TWin.Position.y1 = 128; // 10000
else
TWin.Position.y1 = 256; // 00000
+ TWin.ymask = TWin.Position.y1 - 1;
// Texture window size is determined by the least bit set of the relevant 5 bits
TWin.Position.x1 = 128; // 10000
else
TWin.Position.x1 = 256; // 00000
+ TWin.xmask = TWin.Position.x1 - 1;
// Re-calculate the bit field, because we can't trust what is passed in the data