mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 16:34:15 +00:00
46 lines
1.9 KiB
Plaintext
46 lines
1.9 KiB
Plaintext
;colors.a02 - Atari 2600 Color/BW Assembly Language Routines
|
|
|
|
;getclr(mask, clr, bw) - Get Color Based on Color B&W Switch Position
|
|
;Args: A - Mask for Color Cycling (0=None)
|
|
; Y - Color/Luminance to use in Color Mode
|
|
; X - Color/Luminance to use in B&W Mode
|
|
;Returns: Color to Use
|
|
GETCLR: STA TEMP2 ;Save Color Cycling Mask
|
|
LDA SWCHB ;Read Console Switches
|
|
AND #%00001000 ;Test TV Type Switch
|
|
BNE GETCLC ;If Off
|
|
TXA ; Load B&W Mode Color/Luminance
|
|
EOR TEMP2 ; Apply Mask
|
|
AND #$0F ; and Strip High Nybble
|
|
RTS ;Else
|
|
GETCLC: TYA ; Load Color Mode Color/Luminance
|
|
EOR TEMP2 ; and Apply Apply Mask
|
|
RTS ;Return Selected Color
|
|
|
|
;setclr(mask, &clrtbl) - Set Object Colors
|
|
;Args: X,Y = Pointer to 8-Byte Color Table Color Table
|
|
; Player0, Player1, Playfield, Background (Color)
|
|
; Player0, Player1, Playfield, Background (B&W)
|
|
;Sets: TEMP0,TEMP1 = Pointer to Color Table
|
|
;Affects: A,X,Y,N,Z
|
|
SETCLR: STY TEMP1 ;Save Pointer to Color Table
|
|
STX TEMP0
|
|
STA TEMP2 ;Save Color Cycling Mask
|
|
LDX #3 ;Setting 4 colors (0-3)
|
|
LDY #3 ;Refault to the color entries in the table (0-3)
|
|
LDA SWCHB ;Read Console Switches
|
|
AND #%00001000 ;Test TV Type Switch
|
|
BNE SETCLL ;If On
|
|
LDA #$0F ; Use Color Entries
|
|
AND TEMP2 ;Else
|
|
STA TEMP2 ; Strip High Nybble from Mask
|
|
LDY #7 ; and Use B&W Entries
|
|
SETCLL: LDA (TEMP0),Y ;Get Color/B&W Value
|
|
EOR TEMP2 ;Apply Color Cycling Mask
|
|
STA COLUP0,x ;and Set Object Color
|
|
DEY ;Decrement Table Pointer
|
|
DEX ;Decrement Register Pointer
|
|
BPL SETCLL ;If >0, Loop
|
|
RTS ;Return
|
|
|