swdec_utils.c

freescale i.mx31 BSP CE5.0全部源码

/*------------------------------------------------------------------------------
--                                                                            --
--       This software is confidential and proprietary and may be used        --
--        only as expressly authorized by a licensing agreement from          --
--                                                                            --
--                            Hantro Products Oy.                             --
--                                                                            --
--      In the event of publication, the following notice is applicable:      --
--                                                                            --
--                   (C) COPYRIGHT 2004 HANTRO PRODUCTS OY                    --
--                            ALL RIGHTS RESERVED                             --
--                                                                            --
--         The entire notice above must be reproduced on all copies.          --
--                                                                            --
--------------------------------------------------------------------------------
--
--  Abstract : Stream decoding utilities
--
-------------------------------------------------------------------------------*/



/*------------------------------------------------------------------------------

    Table of contents
   
     1. Include headers
     2. External identifiers
     3. Module defines
     4. Module identifiers
     5. Fuctions
        5.1     SwDec_GetBits
        5.2     SwDec_ShowBits
        5.3     SwDec_ShowBitsAligned
        5.4     SwDec_FlushBits
        5.5     SwDec_GetStuffing
        5.6     SwDec_FindSync
        5.7     SwDec_GetStartCode
        5.8     SwDec_NumBits
        5.9     SwDec_UnFlushBits
        5.10    SwDec_CheckStuffing
        5.11    SwDec_ShowBits32
        5.12    SwDec_GetOneBit
        
------------------------------------------------------------------------------*/



/*------------------------------------------------------------------------------
    1. Include headers
------------------------------------------------------------------------------*/

#include "SwDec_Utils.h"

/*------------------------------------------------------------------------------
    2. External identifiers 
------------------------------------------------------------------------------*/


/*------------------------------------------------------------------------------
    3. Module defines 
------------------------------------------------------------------------------*/

enum {
    SV_MARKER_MASK        = 0x1FFFF,
    SV_END_MASK           = 0x3FFFFF,
    SECOND_BYTE_ZERO_MASK = 0x00FF0000
};

#ifndef MP4DEC_H263_ONLY
/* to check first 23 bits */
#define START_CODE_MASK      0xFFFFFE00
/* to check first 16 bits */
#define RESYNC_MASK          0xFFFF0000


/*------------------------------------------------------------------------------
    4. Module indentifiers 
------------------------------------------------------------------------------*/

static const u32 stuffingTable[8] = {0x0,0x1,0x3,0x7,0xF,0x1F,0x3F,0x7F};

/* table containing start code id for each possible start code suffix. Start
 * code suffixes that are either reserved or non-applicable have been marked
 * with 0 */
static const u32 startCodeTable[256] =
{
    SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,
    SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,
    SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,
    SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,
    SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,SC_VO_START,
    SC_VO_START,SC_VO_START, 
    SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,
    SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,
    SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,SC_VOL_START,
    SC_VOL_START, 
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 
    SC_VOS_START,SC_VOS_END,0,SC_GVOP_START,0,SC_VISO_START, SC_VOP_START,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0,0,0,0,0,0,0,0,0
};
#endif
/*------------------------------------------------------------------------------

   5.1  Function name: SwDec_GetBits

        Purpose: read and remove bits from mpeg-4 input stream
                 
        Input: 
            Pointer to decContainer_t structure
            Number of bits to read [0,31]

        Output:
            u32 containing bits read from stream. Value END_OF_STREAM
            reserved to indicate failure.

------------------------------------------------------------------------------*/

u32 SwDec_GetBits(decContainer_t *pDecContainer, u32 numBits)
{
    
    u32 out;

    ASSERT(pDecContainer);
    ASSERT(numBits < 32);

    out = SwDec_ShowBits(pDecContainer, numBits);

    if (SwDec_FlushBits(pDecContainer, numBits) == HANTRO_OK)
    {
        return(out);
    }
    else
    {
        return(END_OF_STREAM);
    }

}

/*------------------------------------------------------------------------------

   5.2  Function name: SwDec_ShowBits

        Purpose: read bits from mpeg-4 input stream. Bits are located right
        aligned in the 32-bit output word. In case stream ends,
        function fills the word with zeros. For example, numBits = 18 and
        there are 7 bits left in the stream buffer -> return
            00000000000000xxxxxxx00000000000,
        where 'x's represent actual bits read from buffer.
                 
        Input: 
            Pointer to decContainer_t structure
            Number of bits to read [0,32]

        Output:
            u32 containing bits read from stream

------------------------------------------------------------------------------*/

u32 SwDec_ShowBits(decContainer_t *pDecContainer, u32 numBits)
{
    
    u32 i;
    i32 bits, shift;
    u32 out;
    u8 *pStrm;

    ASSERT(pDecContainer);
    ASSERT(pDecContainer->StrmDesc.pStrmCurrPos);
    ASSERT(pDecContainer->StrmDesc.bitPosInWord < 8);
    ASSERT(pDecContainer->StrmDesc.bitPosInWord ==
           (pDecContainer->StrmDesc.strmBuffReadBits & 0x7));
    ASSERT(pDecContainer->StrmDesc.strmBuffSize);
    ASSERT(numBits <= 32);

    pStrm = pDecContainer->StrmDesc.pStrmCurrPos;

    /* bits left in the buffer */
    bits = (i32)pDecContainer->StrmDesc.strmBuffSize*8 -
               (i32)pDecContainer->StrmDesc.strmBuffReadBits;
        
    if (!numBits || !bits)
    {
        return(0);
    }

    /* at least 32-bits in the buffer -> get 32 bits and drop extra bits out */
    if (bits >= 32)
    {
        out = ((u32)pStrm[0] << 24) | ((u32)pStrm[1] << 16) | 
                  ((u32)pStrm[2] <<  8) | ((u32)pStrm[3]);
        if (pDecContainer->StrmDesc.bitPosInWord)
        {
            out <<= pDecContainer->StrmDesc.bitPosInWord;
            out |=
                (u32)pStrm[4]>>(8-pDecContainer->StrmDesc.bitPosInWord);
        }
        out >>= (32 - numBits);
    }
    else
    {
        shift = 24 + (i32)pDecContainer->StrmDesc.bitPosInWord;
        out = (u32)pStrm[0] << shift;
        bits -= 8 - (i32)pDecContainer->StrmDesc.bitPosInWord;
        i = 1;
        while (bits > 0)
        {
            shift -= 8;
            out |= (u32)pStrm[i] << shift;
            bits -= 8;
            i++;
        }
        out >>= (32 - numBits);
    }

    return(out);

}

/*------------------------------------------------------------------------------

   5.3  Function name: SwDec_ShowBitsAligned

        Purpose: read bits from mpeg-4 input stream at byte aligned position
        given as parameter (offset from current stream position).
                 
        Input: 
            Pointer to decContainer_t structure
            Number of bits to read [1,32]
            Byte offset from current stream position

        Output:
            u32 containing bits read from stream

------------------------------------------------------------------------------*/
 
u32 SwDec_ShowBitsAligned(decContainer_t *pDecContainer, u32 numBits,
    u32 byteOffset)
{
    
    u32 i;
    u32 out;
    u32 bytes,shift;
    u8 *pStrm;

    ASSERT(pDecContainer);
    ASSERT(pDecContainer->StrmDesc.pStrmCurrPos);
    ASSERT(pDecContainer->StrmDesc.strmBuffSize);
    ASSERT(numBits);
    ASSERT(numBits <= 32);

    out = 0;
    pStrm = pDecContainer->StrmDesc.pStrmCurrPos + byteOffset;

    /* at least four bytes available starting byteOffset bytes ahead */
    if ( (pDecContainer->StrmDesc.strmBuffSize >= (4+byteOffset)) &&
         ((pDecContainer->StrmDesc.strmBuffReadBits>>3) <=
          (pDecContainer->StrmDesc.strmBuffSize - byteOffset - 4)) )
    {
        out = ((u32)pStrm[0] << 24) | ((u32)pStrm[1] << 16) |
                  ((u32)pStrm[2] <<  8) | ((u32)pStrm[3]);
        out >>= (32 - numBits);
    }
    else
    {
        bytes = pDecContainer->StrmDesc.strmBuffSize -
                    (pDecContainer->StrmDesc.strmBuffReadBits >> 3);
        if (bytes > byteOffset)
        {
            bytes -= byteOffset;
        }
        else
        {
            bytes = 0;
        }

        shift = 24;
        i = 0;
        while (bytes)
        {
            out |= (u32)pStrm[i] << shift;
            i++;
            shift -= 8;
            bytes--;
        }

        out >>= (32 - numBits);
    }

    return(out);

}

/*------------------------------------------------------------------------------

   5.4  Function name: SwDec_FlushBits

        Purpose: removes bits from mpeg-4 input stream
                 
        Input: 
            Pointer to decContainer_t structure
            Number of bits to remove [0,2^32)

        Output:
            HANTRO_OK if operation was successful
            END_OF_STREAM if stream buffer run empty

------------------------------------------------------------------------------*/

u32 SwDec_FlushBits(decContainer_t *pDecContainer, u32 numBits)
{

    u32 tmp;

    ASSERT(pDecContainer);
    ASSERT(pDecContainer->StrmDesc.pStrmBuffStart);
    ASSERT(pDecContainer->StrmDesc.pStrmCurrPos);
    ASSERT(pDecContainer->StrmDesc.bitPosInWord < 8);
    ASSERT(pDecContainer->StrmDesc.bitPosInWord ==
           (pDecContainer->StrmDesc.strmBuffReadBits & 0x7));

    if ( (pDecContainer->StrmDesc.strmBuffReadBits + numBits) >
         (8*pDecContainer->StrmDesc.strmBuffSize) )
    {
        pDecContainer->StrmDesc.strmBuffReadBits =
            8 * pDecContainer->StrmDesc.strmBuffSize;
        pDecContainer->StrmDesc.bitPosInWord = 0;
        pDecContainer->StrmDesc.pStrmCurrPos =
            pDecContainer->StrmDesc.pStrmBuffStart + 
            pDecContainer->StrmDesc.strmBuffSize;
        return(END_OF_STREAM);