Bitfield « bit « C Data Type Q&A

1. Bitfield masks in C    stackoverflow.com

Is there a portable way in C to find out the mask for a bit field at compile time? Ideally, I'd like to be able to atomically clear a field like this:

struct ...

2. Tips on redefining a register bitfield in C    stackoverflow.com

I am struggling trying to come up with a clean way to redefine some register bitfields to be usable on a chip I am working with. For example, this is what one ...

3. 16bit bitfield leads to *read from uninitialised memory* warning    stackoverflow.com

I have this typedef:

typedef union
{
    unsigned Value;
    unsigned Timestamp:16;
} BITFIELD;

BITFIELD bitfield;

// read from uninitialised memory - may result in unexpected behaviour
bitfield.Timestamp ...

4. A "dynamic bitfield" in C    stackoverflow.com

In this question, assume all integers are unsigned for simplicity. Suppose I would like to write 2 functions, pack and unpack, which let you pack integers of smaller width into, say, a ...

5. How to replace bits in a bitfield without affecting other bits using c    stackoverflow.com

I wanted to replace bit/bits(more than 1) in a 32/64 bit data field without affecting other bits.Say for example: I have a 64 bit register where bits 5&6 can take values 0,1,2,3.

5:6 ...

6. Type of lvalue.bitfield when the underlying bitfield type is not int in C    stackoverflow.com

Someone drew my attention to the following program:

#include <stdio.h>

struct X50 {
 long long int z:50;
} s50 = { 2 };

struct X10 {
 long long int z:10;
} s10 = { 2 };

int ...

7. Will this bitfield work the way I expect?    stackoverflow.com

I've been doing some reading about bitfields in C, how the C standard doesn't enforce any particular ordering of the fields in a machine word, and so on. I hope this question ...