littleendian_strings.h

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#ifndef MINOS_LESTRINGS
#define MINOS_LESTRINGS

// $Id: littleendian_strings.h,v 1.3 2004/04/05 20:09:02 bv Exp $
//
// Utility functions for translating between an array of little-endian
// long words (i.e. 32 bit values) and an array of characters.
//
// This is necessary because the base type of RawDataBlock is an
// array of Int_t's which transform differently under endianess
// than an array of Char_t's.  Since the DAQ is simply copying 
// memory from a char string to the location in the raw block,
// following some other data, on a little-endian machine then 
// the unpacking code needs to account for this when processed 
// on a big-endian machine (e.g. SGI-IRIX).
//

#ifdef R__BYTESWAP
// little endian is the opposite of network order
// while the ROOT's R__BYTESWAP flags cases that are opposite to 
// network order so if it is defined then nothing needs to happen
#define minos_letohl(x)  (x)
#define minos_htolel(x)  (x)
#else
// this section is for architectures with network order
// in this case the code is non-trivial because the packing is
// assumed to be little endian
static UInt_t
UInt_abcd_dcba(UInt_t x)
{
   return ( (x << 24)           | ((x & 0xff00) << 8) | 
            ((x >> 8) & 0xff00) | (x >> 24) );
}

#define minos_letohl(x) UInt_abcd_dcba(x)
#define minos_htolel(x) UInt_abcd_dcba(x)
#endif

UInt_t  nwords_in_string(const Char_t* x);
void    pack_string_in_lel(Int_t* dest_i ,const Char_t* src_c);
Char_t* unpack_lel_to_string(const Int_t* src_i, UInt_t nwd);

#endif //MINOS_LESTRINGS

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