util.h

mpeng Lib

/*
 * Copyright (c) 1992 The Regents of the University of California.
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice and the following
 * two paragraphs appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

/* Status codes for bit stream i/o operations. */

#define NO_VID_STREAM -1
#define UNDERFLOW -2
#define OK 1

/* Size increment of extension data buffers. */

#define EXT_BUF_SIZE 1024

/* External declarations for bitstream i/o operations. */
extern unsigned int bitMask[];
extern unsigned int nBitMask[];
extern unsigned int rBitMask[];
extern unsigned int bitTest[];

/* External declarations of bitstream global variables. */
extern unsigned int curBits;
extern int bitOffset;
extern int bufLength;
extern unsigned int *bitBuffer;

/* Macro for updating bit counter if analysis tool is on. */
#define UPDATE_COUNT(numbits)

#ifdef NO_SANITY_CHECKS
#define get_bits1(result)                                                 \
{                                                                         \
  UPDATE_COUNT(1);                                                        \
  result = ((curBits & 0x80000000) != 0);                              \
  curBits <<= 1;                                                          \
  bitOffset++;                                                            \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset = 0;                                                        \
    bitBuffer++;                                                          \
    curBits = *bitBuffer;                                                 \
    bufLength--;                                                          \
  }                                                                       \
}

#define get_bits2(result)                                                 \
{                                                                         \
  UPDATE_COUNT(2);                                                        \
  bitOffset += 2;                                                         \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset -= 32;                                                      \
    bitBuffer++;                                                          \
    bufLength--;                                                          \
    if (bitOffset) {                                                      \
      curBits |= (*bitBuffer >> (2 - bitOffset));                         \
    }                                                                     \
    result = ((curBits & 0xc0000000) >> 30);                           \
    curBits = *bitBuffer << bitOffset;                                    \
  }                                                                       \
                                                                          \
  result = ((curBits & 0xc0000000) >> 30);                             \
  curBits <<= 2;                                                          \
}

#define get_bitsX(num, mask, shift,  result)                              \
{                                                                         \
  UPDATE_COUNT(num);                                                      \
  bitOffset += num;                                                       \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset -= 32;                                                      \
    bitBuffer++;                                                          \
    bufLength--;                                                          \
    if (bitOffset) {                                                      \
      curBits |= (*bitBuffer >> (num - bitOffset));                       \
    }                                                                     \
    result = ((curBits & mask) >> shift);                              \
    curBits = *bitBuffer << bitOffset;                                    \
  }                                                                       \
  else {                                                                  \
    result = ((curBits & mask) >> shift);                              \
    curBits <<= num;                                                      \
  }                                                                       \
}
#else

#define get_bits1(result)                                                 \
{                                                                         \
  /* Check for underflow. */                                              \
                                                                          \
  if (bufLength < 2) {                                                    \
    correct_underflow();                                                  \
  }                                                                       \
  UPDATE_COUNT(1);                                                        \
  result = ((curBits & 0x80000000) != 0);                              \
  curBits <<= 1;                                                          \
  bitOffset++;                                                            \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset = 0;                                                        \
    bitBuffer++;                                                          \
    curBits = *bitBuffer;                                                 \
    bufLength--;                                                          \
  }                                                                       \
}

#define get_bits2(result)                                                 \
{                                                                         \
  /* Check for underflow. */                                              \
                                                                          \
  if (bufLength < 2) {                                                    \
    correct_underflow();                                                  \
  }                                                                       \
  UPDATE_COUNT(2);                                                        \
  bitOffset += 2;                                                         \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset -= 32;                                                      \
    bitBuffer++;                                                          \
    bufLength--;                                                          \
    if (bitOffset) {                                                      \
      curBits |= (*bitBuffer >> (2 - bitOffset));                         \
    }                                                                     \
    result = ((curBits & 0xc0000000) >> 30);                           \
    curBits = *bitBuffer << bitOffset;                                    \
  }                                                                       \
                                                                          \
  result = ((curBits & 0xc0000000) >> 30);                             \
  curBits <<= 2;                                                          \
}

#define get_bitsX(num, mask, shift,  result)                              \
{                                                                         \
  /* Check for underflow. */                                              \
                                                                          \
  if (bufLength < 2) {                                                    \
    correct_underflow();                                                  \
  }                                                                       \
  UPDATE_COUNT(num);                                                      \
  bitOffset += num;                                                       \
                                                                          \
  if (bitOffset & 0x20) {                                                 \
    bitOffset -= 32;                                                      \
    bitBuffer++;                                                          \
    bufLength--;                                                          \
    if (bitOffset) {                                                      \
      curBits |= (*bitBuffer >> (num - bitOffset));                       \
    }                                                                     \
    result = ((curBits & mask) >> shift);                              \
    curBits = *bitBuffer << bitOffset;                                    \
  }                                                                       \
  else {                                                                  \
   result = ((curBits & mask) >> shift);                               \
   curBits <<= num;                                                       \
  }                                                                       \
}
#endif

#define get_bits3(result) get_bitsX(3,   0xe0000000, 29, result)
#define get_bits4(result) get_bitsX(4,   0xf0000000, 28, result)
#define get_bits5(result) get_bitsX(5,   0xf8000000, 27, result)
#define get_bits6(result) get_bitsX(6,   0xfc000000, 26, result)