31 lines
713 B
ArmAsm
31 lines
713 B
ArmAsm
! memset() Author: Kees J. Bot
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! 27 Jan 1994
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.sect .text; .sect .rom; .sect .data; .sect .bss
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! void *memset(void *s, int c, size_t n)
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! Set a chunk of memory to the same byte value.
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!
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.sect .text
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.define _memset
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_memset:
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push bp
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mov bp, sp
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push di
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mov di, 4(bp) ! The string
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movb al, 6(bp) ! The fill byte
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mov cx, 8(bp) ! Length
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cld
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cmp cx, #16
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jb sbyte ! Don't bother being smart with short arrays
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test di, #1
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jnz sbyte ! Bit 0 set, use byte store
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sword: movb ah, al ! One byte to two bytes
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sar cx, #1
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rep stos ! Store words
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adc cx, cx ! One more byte?
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sbyte:
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rep stosb ! Store bytes
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done: mov ax, 4(bp) ! Return some value you have no need for
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pop di
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pop bp
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ret
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