1
0
mirror of https://github.com/cc65/cc65.git synced 2024-12-25 02:29:52 +00:00
cc65/libsrc/common/strchr.s
cuz 4744e3602c Added the capability to search for the terminating zero of the given string.
Don't know what the standard says about it, but the feature seems reasonable
and other compilers handle it this way.


git-svn-id: svn://svn.cc65.org/cc65/trunk@42 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-06-09 12:07:53 +00:00

49 lines
906 B
ArmAsm

;
; Ullrich von Bassewitz, 31.05.1998
;
; const char* strchr (const char* s, int c);
;
.export _strchr
.import popax
.importzp ptr1, tmp1
_strchr:
sta tmp1 ; Save c
jsr popax ; get s
sta ptr1
stx ptr1+1
ldy #0
Loop: lda (ptr1),y ; Get next char
beq EOS ; Jump on end of string
cmp tmp1 ; Found?
beq Found ; Jump if yes
iny
bne Loop
inc ptr1+1
bne Loop ; Branch always
; End of string. Check if we're searching for the terminating zero
EOS: lda tmp1 ; Get the char we're searching for
bne NotFound ; Jump if not searching for terminator
; Found. Calculate pointer to c.
Found: ldx ptr1+1 ; Load high byte of pointer
tya ; Low byte offset
clc
adc ptr1
bcc Found1
inx
Found1: rts
; Not found, return NULL
NotFound:
lda #0
tax
rts