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      1 /**
      2  *
      3  * File Name:  omxVCM4P2_IDCT8x8blk.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 modules for 8x8 block IDCT
     14  *
     15  */
     16 
     17 
     18 #include <math.h>
     19 #include "omxtypes.h"
     20 #include "armOMX.h"
     21 #include "omxVC.h"
     22 
     23 #include "armCOMM.h"
     24 #include "armVCM4P2_DCT_Table.h"
     25 
     26 /**
     27  * Function:  omxVCM4P2_IDCT8x8blk   (6.2.3.2.1)
     28  *
     29  * Description:
     30  * Computes a 2D inverse DCT for a single 8x8 block, as defined in
     31  * [ISO14496-2].
     32  *
     33  * Input Arguments:
     34  *
     35  *   pSrc - pointer to the start of the linearly arranged IDCT input buffer;
     36  *            must be aligned on a 16-byte boundary.  According to
     37  *            [ISO14496-2], the input coefficient values should lie within the
     38  *            range [-2048, 2047].
     39  *
     40  * Output Arguments:
     41  *
     42  *   pDst - pointer to the start of the linearly arranged IDCT output buffer;
     43  *            must be aligned on a 16-byte boundary.
     44  *
     45  * Return Value:
     46  *
     47  *    OMX_Sts_NoErr - no error
     48  *    OMX_Sts_BadArgErr - bad arguments:
     49  *    -    pSrc or pDst is NULL.
     50  *    -    pSrc or pDst is not 16-byte aligned.
     51  *
     52  */
     53 OMXResult omxVCM4P2_IDCT8x8blk (const OMX_S16 *pSrc, OMX_S16 *pDst)
     54 {
     55     OMX_INT x, y, u, v;
     56 
     57     /* Argument error checks */
     58     armRetArgErrIf(pSrc == NULL, OMX_Sts_BadArgErr);
     59     armRetArgErrIf(!armIs16ByteAligned(pSrc), OMX_Sts_BadArgErr);
     60     armRetArgErrIf(pDst == NULL, OMX_Sts_BadArgErr);
     61     armRetArgErrIf(!armIs16ByteAligned(pDst), OMX_Sts_BadArgErr);
     62 
     63     for (x = 0; x < 8; x++)
     64     {
     65         for (y = 0; y < 8; y++)
     66         {
     67             OMX_F64 sum = 0.0;
     68             for (u = 0; u < 8; u++)
     69             {
     70                 for (v = 0; v < 8; v++)
     71                 {
     72                     sum += pSrc[(u * 8) + v] *
     73                         armVCM4P2_preCalcDCTCos[x][u] *
     74                         armVCM4P2_preCalcDCTCos[y][v];
     75                 }
     76             }
     77             pDst[(x * 8) + y] = (OMX_S16) floor(sum + 0.5);
     78 
     79             /* Saturate to [-256, 255] */
     80             pDst[(x * 8) + y] = armClip (
     81                                             -256,
     82                                             255,
     83                                             pDst[(x * 8) + y]);
     84         }
     85     }
     86 
     87     return OMX_Sts_NoErr;
     88 }
     89 
     90 /* End of file */
     91 
     92 
     93