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;
; Christian Groessler, 10.02.2009
; derived from strncmp.s and stricmp.s
;
; int __fastcall__ strnicmp (const char* s1, const char* s2, size_t count);
; int __fastcall__ strncasecmp (const char* s1, const char* s2, size_t count);
;
.export _strnicmp, _strncasecmp
.import popax, popptr1
.importzp ptr1, ptr2, ptr3, tmp1, tmp2
.import ctypemaskdirect
.include "ctype.inc"
_strnicmp:
_strncasecmp:
; Convert the given counter value in a/x from a downward counter into an
; upward counter, so we can increment the counter in the loop below instead
; of decrementing it. This adds some overhead now, but is cheaper than
; executing a more complex test in each iteration of the loop. We do also
; correct the value by one, so we can do the test on top of the loop.
eor #$FF
sta ptr3
txa
eor #$FF
sta ptr3+1
; Get the remaining arguments
jsr popax ; get s2
sta ptr2
stx ptr2+1
jsr popptr1 ; get s1
; Loop setup
; ldy #0 Y=0 guaranteed by popptr1
; Start of compare loop. Check the counter.
Loop: inc ptr3
beq IncHi ; increment high byte
; Compare a byte from the strings
Comp: lda (ptr2),y
sta tmp2 ; remember original char
jsr ctypemaskdirect ; get character classification
and #CT_LOWER ; lower case char?
beq L1 ; jump if no
lda #<('A'-'a') ; make upper case char
adc tmp2 ; ctypemaskdirect ensures carry clear!
sta tmp2 ; remember upper case equivalent
L1: lda (ptr1),y ; get character from first string
sta tmp1 ; remember original char
jsr ctypemaskdirect ; get character classification
and #CT_LOWER ; lower case char?
beq L2 ; jump if no
lda #<('A'-'a') ; make upper case char
adc tmp1 ; ctypemaskdirect ensures carry clear!
sta tmp1 ; remember upper case equivalent
L2: ldx tmp1
cpx tmp2 ; compare characters
bne NotEqual ; jump if strings different
txa ; end of strings?
beq Equal1 ; jump if EOS reached, a/x == 0
; Increment the pointers
iny
bne Loop
inc ptr1+1
inc ptr2+1
bne Loop ; branch always
; Increment hi byte
IncHi: inc ptr3+1
bne Comp ; jump if counter not zero
; Exit code if strings are equal. a/x not set
Equal: lda #$00
tax
Equal1: rts
; Exit code if strings not equal
NotEqual:
bcs L3
ldx #$FF ; make result negative
rts
L3: ldx #$01 ; make result positive
rts
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