Question

In 3 operations how can I turn a byte into a 32 bit int that matches this:

0x1fffe

I can only explicitly access a byte at a time thus I start with 0xFF and then shift it.

I can do it using 4 operations but I cant find a way to eliminate one operation.

    int mask2 = 0xFF << 8;
    mask2 = mask2 | 0xFE;
    mask2 = mask2 + mask2;
    mask2 = mask2 | 0x02;

Any ideas?

In other words, I need a mask, 0x1FFFE to be made in 3 operations while only accessing a byte at a time like the example.

Answer 1

Maybe this is what you want… you start with one single byte value (0xff), and you work on it with 3 bitwise operations, obtaining 0x1fffe.

int in = 0xff;
int out = in<<9 | in<<1;