; int isdigit (int c);
;
- .export _isdigit
- .import __ctype
+ .export _isdigit
+ .include "ctype.inc"
_isdigit:
- tay
- lda __ctype,y ; Get character classification
- and #$04 ; Mask digit bit
- rts
+ cpx #$00 ; Char range ok?
+ bne @L1 ; Jump if no
+ tay
+ lda __ctype,y ; Get character classification
+ and #CT_DIGIT ; Mask digit bit
+ rts
+
+@L1: lda #$00 ; Return false
+ tax
+ rts