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https://github.com/sehugg/8bitworkshop.git
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65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
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/*
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Scrolling demo.
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We've selected horizontal mirroring as the default, so
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nametables A and C are stacked on top of each other.
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The vertical scroll area is 480 pixels high; note how
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the nametables wrap around.
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*/
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#include "neslib.h"
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#include <string.h>
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// link the pattern table into CHR ROM
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//#link "chr_generic.s"
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// function to write a string into the name table
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// adr = start address in name table
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// str = pointer to string
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void put_str(unsigned int adr, const char *str) {
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vram_adr(adr); // set PPU read/write address
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vram_write(str, strlen(str)); // write bytes to PPU
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}
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// function to scroll window up and down until end
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void scroll_demo() {
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int x = 0; // x scroll position
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int y = 0; // y scroll position
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int dy = 1; // y scroll direction
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// infinite loop
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while (1) {
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// wait for next frame
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ppu_wait_frame();
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// update y variable
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y += dy;
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// change direction when hitting either edge of scroll area
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if (y >= 479) dy = -1;
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if (y == 0) dy = 1;
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// set scroll register
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scroll(x, y);
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}
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}
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// main function, run after console reset
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void main(void) {
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// set palette colors
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pal_col(0,0x02); // set screen to dark blue
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pal_col(1,0x14); // pink
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pal_col(2,0x20); // grey
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pal_col(3,0x30); // white
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// write text to name table
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put_str(NTADR_A(2,0), "Nametable A, Line 0");
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put_str(NTADR_A(2,15), "Nametable A, Line 15");
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put_str(NTADR_A(2,29),"Nametable A, Line 29");
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put_str(NTADR_C(2,0), "Nametable C, Line 0");
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put_str(NTADR_C(2,15), "Nametable C, Line 15");
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put_str(NTADR_C(2,29),"Nametable C, Line 29");
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// enable PPU rendering (turn on screen)
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ppu_on_all();
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// scroll window back and forth
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scroll_demo();
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}
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