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 $Id$

*******************************************************************************/
/*!
  \file   dct.cpp
  \brief  DCT Implementations  $Revision: 36871 $
  Library functions to calculate standard DCTs. This will most likely be replaced by hand-optimized
  functions for the specific target processor.

  Three different implementations of the dct type II and the dct type III transforms are provided.

  By default implementations which are based on a single, standard complex FFT-kernel are used (dctII_f() and dctIII_f()).
  These are specifically helpful in cases where optimized FFT libraries are already available. The FFT used in these
  implementation is FFT rad2 from FDK_tools.

  Of course, one might also use DCT-libraries should they be available. The DCT and DST
  type IV implementations are only available in a version based on a complex FFT kernel.
*/

#include "dct.h"


#include "FDK_tools_rom.h"
#include "fft.h"


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


/*!
 *
 * \brief Perform dct type 3
 * The dct 3 is calculated by a inverse real fft, with
 * some pre twiddeling before the inverse real fft, as discribed by Takuya OOURA.
 * (http://momonga.t.u-tokyo.ac.jp/~ooura/fftman/ftmn2_32.html#sec2_3_2)
 * The real inverse fft is calculated by a inverse complex fft, as described
 * in numerical recipes in C, Cambridge University press
 * the auxiliary function is built by reversing the odd samples
 *
 * Instead of doing 2 times the conjugation to calculate the
 * inverse cfft with the cfft, one can also swap elements before
 * calling the cfft to get the same result:
 * swap
 * r(1),i(1) with r(n-1),i(n-1),
 * r(2),i(2) with r(n-2),i(n-2), ...
 * r(n/2-1),i(n/2-1) with r(n/2+1),i(n/2+1)
 *
 *
 * Scaling 1 shift in pre twiddeling,
 *         log2(L)-1 in cfft
 */
#if !defined(FUNCTION_dct_III)
void dct_III(FIXP_DBL *pDat, /*!< pointer to input/output */
             FIXP_DBL *tmp,  /*!< pointer to temporal working buffer */
             int L,          /*!< lenght of transform */
             int *pDat_e
             )
{
  FDK_ASSERT(L == 64 || L == 32);
  int  i;
  FIXP_DBL xr, accu1, accu2;
  int inc;
  int M = L>>1;
  int ld_M;

  if (L == 64)  ld_M = 5;
  else          ld_M = 4;

  /* This loop performs multiplication for index i (i*inc) */
  inc = (64/2) >> ld_M; /* 64/L */

  FIXP_DBL *pTmp_0 = &tmp[2];
  FIXP_DBL *pTmp_1 = &tmp[(M-1)*2];

  for(i=1; i<M>>1; i++,pTmp_0+=2,pTmp_1-=2) {

    FIXP_DBL accu3,accu4,accu5,accu6;

    cplxMultDiv2(&accu2, &accu1, pDat[L - i], pDat[i], sin_twiddle_L64[i*inc]);
    cplxMultDiv2(&accu4, &accu3, pDat[M+i], pDat[M-i], sin_twiddle_L64[(M-i)*inc]);
    accu3 >>= 1; accu4 >>= 1;

    /* This method is better for ARM926, that uses operand2 shifted right by 1 always */
    cplxMultDiv2(&accu6, &accu5, (accu3 - (accu1>>1)), ((accu2>>1) + accu4), sin_twiddle_L64[(4*i)*inc]);
    xr = (accu1>>1) + accu3;
    pTmp_0[0] = (xr>>1) - accu5;
    pTmp_1[0] = (xr>>1) + accu5;

    xr = (accu2>>1) - accu4;
    pTmp_0[1] =  (xr>>1) - accu6;
    pTmp_1[1] = -((xr>>1) + accu6);

  }

  xr     = fMultDiv2(pDat[M], sin_twiddle_L64[64/2].v.re );/* cos((PI/(2*L))*M); */
  tmp[0] = ((pDat[0]>>1) + xr)>>1;
  tmp[1] = ((pDat[0]>>1) - xr)>>1;

  cplxMultDiv2(&accu2, &accu1, pDat[L - (M/2)], pDat[M/2], sin_twiddle_L64[64/4]);
  tmp[M]   = accu1>>1;
  tmp[M+1] = accu2>>1;

  /* dit_fft expects 1 bit scaled input values */
  fft(M, tmp, pDat_e);

  /* ARM926: 12 cycles per 2-iteration, no overhead code by compiler */
  pTmp_1 = &tmp[L];
  for (i = M>>1; i--;)
  {
    FIXP_DBL tmp1, tmp2, tmp3, tmp4;
    tmp1 = *tmp++;
    tmp2 = *tmp++;
    tmp3 = *--pTmp_1;
    tmp4 = *--pTmp_1;
    *pDat++ = tmp1;
    *pDat++ = tmp3;
    *pDat++ = tmp2;
    *pDat++ = tmp4;
  }

  *pDat_e += 2;
}
#endif

/*!
 *
 * \brief Perform dct type 2
 * The dct 2 is calculated by a real inverse fft, with
 * some pre twiddeling after the  fft, as discribed by Takuya OOURA.
 * (http://momonga.t.u-tokyo.ac.jp/~ooura/fftman/ftmn2_32.html#sec2_3_2)
 * The real inverse fft is calculated by a inverse complex fft, as described
 * in numerical recipes in C, Cambridge University press
 * the auxilery function is build by reversing the odd samples
 *
 * Scaling 1 shift in pre twiddeling,
 *         5 in cfft
 */
#if !defined(FUNCTION_dct_II)
void dct_II(FIXP_DBL *pDat, /*!< pointer to input/output */
            FIXP_DBL *tmp,  /*!< pointer to temporal working buffer */
            int L,          /*!< lenght of transform */
            int *pDat_e
            )
{
    FDK_ASSERT(L == 64 || L == 32);
    FIXP_DBL accu1,accu2;
    FIXP_DBL *pTmp_0, *pTmp_1;

    int i;
    int inc;
    int M =  L>>1;
    int ld_M;

    FDK_ASSERT(L == 64 || L == 32);
    ld_M = 4 + (L >> 6);  /* L=64: 5,  L=32: 4 */

    inc = (64/2) >> ld_M; /* L=64: 1,  L=32: 2 */

    FIXP_DBL *pdat  = &pDat[0];
    FIXP_DBL accu3, accu4;
    pTmp_0 = &tmp[0];
    pTmp_1 = &tmp[L-1];
    for (i = M>>1; i--; )
    {
      accu1 = *pdat++;
      accu2 = *pdat++;
      accu3 = *pdat++;
      accu4 = *pdat++;
      accu1 >>= 1;
      accu2 >>= 1;
      accu3 >>= 1;
      accu4 >>= 1;
      *pTmp_0++ = accu1;
      *pTmp_0++ = accu3;
      *pTmp_1-- = accu2;
      *pTmp_1-- = accu4;
    }


    fft(M, tmp, pDat_e);

    pTmp_0 = &tmp[2];
    pTmp_1 = &tmp[(M-1)*2];

    for (i=1; i<M>>1; i++,pTmp_0+=2,pTmp_1-=2) {

      FIXP_DBL a1,a2;
      FIXP_DBL accu3, accu4;

      a1 = ((pTmp_0[1]>>1) + (pTmp_1[1]>>1));
      a2 = ((pTmp_1[0]>>1) - (pTmp_0[0]>>1));

      cplxMultDiv2(&accu1, &accu2, a2, a1, sin_twiddle_L64[(4*i)*inc]);
      accu1<<=1; accu2<<=1;

      a1 = ((pTmp_0[0]>>1) + (pTmp_1[0]>>1));
      a2 = ((pTmp_0[1]>>1) - (pTmp_1[1]>>1));

      cplxMultDiv2(&accu3, &accu4, (a1 + accu2), -(accu1 + a2), sin_twiddle_L64[i*inc]);
      pDat[L - i] = accu4;
      pDat[i]     = accu3;

      cplxMultDiv2(&accu3, &accu4, (a1 - accu2), -(accu1 - a2), sin_twiddle_L64[(M-i)*inc]);
      pDat[M + i] = accu4;
      pDat[M - i] = accu3;

    }

    cplxMultDiv2(&accu1, &accu2, tmp[M], tmp[M+1], sin_twiddle_L64[(M/2)*inc]);
    pDat[L - (M/2)] = accu2;
    pDat[M/2]       = accu1;

    pDat[0] = (tmp[0]>>1)+(tmp[1]>>1);
    pDat[M] =  fMult(((tmp[0]>>1)-(tmp[1]>>1)), sin_twiddle_L64[64/2].v.re);/* cos((PI/(2*L))*M); */

    *pDat_e += 2;
}
#endif

static
void getTables(const FIXP_WTP **twiddle, const FIXP_STP **sin_twiddle, int *sin_step, int length)
{
  int ld2_length;

 /* Get ld2 of length - 2 + 1
     -2: because first table entry is window of size 4
     +1: because we already include +1 because of ceil(log2(length)) */
  ld2_length = DFRACT_BITS-1-fNormz((FIXP_DBL)length) - 1;

  /* Extract sort of "eigenvalue" (the 4 left most bits) of length. */
  switch ( (length) >> (ld2_length-1) ) {
    case 0x4: /* radix 2 */
      *sin_twiddle = SineTable512;
      *sin_step = 1<<(9 - ld2_length);
      *twiddle = windowSlopes[0][0][ld2_length-1];
      break;
    case 0x7: /* 10 ms */
      *sin_twiddle = SineTable480;
      *sin_step = 1<<(8 - ld2_length);
      *twiddle = windowSlopes[0][1][ld2_length];
      break;
    default:
      *sin_twiddle = NULL;
      *sin_step = 0;
      *twiddle = NULL;
      break;
  }

  FDK_ASSERT(*twiddle != NULL);

  FDK_ASSERT(*sin_step > 0);

}

#if !defined(FUNCTION_dct_IV)

void dct_IV(FIXP_DBL *pDat,
            int L,
            int *pDat_e)
{
  int sin_step = 0;
  int M = L >> 1;

  const FIXP_WTP *twiddle;
  const FIXP_STP *sin_twiddle;

  FDK_ASSERT(L >= 4);

  getTables(&twiddle, &sin_twiddle, &sin_step, L);

#ifdef FUNCTION_dct_IV_func1
  if (M>=4 && (M&3) == 0) {
     /* ARM926: 44 cycles for 2 iterations = 22 cycles/iteration */
    dct_IV_func1(M>>2, twiddle,  &pDat[0], &pDat[L-1]);
  } else
#endif /* FUNCTION_dct_IV_func1 */
  {
    FIXP_DBL *RESTRICT pDat_0 = &pDat[0];
    FIXP_DBL *RESTRICT pDat_1 = &pDat[L - 2];
    register int i;

    /* 29 cycles on ARM926 */
    for (i = 0; i < M-1; i+=2,pDat_0+=2,pDat_1-=2)
    {
      register FIXP_DBL accu1,accu2,accu3,accu4;

      accu1 = pDat_1[1]; accu2 = pDat_0[0];
      accu3 = pDat_0[1]; accu4 = pDat_1[0];

      cplxMultDiv2(&accu1, &accu2, accu1, accu2, twiddle[i]);
      cplxMultDiv2(&accu3, &accu4, accu4, accu3, twiddle[i+1]);

      pDat_0[0] = accu2; pDat_0[1] = accu1;
      pDat_1[0] = accu4; pDat_1[1] = -accu3;
    }
    if (M&1)
    {
      register FIXP_DBL accu1,accu2;

      accu1 = pDat_1[1]; accu2 = pDat_0[0];

      cplxMultDiv2(&accu1, &accu2, accu1, accu2, twiddle[i]);

      pDat_0[0] = accu2; pDat_0[1] = accu1;
    }
  }

  fft(M, pDat, pDat_e);

#ifdef FUNCTION_dct_IV_func2
  if (M>=4 && (M&3) == 0) {
     /* ARM926: 42 cycles for 2 iterations = 21 cycles/iteration */
    dct_IV_func2(M>>2, sin_twiddle, &pDat[0], &pDat[L], sin_step);
  } else
#endif /* FUNCTION_dct_IV_func2 */
  {
    FIXP_DBL *RESTRICT pDat_0 = &pDat[0];
    FIXP_DBL *RESTRICT pDat_1 = &pDat[L - 2];
    register FIXP_DBL accu1,accu2,accu3,accu4;
    int idx, i;

    /* Sin and Cos values are 0.0f and 1.0f */
    accu1 = pDat_1[0];
    accu2 = pDat_1[1];

    pDat_1[1] = -(pDat_0[1]>>1);
    pDat_0[0] = (pDat_0[0]>>1);


    /* 28 cycles for ARM926 */  
    for (idx = sin_step,i=1; i<(M+1)>>1; i++, idx+=sin_step)
    {
      FIXP_STP twd = sin_twiddle[idx];
      cplxMultDiv2(&accu3, &accu4, accu1, accu2, twd);
      pDat_0[1] =  accu3;
      pDat_1[0] =  accu4;
      
      pDat_0+=2;
      pDat_1-=2;

      cplxMultDiv2(&accu3, &accu4, pDat_0[1], pDat_0[0], twd);

      accu1 = pDat_1[0];
      accu2 = pDat_1[1];

      pDat_1[1] = -accu3;
      pDat_0[0] =  accu4;
    }

    if ( (M&1) == 0 )
    {
      /* Last Sin and Cos value pair are the same */
      accu1 = fMultDiv2(accu1, WTC(0x5a82799a));
      accu2 = fMultDiv2(accu2, WTC(0x5a82799a));

      pDat_1[0] = accu1 + accu2;
      pDat_0[1] = accu1 - accu2;
    }
  }

  /* Add twiddeling scale. */
  *pDat_e += 2;
}
#endif /* defined (FUNCTION_dct_IV) */

#if !defined(FUNCTION_dst_IV)
void dst_IV(FIXP_DBL *pDat,
            int L,
            int *pDat_e )
{
  int sin_step = 0;
  int M = L >> 1;

  const FIXP_WTP *twiddle;
  const FIXP_STP *sin_twiddle;

#ifdef DSTIV2_ENABLE
  if (L == 2) {
    const FIXP_STP tab = STCP(0x7641AF3D, 0x30FB9452);
    FIXP_DBL tmp1, tmp2;

    cplxMultDiv2(&tmp2, &tmp1, pDat[0], pDat[1], tab);

    pDat[0] = tmp1;
    pDat[1] = tmp2;

    *pDat_e += 1;

    return;
  }
#else
  FDK_ASSERT(L >= 4);
#endif

  getTables(&twiddle, &sin_twiddle, &sin_step, L);

#ifdef FUNCTION_dst_IV_func1
  if ( (M>=4) && ((M&3) == 0) ) {
    dst_IV_func1(M, twiddle, &pDat[0], &pDat[L]);
  } else 
#endif
  {
    FIXP_DBL *RESTRICT pDat_0 = &pDat[0];
    FIXP_DBL *RESTRICT pDat_1 = &pDat[L - 2];
  
    register int i;

    /* 34 cycles on ARM926 */
    for (i = 0; i < M-1; i+=2,pDat_0+=2,pDat_1-=2) 
    {
      register FIXP_DBL accu1,accu2,accu3,accu4;

      accu1 =  pDat_1[1]; accu2 = -pDat_0[0];
      accu3 =  pDat_0[1]; accu4 = -pDat_1[0];
    
      cplxMultDiv2(&accu1, &accu2, accu1, accu2, twiddle[i]);
      cplxMultDiv2(&accu3, &accu4, accu4, accu3, twiddle[i+1]);

      pDat_0[0] = accu2; pDat_0[1] = accu1;
      pDat_1[0] = accu4; pDat_1[1] = -accu3;
    }
    if (M&1)
    {
      register FIXP_DBL accu1,accu2;

      accu1 =  pDat_1[1]; accu2 = -pDat_0[0];
    
      cplxMultDiv2(&accu1, &accu2, accu1, accu2, twiddle[i]);

      pDat_0[0] = accu2; pDat_0[1] = accu1;
    }
  }

  fft(M, pDat, pDat_e);

#ifdef FUNCTION_dst_IV_func2
  if ( (M>=4) && ((M&3) == 0) ) {
    dst_IV_func2(M>>2, sin_twiddle + sin_step, &pDat[0], &pDat[L - 1], sin_step);
  } else
#endif /* FUNCTION_dst_IV_func2 */
  {
    FIXP_DBL *RESTRICT pDat_0;
    FIXP_DBL *RESTRICT pDat_1;
    register FIXP_DBL accu1,accu2,accu3,accu4;
    int idx, i;

    pDat_0 = &pDat[0];
    pDat_1 = &pDat[L - 2];

    /* Sin and Cos values are 0.0f and 1.0f */
    accu1 = pDat_1[0];
    accu2 = pDat_1[1];

    pDat_1[1] = -(pDat_0[0]>>1);
    pDat_0[0] = (pDat_0[1]>>1);

    for (idx = sin_step,i=1; i<(M+1)>>1; i++, idx+=sin_step)
    {
      FIXP_STP twd = sin_twiddle[idx];

      cplxMultDiv2(&accu3, &accu4, accu1, accu2, twd);
      pDat_1[0] =  -accu3;
      pDat_0[1] =  -accu4;

      pDat_0+=2;
      pDat_1-=2;

      cplxMultDiv2(&accu3, &accu4, pDat_0[1], pDat_0[0], twd);

      accu1 = pDat_1[0];
      accu2 = pDat_1[1];

      pDat_0[0] =  accu3;
      pDat_1[1] = -accu4;
    }

    if ( (M&1) == 0 )
    {
      /* Last Sin and Cos value pair are the same */
      accu1 = fMultDiv2(accu1, WTC(0x5a82799a));
      accu2 = fMultDiv2(accu2, WTC(0x5a82799a));

      pDat_0[1] = - accu1 - accu2;
      pDat_1[0] =   accu2 - accu1;
    }
  }

  /* Add twiddeling scale. */
  *pDat_e += 2;
}
#endif /* !defined(FUNCTION_dst_IV) */