96 lines
2.1 KiB
C
96 lines
2.1 KiB
C
#define PIXEL_C
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#include "config.h"
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#include "pixel.h"
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#include "borg_hw/borg_hw.h"
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unsigned char shl_table[] = {0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
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void clear_screen(unsigned char value){
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unsigned char p,*pix,v=0xff;
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unsigned int i;
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for(p=0;p<NUMPLANE;p++){
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pix=&pixmap[p][0][0];
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if(p==value)
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v=0;
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for(i=0;i<NUM_ROWS*LINEBYTES;i++)
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pix[i]=v;
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}
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}
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void setpixel(pixel p, unsigned char value ){
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p.x %= NUM_COLS;
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if(value>NUMPLANE)
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value=NUMPLANE;
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unsigned char pos = (p.y%NUM_ROWS)*LINEBYTES + (p.x/8);
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unsigned char mask = shl_table[p.x%8];
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unsigned char plane;
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for(plane=0;plane<value;plane++)
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pixmap[plane][0][pos]|=mask;
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mask ^=0xff;
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for(;plane<NUMPLANE;plane++)
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pixmap[plane][0][pos]&=mask;
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}
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//shifts pixmap left. It is really shifted right, but because col0 is left in the Display it's left.
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void shift_pixmap_l(){
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unsigned char plane, row, byte;
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for(plane=0; plane<NUMPLANE; plane++){
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for(row=0;row<NUM_ROWS; row++){
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for(byte=0;byte<(LINEBYTES-1);byte++){
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pixmap[plane][row][byte] >>= 1;
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pixmap[plane][row][byte] |= (pixmap[plane][row][byte+1] & 0x01) * 0x80;;
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}
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pixmap[plane][row][LINEBYTES-1] >>= 1;
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}
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}
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}
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unsigned char get_pixel(pixel p){
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if( (p.x >= NUM_COLS) || (p.y >= NUM_ROWS) ){
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return 0xff;
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}else{
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return 0!= (pixmap[0][p.y][p.x/8] & shl_table[p.x%8]);
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}
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}
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/**
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* An implementation of Bresenham's line drawing algorithm.
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* @param p1 first coordinate of the line
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* @param p2 second coordinate of the line
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* @param color brightness level of the line
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*/
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void line(pixel p1,
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pixel const p2,
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unsigned char const color)
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{
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operand_t const dx = p1.x < p2.x ? p2.x - p1.x : p1.x - p2.x;
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operand_t const sx = p1.x < p2.x ? 1 : -1;
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operand_t const dy = p1.y < p2.y ? p2.y - p1.y : p1.y - p2.y;
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operand_t const sy = p1.y < p2.y ? 1 : -1;
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operand_t error = dx - dy;
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while(1)
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{
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setpixel(p1, color);
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if ((p1.x == p2.x) && (p1.y == p2.y))
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break;
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operand_t const error2 = 2 * error;
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if (error2 > -dy)
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{
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error -= dy;
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p1.x += sx;
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}
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if (error2 < dx)
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{
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error += dx;
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p1.y += sy;
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}
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}
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}
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