mirror of
https://github.com/sehugg/8bitworkshop.git
synced 2024-06-14 00:29:35 +00:00
38 lines
969 B
C
38 lines
969 B
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; // screen buffer
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void main(void) {
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clrscr();
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printf("\r\n Hello World!");
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printf("\r\n\r\n This is how we scroll");
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printf("\r\n\r\n One line at a time");
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printf("\r\n\r\n But we don't have time");
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printf("\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 address
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scrnbuf = (byte*)((VIC.addr << 6) & 0x3c00);
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// infinite loop
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while (1) {
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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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// wait for vsync
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waitvsync();
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// every 8 pixels, move screen cells
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if ((x & 7) == 0) {
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memcpy(scrnbuf, scrnbuf+1, 40*8-1);
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}
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}
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}
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