xref: /aosp_15_r20/external/aac/libSACdec/src/sac_tsd.cpp (revision e54365361535b070c2db7374cec45c159c7d0e7a)

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

© Copyright  1995 - 2019 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
deployed. AAC has been standardized by ISO and IEC as part of the MPEG
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
with enhanced sound quality, are also available from Fraunhofer. Users are
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are permitted without payment of copyright license fees provided that you
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You must retain the complete text of this software license in redistributions of
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Attention: Audio and Multimedia Departments - FDK AAC LL
Am Wolfsmantel 33
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----------------------------------------------------------------------------- */

/*********************** MPEG surround decoder library *************************

   Author(s):   Matthias Hildenbrand

   Description: USAC MPS212 Transient Steering Decorrelator (TSD)

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

#include "sac_tsd.h"

#define TSD_START_BAND (7)
#define SIZE_S (4)
#define SIZE_C (5)

/*** Tables ***/
RAM_ALIGN
LNK_SECTION_CONSTDATA
static const UCHAR nBitsTsdCW_32slots[32] = {
    5,  9,  13, 16, 18, 20, 22, 24, 25, 26, 27, 28, 29, 29, 30, 30,
    30, 29, 29, 28, 27, 26, 25, 24, 22, 20, 18, 16, 13, 9,  5,  0};

RAM_ALIGN
LNK_SECTION_CONSTDATA
static const UCHAR nBitsTsdCW_64slots[64] = {
    6,  11, 16, 20, 23, 27, 30, 33, 35, 38, 40, 42, 44, 46, 48, 49,
    51, 52, 53, 55, 56, 57, 58, 58, 59, 60, 60, 60, 61, 61, 61, 61,
    61, 61, 61, 60, 60, 60, 59, 58, 58, 57, 56, 55, 53, 52, 51, 49,
    48, 46, 44, 42, 40, 38, 35, 33, 30, 27, 23, 20, 16, 11, 6,  0};

RAM_ALIGN
LNK_SECTION_CONSTDATA
static const FIXP_DPK phiTsd[8] = {
    {{(FIXP_DBL)0x7fffffff, (FIXP_DBL)0x00000000}},
    {{(FIXP_DBL)0x5a82799a, (FIXP_DBL)0x5a82799a}},
    {{(FIXP_DBL)0x00000000, (FIXP_DBL)0x7fffffff}},
    {{(FIXP_DBL)0xa57d8666, (FIXP_DBL)0x5a82799a}},
    {{(FIXP_DBL)0x80000000, (FIXP_DBL)0x00000000}},
    {{(FIXP_DBL)0xa57d8666, (FIXP_DBL)0xa57d8666}},
    {{(FIXP_DBL)0x00000000, (FIXP_DBL)0x80000000}},
    {{(FIXP_DBL)0x5a82799a, (FIXP_DBL)0xa57d8666}}};

/*** Static Functions ***/
static void longmult1(USHORT a[], USHORT b, USHORT d[], int len) {
  int k;
  ULONG tmp;
  ULONG b0 = (ULONG)b;

  tmp = ((ULONG)a[0]) * b0;
  d[0] = (USHORT)tmp;

  for (k = 1; k < len; k++) {
    tmp = (tmp >> 16) + ((ULONG)a[k]) * b0;
    d[k] = (USHORT)tmp;
  }
}

static void longdiv(USHORT b[], USHORT a, USHORT d[], USHORT *pr, int len) {
  ULONG r;
  ULONG tmp;
  int k;

  FDK_ASSERT(a != 0);

  r = 0;

  for (k = len - 1; k >= 0; k--) {
    tmp = ((ULONG)b[k]) + (r << 16);

    if (tmp) {
      d[k] = (USHORT)(tmp / a);
      r = tmp - d[k] * a;
    } else {
      d[k] = 0;
    }
  }
  *pr = (USHORT)r;
}

static void longsub(USHORT a[], USHORT b[], int lena, int lenb) {
  int h;
  LONG carry = 0;

  FDK_ASSERT(lena >= lenb);
  for (h = 0; h < lenb; h++) {
    carry += ((LONG)a[h]) - ((LONG)b[h]);
    a[h] = (USHORT)carry;
    carry = carry >> 16;
  }

  for (; h < lena; h++) {
    carry = ((LONG)a[h]) + carry;
    a[h] = (USHORT)carry;
    carry = carry >> 16;
  }

  FDK_ASSERT(carry ==
             0); /* carry != 0 indicates subtraction underflow, e.g. b > a */
  return;
}

static int longcompare(USHORT a[], USHORT b[], int len) {
  int i;

  for (i = len - 1; i > 0; i--) {
    if (a[i] != b[i]) break;
  }
  return (a[i] >= b[i]) ? 1 : 0;
}

FDK_INLINE int isTrSlot(const TSD_DATA *pTsdData, const int ts) {
  return (pTsdData->bsTsdTrPhaseData[ts] >= 0);
}

/*** Public Functions ***/
int TsdRead(HANDLE_FDK_BITSTREAM hBs, const int numSlots, TSD_DATA *pTsdData) {
  int nBitsTrSlots = 0;
  int bsTsdNumTrSlots;
  const UCHAR *nBitsTsdCW_tab = NULL;

  switch (numSlots) {
    case 32:
      nBitsTrSlots = 4;
      nBitsTsdCW_tab = nBitsTsdCW_32slots;
      break;
    case 64:
      nBitsTrSlots = 5;
      nBitsTsdCW_tab = nBitsTsdCW_64slots;
      break;
    default:
      return 1;
  }

  /*** Read TempShapeData for bsTempShapeConfig == 3 ***/
  pTsdData->bsTsdEnable = FDKreadBit(hBs);
  if (!pTsdData->bsTsdEnable) {
    return 0;
  }

  /*** Parse/Decode TsdData() ***/
  pTsdData->numSlots = numSlots;

  bsTsdNumTrSlots = FDKreadBits(hBs, nBitsTrSlots);

  /* Decode transient slot positions */
  {
    int nBitsTsdCW = (int)nBitsTsdCW_tab[bsTsdNumTrSlots];
    SCHAR *phaseData = pTsdData->bsTsdTrPhaseData;
    int p = bsTsdNumTrSlots + 1;
    int k, h;
    USHORT s[SIZE_S] = {0};
    USHORT c[SIZE_C] = {0};
    USHORT r[1];

    /* Init with TsdSepData[k] = 0 */
    for (k = 0; k < numSlots; k++) {
      phaseData[k] = -1; /* means TsdSepData[] = 0 */
    }

    for (h = (SIZE_S - 1); h >= 0; h--) {
      if (nBitsTsdCW > h * 16) {
        s[h] = (USHORT)FDKreadBits(hBs, nBitsTsdCW - h * 16);
        nBitsTsdCW = h * 16;
      }
    }

    /* c = prod_{h=1}^{p} (k-p+h)/h */
    k = numSlots - 1;
    c[0] = k - p + 1;
    for (h = 2; h <= p; h++) {
      longmult1(c, (k - p + h), c, 5); /* c *= k - p + h; */
      longdiv(c, h, c, r, 5);          /* c /= h; */
      FDK_ASSERT(*r == 0);
    }

    /* go through all slots */
    for (; k >= 0; k--) {
      if (p > k) {
        for (; k >= 0; k--) {
          phaseData[k] = 1; /* means TsdSepData[] = 1 */
        }
        break;
      }
      if (longcompare(s, c, 4)) { /* (s >= c) */
        longsub(s, c, 4, 4);      /* s -= c; */
        phaseData[k] = 1;         /* means TsdSepData[] = 1 */
        if (p == 1) {
          break;
        }
        /* Update c for next iteration: c_new = c_old * p / k */
        longmult1(c, p, c, 5);
        p--;
      } else {
        /* Update c for next iteration: c_new = c_old * (k-p) / k */
        longmult1(c, (k - p), c, 5);
      }
      longdiv(c, k, c, r, 5);
      FDK_ASSERT(*r == 0);
    }

    /* Read phase data */
    for (k = 0; k < numSlots; k++) {
      if (phaseData[k] == 1) {
        phaseData[k] = FDKreadBits(hBs, 3);
      }
    }
  }

  return 0;
}

void TsdGenerateNonTr(const int numHybridBands, const TSD_DATA *pTsdData,
                      const int ts, FIXP_DBL *pVdirectReal,
                      FIXP_DBL *pVdirectImag, FIXP_DBL *pVnonTrReal,
                      FIXP_DBL *pVnonTrImag, FIXP_DBL **ppDecorrInReal,
                      FIXP_DBL **ppDecorrInImag) {
  int k = 0;

  if (!isTrSlot(pTsdData, ts)) {
    /* Let allpass based decorrelator read from direct input. */
    *ppDecorrInReal = pVdirectReal;
    *ppDecorrInImag = pVdirectImag;
    return;
  }

  /* Generate nonTr input signal for allpass based decorrelator */
  for (; k < TSD_START_BAND; k++) {
    pVnonTrReal[k] = pVdirectReal[k];
    pVnonTrImag[k] = pVdirectImag[k];
  }
  for (; k < numHybridBands; k++) {
    pVnonTrReal[k] = (FIXP_DBL)0;
    pVnonTrImag[k] = (FIXP_DBL)0;
  }
  *ppDecorrInReal = pVnonTrReal;
  *ppDecorrInImag = pVnonTrImag;
}

void TsdApply(const int numHybridBands, const TSD_DATA *pTsdData, int *pTsdTs,
              const FIXP_DBL *pVdirectReal, const FIXP_DBL *pVdirectImag,
              FIXP_DBL *pDnonTrReal, FIXP_DBL *pDnonTrImag) {
  const int ts = *pTsdTs;

  if (isTrSlot(pTsdData, ts)) {
    int k;
    const FIXP_DPK *phi = &phiTsd[pTsdData->bsTsdTrPhaseData[ts]];
    FDK_ASSERT((pTsdData->bsTsdTrPhaseData[ts] >= 0) &&
               (pTsdData->bsTsdTrPhaseData[ts] < 8));

    /* d = d_nonTr + v_direct * exp(j * bsTsdTrPhaseData[ts]/4 * pi ) */
    for (k = TSD_START_BAND; k < numHybridBands; k++) {
      FIXP_DBL tempReal, tempImag;
      cplxMultDiv2(&tempReal, &tempImag, pVdirectReal[k], pVdirectImag[k],
                   *phi);
      pDnonTrReal[k] = SATURATE_LEFT_SHIFT(
          (pDnonTrReal[k] >> 2) + (tempReal >> 1), 2, DFRACT_BITS);
      pDnonTrImag[k] = SATURATE_LEFT_SHIFT(
          (pDnonTrImag[k] >> 2) + (tempImag >> 1), 2, DFRACT_BITS);
    }
  }

  /* The modulo MAX_TSD_TIME_SLOTS operation is to avoid illegal memory accesses
   * in case of errors. */
  *pTsdTs = (ts + 1) & (MAX_TSD_TIME_SLOTS - 1);
  return;
}