Is there a concise way to create bit masks in C?
I need to create开发者_StackOverflow three bit masks that end up in three 32-bit unsigned ints
(let's call them x, y and z). The masks should end up like this:
x: 0000 0001 1111 1111 1111 1111 1111 1111
y: 0000 1110 0000 0000 0000 0000 0000 0000
z: 1111 0000 0000 0000 0000 0000 0000 0000
So far I've got this:
unsigned int x = (1<<25)-1;
unsigned int y = (~x)&((1<<28)-1);
unsigned int z = (~x)<<3;
But it seems a bit messy. Can anyone come up with a more concise (and readable) way?
unsigned int x = 0x01FFFFFF,
y = 0x0E000000,
z = 0xF0000000;
Is this readable for you?
If you are using C99, use the "new" fixed width types:
uint32_t x, y, z;
x = 0x01FFFFFF;
y = 0x0E000000;
z = 0xF0000000;
Or you could use "ugly" octal :-)
x = 000177777777; // 00 000 001 111 111 111 111 111 111 111 111
y = 001600000000; // 00 001 110 000 000 000 000 000 000 000 000
z = 036000000000; // 11 110 000 000 000 000 000 000 000 000 000
Simply put into your unsigned int the number you want (if you prefer using hexadecimal notation):
unsigned int mask= 8 ; // 00000000 00000000 00000000 00001000
unsigned int mask = 0x08 ;
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