xref: /external/aac/libFDK/src/qmf.cpp

/* -----------------------------------------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android

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Attention: Audio and Multimedia Departments - FDK AAC LL
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----------------------------------------------------------------------------------------------------------- */

/********************************  Fraunhofer IIS  ***************************

   Author(s):   Markus Lohwasser, Josef Hoepfl, Manuel Jander
   Description: QMF filterbank

******************************************************************************/

/*!
  \file
  \brief  Complex qmf analysis/synthesis,
  This module contains the qmf filterbank for analysis [ cplxAnalysisQmfFiltering() ] and
  synthesis [ cplxSynthesisQmfFiltering() ]. It is a polyphase implementation of a complex
  exponential modulated filter bank. The analysis part usually runs at half the sample rate
  than the synthesis part. (So called "dual-rate" mode.)

  The coefficients of the prototype filter are specified in #sbr_qmf_64_640 (in sbr_rom.cpp).
  Thus only a 64 channel version (32 on the analysis side) with a 640 tap prototype filter
  are used.

  \anchor PolyphaseFiltering <h2>About polyphase filtering</h2>
  The polyphase implementation of a filterbank requires filtering at the input and output.
  This is implemented as part of cplxAnalysisQmfFiltering() and cplxSynthesisQmfFiltering().
  The implementation requires the filter coefficients in a specific structure as described in
  #sbr_qmf_64_640_qmf (in sbr_rom.cpp).

  This module comprises the computationally most expensive functions of the SBR decoder. The accuracy of
  computations is also important and has a direct impact on the overall sound quality. Therefore a special
  test program is available which can be used to only test the filterbank: main_audio.cpp

  This modules also uses scaling of data to provide better SNR on fixed-point processors. See #QMF_SCALE_FACTOR (in sbr_scale.h) for details.
  An interesting note: The function getScalefactor() can constitute a significant amount of computational complexity - very much depending on the
  bitrate. Since it is a rather small function, effective assembler optimization might be possible.

*/

#include "qmf.h"


#include "fixpoint_math.h"
#include "dct.h"

#ifdef QMFSYN_STATES_16BIT
#define QSSCALE (7)
#define FX_DBL2FX_QSS(x) ((FIXP_QSS) ((x)>>(DFRACT_BITS-QSS_BITS-QSSCALE) ))
#define FX_QSS2FX_DBL(x) ((FIXP_DBL)((LONG)x)<<(DFRACT_BITS-QSS_BITS-QSSCALE))
#else
#define QSSCALE (0)
#define FX_DBL2FX_QSS(x) (x)
#define FX_QSS2FX_DBL(x) (x)
#endif


#if defined(__arm__)
#include "arm/qmf_arm.cpp"

#endif

/*!
 * \brief Algorithmic scaling in sbrForwardModulation()
 *
 * The scaling in sbrForwardModulation() is caused by:
 *
 *   \li 1 R_SHIFT in sbrForwardModulation()
 *   \li 5/6 R_SHIFT in dct3() if using 32/64 Bands
 *   \li 1 ommited gain of 2.0 in qmfForwardModulation()
 */
#define ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK 7

/*!
 * \brief Algorithmic scaling in cplxSynthesisQmfFiltering()
 *
 * The scaling in cplxSynthesisQmfFiltering() is caused by:
 *
 *   \li  5/6 R_SHIFT in dct2() if using 32/64 Bands
 *   \li  1 ommited gain of 2.0 in qmfInverseModulation()
 *   \li -6 division by 64 in synthesis filterbank
 *   \li x bits external influence
 */
#define ALGORITHMIC_SCALING_IN_SYNTHESIS_FILTERBANK 1


/*!
  \brief Perform Synthesis Prototype Filtering on a single slot of input data.

  The filter takes 2 * qmf->no_channels of input data and
  generates qmf->no_channels time domain output samples.
*/
static
#ifndef FUNCTION_qmfSynPrototypeFirSlot
void qmfSynPrototypeFirSlot(
#else
void qmfSynPrototypeFirSlot_fallback(
#endif
                             HANDLE_QMF_FILTER_BANK qmf,
                             FIXP_QMF *RESTRICT realSlot,            /*!< Input: Pointer to real Slot */
                             FIXP_QMF *RESTRICT imagSlot,            /*!< Input: Pointer to imag Slot */
                             INT_PCM  *RESTRICT timeOut,             /*!< Time domain data */
                             int       stride
                            )
{
  FIXP_QSS* FilterStates = (FIXP_QSS*)qmf->FilterStates;
  int       no_channels = qmf->no_channels;
  const FIXP_PFT *p_Filter = qmf->p_filter;
  int p_stride = qmf->p_stride;
  int j;
  FIXP_QSS *RESTRICT sta = FilterStates;
  const FIXP_PFT *RESTRICT p_flt, *RESTRICT p_fltm;
  int scale = ((DFRACT_BITS-SAMPLE_BITS)-1-qmf->outScalefactor);

  p_flt  = p_Filter+p_stride*QMF_NO_POLY;          /*                     5-ter von 330 */
  p_fltm = p_Filter+(qmf->FilterSize/2)-p_stride*QMF_NO_POLY;  /* 5 + (320 - 2*5) = 315-ter von 330 */

  FDK_ASSERT(SAMPLE_BITS-1-qmf->outScalefactor >= 0); //   (DFRACT_BITS-SAMPLE_BITS)-1-qmf->outScalefactor >= 0);

  for (j = no_channels-1; j >= 0; j--) {  /* ---- l�uft ueber alle Linien eines Slots ---- */
    FIXP_QMF imag  =  imagSlot[j];  // no_channels-1 .. 0
    FIXP_QMF real  =  realSlot[j];  // ~~"~~
    {
      INT_PCM tmp;
      FIXP_DBL Are = FX_QSS2FX_DBL(sta[0]) + fMultDiv2( p_fltm[0] , real);

      if (qmf->outGain!=(FIXP_DBL)0x80000000) {
        Are = fMult(Are,qmf->outGain);
      }

  #if SAMPLE_BITS > 16
      tmp = (INT_PCM)(SATURATE_SHIFT(fAbs(Are), scale, SAMPLE_BITS));
  #else
      tmp = (INT_PCM)(SATURATE_RIGHT_SHIFT(fAbs(Are), scale, SAMPLE_BITS));
  #endif
      if (Are < (FIXP_QMF)0) {
        tmp = -tmp;
      }
      timeOut[ (j)*stride ] = tmp;
    }

    sta[0] = sta[1] + FX_DBL2FX_QSS(fMultDiv2( p_flt [4] , imag ));
    sta[1] = sta[2] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[1] , real ));
    sta[2] = sta[3] + FX_DBL2FX_QSS(fMultDiv2( p_flt [3] , imag ));
    sta[3] = sta[4] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[2] , real ));
    sta[4] = sta[5] + FX_DBL2FX_QSS(fMultDiv2( p_flt [2] , imag ));
    sta[5] = sta[6] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[3] , real ));
    sta[6] = sta[7] + FX_DBL2FX_QSS(fMultDiv2( p_flt [1] , imag ));
    sta[7] = sta[8] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[4] , real ));
    sta[8] =          FX_DBL2FX_QSS(fMultDiv2( p_flt [0] , imag ));

    p_flt  += (p_stride*QMF_NO_POLY);
    p_fltm -= (p_stride*QMF_NO_POLY);
    sta    += 9; // = (2*QMF_NO_POLY-1);
  }
}

#ifndef FUNCTION_qmfSynPrototypeFirSlot_NonSymmetric
/*!
  \brief Perform Synthesis Prototype Filtering on a single slot of input data.

  The filter takes 2 * qmf->no_channels of input data and
  generates qmf->no_channels time domain output samples.
*/
static
void qmfSynPrototypeFirSlot_NonSymmetric(
                             HANDLE_QMF_FILTER_BANK qmf,
                             FIXP_QMF *RESTRICT realSlot,            /*!< Input: Pointer to real Slot */
                             FIXP_QMF *RESTRICT imagSlot,            /*!< Input: Pointer to imag Slot */
                             INT_PCM  *RESTRICT timeOut,             /*!< Time domain data */
                             int       stride
                            )
{
  FIXP_QSS* FilterStates = (FIXP_QSS*)qmf->FilterStates;
  int       no_channels = qmf->no_channels;
  const FIXP_PFT *p_Filter = qmf->p_filter;
  int p_stride = qmf->p_stride;
  int j;
  FIXP_QSS *RESTRICT sta = FilterStates;
  const FIXP_PFT *RESTRICT p_flt, *RESTRICT p_fltm;
  int scale = ((DFRACT_BITS-SAMPLE_BITS)-1-qmf->outScalefactor);

  p_flt  = p_Filter;                           /*!< Pointer to first half of filter coefficients */
  p_fltm = &p_flt[qmf->FilterSize/2];  /* at index 320, overall 640 coefficients */

  FDK_ASSERT(SAMPLE_BITS-1-qmf->outScalefactor >= 0); //   (DFRACT_BITS-SAMPLE_BITS)-1-qmf->outScalefactor >= 0);

  for (j = no_channels-1; j >= 0; j--) {  /* ---- l�uft ueber alle Linien eines Slots ---- */

    FIXP_QMF imag  =  imagSlot[j];  // no_channels-1 .. 0
    FIXP_QMF real  =  realSlot[j];  // ~~"~~
    {
      INT_PCM tmp;
      FIXP_QMF Are = sta[0] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[4] , real ));

  #if SAMPLE_BITS > 16
      tmp = (INT_PCM)(SATURATE_SHIFT(fAbs(Are), scale, SAMPLE_BITS));
  #else
      tmp = (INT_PCM)(SATURATE_RIGHT_SHIFT(fAbs(Are), scale, SAMPLE_BITS));
  #endif
      if (Are < (FIXP_QMF)0) {
        tmp = -tmp;
      }
      timeOut[j*stride] = tmp;
    }

    sta[0] = sta[1] + FX_DBL2FX_QSS(fMultDiv2( p_flt [4] , imag ));
    sta[1] = sta[2] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[3] , real ));
    sta[2] = sta[3] + FX_DBL2FX_QSS(fMultDiv2( p_flt [3] , imag ));

    sta[3] = sta[4] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[2] , real ));
    sta[4] = sta[5] + FX_DBL2FX_QSS(fMultDiv2( p_flt [2] , imag ));
    sta[5] = sta[6] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[1] , real ));
    sta[6] = sta[7] + FX_DBL2FX_QSS(fMultDiv2( p_flt [1] , imag ));

    sta[7] = sta[8] + FX_DBL2FX_QSS(fMultDiv2( p_fltm[0] , real ));
    sta[8] =          FX_DBL2FX_QSS(fMultDiv2( p_flt [0] , imag ));

    p_flt  += (p_stride*QMF_NO_POLY);
    p_fltm += (p_stride*QMF_NO_POLY);
    sta    += 9; // = (2*QMF_NO_POLY-1);
  }

}
#endif /* FUNCTION_qmfSynPrototypeFirSlot_NonSymmetric */

#ifndef FUNCTION_qmfAnaPrototypeFirSlot
/*!
  \brief Perform Analysis Prototype Filtering on a single slot of input data.
*/
static
void qmfAnaPrototypeFirSlot( FIXP_QMF *analysisBuffer,
                             int       no_channels,             /*!< Number channels of analysis filter */
                             const FIXP_PFT *p_filter,
                             int       p_stride,                /*!< Stide of analysis filter    */
                             FIXP_QAS *RESTRICT pFilterStates
                            )
{
    int k;

    FIXP_DBL accu;
    const FIXP_PFT *RESTRICT p_flt = p_filter;
    FIXP_QMF *RESTRICT pData_0 = analysisBuffer + 2*no_channels - 1;
    FIXP_QMF *RESTRICT pData_1 = analysisBuffer;

    FIXP_QAS *RESTRICT sta_0 = (FIXP_QAS *)pFilterStates;
    FIXP_QAS *RESTRICT sta_1 = (FIXP_QAS *)pFilterStates + (2*QMF_NO_POLY*no_channels) - 1;
    int pfltStep = QMF_NO_POLY * (p_stride);
    int staStep1 = no_channels<<1;
    int staStep2 = (no_channels<<3) - 1; /* Rewind one less */

    /* FIR filter 0 */
    accu =   fMultDiv2( p_flt[0], *sta_1);  sta_1 -= staStep1;
    accu +=  fMultDiv2( p_flt[1], *sta_1);  sta_1 -= staStep1;
    accu +=  fMultDiv2( p_flt[2], *sta_1);  sta_1 -= staStep1;
    accu +=  fMultDiv2( p_flt[3], *sta_1);  sta_1 -= staStep1;
    accu +=  fMultDiv2( p_flt[4], *sta_1);
    *pData_1++ = FX_DBL2FX_QMF(accu<<1);
    sta_1 += staStep2;

    p_flt += pfltStep;

    /* FIR filters 1..63 127..65 */
    for (k=0; k<no_channels-1; k++)
    {
      accu =  fMultDiv2( p_flt[0], *sta_0);  sta_0 += staStep1;
      accu += fMultDiv2( p_flt[1], *sta_0);  sta_0 += staStep1;
      accu += fMultDiv2( p_flt[2], *sta_0);  sta_0 += staStep1;
      accu += fMultDiv2( p_flt[3], *sta_0);  sta_0 += staStep1;
      accu += fMultDiv2( p_flt[4], *sta_0);
      *pData_0-- = FX_DBL2FX_QMF(accu<<1);
      sta_0 -= staStep2;

      accu =   fMultDiv2( p_flt[0], *sta_1);  sta_1 -= staStep1;
      accu +=  fMultDiv2( p_flt[1], *sta_1);  sta_1 -= staStep1;
      accu +=  fMultDiv2( p_flt[2], *sta_1);  sta_1 -= staStep1;
      accu +=  fMultDiv2( p_flt[3], *sta_1);  sta_1 -= staStep1;
      accu +=  fMultDiv2( p_flt[4], *sta_1);
      *pData_1++ = FX_DBL2FX_QMF(accu<<1);
      sta_1 += staStep2;

      p_flt += pfltStep;
    }

    /* FIR filter 64 */
    accu =  fMultDiv2( p_flt[0], *sta_0);  sta_0 += staStep1;
    accu += fMultDiv2( p_flt[1], *sta_0);  sta_0 += staStep1;
    accu += fMultDiv2( p_flt[2], *sta_0);  sta_0 += staStep1;
    accu += fMultDiv2( p_flt[3], *sta_0);  sta_0 += staStep1;
    accu += fMultDiv2( p_flt[4], *sta_0);
    *pData_0-- = FX_DBL2FX_QMF(accu<<1);
    sta_0 -= staStep2;
}
#endif /* !defined(FUNCTION_qmfAnaPrototypeFirSlot) */


#ifndef FUNCTION_qmfAnaPrototypeFirSlot_NonSymmetric
/*!
  \brief Perform Analysis Prototype Filtering on a single slot of input data.
*/
static
void qmfAnaPrototypeFirSlot_NonSymmetric(
                                        FIXP_QMF *analysisBuffer,
                                        int       no_channels,             /*!< Number channels of analysis filter */
                                        const FIXP_PFT *p_filter,
                                        int       p_stride,                /*!< Stide of analysis filter    */
                                        FIXP_QAS *RESTRICT pFilterStates
                                       )
{
  const FIXP_PFT *RESTRICT p_flt = p_filter;
  int  p, k;

  for (k = 0; k < 2*no_channels; k++)
  {
    FIXP_DBL accu = (FIXP_DBL)0;

    p_flt += QMF_NO_POLY * (p_stride - 1);

    /*
      Perform FIR-Filter
    */
    for (p = 0; p < QMF_NO_POLY; p++) {
      accu +=  fMultDiv2(*p_flt++, pFilterStates[2*no_channels * p]);
    }
    analysisBuffer[2*no_channels - 1 - k] = FX_DBL2FX_QMF(accu<<1);
    pFilterStates++;
  }
}
#endif /* FUNCTION_qmfAnaPrototypeFirSlot_NonSymmetric */

/*!
 *
 * \brief Perform real-valued forward modulation of the time domain
 *        data of timeIn and stores the real part of the subband
 *        samples in rSubband
 *
 */
static void
qmfForwardModulationLP_even( HANDLE_QMF_FILTER_BANK anaQmf, /*!< Handle of Qmf Analysis Bank  */
                             FIXP_QMF *timeIn,              /*!< Time Signal */
                             FIXP_QMF *rSubband )           /*!< Real Output */
{
  int i;
  int L = anaQmf->no_channels;
  int M = L>>1;
  int scale;
  FIXP_QMF accu;

  const FIXP_QMF *timeInTmp1 = (FIXP_QMF *) &timeIn[3 * M];
  const FIXP_QMF *timeInTmp2 = timeInTmp1;
  FIXP_QMF *rSubbandTmp = rSubband;

  rSubband[0] = timeIn[3 * M] >> 1;

  for (i = M-1; i != 0; i--) {
    accu = ((*--timeInTmp1) >> 1) + ((*++timeInTmp2) >> 1);
    *++rSubbandTmp = accu;
  }

  timeInTmp1 = &timeIn[2 * M];
  timeInTmp2 = &timeIn[0];
  rSubbandTmp = &rSubband[M];

  for (i = L-M; i != 0; i--) {
    accu = ((*timeInTmp1--) >> 1) - ((*timeInTmp2++) >> 1);
    *rSubbandTmp++ = accu;
  }

  dct_III(rSubband, timeIn, L, &scale);
}

#if !defined(FUNCTION_qmfForwardModulationLP_odd)
static void
qmfForwardModulationLP_odd( HANDLE_QMF_FILTER_BANK anaQmf, /*!< Handle of Qmf Analysis Bank  */
                            const FIXP_QMF *timeIn,        /*!< Time Signal */
                            FIXP_QMF *rSubband )           /*!< Real Output */
{
  int i;
  int L = anaQmf->no_channels;
  int M = L>>1;
  int shift = (anaQmf->no_channels>>6) + 1;

  for (i = 0; i < M; i++) {
    rSubband[M + i]     = (timeIn[L - 1 - i]>>1) - (timeIn[i]>>shift);
    rSubband[M - 1 - i] = (timeIn[L + i]>>1)     + (timeIn[2 * L - 1 - i]>>shift);
  }

  dct_IV(rSubband, L, &shift);
}
#endif /* !defined(FUNCTION_qmfForwardModulationLP_odd) */



/*!
 *
 * \brief Perform complex-valued forward modulation of the time domain
 *        data of timeIn and stores the real part of the subband
 *        samples in rSubband, and the imaginary part in iSubband
 *
 *        Only the lower bands are obtained (upto anaQmf->lsb). For
 *        a full bandwidth analysis it is required to set both anaQmf->lsb
 *        and anaQmf->usb to the amount of QMF bands.
 *
 */
static void
qmfForwardModulationHQ( HANDLE_QMF_FILTER_BANK anaQmf,     /*!< Handle of Qmf Analysis Bank  */
                        const FIXP_QMF *RESTRICT timeIn,   /*!< Time Signal */
                        FIXP_QMF *RESTRICT rSubband,       /*!< Real Output */
                        FIXP_QMF *RESTRICT iSubband        /*!< Imaginary Output */
                       )
{
  int i;
  int L = anaQmf->no_channels;
  int L2 = L<<1;
  int shift = 0;

  for (i = 0; i < L; i+=2) {
    FIXP_QMF x0, x1, y0, y1;

    x0 = timeIn[i] >> 1;
    x1 = timeIn[i+1] >> 1;
    y0 = timeIn[L2 - 1 - i] >> 1;
    y1 = timeIn[L2 - 2 - i] >> 1;

    rSubband[i] = x0 - y0;
    rSubband[i+1] = x1 - y1;
    iSubband[i] = x0 + y0;
    iSubband[i+1] = x1 + y1;
  }

  dct_IV(rSubband, L, &shift);
  dst_IV(iSubband, L, &shift);

  {
    {
      const FIXP_QTW *RESTRICT sbr_t_cos;
      const FIXP_QTW *RESTRICT sbr_t_sin;
      sbr_t_cos = anaQmf->t_cos;
      sbr_t_sin = anaQmf->t_sin;

      for (i = 0; i < anaQmf->lsb; i++) {
        cplxMult(&iSubband[i], &rSubband[i], iSubband[i], rSubband[i], sbr_t_cos[i], sbr_t_sin[i]);
      }
    }
  }
}

/*
 * \brief Perform one QMF slot analysis of the time domain data of timeIn
 *        with specified stride and stores the real part of the subband
 *        samples in rSubband, and the imaginary part in iSubband
 *
 *        Only the lower bands are obtained (upto anaQmf->lsb). For
 *        a full bandwidth analysis it is required to set both anaQmf->lsb
 *        and anaQmf->usb to the amount of QMF bands.
 */
void
qmfAnalysisFilteringSlot( HANDLE_QMF_FILTER_BANK anaQmf,  /*!< Handle of Qmf Synthesis Bank  */
                          FIXP_QMF      *qmfReal,         /*!< Low and High band, real */
                          FIXP_QMF      *qmfImag,         /*!< Low and High band, imag */
                          const INT_PCM *RESTRICT timeIn, /*!< Pointer to input */
                          const int      stride,          /*!< stride factor of input */
                          FIXP_QMF      *pWorkBuffer      /*!< pointer to temporal working buffer */
                         )
{
    int i;
    int offset = anaQmf->no_channels*(QMF_NO_POLY*2-1);
    /*
      Feed time signal into oldest anaQmf->no_channels states
    */
    {
      FIXP_QAS *RESTRICT FilterStatesAnaTmp = ((FIXP_QAS*)anaQmf->FilterStates)+offset;

      /* Feed and scale actual time in slot */
      for(i=anaQmf->no_channels>>1; i!=0; i--) {
        /* Place INT_PCM value left aligned in scaledTimeIn */
#if (QAS_BITS==SAMPLE_BITS)
        *FilterStatesAnaTmp++ = (FIXP_QAS)*timeIn; timeIn += stride;
        *FilterStatesAnaTmp++ = (FIXP_QAS)*timeIn; timeIn += stride;
#elif (QAS_BITS>SAMPLE_BITS)
        *FilterStatesAnaTmp++ = (FIXP_QAS)((*timeIn)<<(QAS_BITS-SAMPLE_BITS)); timeIn += stride;
        *FilterStatesAnaTmp++ = (FIXP_QAS)((*timeIn)<<(QAS_BITS-SAMPLE_BITS)); timeIn += stride;
#else
        *FilterStatesAnaTmp++ = (FIXP_QAS)((*timeIn)>>(SAMPLE_BITS-QAS_BITS)); timeIn += stride;
        *FilterStatesAnaTmp++ = (FIXP_QAS)((*timeIn)>>(SAMPLE_BITS-QAS_BITS)); timeIn += stride;
#endif
      }
    }

    if (anaQmf->flags & QMF_FLAG_NONSYMMETRIC) {
      qmfAnaPrototypeFirSlot_NonSymmetric(
                              pWorkBuffer,
                              anaQmf->no_channels,
                              anaQmf->p_filter,
                              anaQmf->p_stride,
                              (FIXP_QAS*)anaQmf->FilterStates
                            );
    } else {
      qmfAnaPrototypeFirSlot( pWorkBuffer,
                              anaQmf->no_channels,
                              anaQmf->p_filter,
                              anaQmf->p_stride,
                              (FIXP_QAS*)anaQmf->FilterStates
                            );
    }

    if (anaQmf->flags & QMF_FLAG_LP) {
      if (anaQmf->flags & QMF_FLAG_CLDFB)
        qmfForwardModulationLP_odd( anaQmf,
                                    pWorkBuffer,
                                    qmfReal );
      else
        qmfForwardModulationLP_even( anaQmf,
                                     pWorkBuffer,
                                     qmfReal );

    } else {
      qmfForwardModulationHQ( anaQmf,
                              pWorkBuffer,
                              qmfReal,
                              qmfImag
                             );
    }
    /*
      Shift filter states

      Should be realized with modulo adressing on a DSP instead of a true buffer shift
    */
    FDKmemmove ((FIXP_QAS*)anaQmf->FilterStates, (FIXP_QAS*)anaQmf->FilterStates+anaQmf->no_channels, offset*sizeof(FIXP_QAS));
}


/*!
 *
 * \brief Perform complex-valued subband filtering of the time domain
 *        data of timeIn and stores the real part of the subband
 *        samples in rAnalysis, and the imaginary part in iAnalysis
 * The qmf coefficient table is symmetric. The symmetry is expoited by
 * shrinking the coefficient table to half the size. The addressing mode
 * takes care of the symmetries.
 *
 * Only the lower bands are obtained (upto anaQmf->lsb). For
 * a full bandwidth analysis it is required to set both anaQmf->lsb
 * and anaQmf->usb to the amount of QMF bands.
 *
 * \sa PolyphaseFiltering
 */

void
qmfAnalysisFiltering( HANDLE_QMF_FILTER_BANK anaQmf,    /*!< Handle of Qmf Analysis Bank */
                      FIXP_QMF **qmfReal,               /*!< Pointer to real subband slots */
                      FIXP_QMF **qmfImag,               /*!< Pointer to imag subband slots */
                      QMF_SCALE_FACTOR *scaleFactor,
                      const INT_PCM *timeIn,            /*!< Time signal */
                      const int  stride,
                      FIXP_QMF  *pWorkBuffer            /*!< pointer to temporal working buffer */
                      )
{
  int i;
  int no_channels = anaQmf->no_channels;

  scaleFactor->lb_scale = -ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK;
  scaleFactor->lb_scale -= anaQmf->filterScale;

  for (i = 0; i < anaQmf->no_col; i++)
  {
      FIXP_QMF *qmfImagSlot = NULL;

      if (!(anaQmf->flags & QMF_FLAG_LP)) {
        qmfImagSlot = qmfImag[i];
      }

      qmfAnalysisFilteringSlot( anaQmf, qmfReal[i], qmfImagSlot, timeIn , stride, pWorkBuffer );

      timeIn += no_channels*stride;

  } /* no_col loop  i  */
}

/*!
 *
 * \brief Perform low power inverse modulation of the subband
 *        samples stored in rSubband (real part) and iSubband (imaginary
 *        part) and stores the result in pWorkBuffer.
 *
 */
inline
static void
qmfInverseModulationLP_even( HANDLE_QMF_FILTER_BANK synQmf,   /*!< Handle of Qmf Synthesis Bank  */
                             const FIXP_QMF *qmfReal,         /*!< Pointer to qmf real subband slot (input) */
                             const int   scaleFactorLowBand,  /*!< Scalefactor for Low band */
                             const int   scaleFactorHighBand, /*!< Scalefactor for High band */
                             FIXP_QMF *pTimeOut               /*!< Pointer to qmf subband slot (output)*/
                           )
{
  int i;
  int L = synQmf->no_channels;
  int M = L>>1;
  int scale;
  FIXP_QMF tmp;
  FIXP_QMF *RESTRICT tReal = pTimeOut;
  FIXP_QMF *RESTRICT tImag = pTimeOut + L;

  /* Move input to output vector with offset */
  scaleValues(&tReal[0],             &qmfReal[0],             synQmf->lsb,             scaleFactorLowBand);
  scaleValues(&tReal[0+synQmf->lsb], &qmfReal[0+synQmf->lsb], synQmf->usb-synQmf->lsb, scaleFactorHighBand);
  FDKmemclear(&tReal[0+synQmf->usb], (L-synQmf->usb)*sizeof(FIXP_QMF));

  /* Dct type-2 transform */
  dct_II(tReal, tImag, L, &scale);

  /* Expand output and replace inplace the output buffers */
  tImag[0] = tReal[M];
  tImag[M] = (FIXP_QMF)0;
  tmp = tReal [0];
  tReal [0] = tReal[M];
  tReal [M] = tmp;

  for (i = 1; i < M/2; i++) {
    /* Imag */
    tmp = tReal[L - i];
    tImag[M - i] =  tmp;
    tImag[i + M] = -tmp;

    tmp = tReal[M + i];
    tImag[i] =  tmp;
    tImag[L - i] = -tmp;

    /* Real */
    tReal [M + i] = tReal[i];
    tReal [L - i] = tReal[M - i];
    tmp = tReal[i];
    tReal[i] = tReal [M - i];
    tReal [M - i] = tmp;

  }
  /* Remaining odd terms */
  tmp = tReal[M + M/2];
  tImag[M/2]     =  tmp;
  tImag[M/2 + M] = -tmp;

  tReal [M + M/2] = tReal[M/2];
}

inline
static void
qmfInverseModulationLP_odd( HANDLE_QMF_FILTER_BANK synQmf,   /*!< Handle of Qmf Synthesis Bank  */
                            const FIXP_QMF *qmfReal,         /*!< Pointer to qmf real subband slot (input) */
                            const int scaleFactorLowBand,    /*!< Scalefactor for Low band */
                            const int scaleFactorHighBand,   /*!< Scalefactor for High band */
                            FIXP_QMF *pTimeOut               /*!< Pointer to qmf subband slot (output)*/
                          )
{
  int i;
  int L = synQmf->no_channels;
  int M = L>>1;
  int shift = 0;

  /* Move input to output vector with offset */
  scaleValues(pTimeOut+M,              qmfReal,             synQmf->lsb,             scaleFactorLowBand);
  scaleValues(pTimeOut+M+synQmf->lsb,  qmfReal+synQmf->lsb, synQmf->usb-synQmf->lsb, scaleFactorHighBand);
  FDKmemclear(pTimeOut+M+synQmf->usb, (L-synQmf->usb)*sizeof(FIXP_QMF));

  dct_IV(pTimeOut+M, L, &shift);
  for (i = 0; i < M; i++) {
    pTimeOut[i]             =  pTimeOut[L - 1 - i];
    pTimeOut[2 * L - 1 - i] = -pTimeOut[L + i];
  }
}


/*!
 *
 * \brief Perform complex-valued inverse modulation of the subband
 *        samples stored in rSubband (real part) and iSubband (imaginary
 *        part) and stores the result in pWorkBuffer.
 *
 */
inline
static void
qmfInverseModulationHQ( HANDLE_QMF_FILTER_BANK synQmf,  /*!< Handle of Qmf Synthesis Bank     */
                        const FIXP_QMF *qmfReal,        /*!< Pointer to qmf real subband slot */
                        const FIXP_QMF *qmfImag,        /*!< Pointer to qmf imag subband slot */
                        const int   scaleFactorLowBand, /*!< Scalefactor for Low band         */
                        const int   scaleFactorHighBand,/*!< Scalefactor for High band        */
                        FIXP_QMF  *pWorkBuffer          /*!< WorkBuffer (output)              */
                      )
{
  int i;
  int L = synQmf->no_channels;
  int M = L>>1;
  int shift = 0;
  FIXP_QMF *RESTRICT tReal = pWorkBuffer;
  FIXP_QMF *RESTRICT tImag = pWorkBuffer+L;

  if (synQmf->flags & QMF_FLAG_CLDFB){
    for (i = 0; i < synQmf->lsb; i++) {
      cplxMult(&tImag[i], &tReal[i],
                scaleValue(qmfImag[i],scaleFactorLowBand), scaleValue(qmfReal[i],scaleFactorLowBand),
                synQmf->t_cos[i], synQmf->t_sin[i]);
    }
    for (; i < synQmf->usb; i++) {
      cplxMult(&tImag[i], &tReal[i],
                scaleValue(qmfImag[i],scaleFactorHighBand), scaleValue(qmfReal[i],scaleFactorHighBand),
                synQmf->t_cos[i], synQmf->t_sin[i]);
    }
  }

  if ( (synQmf->flags & QMF_FLAG_CLDFB) == 0) {
    scaleValues(&tReal[0],             &qmfReal[0],             synQmf->lsb,             scaleFactorLowBand);
    scaleValues(&tReal[0+synQmf->lsb], &qmfReal[0+synQmf->lsb], synQmf->usb-synQmf->lsb, scaleFactorHighBand);
    scaleValues(&tImag[0],             &qmfImag[0],             synQmf->lsb,             scaleFactorLowBand);
    scaleValues(&tImag[0+synQmf->lsb], &qmfImag[0+synQmf->lsb], synQmf->usb-synQmf->lsb, scaleFactorHighBand);
  }

  FDKmemclear(&tReal[synQmf->usb], (synQmf->no_channels-synQmf->usb)*sizeof(FIXP_QMF));
  FDKmemclear(&tImag[synQmf->usb], (synQmf->no_channels-synQmf->usb)*sizeof(FIXP_QMF));

  dct_IV(tReal, L, &shift);
  dst_IV(tImag, L, &shift);

  if (synQmf->flags & QMF_FLAG_CLDFB){
    for (i = 0; i < M; i++) {
      FIXP_QMF r1, i1, r2, i2;
      r1 = tReal[i];
      i2 = tImag[L - 1 - i];
      r2 = tReal[L - i - 1];
      i1 = tImag[i];

      tReal[i] = (r1 - i1)>>1;
      tImag[L - 1 - i] = -(r1 + i1)>>1;
      tReal[L - i - 1] =  (r2 - i2)>>1;
      tImag[i] = -(r2 + i2)>>1;
    }
  } else
  {
    /* The array accesses are negative to compensate the missing minus sign in the low and hi band gain. */
    /* 26 cycles on ARM926 */
    for (i = 0; i < M; i++) {
      FIXP_QMF r1, i1, r2, i2;
      r1 = -tReal[i];
      i2 = -tImag[L - 1 - i];
      r2 = -tReal[L - i - 1];
      i1 = -tImag[i];

      tReal[i] = (r1 - i1)>>1;
      tImag[L - 1 - i] = -(r1 + i1)>>1;
      tReal[L - i - 1] =  (r2 - i2)>>1;
      tImag[i] = -(r2 + i2)>>1;
    }
  }
}

void qmfSynthesisFilteringSlot( HANDLE_QMF_FILTER_BANK  synQmf,
                                const FIXP_QMF  *realSlot,
                                const FIXP_QMF  *imagSlot,
                                const int        scaleFactorLowBand,
                                const int        scaleFactorHighBand,
                                INT_PCM         *timeOut,
                                const int        stride,
                                FIXP_QMF        *pWorkBuffer)
{
    if (!(synQmf->flags & QMF_FLAG_LP))
      qmfInverseModulationHQ ( synQmf,
                               realSlot,
                               imagSlot,
                               scaleFactorLowBand,
                               scaleFactorHighBand,
                               pWorkBuffer
                             );
    else
    {
      if (synQmf->flags & QMF_FLAG_CLDFB) {
        qmfInverseModulationLP_odd ( synQmf,
                                 realSlot,
                                 scaleFactorLowBand,
                                 scaleFactorHighBand,
                                 pWorkBuffer
                               );
      } else {
        qmfInverseModulationLP_even ( synQmf,
                                 realSlot,
                                 scaleFactorLowBand,
                                 scaleFactorHighBand,
                                 pWorkBuffer
                               );
      }
    }

    if (synQmf->flags & QMF_FLAG_NONSYMMETRIC) {
        qmfSynPrototypeFirSlot_NonSymmetric (
                                 synQmf,
                                 pWorkBuffer,
                                 pWorkBuffer+synQmf->no_channels,
                                 timeOut,
                                 stride
                               );
    } else {
        qmfSynPrototypeFirSlot ( synQmf,
                                 pWorkBuffer,
                                 pWorkBuffer+synQmf->no_channels,
                                 timeOut,
                                 stride
                               );
    }
}


/*!
 *
 *
 * \brief Perform complex-valued subband synthesis of the
 *        low band and the high band and store the
 *        time domain data in timeOut
 *
 * First step: Calculate the proper scaling factor of current
 * spectral data in qmfReal/qmfImag, old spectral data in the overlap
 * range and filter states.
 *
 * Second step: Perform Frequency-to-Time mapping with inverse
 * Modulation slot-wise.
 *
 * Third step: Perform FIR-filter slot-wise. To save space for filter
 * states, the MAC operations are executed directly on the filter states
 * instead of accumulating several products in the accumulator. The
 * buffer shift at the end of the function should be replaced by a
 * modulo operation, which is available on some DSPs.
 *
 * Last step: Copy the upper part of the spectral data to the overlap buffer.
 *
 * The qmf coefficient table is symmetric. The symmetry is exploited by
 * shrinking the coefficient table to half the size. The addressing mode
 * takes care of the symmetries.  If the #define #QMFTABLE_FULL is set,
 * coefficient addressing works on the full table size. The code will be
 * slightly faster and slightly more compact.
 *
 * Workbuffer requirement: 2 x sizeof(**QmfBufferReal) * synQmf->no_channels
 */
void
qmfSynthesisFiltering( HANDLE_QMF_FILTER_BANK synQmf,       /*!< Handle of Qmf Synthesis Bank  */
                       FIXP_QMF  **QmfBufferReal,           /*!< Low and High band, real */
                       FIXP_QMF  **QmfBufferImag,           /*!< Low and High band, imag */
                       const QMF_SCALE_FACTOR *scaleFactor,
                       const INT   ov_len,                  /*!< split Slot of overlap and actual slots */
                       INT_PCM    *timeOut,                 /*!< Pointer to output */
                       const INT   stride,                  /*!< stride factor of output */
                       FIXP_QMF   *pWorkBuffer              /*!< pointer to temporal working buffer */
                      )
{
  int i;
  int L = synQmf->no_channels;
  SCHAR scaleFactorHighBand;
  SCHAR scaleFactorLowBand_ov, scaleFactorLowBand_no_ov;

  /* adapt scaling */
  scaleFactorHighBand = -ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK - scaleFactor->hb_scale;
  scaleFactorLowBand_ov = - ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK - scaleFactor->ov_lb_scale;
  scaleFactorLowBand_no_ov = - ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK - scaleFactor->lb_scale;

  for (i = 0; i < synQmf->no_col; i++)  /* ----- no_col loop ----- */
  {
    const FIXP_DBL *QmfBufferImagSlot = NULL;

    SCHAR scaleFactorLowBand = (i<ov_len) ? scaleFactorLowBand_ov : scaleFactorLowBand_no_ov;

    if (!(synQmf->flags & QMF_FLAG_LP))
        QmfBufferImagSlot = QmfBufferImag[i];

    qmfSynthesisFilteringSlot(  synQmf,
                                QmfBufferReal[i],
                                QmfBufferImagSlot,
                                scaleFactorLowBand,
                                scaleFactorHighBand,
                                timeOut+(i*L*stride),
                                stride,
                                pWorkBuffer);
  } /* no_col loop  i  */

}


/*!
 *
 * \brief Create QMF filter bank instance
 *
 * \return 0 if successful
 *
 */
static int
qmfInitFilterBank (HANDLE_QMF_FILTER_BANK h_Qmf,     /*!< Handle to return */
                   void *pFilterStates,              /*!< Handle to filter states */
                   int noCols,                       /*!< Number of timeslots per frame */
                   int lsb,                          /*!< Lower end of QMF frequency range */
                   int usb,                          /*!< Upper end of QMF frequency range */
                   int no_channels,                  /*!< Number of channels (bands) */
                   UINT flags)                       /*!< flags */
{
  FDKmemclear(h_Qmf,sizeof(QMF_FILTER_BANK));

  if (flags & QMF_FLAG_MPSLDFB)
  {
    return -1;
  }

  if ( !(flags & QMF_FLAG_MPSLDFB) && (flags & QMF_FLAG_CLDFB) )
  {
    flags |= QMF_FLAG_NONSYMMETRIC;
    h_Qmf->filterScale = QMF_CLDFB_PFT_SCALE;

    h_Qmf->p_stride = 1;
    switch (no_channels) {
      case 64:
        h_Qmf->t_cos = qmf_phaseshift_cos64_cldfb;
        h_Qmf->t_sin = qmf_phaseshift_sin64_cldfb;
        h_Qmf->p_filter = qmf_cldfb_640;
        h_Qmf->FilterSize = 640;
        break;
      case 32:
        h_Qmf->t_cos = qmf_phaseshift_cos32_cldfb;
        h_Qmf->t_sin = qmf_phaseshift_sin32_cldfb;
        h_Qmf->p_filter = qmf_cldfb_320;
        h_Qmf->FilterSize = 320;
        break;
      default:
        return -1;
    }
  }

  if ( !(flags & QMF_FLAG_MPSLDFB) && ((flags & QMF_FLAG_CLDFB) == 0) )
  {
    switch (no_channels) {
      case 64:
        h_Qmf->p_filter = qmf_64;
        h_Qmf->t_cos = qmf_phaseshift_cos64;
        h_Qmf->t_sin = qmf_phaseshift_sin64;
        h_Qmf->p_stride = 1;
        h_Qmf->FilterSize = 640;
        h_Qmf->filterScale = 0;
        break;
      case 32:
        h_Qmf->p_filter = qmf_64;
        h_Qmf->t_cos = qmf_phaseshift_cos32;
        h_Qmf->t_sin = qmf_phaseshift_sin32;
        h_Qmf->p_stride = 2;
        h_Qmf->FilterSize = 640;
        h_Qmf->filterScale = 0;
        break;
      default:
        return -1;
    }
  }

  h_Qmf->flags = flags;

  h_Qmf->no_channels = no_channels;
  h_Qmf->no_col = noCols;

  h_Qmf->lsb = lsb;
  h_Qmf->usb = fMin(usb, h_Qmf->no_channels);

  h_Qmf->FilterStates = (void*)pFilterStates;

  h_Qmf->outScalefactor = ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK + ALGORITHMIC_SCALING_IN_SYNTHESIS_FILTERBANK + h_Qmf->filterScale;

  if ( (h_Qmf->p_stride == 2)
    || ((flags & QMF_FLAG_CLDFB) && (no_channels == 32)) ) {
    h_Qmf->outScalefactor -= 1;
  }
  h_Qmf->outGain = (FIXP_DBL)0x80000000; /* default init value will be not applied */

  return (0);
}

/*!
 *
 * \brief Adjust synthesis qmf filter states
 *
 * \return void
 *
 */
static inline void
qmfAdaptFilterStates (HANDLE_QMF_FILTER_BANK synQmf,     /*!< Handle of Qmf Filter Bank */
                      int scaleFactorDiff)               /*!< Scale factor difference to be applied */
{
  if (synQmf == NULL || synQmf->FilterStates == NULL) {
    return;
  }
  scaleValues((FIXP_QSS*)synQmf->FilterStates, synQmf->no_channels*(QMF_NO_POLY*2 - 1), scaleFactorDiff);
}

/*!
 *
 * \brief Create QMF filter bank instance
 *
 * Only the lower bands are obtained (upto anaQmf->lsb). For
 * a full bandwidth analysis it is required to set both anaQmf->lsb
 * and anaQmf->usb to the amount of QMF bands.
 *
 * \return 0 if succesful
 *
 */
int
qmfInitAnalysisFilterBank (HANDLE_QMF_FILTER_BANK h_Qmf,   /*!< Returns handle */
                           FIXP_QAS *pFilterStates,        /*!< Handle to filter states */
                           int noCols,                     /*!< Number of timeslots per frame */
                           int lsb,                        /*!< lower end of QMF */
                           int usb,                        /*!< upper end of QMF */
                           int no_channels,                /*!< Number of channels (bands) */
                           int flags)                      /*!< Low Power flag */
{
  int err = qmfInitFilterBank(h_Qmf, pFilterStates, noCols, lsb, usb, no_channels, flags);
  if ( !(flags & QMF_FLAG_KEEP_STATES) && (h_Qmf->FilterStates != NULL) ) {
    FDKmemclear(h_Qmf->FilterStates, (2*QMF_NO_POLY-1)*h_Qmf->no_channels*sizeof(FIXP_QAS));
  }

  return err;
}

/*!
 *
 * \brief Create QMF filter bank instance
 *
 * Only the lower bands are obtained (upto anaQmf->lsb). For
 * a full bandwidth analysis it is required to set both anaQmf->lsb
 * and anaQmf->usb to the amount of QMF bands.
 *
 * \return 0 if succesful
 *
 */
int
qmfInitSynthesisFilterBank (HANDLE_QMF_FILTER_BANK h_Qmf,   /*!< Returns handle */
                            FIXP_QSS *pFilterStates,        /*!< Handle to filter states */
                            int noCols,                     /*!< Number of timeslots per frame */
                            int lsb,                        /*!< lower end of QMF */
                            int usb,                        /*!< upper end of QMF */
                            int no_channels,                /*!< Number of channels (bands) */
                            int flags)                      /*!< Low Power flag */
{
  int oldOutScale = h_Qmf->outScalefactor;
  int err = qmfInitFilterBank(h_Qmf, pFilterStates, noCols, lsb, usb, no_channels, flags);
  if ( h_Qmf->FilterStates != NULL ) {
    if ( !(flags & QMF_FLAG_KEEP_STATES) ) {
      FDKmemclear(h_Qmf->FilterStates, (2*QMF_NO_POLY-1)*h_Qmf->no_channels*sizeof(FIXP_QSS));
    } else {
      qmfAdaptFilterStates(h_Qmf, oldOutScale-h_Qmf->outScalefactor);
    }
  }
  return err;
}




/*!
 *
 * \brief Change scale factor for output data and adjust qmf filter states
 *
 * \return void
 *
 */
void
qmfChangeOutScalefactor (HANDLE_QMF_FILTER_BANK synQmf,     /*!< Handle of Qmf Synthesis Bank */
                         int outScalefactor                 /*!< New scaling factor for output data */
                        )
{
  if (synQmf == NULL || synQmf->FilterStates == NULL) {
    return;
  }

  /* Add internal filterbank scale */
  outScalefactor += ALGORITHMIC_SCALING_IN_ANALYSIS_FILTERBANK + ALGORITHMIC_SCALING_IN_SYNTHESIS_FILTERBANK + synQmf->filterScale;

  if ( (synQmf->p_stride == 2)
    || ((synQmf->flags & QMF_FLAG_CLDFB) && (synQmf->no_channels == 32)) ) {
    outScalefactor -= 1;
  }

  /* adjust filter states when scale factor has been changed */
  if (synQmf->outScalefactor != outScalefactor)
  {
    int diff;

    if (outScalefactor > (SAMPLE_BITS - 1)) {
      outScalefactor = SAMPLE_BITS - 1;
    } else if (outScalefactor < (1 - SAMPLE_BITS)) {
      outScalefactor = 1 - SAMPLE_BITS;
    }

    diff = synQmf->outScalefactor - outScalefactor;

    qmfAdaptFilterStates(synQmf, diff);

    /* save new scale factor */
    synQmf->outScalefactor = outScalefactor;
  }
}

/*!
 *
 * \brief Change gain for output data
 *
 * \return void
 *
 */
void
qmfChangeOutGain (HANDLE_QMF_FILTER_BANK synQmf,     /*!< Handle of Qmf Synthesis Bank */
                  FIXP_DBL outputGain                /*!< New gain for output data */
                 )
{
  synQmf->outGain = outputGain;
}