/***************************  Fraunhofer IIS FDK Tools  **********************

                        (C) Copyright Fraunhofer IIS (2011)
                               All Rights Reserved

    Please be advised that this software and/or program delivery is
    Confidential Information of Fraunhofer and subject to and covered by the

    Fraunhofer IIS Software Evaluation Agreement
    between Google Inc. and  Fraunhofer
    effective and in full force since March 1, 2012.

    You may use this software and/or program only under the terms and
    conditions described in the above mentioned Fraunhofer IIS Software
    Evaluation Agreement. Any other and/or further use requires a separate agreement.


   $Id$
   Author(s):   Josef Hoepfl, Manuel Jander
   Description: MDCT routines

   This software and/or program is protected by copyright law and international
   treaties. Any reproduction or distribution of this software and/or program,
   or any portion of it, may result in severe civil and criminal penalties, and
   will be prosecuted to the maximum extent possible under law.

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

#include "mdct.h"


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

#define OPT_OVERLAP_ADD

void mdct_init( H_MDCT hMdct,
                FIXP_DBL *overlap,
                INT overlapBufferSize )
{
  hMdct->overlap.freq = overlap;
  //FDKmemclear(overlap, overlapBufferSize*sizeof(FIXP_DBL));
  hMdct->prev_fr = 0;
  hMdct->prev_nr = 0;
  hMdct->prev_tl = 0;
  hMdct->ov_size = overlapBufferSize;
}

INT  mdct( H_MDCT hMdct,
           FIXP_DBL *spectrum,
           INT *scalefactor,
           INT_PCM *input,
           INT tl,
           INT nr,
           INT fr,
           const FIXP_WTP *wrs )
{
  /* Fold and windowing */

  /* DCT IV */
  // dct_IV();
  return tl;
}

void imdct_gain(FIXP_DBL *pGain_m, int *pGain_e, int tl)
{
  FIXP_DBL gain_m = *pGain_m;
  int gain_e = *pGain_e;
  int log2_tl;

  log2_tl = DFRACT_BITS-1-fNormz((FIXP_DBL)tl);

  gain_e += -MDCT_OUTPUT_GAIN - log2_tl - MDCT_OUT_HEADROOM + 1;

  /* Detect non-radix 2 transform length and add amplitude compensation factor
     which cannot be included into the exponent above */
  switch ( (tl) >> (log2_tl - 2) ) {
    case 0x7: /* 10 ms, 1/tl = 1.0/(FDKpow(2.0, -log2_tl) * 0.53333333333333333333) */
      if (gain_m == (FIXP_DBL)0) {
        gain_m = FL2FXCONST_DBL(0.53333333333333333333f);
      } else {
        gain_m = fMult(gain_m, FL2FXCONST_DBL(0.53333333333333333333f));
      }
      break;
    case 0x6: /* 3/4 of radix 2, 1/tl = 1.0/(FDKpow(2.0, -log2_tl) * 2.0/3.0) */
      if (gain_m == (FIXP_DBL)0) {
        gain_m = FL2FXCONST_DBL(2.0/3.0f);
      } else {
        gain_m = fMult(gain_m, FL2FXCONST_DBL(2.0/3.0f));
      }
      break;
    case 0x4:
      /* radix 2, nothing to do. */
      break;
    default:
      /* unsupported */
      FDK_ASSERT(0);
      break;
  }

  *pGain_m = gain_m;
  *pGain_e = gain_e;
}

INT imdct_drain(
        H_MDCT hMdct,
        FIXP_DBL *output,
        INT nrSamplesRoom
        )
{
  int buffered_samples = 0;

  if (nrSamplesRoom > 0) {
    buffered_samples = hMdct->ov_offset;

    FDK_ASSERT(buffered_samples <= nrSamplesRoom);

    if (buffered_samples > 0)  {
      FDKmemcpy(output, hMdct->overlap.time, buffered_samples*sizeof(FIXP_DBL));
      hMdct->ov_offset = 0;
    }
  }
  return buffered_samples;
}

INT imdct_copy_ov_and_nr(
        H_MDCT hMdct,
        FIXP_DBL * pTimeData,
        INT nrSamples
        )
{
  FIXP_DBL *pOvl;
  int nt, nf, i;

  nt = fMin(hMdct->ov_offset, nrSamples);
  nrSamples -= nt;
  nf = fMin(hMdct->prev_nr, nrSamples);
  nrSamples -= nf;
  FDKmemcpy(pTimeData, hMdct->overlap.time, nt*sizeof(FIXP_DBL));
  pTimeData += nt;

  pOvl = hMdct->overlap.freq + hMdct->ov_size - 1;
  for (i=0; i<nf; i++) {
    FIXP_DBL x = - (*pOvl--);
    *pTimeData = IMDCT_SCALE_DBL(x);
    pTimeData ++;
  }

  return (nt+nf);
}

void imdct_adapt_parameters(H_MDCT hMdct, int *pfl, int *pnl, int tl, const FIXP_WTP *wls, int noOutSamples)
{
  int fl = *pfl, nl = *pnl;
  int window_diff, use_current = 0, use_previous = 0;
  if (hMdct->prev_tl == 0) {
    hMdct->prev_wrs    = wls;
    hMdct->prev_fr     = fl;
    hMdct->prev_nr     = (noOutSamples-fl)>>1;
    hMdct->prev_tl     = noOutSamples;
    hMdct->ov_offset   = 0;
    use_current = 1;
  }

  window_diff = (hMdct->prev_fr - fl)>>1;

  /* check if the previous window slope can be adjusted to match the current window slope */
  if (hMdct->prev_nr + window_diff > 0) {
    use_current = 1;
  }
  /* check if the current window slope can be adjusted to match the previous window slope */
  if (nl - window_diff > 0 ) {
    use_previous = 1;
  }

  /* if both is possible choose the larger of both window slope lengths */
  if (use_current && use_previous) {
    if (fl < hMdct->prev_fr) {
      use_current = 0;
    } else {
      use_previous = 0;
    }
  }
  /*
   * If the previous transform block is big enough, enlarge previous window overlap,
   * if not, then shrink current window overlap.
   */
  if (use_current) {
    hMdct->prev_nr += window_diff;
    hMdct->prev_fr = fl;
    hMdct->prev_wrs = wls;
  } else {
    nl -= window_diff;
    fl = hMdct->prev_fr;
  }

  *pfl = fl;
  *pnl = nl;
}

INT  imdct_block(
        H_MDCT hMdct,
        FIXP_DBL *output,
        FIXP_DBL *spectrum,
        const SHORT scalefactor[],
        const INT nSpec,
        const INT noOutSamples,
        const INT tl,
        const FIXP_WTP *wls,
        INT fl,
        const FIXP_WTP *wrs,
        const INT fr,
        FIXP_DBL gain
        )
{
  FIXP_DBL *pOvl;
  FIXP_DBL *pOut0 = output, *pOut1;
  INT nl, nr;
  int w, i, nrSamples = 0, specShiftScale, transform_gain_e = 0;

  /* Derive NR and NL */
  nr = (tl - fr)>>1;
  nl = (tl - fl)>>1;

  /* Include 2/N IMDCT gain into gain factor and exponent. */
  imdct_gain(&gain, &transform_gain_e, tl);

  /* Detect FRprevious / FL mismatches and override parameters accordingly */
  if (hMdct->prev_fr != fl) {
    imdct_adapt_parameters(hMdct, &fl, &nl, tl, wls, noOutSamples);
  }

  pOvl = hMdct->overlap.freq + hMdct->ov_size - 1;

  if ( noOutSamples > nrSamples ) {
    /* Purge buffered output. */
    for (i=0; i<hMdct->ov_offset; i++) {
      *pOut0 = hMdct->overlap.time[i];
      pOut0 ++;
    }
    nrSamples = hMdct->ov_offset;
    hMdct->ov_offset = 0;
  }

  for (w=0; w<nSpec; w++)
  {
    FIXP_DBL *pSpec, *pCurr;
    const FIXP_WTP *pWindow;

    specShiftScale = transform_gain_e;

    /* Setup window pointers */
    pWindow = hMdct->prev_wrs;

    /* Current spectrum */
    pSpec = spectrum+w*tl;

    /* DCT IV of current spectrum. */
    dct_IV(pSpec, tl, &specShiftScale);

    /* Optional scaling of time domain - no yet windowed - of current spectrum */
    /* and de-scale current spectrum signal (time domain, no yet windowed) */	
    if (gain != (FIXP_DBL)0) {
      scaleValuesWithFactor(pSpec, gain, tl, scalefactor[w] + specShiftScale);
    } else {
      scaleValues(pSpec, tl, scalefactor[w] + specShiftScale);
    }

    if ( noOutSamples <= nrSamples ) {
      /* Divert output first half to overlap buffer if we already got enough output samples. */
      pOut0 = hMdct->overlap.time + hMdct->ov_offset;
      hMdct->ov_offset += hMdct->prev_nr + fl/2;
    } else {
      /* Account output samples */
      nrSamples += hMdct->prev_nr + fl/2;
    }

    /* NR output samples 0 .. NR. -overlap[TL/2..TL/2-NR] */
    for (i=0; i<hMdct->prev_nr; i++) {
      FIXP_DBL x = - (*pOvl--);
      *pOut0 = IMDCT_SCALE_DBL(x);
      pOut0 ++;
    }

    if ( noOutSamples <= nrSamples ) {
      /* Divert output second half to overlap buffer if we already got enough output samples. */
      pOut1 = hMdct->overlap.time + hMdct->ov_offset + fl/2 - 1;
      hMdct->ov_offset += fl/2 + nl;
    } else {
      pOut1 = pOut0 + (fl - 1);
      nrSamples += fl/2 + nl;
    }

    /* output samples before window crossing point NR .. TL/2. -overlap[TL/2-NR..TL/2-NR-FL/2] + current[NR..TL/2] */
    /* output samples after window crossing point TL/2 .. TL/2+FL/2. -overlap[0..FL/2] - current[TL/2..FL/2] */
    pCurr = pSpec + tl - fl/2;
    for (i=0; i<fl/2; i++) {
      FIXP_DBL x0, x1;

      cplxMult(&x1, &x0, *pCurr++, - *pOvl--, pWindow[i]);
      *pOut0 = IMDCT_SCALE_DBL(x0);
      *pOut1 = IMDCT_SCALE_DBL(-x1);
      pOut0 ++;
      pOut1 --;
    }
    pOut0 += (fl/2);

    /* NL output samples TL/2+FL/2..TL. - current[FL/2..0] */
    pOut1 += (fl/2) + 1;
    pCurr = pSpec + tl - fl/2 - 1;
    for (i=0; i<nl; i++) {
      FIXP_DBL x = - (*pCurr--);
      *pOut1 = IMDCT_SCALE_DBL(x);
      pOut1 ++;
    }

    /* Set overlap source pointer for next window pOvl = pSpec + tl/2 - 1; */
    pOvl = pSpec + tl/2 - 1;

    /* Previous window values. */
    hMdct->prev_nr = nr;
    hMdct->prev_fr = fr;
    hMdct->prev_tl = tl;
    hMdct->prev_wrs = wrs;
  }

  /* Save overlap */
  
  pOvl = hMdct->overlap.freq + hMdct->ov_size - tl/2;
  FDK_ASSERT(pOvl >= hMdct->overlap.time + hMdct->ov_offset);
  FDK_ASSERT(tl/2 <= hMdct->ov_size);
  for (i=0; i<tl/2; i++) {
    pOvl[i] = spectrum[i+(nSpec-1)*tl];
  }

  return nrSamples;
}