rfx_bitstream.h

 
#ifndef FREERDP_LIB_CODEC_RFX_BITSTREAM_H
#define FREERDP_LIB_CODEC_RFX_BITSTREAM_H
 
#include <winpr/assert.h>
#include <winpr/cast.h>
 
#include <freerdp/codec/rfx.h>
 
#ifdef __cplusplus
extern "C"
{
#endif
 
  typedef struct
  {
    BYTE* buffer;
    uint32_t nbytes;
    uint32_t byte_pos;
    uint32_t bits_left;
  } RFX_BITSTREAM;
 
  static inline void rfx_bitstream_attach(RFX_BITSTREAM* bs, BYTE* WINPR_RESTRICT buffer,
                                          size_t nbytes)
  {
    WINPR_ASSERT(bs);
    bs->buffer = (buffer);
 
    WINPR_ASSERT(nbytes <= UINT32_MAX);
    bs->nbytes = WINPR_ASSERTING_INT_CAST(uint32_t, nbytes);
    bs->byte_pos = 0;
    bs->bits_left = 8;
  }
 
  WINPR_ATTR_NODISCARD
  static inline uint32_t rfx_bitstream_get_bits(RFX_BITSTREAM* bs, uint32_t nbits)
  {
    UINT16 n = 0;
    while (bs->byte_pos < bs->nbytes && nbits > 0)
    {
      uint32_t b = nbits;
      if (b > bs->bits_left)
        b = bs->bits_left;
      if (n)
        n <<= b;
      n |= (bs->buffer[bs->byte_pos] >> (bs->bits_left - b)) & ((1 << b) - 1);
      bs->bits_left -= b;
      nbits -= b;
      if (bs->bits_left == 0)
      {
        bs->bits_left = 8;
        bs->byte_pos++;
      }
    }
    return n;
  }
 
  static inline void rfx_bitstream_put_bits(RFX_BITSTREAM* bs, uint32_t _bits, uint32_t _nbits)
  {
    UINT16 bits = WINPR_ASSERTING_INT_CAST(UINT16, _bits);
 
    uint32_t nbits = (_nbits);
    while (bs->byte_pos < bs->nbytes && nbits > 0)
    {
      uint32_t b = nbits;
      if (b > bs->bits_left)
        b = bs->bits_left;
      bs->buffer[bs->byte_pos] |= ((bits >> (nbits - b)) & ((1 << b) - 1))
                                  << (bs->bits_left - b);
      bs->bits_left -= b;
      nbits -= b;
      if (bs->bits_left == 0)
      {
        bs->bits_left = 8;
        bs->byte_pos++;
      }
    }
  }
 
  static inline void rfx_bitstream_flush(RFX_BITSTREAM* bs)
  {
    WINPR_ASSERT(bs);
    if (bs->bits_left != 8)
    {
      uint32_t _nbits = 8 - bs->bits_left;
      rfx_bitstream_put_bits(bs, 0, _nbits);
    }
  }
 
  WINPR_ATTR_NODISCARD
  static inline BOOL rfx_bitstream_eos(RFX_BITSTREAM* bs)
  {
    WINPR_ASSERT(bs);
    return ((bs)->byte_pos >= (bs)->nbytes);
  }
 
  WINPR_ATTR_NODISCARD
  static inline uint32_t rfx_bitstream_left(RFX_BITSTREAM* bs)
  {
    WINPR_ASSERT(bs);
 
    if ((bs)->byte_pos >= (bs)->nbytes)
      return 0;
 
    return ((bs)->nbytes - (bs)->byte_pos - 1) * 8 + (bs)->bits_left;
  }
 
  WINPR_ATTR_NODISCARD
  static inline uint32_t rfx_bitstream_get_processed_bytes(RFX_BITSTREAM* bs)
  {
    WINPR_ASSERT(bs);
    if ((bs)->bits_left < 8)
      return (bs)->byte_pos + 1;
    return (bs)->byte_pos;
  }
 
#ifdef __cplusplus
}
#endif
#endif /* FREERDP_LIB_CODEC_RFX_BITSTREAM_H */