/*
 * Copyright 2004, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
 * Copyright 2015, Augustin Cavalier <waddlesplash>. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Effect from corTeX / Optimum.
 */

#include <SupportDefs.h>

#include "DrawStars.h"


// Hand-translated from x86 assembly.
/* draw a star (5 pixels) */
void draw_stars(int star_width, char* dstParam, char incParam)
{
        unsigned char* dst;
        unsigned char inc, al, cl;
        dst = (unsigned char*)dstParam;
        inc = (unsigned char)incParam;

        dst[star_width] += inc;
        if (dst[star_width] < inc) {
                // Overflowed.
                dst[star_width] = 255;
        }

        inc >>= 1;
        cl = dst[star_width - 1];
        cl += inc;
        if (cl < inc) {
                *dst = 255;
                dst[star_width - 1] = 255;
        } else {
                al = *dst;
                al += inc;
                if (al >= inc)
                        *dst = al;
                else
                        *dst = 255;
                dst[star_width - 1] = cl;
        }

        al = dst[star_width * 2];
        cl = dst[star_width + 1];
        al += inc;
        cl += inc;
        if (al < inc) {
                if (cl >= inc) {
                        dst[star_width * 2] = 255;
                        dst[star_width + 1] = cl;
                        return;
                }
        } else {
                if (cl >= inc) {
                        dst[star_width * 2] = al;
                        dst[star_width + 1] = cl;
                        return;
                }
        }

        dst[star_width * 2] = 255;
        dst[star_width + 1] = 255;
}