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Colin Leroy-Mira 2024-04-19 07:57:47 +02:00
parent 71d82ab5d9
commit a823d90082
2 changed files with 103 additions and 25 deletions
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95
libsrc/common/strcasestr.s Normal file
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@ -0,0 +1,95 @@
;
; Ullrich von Bassewitz, 11.12.1998
;
; char* strcasestr (const char* haystack, const char* needle);
;
.export _strcasestr
.import popptr1, return0, tolowerdirect
.importzp ptr1, ptr2, ptr3, ptr4, tmp1, tmp2, tmp3, tmp4
.include "ctype.inc"
.segment "LOWCODE"
_strcasestr:
sta ptr2 ; Save needle
stx ptr2+1
sta ptr4 ; Setup temp copy for later
jsr popptr1 ; Get haystack to ptr1
; If needle is empty, return haystack
; ldy #$00 Y=0 guaranteed by popptr1
lda (ptr2),y ; Get first byte of needle
beq @Found ; Needle is empty --> we're done
; Search for the beginning of the string (this is not an optimal search
; strategy [in fact, it's pretty dumb], but it's simple to implement).
jsr tolowerdirect ; Lowercase
sta tmp1 ; Save start of needle
@L1: lda (ptr1),y ; Get next char from haystack
beq @NotFound ; Jump if end
jsr tolowerdirect ; Lowercase
cmp tmp1 ; Start of needle found?
beq @L2 ; Jump if so
iny ; Next char
bne @L1
inc ptr1+1 ; Bump high byte
bne @L1 ; Branch always
; We found the start of needle in haystack
@L2: tya ; Get offset
clc
adc ptr1
sta ptr1 ; Make ptr1 point to start
bcc @L3
inc ptr1+1
; ptr1 points to the start of needle in haystack now. Setup temporary pointers for the
; search. The low byte of ptr4 is already set.
@L3: sta ptr3
lda ptr1+1
sta ptr3+1
lda ptr2+1
sta ptr4+1
ldy #1 ; First char is identical, so start on second
; Do the compare
@L4: lda (ptr4),y ; Get char from needle
beq @Found ; Jump if end of needle (-> found)
jsr tolowerdirect ; Lowercase
sta tmp2
lda (ptr3),y ; Compare with haystack
jsr tolowerdirect ; Lowercase
cmp tmp2
bne @L5 ; Jump if not equal
iny ; Next char
bne @L4
inc ptr3+1
inc ptr4+1 ; Bump hi byte of pointers
bne @L4 ; Next char (branch always)
; The strings did not compare equal, search next start of needle
@L5: ldy #1 ; Start after this char
bne @L1 ; Branch always
; We found the start of needle
@Found: lda ptr1
ldx ptr1+1
rts
; We reached end of haystack without finding needle
@NotFound:
jmp return0 ; return NULL

33
libsrc/common/strstr.s
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@ -4,20 +4,11 @@
; char* strstr (const char* haystack, const char* needle);
;
.export _strstr, _strcasestr
.import popptr1, return0, tolowerdirect
.importzp ptr1, ptr2, ptr3, ptr4, tmp1, tmp2
maybe_lower: ; Lowercase char in A if needed
jmp tolowerdirect ; patched on entry with either JMP or RTS
.export _strstr
.import popptr1
.importzp ptr1, ptr2, ptr3, ptr4, tmp1
_strstr:
ldy #$60 ; RTS
bne :+
_strcasestr:
ldy #$4C ; JMP absolute
: sty maybe_lower
sta ptr2 ; Save needle
stx ptr2+1
sta ptr4 ; Setup temp copy for later
@ -33,12 +24,9 @@ _strcasestr:
; Search for the beginning of the string (this is not an optimal search
; strategy [in fact, it's pretty dumb], but it's simple to implement).
jsr maybe_lower ; Lowercase if needed
sta tmp1 ; Save start of needle
@L1: lda (ptr1),y ; Get next char from haystack
beq @NotFound ; Jump if end
jsr maybe_lower ; Lowercase if needed
cmp tmp1 ; Start of needle found?
beq @L2 ; Jump if so
iny ; Next char
@ -55,7 +43,7 @@ _strcasestr:
bcc @L3
inc ptr1+1
; ptr1 points to the start of needle in haystack now. Setup temporary pointers for the
; ptr1 points to the start of needle now. Setup temporary pointers for the
; search. The low byte of ptr4 is already set.
@L3: sta ptr3
@ -69,14 +57,7 @@ _strcasestr:
@L4: lda (ptr4),y ; Get char from needle
beq @Found ; Jump if end of needle (-> found)
jsr maybe_lower ; Lowercase if needed
sta tmp2
lda (ptr3),y ; Compare with haystack
jsr maybe_lower ; Lowercase if needed
cmp tmp2
cmp (ptr3),y ; Compare with haystack
bne @L5 ; Jump if not equal
iny ; Next char
bne @L4
@ -98,4 +79,6 @@ _strcasestr:
; We reached end of haystack without finding needle
@NotFound:
jmp return0 ; return NULL
lda #$00 ; return NULL
tax
rts