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42 lines
728 B
ArmAsm
42 lines
728 B
ArmAsm
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; Ullrich von Bassewitz, 31.05.1998
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; const char* strchr (const char* s, int c);
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;
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.export _strchr
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.import popax
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.importzp ptr1, tmp1
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_strchr:
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sta tmp1 ; Save c
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jsr popax ; get s
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sta ptr1
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stx ptr1+1
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ldy #0
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scloop: lda (ptr1),y ; get next char
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beq strz ; jump if end of string
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cmp tmp1 ; found?
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beq strf ; jump if yes
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iny
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bne scloop
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inc ptr1+1
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bne scloop ; jump always
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; found, calculate pointer to c
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strf: 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 str1
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inx
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str1: rts
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; not found, return zero
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strz: tax ; return 0
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rts
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