hbitio.h

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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
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 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
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/* $Id: hbitio.h 4932 2007-09-07 17:17:23Z bmribler $ */

/*
   **  hbitio.h
   **
   **  Data structures and macros for bitfile access to HDF data objects.
   **  These are mainly used for compression I/O and N-bit data objects.
 */

#ifndef __HBITIO_H
#define __HBITIO_H

/* Define the number of elements in the buffered array */
#define BITBUF_SIZE 4096
/* Macro to define the number of bits cached in the 'bits' variable */
#define BITNUM      (sizeof(uint8)*8)
/* Macro to define the number of bits able to be read/written at a time */
#define DATANUM     (sizeof(uint32)*8)

typedef struct bitrec_t
  {
      int32       acc_id;       /* Access ID for H layer I/O routines */
      int32       bit_id;       /* Bitfile ID for internal use */
  /* Note that since HDF has signed 32bit offset limit we need to change this to signed
     since the get passed to Hxxx calls which take signed 32bit arguments */
      int32      block_offset, /* offset of the current buffered block in the dataset */
                 max_offset,   /* offset of the last byte written to the dataset */
                 byte_offset;  /* offset of the current byte in the dataset */

      intn       count,        /* bit count to next boundary */
                 buf_read;     /* number of bytes read into buffer (necessary for random I/O) */
      uint8       access;       /* What the access on this file is ('r', 'w', etc..) */
      uint8       mode;         /* how are we interacting with the data now ('r', 'w', etc) */
      uint8       bits;         /* extra bit buffer, 0..BITNUM-1 bits */
      uint8      *bytep;        /* current position in buffer */
      uint8      *bytez;        /* end of buffer to compare */
      uint8      *bytea;        /* byte buffer */
  }
bitrec_t;

#ifndef BITMASTER
extern
#endif
const uint8 maskc[9]
#ifdef BITMASTER
=
{0, 1, 3, 7, 15, 31, 63, 127, 255}
#endif
           ;

#ifndef BITMASTER
extern
#endif
const uint32 maskl[33]
#ifdef BITMASTER
=
{0x00000000,
 0x00000001, 0x00000003, 0x00000007, 0x0000000f,
 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
 0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
 0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
 0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
 0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffffUL}
#endif
           ;

/* Function-like Macros */
#define Hputbit(bitid,bit) ((Hbitwrite(bitid,1,(uint32)bit)==FAIL) ? FAIL : SUCCEED)

#endif /* __HBITIO_H */