1 /*****************************************************************************
2 * decoder_fifo.h: interface for decoders PES fifo
4 *****************************************************************************
10 *****************************************************************************/
12 /*****************************************************************************
14 *****************************************************************************/
16 /* ?? move to inline functions */
17 #define DECODER_FIFO_ISEMPTY( fifo ) ( (fifo).i_start == (fifo).i_end )
18 #define DECODER_FIFO_ISFULL( fifo ) ( ( ( (fifo).i_end + 1 - (fifo).i_start ) \
20 #define DECODER_FIFO_START( fifo ) ( (fifo).buffer[ (fifo).i_start ] )
21 #define DECODER_FIFO_INCSTART( fifo ) ( (fifo).i_start = ((fifo).i_start + 1)\
23 #define DECODER_FIFO_END( fifo ) ( (fifo).buffer[ (fifo).i_end ] )
24 #define DECODER_FIFO_INCEND( fifo ) ( (fifo).i_end = ((fifo).i_end + 1) \
27 /*****************************************************************************
29 *****************************************************************************
30 * This rotative FIFO contains PES packets that are to be decoded...
31 *****************************************************************************/
34 vlc_mutex_t data_lock; /* fifo data lock */
35 vlc_cond_t data_wait; /* fifo data conditional variable */
37 /* buffer is an array of PES packets pointers */
38 pes_packet_t * buffer[FIFO_SIZE + 1];
44 /*****************************************************************************
45 * bit_fifo_t : bit fifo descriptor
46 *****************************************************************************
47 * This type describes a bit fifo used to store bits while working with the
48 * input stream at the bit level.
49 *****************************************************************************/
50 typedef struct bit_fifo_s
52 /* This unsigned integer allows us to work at the bit level. This buffer
53 * can contain 32 bits, and the used space can be found on the MSb's side
54 * and the available space on the LSb's side. */
57 /* Number of bits available in the bit buffer */
62 /*****************************************************************************
63 * bit_stream_t : bit stream descriptor
64 *****************************************************************************
65 * This type, based on a PES stream, includes all the structures needed to
66 * handle the input stream like a bit stream.
67 *****************************************************************************/
68 typedef struct bit_stream_s
73 /* The input thread feeds the stream with fresh PES packets */
74 input_thread_t * p_input;
75 /* The decoder fifo contains the data of the PES stream */
76 decoder_fifo_t * p_decoder_fifo;
81 /* Current TS packet (in the current PES packet of the PES stream) */
83 /* Pointer to the next byte that is to be read (in the current TS packet) */
85 /* Pointer to the last byte that is to be read (in the current TS packet */
96 void decoder_fifo_next( bit_stream_t * p_bit_stream );
97 /*****************************************************************************
98 * GetByte : reads the next byte in the input stream
99 *****************************************************************************/
100 static __inline__ byte_t GetByte( bit_stream_t * p_bit_stream )
102 /* Are there some bytes left in the current TS packet ? */
103 /* could change this test to have a if (! (bytes--)) instead */
104 if ( p_bit_stream->p_byte >= p_bit_stream->p_end )
106 /* no, switch to next TS packet */
107 decoder_fifo_next( p_bit_stream );
110 return( *(p_bit_stream->p_byte++));
113 /*****************************************************************************
114 * NeedBits : reads i_bits new bits in the bit stream and stores them in the
116 *****************************************************************************
117 * - i_bits must be less or equal 32 !
118 * - There is something important to notice with that function : if the number
119 * of bits available in the bit buffer when calling NeedBits() is greater than
120 * 24 (i_available > 24) but less than the number of needed bits
121 * (i_available < i_bits), the byte returned by GetByte() will be shifted with
122 * a negative value and the number of bits available in the bit buffer will be
123 * set to more than 32 !
124 *****************************************************************************/
125 static __inline__ void NeedBits( bit_stream_t * p_bit_stream, int i_bits )
127 while ( p_bit_stream->fifo.i_available < i_bits )
129 p_bit_stream->fifo.buffer |= ((u32)GetByte( p_bit_stream )) << (24 - p_bit_stream->fifo.i_available);
130 p_bit_stream->fifo.i_available += 8;
134 /*****************************************************************************
135 * DumpBits : removes i_bits bits from the bit buffer
136 *****************************************************************************
137 * - i_bits <= i_available
138 * - i_bits < 32 (because (u32 << 32) <=> (u32 = u32))
139 *****************************************************************************/
140 static __inline__ void DumpBits( bit_stream_t * p_bit_stream, int i_bits )
142 p_bit_stream->fifo.buffer <<= i_bits;
143 p_bit_stream->fifo.i_available -= i_bits;
146 /*****************************************************************************
147 * DumpBits32 : removes 32 bits from the bit buffer
148 *****************************************************************************
149 * This function actually believes that you have already put 32 bits in the
150 * bit buffer, so you can't you use it anytime.
151 *****************************************************************************/
152 static __inline__ void DumpBits32( bit_stream_t * p_bit_stream )
154 p_bit_stream->fifo.buffer = 0;
155 p_bit_stream->fifo.i_available = 0;
159 * For the following functions, please read VERY CAREFULLY the warning in
160 * NeedBits(). If i_bits > 24, the stream parser must be already aligned
161 * on an 8-bit boundary, or you will get curious results (that is, you
162 * need to call RealignBits() before).
165 /*****************************************************************************
166 * RemoveBits : removes i_bits bits from the bit buffer
167 *****************************************************************************/
168 static __inline__ void RemoveBits( bit_stream_t * p_bit_stream, int i_bits )
170 NeedBits( p_bit_stream, i_bits );
171 DumpBits( p_bit_stream, i_bits );
174 /*****************************************************************************
175 * RemoveBits32 : removes 32 bits from the bit buffer
176 *****************************************************************************/
177 static __inline__ void RemoveBits32( bit_stream_t * p_bit_stream )
179 NeedBits( p_bit_stream, 32 );
180 DumpBits32( p_bit_stream );
183 /*****************************************************************************
184 * ShowBits : return i_bits bits from the bit stream
185 *****************************************************************************/
186 static __inline__ u32 ShowBits( bit_stream_t * p_bit_stream, int i_bits )
188 NeedBits( p_bit_stream, i_bits );
189 return( p_bit_stream->fifo.buffer >> (32 - i_bits) );
192 /*****************************************************************************
193 * GetBits : returns i_bits bits from the bit stream and removes them
194 *****************************************************************************/
195 static __inline__ u32 GetBits( bit_stream_t * p_bit_stream, int i_bits )
199 NeedBits( p_bit_stream, i_bits );
200 i_buffer = p_bit_stream->fifo.buffer >> (32 - i_bits);
201 DumpBits( p_bit_stream, i_bits );
205 /*****************************************************************************
206 * GetBits32 : returns 32 bits from the bit stream and removes them
207 *****************************************************************************/
208 static __inline__ u32 GetBits32( bit_stream_t * p_bit_stream )
212 NeedBits( p_bit_stream, 32 );
213 i_buffer = p_bit_stream->fifo.buffer;
214 DumpBits32( p_bit_stream );
218 /*****************************************************************************
219 * RealignBits : realigns the bit buffer on an 8-bit boundary
220 *****************************************************************************/
221 static __inline__ void RealignBits( bit_stream_t * p_bit_stream )
223 DumpBits( p_bit_stream, p_bit_stream->fifo.i_available & 7 );