bitstream.h

/*
 * WinPR: Windows Portable Runtime
 * BitStream Utils
 *
 * Copyright 2014 Marc-Andre Moreau <marcandre.moreau@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef WINPR_UTILS_BITSTREAM_H
#define WINPR_UTILS_BITSTREAM_H
 
#include <winpr/assert.h>
#include <winpr/winpr.h>
#include <winpr/wtypes.h>
 
#include <winpr/crt.h>
#include <winpr/wlog.h>
 
typedef struct
{
  const BYTE* buffer;
  BYTE* pointer;
  UINT32 position;
  UINT32 length;
  UINT32 capacity;
  UINT32 mask;
  UINT32 offset;
  UINT32 prefetch;
  UINT32 accumulator;
} wBitStream;
 
#define BITDUMP_MSB_FIRST 0x00000001
#define BITDUMP_STDERR 0x00000002
 
#ifdef __cplusplus
extern "C"
{
#endif
 
  static INLINE void BitStream_Prefetch(wBitStream* _bs)
  {
    WINPR_ASSERT(_bs);
 
    (_bs->prefetch) = 0;
 
    const intptr_t diff = _bs->pointer - _bs->buffer;
    if ((diff + 4) < (intptr_t)_bs->capacity)
      (_bs->prefetch) |= ((UINT32)_bs->pointer[4] << 24);
    if ((diff + 5) < (intptr_t)_bs->capacity)
      (_bs->prefetch) |= ((UINT32)_bs->pointer[5] << 16);
    if ((diff + 6) < (intptr_t)_bs->capacity)
      (_bs->prefetch) |= ((UINT32)_bs->pointer[6] << 8);
    if ((diff + 7) < (intptr_t)_bs->capacity)
      (_bs->prefetch) |= ((UINT32)_bs->pointer[7] << 0);
  }
 
  static INLINE void BitStream_Fetch(wBitStream* _bs)
  {
    WINPR_ASSERT(_bs);
    (_bs->accumulator) = 0;
 
    const intptr_t diff = _bs->pointer - _bs->buffer;
    if ((diff + 0) < (intptr_t)_bs->capacity)
      (_bs->accumulator) |= ((UINT32)_bs->pointer[0] << 24);
    if ((diff + 1) < (intptr_t)_bs->capacity)
      (_bs->accumulator) |= ((UINT32)_bs->pointer[1] << 16);
    if ((diff + 2) < (intptr_t)_bs->capacity)
      (_bs->accumulator) |= ((UINT32)_bs->pointer[2] << 8);
    if ((diff + 3) < (intptr_t)_bs->capacity)
      (_bs->accumulator) |= ((UINT32)_bs->pointer[3] << 0);
    BitStream_Prefetch(_bs);
  }
 
  static INLINE void BitStream_Flush(wBitStream* _bs)
  {
    WINPR_ASSERT(_bs);
    const intptr_t diff = _bs->pointer - _bs->buffer;
    if ((diff + 0) < (intptr_t)_bs->capacity)
      _bs->pointer[0] = (_bs->accumulator >> 24) & 0xFF;
    if ((diff + 1) < (intptr_t)_bs->capacity)
      _bs->pointer[1] = (_bs->accumulator >> 16) & 0xFF;
    if ((diff + 2) < (intptr_t)_bs->capacity)
      _bs->pointer[2] = (_bs->accumulator >> 8) & 0xFF;
    if ((diff + 3) < (intptr_t)_bs->capacity)
      _bs->pointer[3] = (_bs->accumulator >> 0) & 0xFF;
  }
 
  static INLINE void BitStream_Shift(wBitStream* _bs, UINT32 _nbits)
  {
    WINPR_ASSERT(_bs);
    if (_nbits == 0)
    {
    }
    else if ((_nbits > 0) && (_nbits < 32))
    {
      _bs->accumulator <<= _nbits;
      _bs->position += _nbits;
      _bs->offset += _nbits;
      if (_bs->offset < 32)
      {
        _bs->mask = (UINT32)((1UL << _nbits) - 1UL);
        _bs->accumulator |= ((_bs->prefetch >> (32 - _nbits)) & _bs->mask);
        _bs->prefetch <<= _nbits;
      }
      else
      {
        _bs->mask = (UINT32)((1UL << _nbits) - 1UL);
        _bs->accumulator |= ((_bs->prefetch >> (32 - _nbits)) & _bs->mask);
        _bs->prefetch <<= _nbits;
        _bs->offset -= 32;
        _bs->pointer += 4;
        BitStream_Prefetch(_bs);
        if (_bs->offset)
        {
          _bs->mask = (UINT32)((1UL << _bs->offset) - 1UL);
          _bs->accumulator |= ((_bs->prefetch >> (32 - _bs->offset)) & _bs->mask);
          _bs->prefetch <<= _bs->offset;
        }
      }
    }
    else
    {
      WLog_WARN("com.winpr.bitstream", "warning: BitStream_Shift(%u)", (unsigned)_nbits);
    }
  }
 
  static INLINE void BitStream_Shift32(wBitStream* _bs)
  {
    WINPR_ASSERT(_bs);
    BitStream_Shift(_bs, 16);
    BitStream_Shift(_bs, 16);
  }
 
  static INLINE void BitStream_Write_Bits(wBitStream* _bs, UINT32 _bits, UINT32 _nbits)
  {
    WINPR_ASSERT(_bs);
    _bs->position += _nbits;
    _bs->offset += _nbits;
    if (_bs->offset < 32)
    {
      _bs->accumulator |= (_bits << (32 - _bs->offset));
    }
    else
    {
      _bs->offset -= 32;
      _bs->mask = ((1 << (_nbits - _bs->offset)) - 1);
      _bs->accumulator |= ((_bits >> _bs->offset) & _bs->mask);
      BitStream_Flush(_bs);
      _bs->accumulator = 0;
      _bs->pointer += 4;
      if (_bs->offset)
      {
        _bs->mask = (UINT32)((1UL << _bs->offset) - 1);
        _bs->accumulator |= ((_bits & _bs->mask) << (32 - _bs->offset));
      }
    }
  }
 
  static INLINE size_t BitStream_GetRemainingLength(wBitStream* _bs)
  {
    WINPR_ASSERT(_bs);
    return (_bs->length - _bs->position);
  }
 
  WINPR_API void BitDump(const char* tag, UINT32 level, const BYTE* buffer, UINT32 length,
                         UINT32 flags);
  WINPR_API UINT32 ReverseBits32(UINT32 bits, UINT32 nbits);
 
  WINPR_API void BitStream_Attach(wBitStream* bs, const BYTE* buffer, UINT32 capacity);
 
  WINPR_API void BitStream_Free(wBitStream* bs);
 
  WINPR_ATTR_MALLOC(BitStream_Free, 1)
  WINPR_API wBitStream* BitStream_New(void);
 
#ifdef __cplusplus
}
#endif
 
#endif /* WINPR_UTILS_BITSTREAM_H */