path: root/libFDK/src/FDK_hybrid.cpp

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

© Copyright  1995 - 2020 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.

 1.    INTRODUCTION
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that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
scheme for digital audio. This FDK AAC Codec software is intended to be used on
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AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
general perceptual audio codecs. AAC-ELD is considered the best-performing
full-bandwidth communications codec by independent studies and is widely
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specifications.

Patent licenses for necessary patent claims for the FDK AAC Codec (including
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Commercially-licensed AAC software libraries, including floating-point versions
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information and documentation.

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are permitted without payment of copyright license fees provided that you
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5.    CONTACT INFORMATION

Fraunhofer Institute for Integrated Circuits IIS
Attention: Audio and Multimedia Departments - FDK AAC LL
Am Wolfsmantel 33
91058 Erlangen, Germany

www.iis.fraunhofer.de/amm
amm-info@iis.fraunhofer.de
----------------------------------------------------------------------------- */

/******************* Library for basic calculation routines ********************

   Author(s):   Markus Lohwasser

   Description: FDK Tools Hybrid Filterbank

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

#include "FDK_hybrid.h"

#include "fft.h"

/*--------------- defines -----------------------------*/
#define FFT_IDX_R(a) (2 * a)
#define FFT_IDX_I(a) (2 * a + 1)

#define HYB_COEF8_0 (0.00746082949812f)
#define HYB_COEF8_1 (0.02270420949825f)
#define HYB_COEF8_2 (0.04546865930473f)
#define HYB_COEF8_3 (0.07266113929591f)
#define HYB_COEF8_4 (0.09885108575264f)
#define HYB_COEF8_5 (0.11793710567217f)
#define HYB_COEF8_6 (0.12500000000000f)
#define HYB_COEF8_7 (HYB_COEF8_5)
#define HYB_COEF8_8 (HYB_COEF8_4)
#define HYB_COEF8_9 (HYB_COEF8_3)
#define HYB_COEF8_10 (HYB_COEF8_2)
#define HYB_COEF8_11 (HYB_COEF8_1)
#define HYB_COEF8_12 (HYB_COEF8_0)

/*--------------- structure definitions ---------------*/

#if defined(ARCH_PREFER_MULT_32x16)
#define FIXP_HTB FIXP_SGL              /* SGL data type. */
#define FIXP_HTP FIXP_SPK              /* Packed SGL data type. */
#define HTC(a) (FX_DBL2FXCONST_SGL(a)) /* Cast to SGL */
#define FL2FXCONST_HTB FL2FXCONST_SGL
#else
#define FIXP_HTB FIXP_DBL            /* SGL data type. */
#define FIXP_HTP FIXP_DPK            /* Packed DBL data type. */
#define HTC(a) ((FIXP_DBL)(LONG)(a)) /* Cast to DBL */
#define FL2FXCONST_HTB FL2FXCONST_DBL
#endif

#define HTCP(real, imag)     \
  {                          \
    { HTC(real), HTC(imag) } \
  } /* How to arrange the packed values. */

struct FDK_HYBRID_SETUP {
  UCHAR nrQmfBands;     /*!< Number of QMF bands to be converted to hybrid. */
  UCHAR nHybBands[3];   /*!< Number of Hybrid bands generated by nrQmfBands. */
  UCHAR synHybScale[3]; /*!< Headroom needed in hybrid synthesis filterbank. */
  SCHAR kHybrid[3];     /*!< Filter configuration of each QMF band. */
  UCHAR protoLen;       /*!< Prototype filter length. */
  UCHAR filterDelay;    /*!< Delay caused by hybrid filter. */
  const INT
      *pReadIdxTable; /*!< Helper table to access input data ringbuffer. */
};

/*--------------- constants ---------------------------*/
static const INT ringbuffIdxTab[2 * 13] = {0, 1,  2,  3,  4, 5,  6,  7, 8,
                                           9, 10, 11, 12, 0, 1,  2,  3, 4,
                                           5, 6,  7,  8,  9, 10, 11, 12};

static const FDK_HYBRID_SETUP setup_3_16 = {
    3, {8, 4, 4}, {4, 3, 3}, {8, 4, 4}, 13, (13 - 1) / 2, ringbuffIdxTab};
static const FDK_HYBRID_SETUP setup_3_12 = {
    3, {8, 2, 2}, {4, 2, 2}, {8, 2, 2}, 13, (13 - 1) / 2, ringbuffIdxTab};
static const FDK_HYBRID_SETUP setup_3_10 = {
    3, {6, 2, 2}, {3, 2, 2}, {-8, -2, 2}, 13, (13 - 1) / 2, ringbuffIdxTab};

static const FIXP_HTP HybFilterCoef8[] = {
    HTCP(0x10000000, 0x00000000), HTCP(0x0df26407, 0xfa391882),
    HTCP(0xff532109, 0x00acdef7), HTCP(0x08f26d36, 0xf70d92ca),
    HTCP(0xfee34b5f, 0x02af570f), HTCP(0x038f276e, 0xf7684793),
    HTCP(0x00000000, 0x05d1eac2), HTCP(0x00000000, 0x05d1eac2),
    HTCP(0x038f276e, 0x0897b86d), HTCP(0xfee34b5f, 0xfd50a8f1),
    HTCP(0x08f26d36, 0x08f26d36), HTCP(0xff532109, 0xff532109),
    HTCP(0x0df26407, 0x05c6e77e)};

static const FIXP_HTB HybFilterCoef2[3] = {FL2FXCONST_HTB(0.01899487526049f),
                                           FL2FXCONST_HTB(-0.07293139167538f),
                                           FL2FXCONST_HTB(0.30596630545168f)};

static const FIXP_HTB HybFilterCoef4[13] = {FL2FXCONST_HTB(-0.00305151927305f),
                                            FL2FXCONST_HTB(-0.00794862316203f),
                                            FL2FXCONST_HTB(0.0f),
                                            FL2FXCONST_HTB(0.04318924038756f),
                                            FL2FXCONST_HTB(0.12542448210445f),
                                            FL2FXCONST_HTB(0.21227807049160f),
                                            FL2FXCONST_HTB(0.25f),
                                            FL2FXCONST_HTB(0.21227807049160f),
                                            FL2FXCONST_HTB(0.12542448210445f),
                                            FL2FXCONST_HTB(0.04318924038756f),
                                            FL2FXCONST_HTB(0.0f),
                                            FL2FXCONST_HTB(-0.00794862316203f),
                                            FL2FXCONST_HTB(-0.00305151927305f)};

/*--------------- function declarations ---------------*/
static INT kChannelFiltering(const FIXP_DBL *const pQmfReal,
                             const FIXP_DBL *const pQmfImag,
                             const INT *const pReadIdx,
                             FIXP_DBL *const mHybridReal,
                             FIXP_DBL *const mHybridImag,
                             const SCHAR hybridConfig);

/*--------------- function definitions ----------------*/

INT FDKhybridAnalysisOpen(HANDLE_FDK_ANA_HYB_FILTER hAnalysisHybFilter,
                          FIXP_DBL *const pLFmemory, const UINT LFmemorySize,
                          FIXP_DBL *const pHFmemory, const UINT HFmemorySize) {
  INT err = 0;

  /* Save pointer to extern memory. */
  hAnalysisHybFilter->pLFmemory = pLFmemory;
  hAnalysisHybFilter->LFmemorySize = LFmemorySize;

  hAnalysisHybFilter->pHFmemory = pHFmemory;
  hAnalysisHybFilter->HFmemorySize = HFmemorySize;

  return err;
}

INT FDKhybridAnalysisInit(HANDLE_FDK_ANA_HYB_FILTER hAnalysisHybFilter,
                          const FDK_HYBRID_MODE mode, const INT qmfBands,
                          const INT cplxBands, const INT initStatesFlag) {
  int k;
  INT err = 0;
  FIXP_DBL *pMem = NULL;
  HANDLE_FDK_HYBRID_SETUP setup = NULL;

  switch (mode) {
    case THREE_TO_TEN:
      setup = &setup_3_10;
      break;
    case THREE_TO_TWELVE:
      setup = &setup_3_12;
      break;
    case THREE_TO_SIXTEEN:
      setup = &setup_3_16;
      break;
    default:
      err = -1;
      goto bail;
  }

  /* Initialize handle. */
  hAnalysisHybFilter->pSetup = setup;
  if (initStatesFlag) {
    hAnalysisHybFilter->bufferLFpos = setup->protoLen - 1;
    hAnalysisHybFilter->bufferHFpos = 0;
  }
  hAnalysisHybFilter->nrBands = qmfBands;
  hAnalysisHybFilter->cplxBands = cplxBands;
  hAnalysisHybFilter->hfMode = 0;

  /* Check available memory. */
  if (((2 * setup->nrQmfBands * setup->protoLen * sizeof(FIXP_DBL)) >
       hAnalysisHybFilter->LFmemorySize)) {
    err = -2;
    goto bail;
  }
  if (hAnalysisHybFilter->HFmemorySize != 0) {
    if (((setup->filterDelay *
          ((qmfBands - setup->nrQmfBands) + (cplxBands - setup->nrQmfBands)) *
          sizeof(FIXP_DBL)) > hAnalysisHybFilter->HFmemorySize)) {
      err = -3;
      goto bail;
    }
  }

  /* Distribute LF memory. */
  pMem = hAnalysisHybFilter->pLFmemory;
  for (k = 0; k < setup->nrQmfBands; k++) {
    hAnalysisHybFilter->bufferLFReal[k] = pMem;
    pMem += setup->protoLen;
    hAnalysisHybFilter->bufferLFImag[k] = pMem;
    pMem += setup->protoLen;
  }

  /* Distribute HF memory. */
  if (hAnalysisHybFilter->HFmemorySize != 0) {
    pMem = hAnalysisHybFilter->pHFmemory;
    for (k = 0; k < setup->filterDelay; k++) {
      hAnalysisHybFilter->bufferHFReal[k] = pMem;
      pMem += (qmfBands - setup->nrQmfBands);
      hAnalysisHybFilter->bufferHFImag[k] = pMem;
      pMem += (cplxBands - setup->nrQmfBands);
    }
  }

  if (initStatesFlag) {
    /* Clear LF buffer */
    for (k = 0; k < setup->nrQmfBands; k++) {
      FDKmemclear(hAnalysisHybFilter->bufferLFReal[k],
                  setup->protoLen * sizeof(FIXP_DBL));
      FDKmemclear(hAnalysisHybFilter->bufferLFImag[k],
                  setup->protoLen * sizeof(FIXP_DBL));
    }

    if (hAnalysisHybFilter->HFmemorySize != 0) {
      if (qmfBands > setup->nrQmfBands) {
        /* Clear HF buffer */
        for (k = 0; k < setup->filterDelay; k++) {
          FDKmemclear(hAnalysisHybFilter->bufferHFReal[k],
                      (qmfBands - setup->nrQmfBands) * sizeof(FIXP_DBL));
          FDKmemclear(hAnalysisHybFilter->bufferHFImag[k],
                      (cplxBands - setup->nrQmfBands) * sizeof(FIXP_DBL));
        }
      }
    }
  }

bail:
  return err;
}

INT FDKhybridAnalysisScaleStates(HANDLE_FDK_ANA_HYB_FILTER hAnalysisHybFilter,
                                 const INT scalingValue) {
  INT err = 0;

  if (hAnalysisHybFilter == NULL) {
    err = 1; /* invalid handle */
  } else {
    int k;
    HANDLE_FDK_HYBRID_SETUP setup = hAnalysisHybFilter->pSetup;

    /* Scale LF buffer */
    for (k = 0; k < setup->nrQmfBands; k++) {
      scaleValues(hAnalysisHybFilter->bufferLFReal[k], setup->protoLen,
                  scalingValue);
      scaleValues(hAnalysisHybFilter->bufferLFImag[k], setup->protoLen,
                  scalingValue);
    }
    if (hAnalysisHybFilter->nrBands > setup->nrQmfBands) {
      /* Scale HF buffer */
      for (k = 0; k < setup->filterDelay; k++) {
        scaleValues(hAnalysisHybFilter->bufferHFReal[k],
                    (hAnalysisHybFilter->nrBands - setup->nrQmfBands),
                    scalingValue);
        scaleValues(hAnalysisHybFilter->bufferHFImag[k],
                    (hAnalysisHybFilter->cplxBands - setup->nrQmfBands),
                    scalingValue);
      }
    }
  }
  return err;
}

INT FDKhybridAnalysisApply(HANDLE_FDK_ANA_HYB_FILTER hAnalysisHybFilter,
                           const FIXP_DBL *const pQmfReal,
                           const FIXP_DBL *const pQmfImag,
                           FIXP_DBL *const pHybridReal,
                           FIXP_DBL *const pHybridImag) {
  int k, hybOffset = 0;
  INT err = 0;
  const int nrQmfBandsLF =
      hAnalysisHybFilter->pSetup
          ->nrQmfBands; /* number of QMF bands to be converted to hybrid */

  const int writIndex = hAnalysisHybFilter->bufferLFpos;
  int readIndex = hAnalysisHybFilter->bufferLFpos;

  if (++readIndex >= hAnalysisHybFilter->pSetup->protoLen) readIndex = 0;
  const INT *pBufferLFreadIdx =
      &hAnalysisHybFilter->pSetup->pReadIdxTable[readIndex];

  /*
   * LF buffer.
   */
  for (k = 0; k < nrQmfBandsLF; k++) {
    /* New input sample. */
    hAnalysisHybFilter->bufferLFReal[k][writIndex] = pQmfReal[k];
    hAnalysisHybFilter->bufferLFImag[k][writIndex] = pQmfImag[k];

    /* Perform hybrid filtering. */
    err |=
        kChannelFiltering(hAnalysisHybFilter->bufferLFReal[k],
                          hAnalysisHybFilter->bufferLFImag[k], pBufferLFreadIdx,
                          pHybridReal + hybOffset, pHybridImag + hybOffset,
                          hAnalysisHybFilter->pSetup->kHybrid[k]);

    hybOffset += hAnalysisHybFilter->pSetup->nHybBands[k];
  }

  hAnalysisHybFilter->bufferLFpos =
      readIndex; /* Index where to write next input sample. */

  if (hAnalysisHybFilter->nrBands > nrQmfBandsLF) {
    /*
     * HF buffer.
     */
    if (hAnalysisHybFilter->hfMode != 0) {
      /* HF delay compensation was applied outside. */
      FDKmemcpy(
          pHybridReal + hybOffset, &pQmfReal[nrQmfBandsLF],
          (hAnalysisHybFilter->nrBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
      FDKmemcpy(
          pHybridImag + hybOffset, &pQmfImag[nrQmfBandsLF],
          (hAnalysisHybFilter->cplxBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
    } else {
      FDK_ASSERT(hAnalysisHybFilter->HFmemorySize != 0);
      /* HF delay compensation, filterlength/2. */
      FDKmemcpy(
          pHybridReal + hybOffset,
          hAnalysisHybFilter->bufferHFReal[hAnalysisHybFilter->bufferHFpos],
          (hAnalysisHybFilter->nrBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
      FDKmemcpy(
          pHybridImag + hybOffset,
          hAnalysisHybFilter->bufferHFImag[hAnalysisHybFilter->bufferHFpos],
          (hAnalysisHybFilter->cplxBands - nrQmfBandsLF) * sizeof(FIXP_DBL));

      FDKmemcpy(
          hAnalysisHybFilter->bufferHFReal[hAnalysisHybFilter->bufferHFpos],
          &pQmfReal[nrQmfBandsLF],
          (hAnalysisHybFilter->nrBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
      FDKmemcpy(
          hAnalysisHybFilter->bufferHFImag[hAnalysisHybFilter->bufferHFpos],
          &pQmfImag[nrQmfBandsLF],
          (hAnalysisHybFilter->cplxBands - nrQmfBandsLF) * sizeof(FIXP_DBL));

      if (++hAnalysisHybFilter->bufferHFpos >=
          hAnalysisHybFilter->pSetup->filterDelay)
        hAnalysisHybFilter->bufferHFpos = 0;
    }
  } /* process HF part*/

  return err;
}

INT FDKhybridAnalysisClose(HANDLE_FDK_ANA_HYB_FILTER hAnalysisHybFilter) {
  INT err = 0;

  if (hAnalysisHybFilter != NULL) {
    hAnalysisHybFilter->pLFmemory = NULL;
    hAnalysisHybFilter->pHFmemory = NULL;
    hAnalysisHybFilter->LFmemorySize = 0;
    hAnalysisHybFilter->HFmemorySize = 0;
  }

  return err;
}

INT FDKhybridSynthesisInit(HANDLE_FDK_SYN_HYB_FILTER hSynthesisHybFilter,
                           const FDK_HYBRID_MODE mode, const INT qmfBands,
                           const INT cplxBands) {
  INT err = 0;
  HANDLE_FDK_HYBRID_SETUP setup = NULL;

  switch (mode) {
    case THREE_TO_TEN:
      setup = &setup_3_10;
      break;
    case THREE_TO_TWELVE:
      setup = &setup_3_12;
      break;
    case THREE_TO_SIXTEEN:
      setup = &setup_3_16;
      break;
    default:
      err = -1;
      goto bail;
  }

  hSynthesisHybFilter->pSetup = setup;
  hSynthesisHybFilter->nrBands = qmfBands;
  hSynthesisHybFilter->cplxBands = cplxBands;

bail:
  return err;
}

void FDKhybridSynthesisApply(HANDLE_FDK_SYN_HYB_FILTER hSynthesisHybFilter,
                             const FIXP_DBL *const pHybridReal,
                             const FIXP_DBL *const pHybridImag,
                             FIXP_DBL *const pQmfReal,
                             FIXP_DBL *const pQmfImag) {
  int k, n, hybOffset = 0;
  const INT nrQmfBandsLF = hSynthesisHybFilter->pSetup->nrQmfBands;

  /*
   * LF buffer.
   */
  for (k = 0; k < nrQmfBandsLF; k++) {
    const int nHybBands = hSynthesisHybFilter->pSetup->nHybBands[k];
    const int scale = hSynthesisHybFilter->pSetup->synHybScale[k];

    FIXP_DBL accu1 = FL2FXCONST_DBL(0.f);
    FIXP_DBL accu2 = FL2FXCONST_DBL(0.f);

    /* Perform hybrid filtering. */
    for (n = 0; n < nHybBands; n++) {
      accu1 += pHybridReal[hybOffset + n] >> scale;
      accu2 += pHybridImag[hybOffset + n] >> scale;
    }
    pQmfReal[k] = SATURATE_LEFT_SHIFT(accu1, scale, DFRACT_BITS);
    pQmfImag[k] = SATURATE_LEFT_SHIFT(accu2, scale, DFRACT_BITS);

    hybOffset += nHybBands;
  }

  if (hSynthesisHybFilter->nrBands > nrQmfBandsLF) {
    /*
     * HF buffer.
     */
    FDKmemcpy(&pQmfReal[nrQmfBandsLF], &pHybridReal[hybOffset],
              (hSynthesisHybFilter->nrBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
    FDKmemcpy(
        &pQmfImag[nrQmfBandsLF], &pHybridImag[hybOffset],
        (hSynthesisHybFilter->cplxBands - nrQmfBandsLF) * sizeof(FIXP_DBL));
  }

  return;
}

static void dualChannelFiltering(const FIXP_DBL *const pQmfReal,
                                 const FIXP_DBL *const pQmfImag,
                                 const INT *const pReadIdx,
                                 FIXP_DBL *const mHybridReal,
                                 FIXP_DBL *const mHybridImag,
                                 const INT invert) {
  FIXP_DBL r1, r6;
  FIXP_DBL i1, i6;

  const FIXP_HTB f0 = HybFilterCoef2[0]; /* corresponds to p1 and p11 */
  const FIXP_HTB f1 = HybFilterCoef2[1]; /* corresponds to p3 and p9  */
  const FIXP_HTB f2 = HybFilterCoef2[2]; /* corresponds to p5 and p7  */

  /* symmetric filter coefficients */
  r1 = fMultDiv2(f0, pQmfReal[pReadIdx[1]]) +
       fMultDiv2(f0, pQmfReal[pReadIdx[11]]);
  i1 = fMultDiv2(f0, pQmfImag[pReadIdx[1]]) +
       fMultDiv2(f0, pQmfImag[pReadIdx[11]]);
  r1 += fMultDiv2(f1, pQmfReal[pReadIdx[3]]) +
        fMultDiv2(f1, pQmfReal[pReadIdx[9]]);
  i1 += fMultDiv2(f1, pQmfImag[pReadIdx[3]]) +
        fMultDiv2(f1, pQmfImag[pReadIdx[9]]);
  r1 += fMultDiv2(f2, pQmfReal[pReadIdx[5]]) +
        fMultDiv2(f2, pQmfReal[pReadIdx[7]]);
  i1 += fMultDiv2(f2, pQmfImag[pReadIdx[5]]) +
        fMultDiv2(f2, pQmfImag[pReadIdx[7]]);

  r6 = pQmfReal[pReadIdx[6]] >> 2;
  i6 = pQmfImag[pReadIdx[6]] >> 2;

  FDK_ASSERT((invert == 0) || (invert == 1));
  mHybridReal[0 + invert] = SATURATE_LEFT_SHIFT((r6 + r1), 1, DFRACT_BITS);
  mHybridImag[0 + invert] = SATURATE_LEFT_SHIFT((i6 + i1), 1, DFRACT_BITS);

  mHybridReal[1 - invert] = SATURATE_LEFT_SHIFT((r6 - r1), 1, DFRACT_BITS);
  mHybridImag[1 - invert] = SATURATE_LEFT_SHIFT((i6 - i1), 1, DFRACT_BITS);
}

static void fourChannelFiltering(const FIXP_DBL *const pQmfReal,
                                 const FIXP_DBL *const pQmfImag,
                                 const INT *const pReadIdx,
                                 FIXP_DBL *const mHybridReal,
                                 FIXP_DBL *const mHybridImag,
                                 const INT invert) {
  const FIXP_HTB *p = HybFilterCoef4;

  FIXP_DBL fft[8];

  static const FIXP_DBL cr[13] = {
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(-1.f), FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(0.70710678118655f),
      FL2FXCONST_DBL(1.f),  FL2FXCONST_DBL(0.70710678118655f),
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(-1.f), FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(0.f)};
  static const FIXP_DBL ci[13] = {
      FL2FXCONST_DBL(-1.f), FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(0.70710678118655f),
      FL2FXCONST_DBL(1.f),  FL2FXCONST_DBL(0.70710678118655f),
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(-1.f), FL2FXCONST_DBL(-0.70710678118655f),
      FL2FXCONST_DBL(0.f),  FL2FXCONST_DBL(0.70710678118655f),
      FL2FXCONST_DBL(1.f)};

  /* FIR filter. */
  /* pre twiddeling with pre-twiddling coefficients c[n]  */
  /* multiplication with filter coefficients p[n]         */
  /* hint: (a + ib)*(c + id) = (a*c - b*d) + i(a*d + b*c) */
  /* write to fft coefficient n'                          */
  fft[FFT_IDX_R(0)] =
      (fMult(p[10], (fMultSub(fMultDiv2(cr[2], pQmfReal[pReadIdx[2]]), ci[2],
                              pQmfImag[pReadIdx[2]]))) +
       fMult(p[6], (fMultSub(fMultDiv2(cr[6], pQmfReal[pReadIdx[6]]), ci[6],
                             pQmfImag[pReadIdx[6]]))) +
       fMult(p[2], (fMultSub(fMultDiv2(cr[10], pQmfReal[pReadIdx[10]]), ci[10],
                             pQmfImag[pReadIdx[10]]))));
  fft[FFT_IDX_I(0)] =
      (fMult(p[10], (fMultAdd(fMultDiv2(ci[2], pQmfReal[pReadIdx[2]]), cr[2],
                              pQmfImag[pReadIdx[2]]))) +
       fMult(p[6], (fMultAdd(fMultDiv2(ci[6], pQmfReal[pReadIdx[6]]), cr[6],
                             pQmfImag[pReadIdx[6]]))) +
       fMult(p[2], (fMultAdd(fMultDiv2(ci[10], pQmfReal[pReadIdx[10]]), cr[10],
                             pQmfImag[pReadIdx[10]]))));

  /* twiddle dee dum */
  fft[FFT_IDX_R(1)] =
      (fMult(p[9], (fMultSub(fMultDiv2(cr[3], pQmfReal[pReadIdx[3]]), ci[3],
                             pQmfImag[pReadIdx[3]]))) +
       fMult(p[5], (fMultSub(fMultDiv2(cr[7], pQmfReal[pReadIdx[7]]), ci[7],
                             pQmfImag[pReadIdx[7]]))) +
       fMult(p[1], (fMultSub(fMultDiv2(cr[11], pQmfReal[pReadIdx[11]]), ci[11],
                             pQmfImag[pReadIdx[11]]))));
  fft[FFT_IDX_I(1)] =
      (fMult(p[9], (fMultAdd(fMultDiv2(ci[3], pQmfReal[pReadIdx[3]]), cr[3],
                             pQmfImag[pReadIdx[3]]))) +
       fMult(p[5], (fMultAdd(fMultDiv2(ci[7], pQmfReal[pReadIdx[7]]), cr[7],
                             pQmfImag[pReadIdx[7]]))) +
       fMult(p[1], (fMultAdd(fMultDiv2(ci[11], pQmfReal[pReadIdx[11]]), cr[11],
                             pQmfImag[pReadIdx[11]]))));

  /* twiddle dee dee */
  fft[FFT_IDX_R(2)] =
      (fMult(p[12], (fMultSub(fMultDiv2(cr[0], pQmfReal[pReadIdx[0]]), ci[0],
                              pQmfImag[pReadIdx[0]]))) +
       fMult(p[8], (fMultSub(fMultDiv2(cr[4], pQmfReal[pReadIdx[4]]), ci[4],
                             pQmfImag[pReadIdx[4]]))) +
       fMult(p[4], (fMultSub(fMultDiv2(cr[8], pQmfReal[pReadIdx[8]]), ci[8],
                             pQmfImag[pReadIdx[8]]))) +
       fMult(p[0], (fMultSub(fMultDiv2(cr[12], pQmfReal[pReadIdx[12]]), ci[12],
                             pQmfImag[pReadIdx[12]]))));
  fft[FFT_IDX_I(2)] =
      (fMult(p[12], (fMultAdd(fMultDiv2(ci[0], pQmfReal[pReadIdx[0]]), cr[0],
                              pQmfImag[pReadIdx[0]]))) +
       fMult(p[8], (fMultAdd(fMultDiv2(ci[4], pQmfReal[pReadIdx[4]]), cr[4],
                             pQmfImag[pReadIdx[4]]))) +
       fMult(p[4], (fMultAdd(fMultDiv2(ci[8], pQmfReal[pReadIdx[8]]), cr[8],
                             pQmfImag[pReadIdx[8]]))) +
       fMult(p[0], (fMultAdd(fMultDiv2(ci[12], pQmfReal[pReadIdx[12]]), cr[12],
                             pQmfImag[pReadIdx[12]]))));

  fft[FFT_IDX_R(3)] =
      (fMult(p[11], (fMultSub(fMultDiv2(cr[1], pQmfReal[pReadIdx[1]]), ci[1],
                              pQmfImag[pReadIdx[1]]))) +
       fMult(p[7], (fMultSub(fMultDiv2(cr[5], pQmfReal[pReadIdx[5]]), ci[5],
                             pQmfImag[pReadIdx[5]]))) +
       fMult(p[3], (fMultSub(fMultDiv2(cr[9], pQmfReal[pReadIdx[9]]), ci[9],
                             pQmfImag[pReadIdx[9]]))));
  fft[FFT_IDX_I(3)] =
      (fMult(p[11], (fMultAdd(fMultDiv2(ci[1], pQmfReal[pReadIdx[1]]), cr[1],
                              pQmfImag[pReadIdx[1]]))) +
       fMult(p[7], (fMultAdd(fMultDiv2(ci[5], pQmfReal[pReadIdx[5]]), cr[5],
                             pQmfImag[pReadIdx[5]]))) +
       fMult(p[3], (fMultAdd(fMultDiv2(ci[9], pQmfReal[pReadIdx[9]]), cr[9],
                             pQmfImag[pReadIdx[9]]))));

  /* fft modulation                                                    */
  /* here: fast manual fft modulation for a fft of length M=4          */
  /* fft_4{x[n]} = x[0]*exp(-i*2*pi/4*m*0) + x[1]*exp(-i*2*pi/4*m*1) +
  x[2]*exp(-i*2*pi/4*m*2) + x[3]*exp(-i*2*pi/4*m*3)   */

  /*
  fft bin m=0:
  X[0, n] = x[0] +   x[1] + x[2] +   x[3]
  */
  mHybridReal[0] = fft[FFT_IDX_R(0)] + fft[FFT_IDX_R(1)] + fft[FFT_IDX_R(2)] +
                   fft[FFT_IDX_R(3)];
  mHybridImag[0] = fft[FFT_IDX_I(0)] + fft[FFT_IDX_I(1)] + fft[FFT_IDX_I(2)] +
                   fft[FFT_IDX_I(3)];

  /*
  fft bin m=1:
  X[1, n] = x[0] - i*x[1] - x[2] + i*x[3]
  */
  mHybridReal[1] = fft[FFT_IDX_R(0)] + fft[FFT_IDX_I(1)] - fft[FFT_IDX_R(2)] -
                   fft[FFT_IDX_I(3)];
  mHybridImag[1] = fft[FFT_IDX_I(0)] - fft[FFT_IDX_R(1)] - fft[FFT_IDX_I(2)] +
                   fft[FFT_IDX_R(3)];

  /*
  fft bin m=2:
  X[2, n] = x[0] -   x[1] + x[2] -   x[3]
  */
  mHybridReal[2] = fft[FFT_IDX_R(0)] - fft[FFT_IDX_R(1)] + fft[FFT_IDX_R(2)] -
                   fft[FFT_IDX_R(3)];
  mHybridImag[2] = fft[FFT_IDX_I(0)] - fft[FFT_IDX_I(1)] + fft[FFT_IDX_I(2)] -
                   fft[FFT_IDX_I(3)];

  /*
  fft bin m=3:
  X[3, n] = x[0] + j*x[1] - x[2] - j*x[3]
  */
  mHybridReal[3] = fft[FFT_IDX_R(0)] - fft[FFT_IDX_I(1)] - fft[FFT_IDX_R(2)] +
                   fft[FFT_IDX_I(3)];
  mHybridImag[3] = fft[FFT_IDX_I(0)] + fft[FFT_IDX_R(1)] - fft[FFT_IDX_I(2)] -
                   fft[FFT_IDX_R(3)];
}

static void eightChannelFiltering(const FIXP_DBL *const pQmfReal,
                                  const FIXP_DBL *const pQmfImag,
                                  const INT *const pReadIdx,
                                  FIXP_DBL *const mHybridReal,
                                  FIXP_DBL *const mHybridImag,
                                  const INT invert) {
  const FIXP_HTP *p = HybFilterCoef8;
  INT k, sc;

  FIXP_DBL mfft[16 + ALIGNMENT_DEFAULT];
  FIXP_DBL *pfft = (FIXP_DBL *)ALIGN_PTR(mfft);

  FIXP_DBL accu1, accu2, accu3, accu4;

  /* pre twiddeling */
  pfft[FFT_IDX_R(0)] =
      pQmfReal[pReadIdx[6]] >>
      (3 + 1); /* fMultDiv2(p[0].v.re, pQmfReal[pReadIdx[6]]); */
  pfft[FFT_IDX_I(0)] =
      pQmfImag[pReadIdx[6]] >>
      (3 + 1); /* fMultDiv2(p[0].v.re, pQmfImag[pReadIdx[6]]); */

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[7]], pQmfImag[pReadIdx[7]],
               p[1]);
  pfft[FFT_IDX_R(1)] = accu1;
  pfft[FFT_IDX_I(1)] = accu2;

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[0]], pQmfImag[pReadIdx[0]],
               p[2]);
  cplxMultDiv2(&accu3, &accu4, pQmfReal[pReadIdx[8]], pQmfImag[pReadIdx[8]],
               p[3]);
  pfft[FFT_IDX_R(2)] = accu1 + accu3;
  pfft[FFT_IDX_I(2)] = accu2 + accu4;

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[1]], pQmfImag[pReadIdx[1]],
               p[4]);
  cplxMultDiv2(&accu3, &accu4, pQmfReal[pReadIdx[9]], pQmfImag[pReadIdx[9]],
               p[5]);
  pfft[FFT_IDX_R(3)] = accu1 + accu3;
  pfft[FFT_IDX_I(3)] = accu2 + accu4;

  pfft[FFT_IDX_R(4)] = fMultDiv2(pQmfImag[pReadIdx[10]], p[7].v.im) -
                       fMultDiv2(pQmfImag[pReadIdx[2]], p[6].v.im);
  pfft[FFT_IDX_I(4)] = fMultDiv2(pQmfReal[pReadIdx[2]], p[6].v.im) -
                       fMultDiv2(pQmfReal[pReadIdx[10]], p[7].v.im);

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[3]], pQmfImag[pReadIdx[3]],
               p[8]);
  cplxMultDiv2(&accu3, &accu4, pQmfReal[pReadIdx[11]], pQmfImag[pReadIdx[11]],
               p[9]);
  pfft[FFT_IDX_R(5)] = accu1 + accu3;
  pfft[FFT_IDX_I(5)] = accu2 + accu4;

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[4]], pQmfImag[pReadIdx[4]],
               p[10]);
  cplxMultDiv2(&accu3, &accu4, pQmfReal[pReadIdx[12]], pQmfImag[pReadIdx[12]],
               p[11]);
  pfft[FFT_IDX_R(6)] = accu1 + accu3;
  pfft[FFT_IDX_I(6)] = accu2 + accu4;

  cplxMultDiv2(&accu1, &accu2, pQmfReal[pReadIdx[5]], pQmfImag[pReadIdx[5]],
               p[12]);
  pfft[FFT_IDX_R(7)] = accu1;
  pfft[FFT_IDX_I(7)] = accu2;

  /* fft modulation */
  fft_8(pfft);
  sc = 1 + 2;

  if (invert) {
    mHybridReal[0] = pfft[FFT_IDX_R(7)] << sc;
    mHybridImag[0] = pfft[FFT_IDX_I(7)] << sc;
    mHybridReal[1] = pfft[FFT_IDX_R(0)] << sc;
    mHybridImag[1] = pfft[FFT_IDX_I(0)] << sc;

    mHybridReal[2] = pfft[FFT_IDX_R(6)] << sc;
    mHybridImag[2] = pfft[FFT_IDX_I(6)] << sc;
    mHybridReal[3] = pfft[FFT_IDX_R(1)] << sc;
    mHybridImag[3] = pfft[FFT_IDX_I(1)] << sc;

    mHybridReal[4] = SATURATE_LEFT_SHIFT(
        (pfft[FFT_IDX_R(2)] + pfft[FFT_IDX_R(5)]), sc, DFRACT_BITS);
    mHybridImag[4] = SATURATE_LEFT_SHIFT(
        (pfft[FFT_IDX_I(2)] + pfft[FFT_IDX_I(5)]), sc, DFRACT_BITS);

    mHybridReal[5] = SATURATE_LEFT_SHIFT(
        (pfft[FFT_IDX_R(3)] + pfft[FFT_IDX_R(4)]), sc, DFRACT_BITS);
    mHybridImag[5] = SATURATE_LEFT_SHIFT(
        (pfft[FFT_IDX_I(3)] + pfft[FFT_IDX_I(4)]), sc, DFRACT_BITS);
  } else {
    for (k = 0; k < 8; k++) {
      mHybridReal[k] = pfft[FFT_IDX_R(k)] << sc;
      mHybridImag[k] = pfft[FFT_IDX_I(k)] << sc;
    }
  }
}

static INT kChannelFiltering(const FIXP_DBL *const pQmfReal,
                             const FIXP_DBL *const pQmfImag,
                             const INT *const pReadIdx,
                             FIXP_DBL *const mHybridReal,
                             FIXP_DBL *const mHybridImag,
                             const SCHAR hybridConfig) {
  INT err = 0;

  switch (hybridConfig) {
    case 2:
    case -2:
      dualChannelFiltering(pQmfReal, pQmfImag, pReadIdx, mHybridReal,
                           mHybridImag, (hybridConfig < 0) ? 1 : 0);
      break;
    case 4:
    case -4:
      fourChannelFiltering(pQmfReal, pQmfImag, pReadIdx, mHybridReal,
                           mHybridImag, (hybridConfig < 0) ? 1 : 0);
      break;
    case 8:
    case -8:
      eightChannelFiltering(pQmfReal, pQmfImag, pReadIdx, mHybridReal,
                            mHybridImag, (hybridConfig < 0) ? 1 : 0);
      break;
    default:
      err = -1;
  }

  return err;
}