Serializing bit field structures

[(2b|!2b)==?]

I have a struct declared as follows:

struct RecordType1
{
unsigned int dt : 24; //3 bytes
unsigned int ts : 16; //2 bytes
unsigned int lsp : 24; //3 bytes (float value represented as int)
unsigned int lst : 16; //2 bytes
unsigned int lsv : 16; //2 bytes
unsigned int x1 : 24; //3 bytes (float value represented as int)
unsigned int x2 : 24; //3 bytes (float value represented as int)
unsigned int x3 : 24; //3 bytes (float value represented as int)
unsigned int x4 : 24; //3 bytes (float value represented as int)
unsigned int bv : 16; //2 bytes
unsigned int ak : 24; //3 bytes (float value represented as int)
unsigned int av : 16; //2 bytes
unsigned int cv : 24; //3 bytes
};

I need to serialize this struct by packing the bits into a contiguous
byte array, and then read it back from the byte array. I cant use
memcpy/sizeof because of boundary alignment ...

I'd appreciate if anyone can show me how to do this. Ieally, I would
like to this in a cross platform (i.e. "ENDIAN-ness" agnostic) way.

[.rhavin grobert]

Re: Serializing bit field structures

On 22 Okt., 10:03, James Kanze <james.ka...@gm ail.comwrote:

[...] since generally the compiler won't allocate a bit field
in a way that would cross a 32 bit boundary. [...] But there's
rarely any sense in having bit fields larger than 8 bits.)

shure? consider:

typedef unsigned __int64 QUAD;

#pragma pack (push, 1)
struct foo {
union {
QUAD qData;
struct {
QUAD nFirstNibble : 4;
QUAD nSecondNibble : 4;
QUAD nThirdNibble : 4;
QUAD nBloodyRest : 54;
};
};
};
#pragma pack (pop)

[Nick Keighley]

Re: Serializing bit field structures

On 22 Oct, 17:31, ".rhavin grobert" <cl...@yahoo.de wrote:

On 22 Okt., 10:03, James Kanze <james.ka...@gm ail.comwrote:
>

[...] since generally the compiler won't allocate a bit field
in a way that would cross a 32 bit boundary. [...] But there's
rarely any sense in having bit fields larger than 8 bits.)

>
shure? consider:
>
typedef unsigned __int64 QUAD;

eek! I suppose since you've hidden __int64 behind
a typedef you can live with that

#pragma pack (push, 1)

eek! ** 2

the guy want's *portable* stuff! How many platforms
does this work on?

struct foo {
  union {
    QUAD qData;
    struct {
      QUAD nFirstNibble  :  4;
      QUAD nSecondNibble :  4;
      QUAD nThirdNibble  :  4;
      QUAD nBloodyRest   : 54;
    };
  };};
>
#pragma pack (pop)

--
Nick Keighley