#include <stdio.h>
#include <SDL/SDL.h>

#define XRES 640
#define YRES 480
#define MAX_ITER 66
#define MAXNUM 0x8000

/* be sure to change the number of bits in the multiplier when doing this
 * bits > 14 need extension of num_t to unsigned int */
#define BITS 14
#define BAIL (1 << (BITS + 1))
#define BAIL_A (1 << BITS)

SDL_Surface *screen;
typedef unsigned short num_t;

typedef struct {
	num_t mag;
	num_t sig;
} sigmag_t;

typedef struct {
	sigmag_t r;
	sigmag_t i;
} cplx_t;

static inline cplx_t convert(num_t x, num_t y)
{
	sigmag_t r, i;
	r.mag = x > MAXNUM ? -x : x;
	r.sig = x > MAXNUM ? 1 : 0;
	i.mag = y > MAXNUM ? -y : y;
	i.sig = y > MAXNUM ? 1 : 0;
	cplx_t res = {r, i};
//	printf("convert: output: x = %d, y = %d\n", res.r.mag, res.i.mag);
	return res;
}

static inline sigmag_t mul(sigmag_t x, sigmag_t y)
{
	num_t xm = x.mag;
	num_t ym = y.mag;
	num_t mag = 
	            (ym & 0x2000 ? xm       : 0) +
	            (ym & 0x1000 ? xm >> 1  : 0) +
	            (ym & 0x0800 ? xm >> 2  : 0) +
	            (ym & 0x0400 ? xm >> 3  : 0) +
	            (ym & 0x0200 ? xm >> 4  : 0) +
	            (ym & 0x0100 ? xm >> 5  : 0) +
	            (ym & 0x0080 ? xm >> 6  : 0) +
	            (ym & 0x0040 ? xm >> 7  : 0) +
	            (ym & 0x0020 ? xm >> 8  : 0) +
	            (ym & 0x0010 ? xm >> 9  : 0) +
	            (ym & 0x0008 ? xm >> 10 : 0) +
	            (ym & 0x0004 ? xm >> 11 : 0) +
	            (ym & 0x0002 ? xm >> 12 : 0) +
	            (ym & 0x0001 ? xm >> 13 : 0);

	num_t sig = x.sig ^ y.sig;
	sigmag_t res = {mag, sig};
	return res;
}

static inline unsigned int calc_piqsl(num_t x, num_t y)
{
//	printf("calc_piqsl: x = %d, y = %d ############################ \n", x, y);
	unsigned int i;
	cplx_t c = convert(x, y);
	cplx_t z = c;
//	printf("xmag = %d, xsig = %d, ymag = %d, ysig = %d\n", c.r.mag, c.r.sig, c.i.mag, c.i.sig);
	for(i = 0; i < MAX_ITER; i++) {
		sigmag_t r2 = mul(z.r, z.r);
		sigmag_t i2 = mul(z.i, z.i);
		sigmag_t ri = mul(z.r, z.i);
//		printf("r2mag: %d  i2mag: %d  i: %d\n", r2.mag, i2.mag, i);
		if((r2.mag + i2.mag) & BAIL || z.r.mag & BAIL   || z.i.mag & BAIL 
		                            || z.r.mag & BAIL_A || z.i.mag & BAIL_A) {
			break;
		}
		num_t rmag = r2.mag - i2.mag + (c.r.sig ? -c.r.mag : c.r.mag);
		num_t imag = (ri.sig ? -ri.mag << 1 : ri.mag << 1) + (c.i.sig ? -c.i.mag : c.i.mag);
		z = convert(rmag, imag);
	}

//	printf("bailed at %d\n", i);
	return (i == MAX_ITER ? 0 : i);
}

void run_mandel()
{
	num_t i, j;
	int dick = 160;
	int zoom = 4;
	unsigned int res, *p;

	SDL_LockSurface(screen);
	p = screen->pixels;

	for(i = 0; i < XRES; i++) {
		for(j = 0; j <3 *dick; j++) {
			res = calc_piqsl((i - XRES/2) << zoom, (j - YRES/2) << zoom);
			res = res == 0 ? 0 : MAX_ITER - res - 3;
			p[i+j*XRES] = ((res & 0x1) << 23) | ((res & 0x8)  << 18) | ((res & 0x40) << 13) |
			              ((res & 0x2) << 14) | ((res & 0x10) <<  9) | ((res & 0x80) << 4) |
				      ((res & 0x4) <<  5) | ((res & 0x20));
			
		}
	}

	SDL_UnlockSurface(screen);
	SDL_Flip(screen);
}

int main()
{
	SDL_Event ev;
	screen = NULL;
	if(SDL_Init(SDL_INIT_VIDEO) < 0) {
		printf("Video init failed.\n");
		return 1;
	}

	screen = SDL_SetVideoMode(XRES, YRES, 32, SDL_SWSURFACE);
	if(!screen) {
		printf("Screen init failed.\n");
		return 1;
	}
	atexit(SDL_Quit);

	run_mandel();
	while(SDL_WaitEvent(&ev)) {
		switch(ev.type) {
		case SDL_QUIT: exit(0);
		default: break;
		}
	}

	return 0;
}