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cc65/libsrc/common/strlen.s
Colin Leroy-Mira 3a439e0e1b Little strdup optimisation
-12 bytes on disk
-20 cycles per strdup
-6 cycles per strlen called from strdup
2024-01-07 14:25:06 +01:00

41 lines
880 B
ArmAsm

;
; Ullrich von Bassewitz, 31.05.1998
;
; Note: strspn & strcspn call internally this function and rely on
; the usage of only ptr4 here! Keep in mind when appling changes
; and check the other implementations too!
;
; size_t __fastcall__ strlen (const char* s);
;
.export _strlen, _strlen_ptr4
.importzp ptr4
.macpack cpu
_strlen:
sta ptr4 ; Save s
stx ptr4+1
_strlen_ptr4:
.if (.cpu .bitand ::CPU_ISET_HUC6280)
clx
cly
.else
ldx #0 ; YX used as counter
.if (.cpu .bitand ::CPU_ISET_65816)
txy
.else
ldy #0
.endif
.endif
L1: lda (ptr4),y
beq L9
iny
bne L1
inc ptr4+1
inx
bne L1
L9: tya ; get low byte of counter, hi's all set
rts