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54 lines
1.7 KiB
ArmAsm
54 lines
1.7 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 11.06.1998
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; Christian Krueger: 08-Aug-2013, optimization
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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, _strlen
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.importzp ptr1, ptr2, tmp1, tmp2
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_strspn:
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jsr _strlen ; get length in a/x and transfer s2 to ptr1
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; Note: It does not make sense to
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; have more than 255 test chars, so
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; we don't support a high byte here! (ptr1+1 is
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; also unchanged in strlen then (important!))
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; -> the original implementation also
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; ignored this case
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sta tmp1 ; tmp1 = strlen of test chars
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jsr popax ; get and save s1
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sta ptr2 ; to ptr2
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stx ptr2+1
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ldx #0 ; low counter byte
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stx tmp2 ; high counter byte
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loadChar:
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ldy #0
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lda (ptr2),y ; get next char from s1
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beq leave ; handly byte of s1
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advance:
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inc ptr2 ; advance string position to test
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bne check
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inc ptr2+1
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dey ; correct next iny (faster/shorter than bne...)
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checkNext:
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iny
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check: cpy tmp1 ; compare with length of test character string
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beq leave
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cmp (ptr1),y ; found matching char?
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bne checkNext
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foundTestChar:
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inx
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bne loadChar
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inc tmp2
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bne loadChar ; like bra...
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leave: txa ; restore position of finding
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ldx tmp2 ; and return
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rts
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