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57 lines
1.3 KiB
ArmAsm
57 lines
1.3 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 11.06.1998
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;
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; size_t strspn (const char* s1, const char* s2);
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;
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.export _strspn
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.import popax
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.importzp ptr1, ptr2, tmp1, tmp2, tmp3
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_strspn:
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sta ptr2 ; Save s2
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stx ptr2+1
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jsr popax ; get s1
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sta ptr1
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stx ptr1+1
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ldx #0 ; low counter byte
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stx tmp1 ; high counter byte
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ldy #$00
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L1: lda (ptr1),y ; get next char from s1
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beq L6 ; jump if done
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sta tmp2 ; save char
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iny
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bne L2
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inc ptr1+1
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L2: sty tmp3 ; save index into s1
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ldy #0 ; get index into s2
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L3: lda (ptr2),y ;
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beq L6 ; jump if done
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cmp tmp2
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beq L4
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iny
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bne L3
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; The character was found in s2. Increment the counter and start over
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L4: ldy tmp3 ; reload index
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inx
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bne L1
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inc tmp1
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bne L1
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; The character was not found, or we reached the end of s1. Return count of
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; characters
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L6: txa ; get low counter byte
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ldx tmp1 ; get high counter byte
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rts
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