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cc65/libsrc/common/tolower.s
cuz dccc89edae Squeezed a few cycles/bytes out of tolower and toupper.
git-svn-id: svn://svn.cc65.org/cc65/trunk@690 b7a2c559-68d2-44c3-8de9-860c34a00d81
2001-04-19 06:46:01 +00:00

20 lines
423 B
ArmAsm

;
; Ullrich von Bassewitz, 02.06.1998
;
; int tolower (int c);
;
.export _tolower
.import __ctype, __cdiff
_tolower:
tay ; Get C into Y
lda __ctype,y ; Get character classification
lsr a
lsr a ; Get bit 1 (upper case char) into carry
tya ; Get char back into A
bcc L9 ; Jump if no upper case char
sbc __cdiff ; make lower case char (carry already set)
L9: rts ; CC are set