mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-11-23 06:32:11 +00:00
87 lines
2.0 KiB
C
87 lines
2.0 KiB
C
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/*
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This demo sets up two DLLs (Display List Lists) of
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16 slots each. By adjusting the address and fine offset
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of the first DL entry, the screen can scroll vertically
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across the two DLLs. It can only wrap from the first 16
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to the second 16 slots.
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Note that this scheme can be used also for double-buffering.
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By swapping between the two DLLs each frame, one DLL can
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be written while the other is displayed.
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*/
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#include "atari7800.h"
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#include <string.h>
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#include "dll.h"
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//#link "dll.c"
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//#link "chr_font.s"
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//#link "generic8x16.s"
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char* hello = "\2\4\6\0\220\222\102";
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/*{pal:"vcs",n:16}*/
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const byte PALETTE[25] = {
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0x02, // background color
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0x8f, 0x4f, 0x1f, // palette 0
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0x34, 0x28, 0x1f, // palette 1
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0x7f, 0x5f, 0x1f, // palette 2
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0x44, 0x38, 0x1f, // palette 3
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0x6f, 0x6f, 0x1f, // palette 4
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0x54, 0x48, 0x1f, // palette 5
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0x0f, 0x7f, 0x1f, // palette 6
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0x14, 0x58, 0x1f, // palette 7
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};
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// set entire palette including background color
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void set_palette(register const byte* pal) {
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byte i;
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register byte* reg = (byte*) 0x20;
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for (i=0; i<32; i++) {
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if (i==0 || (i&3)) *reg = *pal++;
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reg++;
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}
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}
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void main() {
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byte i;
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byte y = 0;
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dll_setup();
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// activate DMA
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MARIA.CHARBASE = 0x80;
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set_palette(PALETTE);
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MARIA.CTRL = CTRL_DMA_ON | CTRL_DBLBYTE | CTRL_160AB;
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dll_clear();
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dll_add_string(hello, y+32, 32, DL_WP(8,0));
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for (i=0; i<8; i++) {
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dll_page(0);
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dll_add_sprite(0xa068, i*4, i*33, DL_WP(4,i));
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dll_add_sprite(0xa06c, i*8, i*25, DL_WP(4,i));
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dll_page(1);
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dll_add_sprite(0xa068, i*4, i*32, DL_WP(4,i));
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dll_add_sprite(0xa06c, 128-i*8, i*24, DL_WP(4,i));
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}
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dll_save();
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while (1) {
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// wait for vsync to end
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while ((MARIA.MSTAT & MSTAT_VBLANK) == 0) ;
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dll_set_scroll(y);
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dll_restore_all();
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// first sprite doesn't have time to draw when y < 40
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dll_page(0);
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dll_add_sprite(0xa06c, y, 128, DL_WP(4,1));
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dll_page(1);
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dll_add_sprite(0xa06c, y, 0, DL_WP(4,1));
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// wait for vsync to start
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while ((MARIA.MSTAT & MSTAT_VBLANK) != 0) ;
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y++;
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}
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}
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