mirror of
https://github.com/nippur72/apple1-videocard-lib.git
synced 2024-06-07 22:29:29 +00:00
116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
// SCREEN 2 VALUES
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// pattern table: $0000-$17FF (256*8*3)
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// sprite patterns: $1800-$19FF
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// color table: $2000-$27FF (256*8*3)
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// name table: $3800-$3AFF (32*24 = 256*3 = 768)
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// sprite attributes: $3B00-$3BFF
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// unused $3C00-$3FFF
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//
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#define SCREEN2_PATTERN_TABLE 0x0000
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#define SCREEN2_NAME_TABLE 0x3800
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#define SCREEN2_COLOR_TABLE 0x2000
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#define SCREEN2_SPRITE_PATTERNS 0x1800
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#define SCREEN2_SPRITE_ATTRS 0x3b00
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#define SCREEN2_SIZE (32*24)
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byte SCREEN2_TABLE[8] = {
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0x02, 0xc0, 0x0e, 0xff, 0x03, 0x76, 0x03, 0x25
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};
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void SCREEN2_INIT() {
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static byte i;
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for(i=0;i<8;i++) {
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write_reg(i, SCREEN2_TABLE[i]);
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}
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}
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void SCREEN2_FILL() {
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static word i;
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// fills name table x3 with increasing numbers
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set_vram_addr(SCREEN2_NAME_TABLE);
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for(i=0;i<SCREEN2_SIZE;i++) {
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POKE(VDP_DATA, i & 0xFF);
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}
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// fill pattern table with 0 (clear screen)
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set_vram_addr(SCREEN2_PATTERN_TABLE);
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for(i=0;i<768*8;i++) {
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POKE(VDP_DATA, 0);
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}
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// fill color table with $1F
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set_vram_addr(SCREEN2_COLOR_TABLE);
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for(i=0;i<768*8;i++) {
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POKE(VDP_DATA, 0x1f);
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}
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}
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void SCREEN2_PUTC(byte ch, byte x, byte y, byte col) {
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byte *source = &FONT[(ch-32)*8];
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byte i;
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word paddr = SCREEN2_PATTERN_TABLE + x*8 + y*256;
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word caddr = SCREEN2_COLOR_TABLE + x*8 + y*256;
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set_vram_addr(paddr); for(i=0;i<8;i++) POKE(VDP_DATA, source[i]);
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set_vram_addr(caddr); for(i=0;i<8;i++) POKE(VDP_DATA, col);
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}
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void SCREEN2_PUTS(byte x, byte y, byte col, char *s) {
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while(*s) {
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SCREEN2_PUTC(*s++, x++, y, col);
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}
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}
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void SCREEN2_PSET(byte x, byte y) {
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word paddr = SCREEN2_PATTERN_TABLE + (x & 0b11111000) + (y & 0b11111000)*32 + y%8;
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byte pattern = 128 >> (x%8);
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byte data;
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set_vram_read_addr(paddr);
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data = PEEK(VDP_DATA);
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set_vram_addr(paddr);
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POKE(VDP_DATA,data | pattern);
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}
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// int vti_abs(int x) {
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// return x < 0 ? -x : x;
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// }
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//
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// // http://members.chello.at/~easyfilter/bresenham.html
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// void vti_ellipse_rect(int x0, int y0, int x1, int y1)
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// {
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// long a,b,b1,dx,dy,e2,err;
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//
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// a = vti_abs(x1-x0);
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// b = vti_abs(y1-y0);
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// b1 = b&1; /* values of diameter */
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// dx = 4*(1-a)*b*b;
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// dy = 4*(b1+1)*a*a; /* error increment */
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// err = dx+dy+b1*a*a; /* error of 1.step */
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//
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// if (x0 > x1) { x0 = x1; x1 += a; } /* if called with swapped points */
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// if (y0 > y1) y0 = y1; /* .. exchange them */
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// y0 += (b+1)/2; y1 = y0-b1; /* starting pixel */
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// a *= 8*a; b1 = 8*b*b;
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//
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// do {
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// SCREEN2_PSET(x1, y0); /* I. Quadrant */
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// SCREEN2_PSET(x0, y0); /* II. Quadrant */
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// SCREEN2_PSET(x0, y1); /* III. Quadrant */
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// SCREEN2_PSET(x1, y1); /* IV. Quadrant */
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// e2 = 2*err;
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// if (e2 <= dy) { y0++; y1--; err += dy += a; } /* y step */
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// if (e2 >= dx || 2*err > dy) { x0++; x1--; err += dx += b1; } /* x step */
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// } while (x0 <= x1);
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//
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// while (y0-y1 < b) { /* too early stop of flat ellipses a=1 */
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// SCREEN2_PSET(x0-1, y0); /* -> finish tip of ellipse */
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// SCREEN2_PSET(x1+1, y0++);
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// SCREEN2_PSET(x0-1, y1);
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// SCREEN2_PSET(x1+1, y1--);
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// }
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// }
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