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      1 /**
      2  *
      3  * File Name:  armVCM4P2_CheckVLCEscapeMode.c
      4  * OpenMAX DL: v1.0.2
      5  * Revision:   9641
      6  * Date:       Thursday, February 7, 2008
      7  *
      8  * (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
      9  *
     10  *
     11  *
     12  * Description:
     13  * Contains module for VLC escape mode check
     14  *
     15  */
     16 
     17 #include "omxtypes.h"
     18 #include "armOMX.h"
     19 
     20 #include "armVC.h"
     21 #include "armCOMM.h"
     22 
     23 /**
     24  * Function: armVCM4P2_CheckVLCEscapeMode
     25  *
     26  * Description:
     27  * Performs escape mode decision based on the run, run+, level, level+ and
     28  * last combinations.
     29  *
     30  * Remarks:
     31  *
     32  * Parameters:
     33  * [in] run             Run value (count of zeros) to be encoded
     34  * [in] level           Level value (non-zero value) to be encoded
     35  * [in] runPlus         Calculated as runPlus = run - (RMAX + 1)
     36  * [in] levelPlus       Calculated as
     37  *                      levelPlus = sign(level)*[abs(level) - LMAX]
     38  * [in] maxStoreRun     Max store possible (considering last and inter/intra)
     39  * [in] maxRunForMultipleEntries
     40  *                      The run value after which level
     41  *                      will be equal to 1:
     42  *                      (considering last and inter/intra status)
     43  * [in] pRunIndexTable  Run Index table defined in
     44  *                      armVCM4P2_Huff_Tables_VLC.c
     45  *                      (considering last and inter/intra status)
     46  *
     47  *
     48  * Return Value:
     49  * Returns an Escape mode which can take values from 0 to 3
     50  * 0 --> no escape mode, 1 --> escape type 1,
     51  * 1 --> escape type 2, 3 --> escape type 3, check section 7.4.1.3
     52  * in the MPEG ISO standard.
     53  *
     54  */
     55 
     56 OMX_U8 armVCM4P2_CheckVLCEscapeMode(
     57      OMX_U32 run,
     58      OMX_U32 runPlus,
     59      OMX_S16 level,
     60      OMX_S16 levelPlus,
     61      OMX_U8  maxStoreRun,
     62      OMX_U8  maxRunForMultipleEntries,
     63      OMX_INT shortVideoHeader,
     64      const OMX_U8  *pRunIndexTable
     65 )
     66 {
     67     OMX_U8 escape = 0, fMode = 0, entries;
     68 
     69     level = armAbs (level);
     70     levelPlus = armAbs (levelPlus);
     71 
     72     /* Check for a valid entry with run, level and Last combination
     73        Mode 0 check */
     74     if (run <= maxStoreRun)
     75     {
     76         entries = pRunIndexTable[run + 1]
     77                   - pRunIndexTable[run];
     78         if (run > maxRunForMultipleEntries)
     79         {
     80             entries = 1;
     81         }
     82         if (level > entries)
     83         {
     84             escape = 1;
     85         }
     86     }
     87     else
     88     {
     89         escape = 1;
     90     }
     91     if(escape && shortVideoHeader)
     92     {
     93         escape = 0;
     94         fMode = 4;
     95     }
     96     /* Check for a valid entry with run, levelPlus and Last combination
     97        Mode 1 check */
     98     if (escape)
     99     {
    100         escape = 0;
    101         fMode = 1;
    102         if (run <= maxStoreRun)
    103         {
    104             entries = pRunIndexTable[run + 1]
    105                       - pRunIndexTable[run];
    106             if (run > maxRunForMultipleEntries)
    107             {
    108                 entries = 1;
    109             }
    110             if (levelPlus > entries)
    111             {
    112                 escape = 1;
    113             }
    114         }
    115         else
    116         {
    117             escape = 1;
    118         }
    119     }
    120 
    121     /* Check for a valid entry with runPlus, level and Last combination
    122        Mode 2 check */
    123     if (escape)
    124     {
    125         escape = 0;
    126         fMode = 2;
    127         if (runPlus <= maxStoreRun)
    128         {
    129             entries = pRunIndexTable[runPlus + 1]
    130                       - pRunIndexTable[runPlus];
    131             if (runPlus > maxRunForMultipleEntries)
    132             {
    133                 entries = 1;
    134             }
    135             if (level > entries)
    136             {
    137                 escape = 1;
    138             }
    139         }
    140         else
    141         {
    142             escape = 1;
    143         }
    144     }
    145 
    146     /* select mode 3 --> FLC */
    147     if (escape)
    148     {
    149         fMode = 3;
    150     }
    151 
    152     return fMode;
    153 }
    154 
    155 /*End of File*/
    156 
    157