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cc65/samples/lynx/mandelbrot.c
Greg King 314cdd7feb Added Atari Lynx versions of three sample programs.
The Lynx target can't build the usual versions because its library doesn't have conio output and stdio.
2022-07-21 03:20:44 +02:00

87 lines
2.4 KiB
C

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