mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-06-10 06:29:28 +00:00
51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
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#include "common.h"
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//#link "common.c"
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byte x = 0; // x scroll position
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byte y = 0; // y scroll position
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byte* scrnbuf[2]; // screen buffer(s)
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byte frame = 0;
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void main(void) {
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byte* src;
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byte* dst;
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clrscr();
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printf("\r\n\r\n\r\n Hello World!");
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printf("\r\n\r\n\r\n This is how we scroll");
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printf("\r\n\r\n\r\n One line at a time");
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printf("\r\n\r\n\r\n And now we have two buffers");
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printf("\r\n\r\n\r\n To copy all the bytes ");
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VIC.ctrl1 = 0x10; // 24 lines
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VIC.ctrl2 = 0x00; // 38 columns
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// get screen buffer addresses
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scrnbuf[0] = (byte*) 0x400;
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scrnbuf[1] = (byte*) 0x3c00;
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memcpy(scrnbuf[1], scrnbuf[0], 24*40);
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// infinite loop
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while (1) {
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// scroll left
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x--;
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// set scroll registers
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VIC.ctrl1 = VIC.ctrl1 & 0xf8;
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VIC.ctrl1 |= (y & 7);
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VIC.ctrl2 = VIC.ctrl2 & 0xf8;
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VIC.ctrl2 |= (x & 7);
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// calculate frame pointers
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src = scrnbuf[frame&1] + (x&7)*128;
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dst = scrnbuf[frame&1^1] + (x&7)*128;
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// wait for vsync
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waitvsync();
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// scroll hidden buffer
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memcpy(dst, src+1, 128);
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// every 8 pixels, switch farmes
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if ((x & 7) == 0) {
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VIC.addr = (VIC.addr & 0xf) | ((frame & 1) ? 0x10 : 0xf0);
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frame++;
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}
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}
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}
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