mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-12-01 14:51:52 +00:00
51 lines
1.0 KiB
Plaintext
51 lines
1.0 KiB
Plaintext
/* Atari VCS Color Bars Program */
|
|
|
|
#pragma origin $F800 //2k Cartridge
|
|
#include <vcshead.h02> //TIA and RIOT Registers
|
|
#include <vcsstub.h02> //Initialize VCS
|
|
|
|
zeropage char clrbkg; //Background Color
|
|
zeropage char clrmov; //Color Movement Flag
|
|
zeropage char clrofs; //Color Offset
|
|
zeropage char clrmsk; //Color/B&W Mask
|
|
|
|
/* Setup Code */
|
|
void setup() {
|
|
return;
|
|
}
|
|
|
|
/* Vertical Blank Code */
|
|
void vrtblk() {
|
|
return;
|
|
}
|
|
|
|
/* Execute Kernel Code */
|
|
void kernel() {
|
|
X=192; //Draw 192 Scanlines
|
|
do {
|
|
clrbkg = X;
|
|
if (!SWCHB & 128) clrbkg<<;
|
|
A = clrbkg + clrofs & clrmsk; //Set Background Color
|
|
WSYNC = A; //Wait for end of Scanline
|
|
COLUBK = A; //Set Background Color
|
|
X--;
|
|
} while (X);
|
|
return;
|
|
}
|
|
|
|
/* Execute Overscan Code */
|
|
void ovrscn() {
|
|
if (!SWCHB & 1) //Game Reset
|
|
clrmov = $FF; //Turn On Scrolling
|
|
if (!SWCHB & 2) //Game Select
|
|
clrmov = 0; //Turn Off Scrolling
|
|
clrmsk = (SWCHB & 8) ? $FF : $0F;
|
|
if (clrmov) {
|
|
if (SWCHB & 64) clrofs--; else clrofs++;
|
|
}
|
|
}
|
|
|
|
#include <vcsfoot.h02> //Finalization Code
|
|
|
|
|