mirror of https://github.com/cc65/cc65.git
87 lines
2.4 KiB
C
87 lines
2.4 KiB
C
/*****************************************************************************\
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** mandelbrot sample program for Atari Lynx **
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** **
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** (w) 2002 by groepaz/hitmen, TGI support by Stefan Haubenthal **
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\*****************************************************************************/
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#include <stdlib.h>
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#include <tgi.h>
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/* Graphics definitions */
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#define SCREEN_X (tgi_getxres())
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#define SCREEN_Y (tgi_getyres())
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#define MAXCOL (tgi_getcolorcount())
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#define maxiterations 32
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#define fpshift (10)
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#define tofp(_x) ((_x)<<fpshift)
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#define fromfp(_x) ((_x)>>fpshift)
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#define fpabs(_x) (abs(_x))
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#define mulfp(_a,_b) ((((signed long)_a)*(_b))>>fpshift)
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#define divfp(_a,_b) ((((signed long)_a)<<fpshift)/(_b))
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/* Use static local variables for speed */
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#pragma static-locals (1);
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static void mandelbrot (signed short x1, signed short y1, signed short x2,
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signed short y2)
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{
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/* */
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register signed short r, r1, i;
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register signed short xs, ys, xx, yy;
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register signed short x, y;
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register unsigned char count;
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register unsigned char maxcol = MAXCOL;
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/* Calc stepwidth */
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xs = ((x2 - x1) / (SCREEN_X));
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ys = ((y2 - y1) / (SCREEN_Y));
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yy = y1;
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for (y = 0; y < (SCREEN_Y); y++) {
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yy += ys;
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xx = x1;
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for (x = 0; x < (SCREEN_X); x++) {
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xx += xs;
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/* Do iterations */
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r = 0;
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i = 0;
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for (count = 0; (count < maxiterations) &&
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(fpabs (r) < tofp (2)) && (fpabs (i) < tofp (2));
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++count) {
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r1 = (mulfp (r, r) - mulfp (i, i)) + xx;
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/* i = (mulfp(mulfp(r,i),tofp(2)))+yy; */
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i = (((signed long) r * i) >> (fpshift - 1)) + yy;
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r = r1;
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}
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if (count == maxiterations) {
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tgi_setcolor (0);
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} else {
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tgi_setcolor (count % maxcol);
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}
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/* Set pixel */
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tgi_setpixel (x, y);
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}
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}
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}
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void main (void)
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{
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/* Install the graphics driver */
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tgi_install (tgi_static_stddrv);
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/* Initialize graphics */
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tgi_init ();
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tgi_clear ();
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/* Calc mandelbrot set */
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mandelbrot (tofp (-2), tofp (-2), tofp (2), tofp (2));
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}
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