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cc65/libsrc/atari/setcolor.s

52 lines
1.1 KiB
ArmAsm

;
; Christian Groessler, June 2004
;
; this file provides a color functions similar to BASIC
;
; void __fastcall__ _setcolor (unsigned char color_reg, unsigned char hue, unsigned char luminace);
; void __fastcall__ _setcolor_low (unsigned char color_reg, unsigned char color_value);
; unsigned char __fastcall__ _getcolor (unsigned char color_reg);
;
.export __setcolor, __setcolor_low, __getcolor
.import popa
.include "atari.inc"
.proc __getcolor
tax
lda COLOR0,x ; get current value
ldx #0
rts
.endproc
.proc __setcolor
; asl a ; not -> BASIC compatible
sta lum ; remember luminance
jsr popa ; get hue
asl a
asl a
asl a
asl a
ora lum
; jmp __setcolor_low
.endproc
.proc __setcolor_low
pha
jsr popa
tax
pla
sta COLOR0,x
rts
.endproc
.bss
lum: .res 1