omxsp_firone_direct_s16.c

The OpenMAX DL (Development Layer) APIs contain a comprehensive set of audio, video, signal processi

/**
 * 
 * File Name:  omxSP_FIROne_Direct_S16.c
 * OpenMAX DL: v1.0.2
 * Revision:   10586
 * Date:       Wednesday, March 5, 2008
 * 
 * (c) Copyright 2007-2008 ARM Limited. All Rights Reserved.
 * 
 * 
 * Description:
 *
 */

#include "omxtypes.h"
#include "armOMX.h"
#include "omxSP.h"
#include "armCOMM.h"

/**
 * Function:  omxSP_FIROne_Direct_S16   (2.2.3.1.2)
 *
 * Description:
 * Single-sample FIR filtering for 16-bit data type. These functions apply 
 * the FIR filter defined by the coefficient vector pTapsQ15 to a single 
 * sample of input data. The result is saturated with rounding if the 
 * operation produces a value outside the range of a signed 16-bit integer.  
 * Rounding behavior is defined in:
 *       section 1.6.7 "Integer Scaling and Rounding Conventions".  
 * The internal accumulator width must be at least 32 bits.  The result is 
 * undefined if any of the partially accumulated values exceeds the range of a 
 * signed 32-bit integer.
 *
 * Input Arguments:
 *   
 *   val      - the single input sample to which the filter is 
 *            applied.
 *   pTapsQ15 - pointer to the vector that contains the filter coefficients, 
 *            represented in Q0.15 format (as defined in section 1.6.5). Given 
 *            that:
 *                    -32768 = pTapsQ15(k) < 32768, 
 *                         0 = k < tapsLen, 
 *            the range on the actual filter coefficients is -1 = bK <1, and 
 *            therefore coefficient normalization may be required during the 
 *            filter design process. 
 *   tapsLen - the number of taps, or, equivalently, the filter order + 1 
 *   pDelayLine - pointer to the 2.tapsLen -element filter memory buffer 
 *            (state). The user is responsible for allocation, initialization, 
 *            and de-allocation. The filter memory elements are initialized to 
 *            zero in most applications. 
 *   pDelayLineIndex - pointer to the filter memory index that is maintained 
 *            internally by the function. The user should initialize the value 
 *            of this index to zero. 
 *
 * Output Arguments:
 *   
 *   pResult - pointer to the filtered output sample 
 *
 * Return Value:
 *    
 *    OMX_Sts_NoErr - no error 
 *    OMX_Sts_BadArgErr - bad arguments; returned if one or more of the 
 *              following is true: 
 *    -    One or more of the following pointers is NULL: 
 *            -  pResult, 
 *            -  pTapsQ15, 
 *            -  pDelayLine, or 
 *            -  pDelayLineIndex 
 *    -    tapslen < 1 
 *    -    *pDelayLineIndex < 0 or *pDelayLineIndex >= (2 * tapslen) 
 *
 */

OMXResult omxSP_FIROne_Direct_S16(
     OMX_S16 val,
     OMX_S16 * pResult,
     const OMX_S16 * pTapsQ15,
     OMX_INT tapsLen,
     OMX_S16 * pDelayLine,
     OMX_INT * pDelayLineIndex
 )
 {
    OMX_U32 index;
    OMX_S32 accum;
    OMX_S16 *pDelayCurrent;

    /* Input parameter check */ 
    armRetArgErrIf((pResult == NULL), OMX_Sts_BadArgErr)
    armRetArgErrIf((pTapsQ15 == NULL), OMX_Sts_BadArgErr)
    armRetArgErrIf((tapsLen <= 0), OMX_Sts_BadArgErr)
    armRetArgErrIf((pDelayLine == NULL), OMX_Sts_BadArgErr)
    armRetArgErrIf((pDelayLineIndex == NULL), OMX_Sts_BadArgErr)
    armRetArgErrIf((*pDelayLineIndex < 0), OMX_Sts_BadArgErr)
    armRetArgErrIf((*pDelayLineIndex >= (2 * tapsLen)), OMX_Sts_BadArgErr)

    /* Update the delay state */
    pDelayCurrent = &pDelayLine [*pDelayLineIndex];
    
    /* Copy input to current delay line position */
    pDelayCurrent [0] = pDelayCurrent [tapsLen] = val;

    accum = 0;
    for (index = 0; index < tapsLen; index++)
    {
        accum += (OMX_S32)pTapsQ15 [index] * 
                 (OMX_S32)pDelayCurrent [index]; 
    }
    
    if (--(*pDelayLineIndex) < 0)
    {
        *pDelayLineIndex = tapsLen - 1;     
    }
    
    /* Store the result */
    *pResult = armSatRoundLeftShift_S32(accum, -15);
    return OMX_Sts_NoErr;
 }


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 *                              END OF FILE
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