n2DLib rotosprite implementation

void rotate(int x, int y, int cx, int cy, Fixed angle, Rect *out)
{
    x -= cx;
    y -= cy;
    out->x = fixtoi(fixmul(itofix(x), fixcos(angle)) + fixmul(itofix(y), fixsin(angle))) + cx;
    out->y = fixtoi(fixmul(itofix(x), -fixsin(angle)) + fixmul(itofix(y), fixcos(angle))) + cy;
}

void getBoundingBox(int x, int y, int w, int h, int cx, int cy, Fixed angle, Rect *out)
{
    Rect tl, tr, bl, br;
    rotate(x, y, cx, cy, angle, &tl);
    rotate(x + w, y, cx, cy, angle, &tr);
    rotate(x, y + h, cx, cy, angle, &bl);
    rotate(x + w, y + h, cx, cy, angle, &br);
    out->x = min(min(min(tl.x, tr.x), bl.x), br.x);
    out->y = min(min(min(tl.y, tr.y), bl.y), br.y);
    out->w = max(max(max(tl.x, tr.x), bl.x), br.x) - out->x;
    out->h = max(max(max(tl.y, tr.y), bl.y), br.y) - out->y;
}

void drawSpriteRotated(const unsigned short* source, const Rect* sr, const Rect* rc, Fixed angle, int flash, unsigned short flashColor)
{
    Rect defaultRect = { source[0] / 2, source[1] / 2, 0, 0 };
    Rect fr;
    unsigned short currentPixel;
    Fixed dX = fixcos(angle), dY = fixsin(angle);

    if(rc == NULL)
        rc = &defaultRect;

    getBoundingBox(-rc->x, -rc->y, source[0], source[1], 0, 0, angle, &fr);
    fr.x += sr->x;
    fr.y += sr->y;
    fr.w += fr.x;
    fr.h += fr.y;

    Rect cp, lsp, cdrp;

    // Feed fixed-point to get fixed-point
    rotate(itofix(fr.x - sr->x), itofix(fr.y - sr->y), 0, 0, -angle, &lsp);

    for(cp.y = fr.y; cp.y <= fr.h; cp.y++)
    {
        cdrp.x = lsp.x;
        cdrp.y = lsp.y;

        for(cp.x = fr.x; cp.x <= fr.w; cp.x++)
        {
            if(cp.x >= 0 && cp.x < 320 && cp.y >= 0 && cp.y < 240)
            {
                currentPixel = getPixel(source, fixtoi(cdrp.x) + rc->x, fixtoi(cdrp.y) + rc->y);
                if(currentPixel != source[2])
                {
                    setPixelUnsafe(cp.x, cp.y, flash ? flashColor : currentPixel);
                }
            }
            cdrp.x += dX;
            cdrp.y += dY;
        }

        lsp.x -= dY;
        lsp.y += dX;
    }
}