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57 lines
1.1 KiB
ArmAsm
57 lines
1.1 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2003-05-05
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;
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; void* __fastcall__ memchr (const void* p, int c, size_t n);
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;
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.export _memchr
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.import popax, popptr1, return0
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.importzp ptr1, ptr2
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.proc _memchr
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eor #$FF
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sta ptr2
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txa
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eor #$FF
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sta ptr2+1 ; Save ones complement of n
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jsr popax ; get c
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pha
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jsr popptr1 ; get p
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; ldy #$00 is guaranteed by popptr1
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pla ; Get c
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ldx ptr2 ; Use X as low counter byte
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L1: inx
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beq L3
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L2: cmp (ptr1),y
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beq found
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iny
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bne L1
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inc ptr1+1
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bne L1 ; Branch always
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L3: inc ptr2+1 ; Bump counter high byte
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bne L2
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; Not found, return NULL
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notfound:
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jmp return0
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; Found, return pointer to char
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found: ldx ptr1+1 ; get high byte of pointer
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tya ; low byte offset
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clc
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adc ptr1
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bcc L9
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inx
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L9: rts
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.endproc
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