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| 18 | jb sbyte /* Don't bother being smart with short arrays */ |
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| 19 | testl $1, %edi |
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| 20 | jne sbyte /* Bit 0 set, use byte store */ |
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| 21 | testl $2, %edi |
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| 22 | jne sword /* Bit 1 set, use word store */ |
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| 23 | slword: |
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| 24 | movb %al, %ah |
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| 25 | movl %eax, %edx |
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| 26 | sall $16, %edx |
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| 27 | orl %edx, %eax /* One byte to four bytes */ |
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| 28 | shrdl $2, %ecx, %edx /* Save low two bits of ecx in edx */ |
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| 29 | shrl $2, %ecx |
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| 1408 | serge | 30 | |
| 1627 | serge | 31 | rep stosl /* Store longwords. */ |
| 32 | shldl $2, %edx, %ecx /* Restore low two bits */ |
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| 33 | sword: |
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| 34 | movb %al, %ah /* One byte to two bytes */ |
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| 35 | shrl $1, %ecx |
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| 36 | |||
| 37 | rep stosw /* Store words */ |
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| 38 | adcl %ecx, %ecx /* One more byte? */ |
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| 1408 | serge | 39 | sbyte: |
| 1627 | serge | 40 | rep stosb /* Store bytes */ |
| 1408 | serge | 41 | done: |
| 1627 | serge | 42 | movl 8(%ebp), %eax /* Return some value you have no need for */ |
| 43 | pop %edi |
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| 44 | pop %ebp |
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| 45 | ret |