input_ext-dec.h 20.2 KB
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/*****************************************************************************
 * input_ext-dec.h: structures exported to the VideoLAN decoders
 *****************************************************************************
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 * Copyright (C) 1999-2001 VideoLAN
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 * $Id: input_ext-dec.h,v 1.72 2002/10/21 10:46:34 fenrir Exp $
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 *
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 * Authors: Christophe Massiot <massiot@via.ecp.fr>
 *          Michel Kaempf <maxx@via.ecp.fr>
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 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
 *****************************************************************************/

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#ifndef _VLC_INPUT_EXT_DEC_H
#define _VLC_INPUT_EXT_DEC_H 1

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/* Structures exported to the decoders */

/*****************************************************************************
 * data_packet_t
 *****************************************************************************
 * Describe a data packet.
 *****************************************************************************/
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struct data_packet_t
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{
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    /* Used to chain the packets that carry data for a same PES or PSI */
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    data_packet_t *  p_next;
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    /* start of the PS or TS packet */
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    byte_t *         p_demux_start;
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    /* start of the PES payload in this packet */
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    byte_t *         p_payload_start;
    byte_t *         p_payload_end; /* guess ? :-) */
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    /* is the packet messed up ? */
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    vlc_bool_t       b_discard_payload;
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    /* pointer to the real data */
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    data_buffer_t *  p_buffer;
};
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/*****************************************************************************
 * pes_packet_t
 *****************************************************************************
 * Describes an PES packet, with its properties, and pointers to the TS packets
 * containing it.
 *****************************************************************************/
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struct pes_packet_t
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{
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    /* Chained list to the next PES packet (depending on the context) */
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    pes_packet_t *  p_next;
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    /* PES properties */
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    vlc_bool_t      b_data_alignment;          /* used to find the beginning of
                                                * a video or audio unit */
    vlc_bool_t      b_discontinuity;          /* This packet doesn't follow the
                                               * previous one */
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    mtime_t         i_pts;            /* PTS for this packet (zero if unset) */
    mtime_t         i_dts;            /* DTS for this packet (zero if unset) */
    int             i_rate;   /* current reading pace (see stream_control.h) */
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    unsigned int    i_pes_size;            /* size of the current PES packet */
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    /* Chained list to packets */
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    data_packet_t * p_first;              /* The first packet contained by this
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                                           * PES (used by decoders). */
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    data_packet_t * p_last;            /* The last packet contained by this
                                        * PES (used by the buffer allocator) */
    unsigned int    i_nb_data; /* Number of data packets in the chained list */
};
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/*****************************************************************************
 * decoder_fifo_t
 *****************************************************************************
 * This rotative FIFO contains PES packets that are to be decoded.
 *****************************************************************************/
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struct decoder_fifo_t
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{
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    VLC_COMMON_MEMBERS

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    /* Thread structures */
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    vlc_mutex_t         data_lock;                         /* fifo data lock */
    vlc_cond_t          data_wait;         /* fifo data conditional variable */
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    /* Data */
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    pes_packet_t *      p_first;
    pes_packet_t **     pp_last;
    int                 i_depth;       /* number of PES packets in the stack */
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    /* Communication interface between input and decoders */
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    input_buffers_t    *p_packets_mgt;   /* packets management services data */

    /* Standard pointers given to the decoders as a toolbox. */
    u16                 i_id;
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    vlc_fourcc_t        i_fourcc;
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    es_sys_t *          p_demux_data;
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    stream_ctrl_t *     p_stream_ctrl;
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    sout_instance_t *   p_sout;
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    /* Module properties */
    module_t *              p_module;
    int                 ( * pf_run ) ( decoder_fifo_t * );
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};
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/*****************************************************************************
 * bit_fifo_t : bit fifo descriptor
 *****************************************************************************
 * This type describes a bit fifo used to store bits while working with the
 * input stream at the bit level.
 *****************************************************************************/
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typedef u32         WORD_TYPE;
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typedef struct bit_fifo_t
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{
    /* This unsigned integer allows us to work at the bit level. This buffer
     * can contain 32 bits, and the used space can be found on the MSb's side
     * and the available space on the LSb's side. */
    WORD_TYPE           buffer;

    /* Number of bits available in the bit buffer */
    int                 i_available;

} bit_fifo_t;

/*****************************************************************************
 * bit_stream_t : bit stream descriptor
 *****************************************************************************
 * This type, based on a PES stream, includes all the structures needed to
 * handle the input stream like a bit stream.
 *****************************************************************************/
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struct bit_stream_t
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{
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    /*
     * Bit structures
     */
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    bit_fifo_t       fifo;
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    /*
     * Input structures
     */
    /* The decoder fifo contains the data of the PES stream */
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    decoder_fifo_t * p_decoder_fifo;
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    /* Callback to the decoder used when changing data packets ; set
     * to NULL if your decoder doesn't need it. */
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    void          (* pf_bitstream_callback)( bit_stream_t *, vlc_bool_t );
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    /* Optional argument to the callback */
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    void *           p_callback_arg;
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    /*
     * PTS retrieval
     */
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    mtime_t          i_pts, i_dts;
    byte_t *         p_pts_validity;
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    /*
     * Byte structures
     */
    /* Current data packet (in the current PES packet of the PES stream) */
    data_packet_t *         p_data;
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    /* Pointer to the next byte that is to be read (in the current packet) */
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    byte_t *                p_byte;
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    /* Pointer to the last byte that is to be read (in the current packet */
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    byte_t *                p_end;
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    /* Temporary buffer in case we're not aligned when changing data packets */
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    WORD_TYPE               i_showbits_buffer;
    data_packet_t           showbits_data;
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};
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/*****************************************************************************
 * Inline functions used by the decoders to read bit_stream_t
 *****************************************************************************/

/*
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 * DISCUSSION : How to use the bit_stream structures
 *
 * sizeof(WORD_TYPE) (usually 32) bits are read at the same time, thus
 * minimizing the number of p_byte changes.
 * Bits are read via GetBits() or ShowBits.
 *
 * XXX : Be aware that if, in the forthcoming functions, i_bits > 24,
 * the data have to be already aligned on an 8-bit boundary, or wrong
 * results will be returned. Use RealignBits() if unsure.
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 */

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#if (WORD_TYPE == u32)
#   define WORD_AT      U32_AT
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#   define WORD_SIGNED  s32
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#elif (WORD_TYPE == u64)
#   define WORD_AT      U64_AT
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#   define WORD_SIGNED  s64
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#else
#   error Unsupported WORD_TYPE
#endif

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/*****************************************************************************
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 * Prototypes from input_ext-dec.c
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 *****************************************************************************/
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VLC_EXPORT( void, InitBitstream,  ( bit_stream_t *, decoder_fifo_t *, void ( * )( bit_stream_t *, vlc_bool_t ), void * p_callback_arg ) );
VLC_EXPORT( vlc_bool_t, NextDataPacket,    ( decoder_fifo_t *, data_packet_t ** ) );
VLC_EXPORT( void, BitstreamNextDataPacket, ( bit_stream_t * ) );
VLC_EXPORT( u32,  UnalignedShowBits,       ( bit_stream_t *, unsigned int ) );
VLC_EXPORT( void, UnalignedRemoveBits,     ( bit_stream_t * ) );
VLC_EXPORT( u32,  UnalignedGetBits,        ( bit_stream_t *, unsigned int ) );
VLC_EXPORT( void, CurrentPTS,              ( bit_stream_t *, mtime_t *, mtime_t * ) );
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VLC_EXPORT( void, NextPTS,                 ( bit_stream_t *, mtime_t *, mtime_t * ) );
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VLC_EXPORT( int,  input_NextPES,           ( decoder_fifo_t *, pes_packet_t ** ) );

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/*****************************************************************************
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 * AlignWord : fill in the bit buffer so that the byte pointer be aligned
 * on a word boundary (XXX: there must be at least sizeof(WORD_TYPE) - 1
 * empty bytes in the bit buffer)
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 *****************************************************************************/
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static inline void AlignWord( bit_stream_t * p_bit_stream )
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{
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    while( (ptrdiff_t)p_bit_stream->p_byte
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             & (sizeof(WORD_TYPE) - 1) )
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    {
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        if( p_bit_stream->p_byte < p_bit_stream->p_end )
        {
            p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
                << (8 * sizeof(WORD_TYPE) - 8
                     - p_bit_stream->fifo.i_available);
            p_bit_stream->fifo.i_available += 8;
        }
        else
        {
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            BitstreamNextDataPacket( p_bit_stream );
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            p_bit_stream->fifo.buffer |= *(p_bit_stream->p_byte++)
                << (8 * sizeof(WORD_TYPE) - 8
                     - p_bit_stream->fifo.i_available);
            p_bit_stream->fifo.i_available += 8;
        }
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    }
}

/*****************************************************************************
 * ShowBits : return i_bits bits from the bit stream
 *****************************************************************************/
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static inline u32 ShowBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
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{
    if( p_bit_stream->fifo.i_available >= i_bits )
    {
        return( p_bit_stream->fifo.buffer >> (8 * sizeof(WORD_TYPE) - i_bits) );
    }

    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
    {
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        return( (p_bit_stream->fifo.buffer |
                    (WORD_AT( p_bit_stream->p_byte )
                        >> p_bit_stream->fifo.i_available))
                    >> (8 * sizeof(WORD_TYPE) - i_bits) );
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    }
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    return( UnalignedShowBits( p_bit_stream, i_bits ) );
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}

/*****************************************************************************
 * ShowSignedBits : return i_bits bits from the bit stream, using signed
 *                  arithmetic
 *****************************************************************************/
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static inline s32 ShowSignedBits( bit_stream_t * p_bit_stream,
                                  unsigned int i_bits )
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{
    if( p_bit_stream->fifo.i_available >= i_bits )
    {
        return( (WORD_SIGNED)p_bit_stream->fifo.buffer
                    >> (8 * sizeof(WORD_TYPE) - i_bits) );
    }

    /* You can probably do something a little faster, but now I'm tired. */
    return( (WORD_SIGNED)(ShowBits( p_bit_stream, i_bits ) << (32 - i_bits))
             >> (32 - i_bits) );
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}

/*****************************************************************************
 * RemoveBits : removes i_bits bits from the bit buffer
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 *              XXX: do not use for 32 bits, see RemoveBits32
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 *****************************************************************************/
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static inline void RemoveBits( bit_stream_t * p_bit_stream,
                               unsigned int i_bits )
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{
    p_bit_stream->fifo.i_available -= i_bits;

    if( p_bit_stream->fifo.i_available >= 0 )
    {
        p_bit_stream->fifo.buffer <<= i_bits;
        return;
    }
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    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
    {
        p_bit_stream->fifo.buffer = WORD_AT( p_bit_stream->p_byte )
                                        << ( -p_bit_stream->fifo.i_available );
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        p_bit_stream->p_byte =
                   (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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        p_bit_stream->fifo.i_available += sizeof(WORD_TYPE) * 8;
        return;
    }

    UnalignedRemoveBits( p_bit_stream );
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}

/*****************************************************************************
 * RemoveBits32 : removes 32 bits from the bit buffer (and as a side effect,
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 *                refill it)
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 *****************************************************************************/
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#if (WORD_TYPE == u32)
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static inline void RemoveBits32( bit_stream_t * p_bit_stream )
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{
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    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
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    {
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        if( p_bit_stream->fifo.i_available )
        {
            p_bit_stream->fifo.buffer = WORD_AT( p_bit_stream->p_byte )
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                            << (32 - p_bit_stream->fifo.i_available);
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            p_bit_stream->p_byte =
                       (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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            return;
        }

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        p_bit_stream->p_byte =
                   (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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        return;
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    }
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    p_bit_stream->fifo.i_available -= 32;
    UnalignedRemoveBits( p_bit_stream );
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}
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#else
#   define RemoveBits32( p_bit_stream )     RemoveBits( p_bit_stream, 32 )
#endif
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/*****************************************************************************
 * GetBits : returns i_bits bits from the bit stream and removes them
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 *           XXX: do not use for 32 bits, see GetBits32
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 *****************************************************************************/
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static inline u32 GetBits( bit_stream_t * p_bit_stream, unsigned int i_bits )
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{
    u32             i_result;

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    p_bit_stream->fifo.i_available -= i_bits;

    if( p_bit_stream->fifo.i_available >= 0 )
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    {
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        i_result = p_bit_stream->fifo.buffer
                        >> (8 * sizeof(WORD_TYPE) - i_bits);
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        p_bit_stream->fifo.buffer <<= i_bits;
        return( i_result );
    }

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    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
    {
        i_result = p_bit_stream->fifo.buffer
                        >> (8 * sizeof(WORD_TYPE) - i_bits);
        p_bit_stream->fifo.buffer = WORD_AT( p_bit_stream->p_byte );
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        p_bit_stream->p_byte =
                   (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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        i_result |= p_bit_stream->fifo.buffer
                        >> (8 * sizeof(WORD_TYPE)
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                                     + p_bit_stream->fifo.i_available);
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        p_bit_stream->fifo.buffer <<= ( -p_bit_stream->fifo.i_available );
        p_bit_stream->fifo.i_available += sizeof(WORD_TYPE) * 8;
        return( i_result );
    }
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    return UnalignedGetBits( p_bit_stream, i_bits );
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}

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/*****************************************************************************
 * GetSignedBits : returns i_bits bits from the bit stream and removes them,
 *                 using signed arithmetic
 *                 XXX: do not use for 32 bits
 *****************************************************************************/
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static inline s32 GetSignedBits( bit_stream_t * p_bit_stream,
                                 unsigned int i_bits )
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{
    if( p_bit_stream->fifo.i_available >= i_bits )
    {
        s32             i_result;

        p_bit_stream->fifo.i_available -= i_bits;
        i_result = (WORD_SIGNED)p_bit_stream->fifo.buffer
                        >> (8 * sizeof(WORD_TYPE) - i_bits);
        p_bit_stream->fifo.buffer <<= i_bits;
        return( i_result );
    }

    /* You can probably do something a little faster, but now I'm tired. */
    return( (WORD_SIGNED)(GetBits( p_bit_stream, i_bits ) << (32 - i_bits))
             >> (32 - i_bits) );
}

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/*****************************************************************************
 * GetBits32 : returns 32 bits from the bit stream and removes them
 *****************************************************************************/
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#if (WORD_TYPE == u32)
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static inline u32 GetBits32( bit_stream_t * p_bit_stream )
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{
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    u32             i_result;
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    if( p_bit_stream->fifo.i_available == 32 )
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    {
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        p_bit_stream->fifo.i_available = 0;
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        i_result = p_bit_stream->fifo.buffer;
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        p_bit_stream->fifo.buffer = 0;
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        return( i_result );
    }
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    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
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    {
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        if( p_bit_stream->fifo.i_available )
        {
            i_result = p_bit_stream->fifo.buffer;
            p_bit_stream->fifo.buffer = WORD_AT( p_bit_stream->p_byte );
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            p_bit_stream->p_byte =
                       (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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            i_result |= p_bit_stream->fifo.buffer
                             >> (p_bit_stream->fifo.i_available);
            p_bit_stream->fifo.buffer <<= (32 - p_bit_stream->fifo.i_available);
            return( i_result );
        }

        i_result = WORD_AT( p_bit_stream->p_byte );
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        p_bit_stream->p_byte =
                   (byte_t *) ( ((WORD_TYPE *)p_bit_stream->p_byte) + 1 );
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        return( i_result );
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    }
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    p_bit_stream->fifo.i_available -= 32;
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    return UnalignedGetBits( p_bit_stream, 32 );
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}
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#else
#   define GetBits32( p_bit_stream )    GetBits( p_bit_stream, 32 )
#endif
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/*****************************************************************************
 * RealignBits : realigns the bit buffer on an 8-bit boundary
 *****************************************************************************/
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static inline void RealignBits( bit_stream_t * p_bit_stream )
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{
    p_bit_stream->fifo.buffer <<= (p_bit_stream->fifo.i_available & 0x7);
    p_bit_stream->fifo.i_available &= ~0x7;
}


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/*****************************************************************************
 * GetChunk : reads a large chunk of data
 *****************************************************************************
 * The position in the stream must be byte-aligned, if unsure call
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 * RealignBits(). p_buffer must point to a buffer at least as big as i_buf_len
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 * otherwise your code will crash.
 *****************************************************************************/
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static inline void GetChunk( bit_stream_t * p_bit_stream,
                             byte_t * p_buffer, size_t i_buf_len )
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{
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    ptrdiff_t           i_available;
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    /* We need to take care because i_buf_len may be < 4. */
    while( p_bit_stream->fifo.i_available > 0 && i_buf_len )
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    {
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        *p_buffer = p_bit_stream->fifo.buffer >> (8 * sizeof(WORD_TYPE) - 8);
        p_buffer++;
        i_buf_len--;
        p_bit_stream->fifo.buffer <<= 8;
        p_bit_stream->fifo.i_available -= 8;
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    }

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    if( (i_available = p_bit_stream->p_end - p_bit_stream->p_byte)
            >= i_buf_len )
    {
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        p_bit_stream->p_decoder_fifo->p_vlc->pf_memcpy( p_buffer,
                                           p_bit_stream->p_byte, i_buf_len );
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        p_bit_stream->p_byte += i_buf_len;
    }
    else
    {
        do
        {
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            p_bit_stream->p_decoder_fifo->p_vlc->pf_memcpy( p_buffer,
                                           p_bit_stream->p_byte, i_available );
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            p_bit_stream->p_byte = p_bit_stream->p_end;
            p_buffer += i_available;
            i_buf_len -= i_available;
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            BitstreamNextDataPacket( p_bit_stream );
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            if( p_bit_stream->p_decoder_fifo->b_die )
                return;
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        }
        while( (i_available = p_bit_stream->p_end - p_bit_stream->p_byte)
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                <= i_buf_len );
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        if( i_buf_len )
        {
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            p_bit_stream->p_decoder_fifo->p_vlc->pf_memcpy( p_buffer,
                                           p_bit_stream->p_byte, i_buf_len );
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            p_bit_stream->p_byte += i_buf_len;
        }
    }
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    if( p_bit_stream->p_byte <= p_bit_stream->p_end - sizeof(WORD_TYPE) )
    {
        AlignWord( p_bit_stream );
    }
}


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/*
 * Communication interface between input and decoders
 */

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/*****************************************************************************
 * Prototypes from input_dec.c
 *****************************************************************************/
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VLC_EXPORT( void, DecoderError, ( decoder_fifo_t * p_fifo ) );
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#endif /* "input_ext-dec.h" */