mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-21 07:33:14 +00:00
96 lines
1.6 KiB
C
96 lines
1.6 KiB
C
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#include "common.h"
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//#link "common.c"
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#include "rasterirq.h"
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//#link "rasterirq.s"
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#include "bcd.h"
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//#link "bcd.c"
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extern const unsigned char sinustable[0x100];
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//#link "sinustable.c"
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///// VARIABLES
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byte frame = 0;
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byte scroll_y = 0;
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byte target_line = 0;
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///// FUNCTIONS
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void line_crunch() {
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// load scroll y
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asm("lda %v", scroll_y);
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asm("and #7");
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asm("ora #$18");
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asm("tax");
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// get current raster line
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asm("lda $d012");
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// wait for next raster line
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asm("@loop:");
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asm("cmp $d012");
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asm("beq @loop");
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// set y scroll (ctrl1)
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asm("stx $d011");
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}
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void display_list(void) {
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// set initial YSCROLL
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VIC.ctrl1 = 0x18 | (scroll_y & 7);
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// do line crunch?
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if (scroll_y < 24) {
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// wait for target line
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target_line = 47 + (scroll_y & 7);
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while (VIC.rasterline != target_line) { }
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// increment YSCROLL
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scroll_y++;
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line_crunch();
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// do additional line crunches?
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if (scroll_y < 17) {
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scroll_y++;
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line_crunch();
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if (scroll_y < 10) {
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scroll_y++;
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line_crunch();
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}
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}
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}
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VIC.bgcolor[0] = COLOR_CYAN;
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VIC.bordercolor = COLOR_BLUE;
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DLIST_RESTART(40);
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}
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void main() {
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int i;
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clrscr();
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memset(COLOR_RAM, COLOR_BLUE, 1000);
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for (i=0; i<40*25; i++)
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POKE(0x400 + i, 205 + (rand() & 1));
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for (i=40*25; i<1024; i++)
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POKE(0x400 + i, i);
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for (i=0; i<1024; i+=40)
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POKE(0x400 + i, 122);
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SET_VIC_BITMAP(0x1000);
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DLIST_SETUP(display_list);
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// game loop, repeat forever
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while (1) {
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// wait for end of frame
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waitvsync();
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// animate and set scroll_y
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frame += 4;
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scroll_y = sinustable[frame] >> 3;
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}
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}
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