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cc65/libsrc/atari5200/textcolor.s
Christian Groessler be6bba66a9 atari5200: conio now uses just four colors altogether
See discussion in PR #870.
2019-04-12 12:49:38 +02:00

29 lines
683 B
ArmAsm

;
; Christian Groessler, 02-Apr-2019
;
; unsigned char __fastcall__ textcolor (unsigned char color);
;
; "color" value is a palette index (0..3) or COLOR_xxx value (0..3)
.export _textcolor
.import conio_color
_textcolor:
; move bits #0 and #1 to bits #6 and #7
and #3
clc
ror a
ror a
ror a ; new conio_color value
ldx conio_color ; get old value
sta conio_color ; store new value
txa
; move bits #6 and #7 to bits #0 and #1
clc
rol a
rol a
rol a
ldx #0
rts