Reading bits from stream. 1

[countdrak]

The file format is such that in every 32 bits 1st 2 bits are control and next 10 are signal3, the next 10 signal2, last 10 is signal1.

How do I read in the 32 bits? Have no idea, so any idea would be appreciated.

 

[TrojanWarBlade]

There are many ways to do this but the most important thing will be how you process the data.
To do this you will need a bitfield structure (or, if you are feeling brave, you could manually mask out the bits for each field individually).
So in your case you might like a structure like this:

typedef struct {
        unsigned    control : 2,
                    signal3 : 10,
                    signal2 : 10,
                    signal1 : 10   } bits;

Then you can use a "bits" pointer and refer to the the relevant 32 bit word and register in it.


Trojan.

 

[TrojanWarBlade]

Note: You might have to reverse the order of the fields in the structure depending upon whether your processor is big-endian or little-endian.


Trojan.

 

[countdrak]

Thanks. That is exactly how I started off, but got lost in the middle. I should scratch it and start again.

 

[ArkM]

Strictly speaking, C does not define bit field order at all. So it seems structure bit field is (almost useless concept. Better use shift and mask (bitwise ops) approach: it's more safe method for the platform-dependent operations...