libfreerdp-codec/rfx_bitstream.h

   1 /**
   2  * FreeRDP: A Remote Desktop Protocol client.
   3  * RemoteFX Codec Library - Bit Stream
   4  *
   5  * Copyright 2011 Vic Lee
   6  *
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19
  20 #ifndef __RFX_BITSTREAM_H
  21 #define __RFX_BITSTREAM_H
  22
  23 #include <freerdp/codec/rfx.h>
  24
  25 struct _RFX_BITSTREAM
  26 {
  27         uint8* buffer;
  28         int nbytes;
  29         int byte_pos;
  30         int bits_left;
  31 };
  32 typedef struct _RFX_BITSTREAM RFX_BITSTREAM;
  33
  34 #define rfx_bitstream_attach(bs, _buffer, _nbytes) do { \
  35         bs->buffer = (uint8*) (_buffer); \
  36         bs->nbytes = (_nbytes); \
  37         bs->byte_pos = 0; \
  38         bs->bits_left = 8; } while (0)
  39
  40 #define rfx_bitstream_get_bits(bs, _nbits, _r) do { \
  41         int nbits = _nbits; \
  42         int b; \
  43         uint16 n = 0; \
  44         while (bs->byte_pos < bs->nbytes && nbits > 0) \
  45         { \
  46                 b = nbits; \
  47                 if (b > bs->bits_left) \
  48                         b = bs->bits_left; \
  49                 if (n) \
  50                         n <<= b; \
  51                 n |= (bs->buffer[bs->byte_pos] >> (bs->bits_left - b)) & ((1 << b) - 1); \
  52                 bs->bits_left -= b; \
  53                 nbits -= b; \
  54                 if (bs->bits_left == 0) \
  55                 { \
  56                         bs->bits_left = 8; \
  57                         bs->byte_pos++; \
  58                 } \
  59         } \
  60         _r = n; } while (0)
  61
  62 #define rfx_bitstream_put_bits(bs, _bits, _nbits) do { \
  63         uint16 bits = (_bits); \
  64         int nbits = (_nbits); \
  65         int b; \
  66         while (bs->byte_pos < bs->nbytes && nbits > 0) \
  67         { \
  68                 b = nbits; \
  69                 if (b > bs->bits_left) \
  70                         b = bs->bits_left; \
  71                 bs->buffer[bs->byte_pos] &= ~(((1 << b) - 1) << (bs->bits_left - b)); \
  72                 bs->buffer[bs->byte_pos] |= ((bits >> (nbits - b)) & ((1 << b) - 1)) << (bs->bits_left - b); \
  73                 bs->bits_left -= b; \
  74                 nbits -= b; \
  75                 if (bs->bits_left == 0) \
  76                 { \
  77                         bs->bits_left = 8; \
  78                         bs->byte_pos++; \
  79                 } \
  80         } } while (0)
  81
  82 #define rfx_bitstream_eos(_bs) ((_bs)->byte_pos >= (_bs)->nbytes)
  83 #define rfx_bitstream_left(_bs) ((_bs)->byte_pos >= (_bs)->nbytes ? 0 : ((_bs)->nbytes - (_bs)->byte_pos - 1) * 8 + (_bs)->bits_left)
  84 #define rfx_bitstream_get_processed_bytes(_bs) ((_bs)->bits_left < 8 ? (_bs)->byte_pos + 1 : (_bs)->byte_pos)
  85
  86 #endif /* __RFX_BITSTREAM_H */