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cc65/libsrc/common/toupper.s
2020-04-02 22:58:16 +02:00

29 lines
845 B
ArmAsm

; toupper.s
;
; This file is part of
; cc65 - a freeware C compiler for 6502 based systems
;
; https://cc65.github.io
;
; See "LICENSE" file for legal information.
;
; int toupper (int c);
;
.export _toupper
.include "ctype.inc"
.import ctypemaskdirect
_toupper:
cpx #$00 ; out of range?
bne @L2 ; if so, return the argument unchanged
tay ; save char
jsr ctypemaskdirect ; get character classification
and #CT_LOWER ; lower case char?
beq @L1 ; jump if no
tya ; restore char
adc #<('A'-'a') ; make upper case char (ctypemaskdirect ensures carry clear)
rts
@L1: tya ; restore char
@L2: rts