apple1-videocard-lib/lib/tms_screen2.h
2021-12-15 16:54:13 +01:00

171 lines
5.2 KiB
C

byte SCREEN2_TABLE[8] = {
0x02, 0xc0, 0x0e, 0xff, 0x03, 0x76, 0x03, 0x25
};
// SCREEN 2 VALUES
// pattern table: $0000-$17FF (256*8*3)
// sprite patterns: $1800-$19FF
// color table: $2000-$27FF (256*8*3)
// name table: $3800-$3AFF (32*24 = 256*3 = 768)
// sprite attributes: $3B00-$3BFF
// unused $3C00-$3FFF
//
const word SCREEN2_PATTERN_TABLE = 0x0000;
const word SCREEN2_NAME_TABLE = 0x3800;
const word SCREEN2_COLOR_TABLE = 0x2000;
const word SCREEN2_SPRITE_PATTERNS = 0x1800;
const word SCREEN2_SPRITE_ATTRS = 0x3b00;
const word SCREEN2_SIZE = (32*24);
// prepare the screen 2 to be used as a bitmap
void screen2_init_bitmap(byte color) {
// erase the first sprite pattern
tms_set_vram_write_addr(SCREEN2_SPRITE_PATTERNS); // start writing in the sprite patterns
for(byte i=0;i<8;i++) {
TMS_WRITE_DATA_PORT(0); NOP;
}
// set all sprite coordinates to 0
tms_set_vram_write_addr(SCREEN2_SPRITE_ATTRS); // start writing in the sprite attribute
for(byte i=0;i<32;i++) {
TMS_WRITE_DATA_PORT(0); NOP; // y coordinate
TMS_WRITE_DATA_PORT(0); NOP; // x coordinate
TMS_WRITE_DATA_PORT(0); NOP; // name
TMS_WRITE_DATA_PORT(i); NOP; // color
}
// fill pattern table with 0 (clear screen)
tms_set_vram_write_addr(SCREEN2_PATTERN_TABLE);
for(word i=768*8;i!=0;i--) {
TMS_WRITE_DATA_PORT(0);
NOP;
}
// fill color table with black on white
tms_set_vram_write_addr(SCREEN2_COLOR_TABLE);
for(word i=768*8;i!=0;i--) {
TMS_WRITE_DATA_PORT(color);
NOP;
}
// fills name table x3 with increasing numbers
tms_set_vram_write_addr(SCREEN2_NAME_TABLE);
for(word i=0;i<SCREEN2_SIZE;i++) {
TMS_WRITE_DATA_PORT(i & 0xFF);
NOP;
}
}
void screen2_putc(byte ch, byte x, byte y, byte col) {
byte *source = &FONT[(word)(ch-32)*8];
word addr = x*8 + y*256;
tms_set_vram_write_addr(SCREEN2_PATTERN_TABLE + addr); for(byte i=0;i<8;i++) TMS_WRITE_DATA_PORT(source[i]);
tms_set_vram_write_addr(SCREEN2_COLOR_TABLE + addr); for(byte i=0;i<8;i++) TMS_WRITE_DATA_PORT(col);
}
void screen2_puts(byte x, byte y, byte col, char *s) {
byte c;
while(c=*s++) {
screen2_putc(c, x++, y, col);
}
}
#define PLOT_MODE_RESET 0
#define PLOT_MODE_SET 1
#define PLOT_MODE_INVERT 2
byte SCREEN2_PLOT_MODE = PLOT_MODE_SET;
void screen2_plot(byte x, byte y) {
byte pow2_table_reversed[8] = { 128,64,32,16,8,4,2,1 };
word paddr = SCREEN2_PATTERN_TABLE + (word)(x & 0b11111000) + (word)(y & 0b11111000)*32 + y%8;
tms_set_vram_read_addr(paddr);
byte data = TMS_READ_DATA_PORT;
byte mask = pow2_table_reversed[x%8];
tms_set_vram_write_addr(paddr);
switch(SCREEN2_PLOT_MODE) {
case PLOT_MODE_RESET:
data &= ~mask;
break;
case PLOT_MODE_SET:
data |= mask;
break;
case PLOT_MODE_INVERT:
data ^= mask;
break;
}
TMS_WRITE_DATA_PORT(data);
}
signed int vti_abs(signed int x) {
return x < 0 ? -x : x;
}
// http://members.chello.at/~easyfilter/bresenham.html
void vti_line(byte _x0, byte _y0, byte _x1, byte _y1) {
signed int x0 = (signed int) _x0;
signed int x1 = (signed int) _x1;
signed int y0 = (signed int) _y0;
signed int y1 = (signed int) _y1;
signed int dx = vti_abs(x1-x0);
signed int dy = -vti_abs(y1-y0);
signed int err = dx+dy; /* error value e_xy */
bool ix = x0<x1;
bool iy = y0<y1;
signed int e2;
for(;;){ /* loop */
screen2_plot((byte)x0, (byte)y0);
if (x0==x1 && y0==y1) break;
e2 = err<<1;//2*err;
if (e2 >= dy) { err += dy; if(ix) ++x0; else --x0; } /* e_xy+e_x > 0 */
if (e2 <= dx) { err += dx; if(iy) ++y0; else --y0; } /* e_xy+e_y < 0 */
}
}
/*
// http://members.chello.at/~easyfilter/bresenham.html
void vti_ellipse_rect(byte _x0, byte _y0, byte _x1, byte _y1)
{
//unsigned int x0,y0,x1,y1;
signed int x0 = (signed int) _x0;
signed int y0 = (signed int) _y0;
signed int x1 = (signed int) _x1;
signed int y1 = (signed int) _y1;
signed int a = vti_abs(x1-x0), b = vti_abs(y1-y0);
signed int b1 = b&1; // values of diameter
signed int dx = 4*(1-a)*b*b, dy = 4*(b1+1)*a*a; // error increment
signed int err = dx+dy+b1*a*a, e2; // error of 1.step
if (x0 > x1) { x0 = x1; x1 += a; } // if called with swapped points
if (y0 > y1) y0 = y1; // .. exchange them
y0 += (b+1)/2; y1 = y0-b1; // starting pixel
a *= 8*a; b1 = 8*b*b;
do {
screen2_plot((byte) x1, (byte) y0); // I. Quadrant
screen2_plot((byte) x0, (byte) y0); // II. Quadrant
screen2_plot((byte) x0, (byte) y1); // III. Quadrant
screen2_plot((byte) x1, (byte) y1); // IV. Quadrant
e2 = 2*err;
if (e2 <= dy) { y0++; y1--; err += dy += a; } // y step
if (e2 >= dx || 2*err > dy) { x0++; x1--; err += dx += b1; } // x step
} while (x0 <= x1);
while (y0-y1 < b) { // too early stop of flat ellipses a=1
screen2_plot((byte) x0-1, (byte) (y0)); // -> finish tip of ellipse
screen2_plot((byte) x1+1, (byte) (y0++));
screen2_plot((byte) x0-1, (byte) (y1));
screen2_plot((byte) x1+1, (byte) (y1--));
}
}
*/