#define BLOCK_SIZE	( 1 << BLOCK_SHIFT )

void BLOCK_FUNC( void ){
	int				v, i, b, lightstep, lighttemp, light;
	byte	pix, *psource, *prowdest;

	psource = pbasesource;
	prowdest = prowdestbase;

	for (v=0 ; v<r_numvblocks ; v++)
	{
	// FIXME: make these locals?
	// FIXME: use delta rather than both right and left, like ASM?
		lightleft = r_lightptr[0];
		lightright = r_lightptr[1];
		r_lightptr += r_lightwidth;
		lightleftstep = (r_lightptr[0] - lightleft) >> BLOCK_SHIFT;
		lightrightstep = (r_lightptr[1] - lightright) >> BLOCK_SHIFT;

		for (i=0 ; i<BLOCK_SIZE ; i++)
		{
			lighttemp = lightleft - lightright;
			lightstep = lighttemp >> BLOCK_SHIFT;

			light = lightright;

			for (b=BLOCK_SIZE-1; b>=0; b--)
			{
				pix = psource[b];
				prowdest[b] = ((unsigned char *)vid.colormap)
						[(light & 0xFF00) + pix];
				light += lightstep;
			}
	
			psource += sourcetstep;
			lightright += lightrightstep;
			lightleft += lightleftstep;
			prowdest += surfrowbytes;
		}

		if (psource >= r_sourcemax)
			psource -= r_stepback;
	}
}

#undef BLOCK_FUNC
#undef BLOCK_SIZE
#undef BLOCK_SHIFT