cbf_compress.c

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/**********************************************************************
 * cbf_compress -- compression and decompression                      *
 *                                                                    *
 * Version 0.6 13 January 1999                                        *
 *                                                                    *
 *            Paul Ellis (ellis@ssrl.slac.stanford.edu) and           *
 *         Herbert J. Bernstein (yaya@bernstein-plus-sons.com)        *
 **********************************************************************/
  
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#ifdef __cplusplus

extern "C" {

#endif

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>

#include "cbf.h"
#include "cbf_alloc.h"
#include "cbf_file.h"
#include "cbf_compress.h"
#include "cbf_canonical.h"
#include "cbf_packed.h"
#include "cbf_byte_offset.h"
#include "cbf_predictor.h"
#include "cbf_uncompressed.h"


  /* Compress an array */

int cbf_compress (void         *source, 
                  size_t        elsize, 
                  int           elsign, 
                  size_t        nelem,
                  unsigned int  compression, 
                  cbf_file     *file, 
                  size_t       *compressedsize,
                  int          *bits, 
                  char         *digest)
{
  int errorcode;
  
  size_t size;


    /* Discard any bits in the buffers */
    
  cbf_failnez (cbf_reset_bits (file))
  
  if (compressedsize)
  
    *compressedsize = 0;


    /* Start a digest? */
    
  if (digest)
  
    cbf_failnez (cbf_start_digest (file))


  errorcode = 0;
  
  size = 0;

  switch (compression)
  {
    case CBF_CANONICAL:
    
      errorcode = cbf_compress_canonical (source, elsize, elsign, nelem,
                                          compression, file, 
                                          &size, bits);
      break;

    case CBF_PACKED:
    case 0:

      errorcode = cbf_compress_packed (source, elsize, elsign, nelem,
                                       compression, file,
                                       &size, bits);
      break;

    case CBF_BYTE_OFFSET:
    
      errorcode = cbf_compress_byte_offset (source, elsize, elsign, nelem,
                                            compression, file, 
                                            &size, bits);
      break;

    case CBF_PREDICTOR:
    
      errorcode = cbf_compress_predictor (source, elsize, elsign, nelem,
                                          compression, file, 
                                          &size, bits);
      break;

    case CBF_NONE:
    
      errorcode = cbf_compress_none (source, elsize, elsign, nelem,
                                     compression, file, 
                                     &size, bits);
      break;

  default:
  
      errorcode = CBF_ARGUMENT;
  }
  
  
    /* Add the compressed size */
    
  if (compressedsize)
  
    *compressedsize += size;


    /* Flush the buffers */

  errorcode |= cbf_flush_bits (file);
  

    /* Get the digest? */
    
  if (digest)
  
     errorcode |= cbf_end_digest (file, digest);


    /* Done */

  return errorcode;
}


  /* Get the parameters of an array (read up to the start of the table) */
  
int cbf_decompress_parameters (int          *eltype, 
                               size_t       *elsize, 
                               int          *elsigned, 
                               int          *elunsigned,
                               size_t       *nelem, 
                               int          *minelem, 
                               int          *maxelem,
                               unsigned int  compression,
                               cbf_file     *file)
{
  unsigned int compression_file, nelem_file;

  int errorcode, minelement_file, maxelement_file, 
                   elsigned_file, elunsigned_file;


    /* Discard any bits in the buffers */

  cbf_failnez (cbf_reset_bits (file));
  
   /* Check compression type */

  if (compression != CBF_CANONICAL   &&
      compression != CBF_PACKED      &&
      compression != CBF_BYTE_OFFSET &&
      compression != CBF_PREDICTOR   &&
      compression != CBF_NONE)

    return CBF_FORMAT;

  if (compression == CBF_NONE)
  {
    nelem_file = 0;

    minelement_file = maxelement_file = 0;
  } 
  else 
  { 
      /* Read the number of elements (64 bits) */

    cbf_failnez (cbf_get_integer (file, (int *) &nelem_file, 0, 64))


      /* Read the minimum element (64 bits) */

    errorcode = cbf_get_integer (file, &minelement_file, 1, 64);

    if (errorcode && errorcode != CBF_OVERFLOW)

      return errorcode;


      /* Read the maximum element (64 bits) */

    errorcode = cbf_get_integer (file, &maxelement_file, 1, 64);

    if (errorcode && errorcode != CBF_OVERFLOW)

      return errorcode;
  }


    /* Update the element sign, type, minimum, maximum and number */

  elsigned_file = !(((unsigned) minelement_file) <= 
                    ((unsigned) maxelement_file) &&
                    ((signed)   minelement_file) >
                    ((signed)   maxelement_file));

  elunsigned_file = !(((signed)   minelement_file) <= 
                      ((signed)   maxelement_file) &&
                      ((unsigned) minelement_file) >  
                      ((unsigned) maxelement_file));

  if (elsigned)
  
    *elsigned = elsigned_file;

  if (elunsigned)
  
    *elunsigned = elunsigned_file;

  if (eltype)
  
    *eltype = CBF_INTEGER;

  if (elsize)

      /* Calculate the minimum number of bytes needed to hold the elements */
      
    if (minelement_file == 0 && maxelement_file == 0)
      
      *elsize = 0;
      
    else

      if ((!elsigned_file ||
          ((signed) minelement_file == (signed short) minelement_file &&
           (signed) maxelement_file == (signed short) maxelement_file)) ||
          (!elunsigned_file ||
          ((unsigned) minelement_file == (unsigned short) minelement_file &&
           (unsigned) maxelement_file == (unsigned short) maxelement_file)))
           
        if ((!elsigned_file ||
            ((signed) minelement_file == (signed char) minelement_file &&
             (signed) maxelement_file == (signed char) maxelement_file)) ||
             (!elunsigned_file ||
            ((unsigned) minelement_file == (unsigned char) minelement_file &&
             (unsigned) maxelement_file == (unsigned char) maxelement_file)))
             
          *elsize = sizeof (char);
          
        else

          *elsize = sizeof (short);
          
      else
        
        *elsize = sizeof (int);

  if (minelem)
  
    *minelem = minelement_file;

  if (maxelem)
  
    *maxelem = maxelement_file;

  if (nelem)
  
    *nelem = nelem_file;


    /* Success */

  return 0;
}


  /* Decompress an array (from the start of the table) */

int cbf_decompress (void         *destination, 
                    size_t        elsize, 
                    int           elsign, 
                    size_t        nelem, 
                    size_t       *nelem_read,
                    unsigned int  compression,
                    int           bits, 
                    int           sign,
                    cbf_file     *file)
{
  switch (compression)
  {
    case CBF_CANONICAL:
    
      return cbf_decompress_canonical (destination, elsize, elsign, nelem,
                                       nelem_read, compression, 
                                       file);

    case CBF_PACKED:
    case 0:

      return cbf_decompress_packed (destination, elsize, elsign, nelem,
                                    nelem_read, compression, 
                                    file);

    case CBF_BYTE_OFFSET:
    
      return cbf_decompress_byte_offset (destination, elsize, elsign, nelem,
                                         nelem_read, compression, 
                                         file);

    case CBF_PREDICTOR:
    
      return cbf_decompress_predictor (destination, elsize, elsign, nelem,
                                       nelem_read, compression,
                                       file);

    case CBF_NONE:
    
      return cbf_decompress_none (destination, elsize, elsign, nelem, 
                                  nelem_read, compression, 
                                  bits, sign, file);
  }


    /* Fail */

  return CBF_ARGUMENT;
}


#ifdef __cplusplus

}

#endif