> asm mov ax ,[ WORD PTR rndval ]

> asm mov dx ,[ WORD PTR rndval +2]

> asm mov bx , ax

> asm dec bl

> asm mov [ BYTE PTR y ], bl // low 8 bits - 1 = y

> asm mov bx , ax

> asm mov cx , dx

> asm mov [ BYTE PTR x ], ah // next 9 bits = x

> asm mov [ BYTE PTR x +1] , dl

I don't understand the need for the second asm mov bx , ax : BX is not used afterwards. Same for CX, it is never used.

> uint32_t rndval = 1;

> uint16_t x,y;

> do

> {

> y = rndval & 0x00F; // Y = low 8 bits

> x = rndval & 0x1F0; // X = High 9 bits

Er... no, if you do that, you only get the lowest 4 bits in y, and then you only get 5 bits in x (and not the right ones, of course).

It should be:

       y = rndval & 0x000000FF;  // Y = low 8 bits

And then you have a 'problem' for x, because you must shift it right, otherwise it doesn't fit in a 16-bit variable:

       x = rndval & 0x0001FF00;  // X = bits 8 to... 16 > 15, irk

So you should just do :

       x = rndval >> 8;  // X = bits 8 to 17, in their right place