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📄 skl_dct_c.c

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/********************************************************
 * Some code. Copyright (C) 2003 by Pascal Massimino.   *
 * All Rights Reserved.      (http://skal.planet-d.net) *
 * For Educational/Academic use ONLY. See 'LICENSE.TXT'.*
 ********************************************************/
/*
 *  skl_dct16_LLM.cpp
 *
 *  "Fast and precise" LLM implementation of FDCT/IDCT, where
 *  rotations are decomposed using:
 *    tmp = (x+y).cos t
 *    x' = tmp + y.(sin t - cos t)
 *    y' = tmp - x.(sin t + cos t)
 *
 *  See details at http://skl.planet-d.net/coding/dct.html
 *  and at the end of this file...
 *
 * Reference (e.g.):
 *  Loeffler C., Ligtenberg A., and Moschytz C.S.:
 *    Practical Fast 1D DCT Algorithm with Eleven Multiplications,
 *  Proc. ICASSP 1989, 988-991.
 *
 *  IEEE-1180-like error specs for FDCT:
 * Peak error:   1.0000
 * Peak MSE:     0.0340
 * Overall MSE:  0.0200
 * Peak ME:      0.0191
 * Overall ME:   -0.0033
 *
 *  error specs for IDCT:
 * Peak error:   1.0000
 * Peak MSE:     0.0065
 * Overall MSE:  0.0051
 * Peak ME:      0.0015
 * Overall ME:   0.0000
 *
 ********************************************************/

//#include "skl.h"
#include <math.h>
#include "dsputil.h"
#include "skl_dct.h"

typedef DCTELEM TYPE;
typedef uint8_t SKL_BYTE;

//////////////////////////////////////////////////////////

#define LOAD_BUTF(m1, m2, a, b, tmp, S) \
  (m1) = (S)[(a)] + (S)[(b)]; \
  (m2) = (S)[(a)] - (S)[(b)]

#define BUTF(a, b, tmp) \
  (tmp) = (a)+(b); \
  (b) = (a)-(b);   \
  (a) = (tmp)

#define ROTATE(m1,m2,c,k1,k2,tmp,Fix,Rnd) \
  (tmp) = ( (m1) + (m2) )*(c); \
  (m1) *= k1; \
  (m2) *= k2; \
  (tmp) += (Rnd); \
  (m1) = ((m1)+(tmp))>>(Fix);             \
  (m2) = ((m2)+(tmp))>>(Fix);

#define ROTATE2(m1,m2,c,k1,k2,tmp) \
  (tmp) = ( (m1) + (m2) )*(c); \
  (m1) *= k1; \
  (m2) *= k2; \
  (m1) = (m1)+(tmp); \
  (m2) = (m2)+(tmp);

#define ROTATE0(m1,m2,c,k1,k2,tmp) \
  (m1) = ( (m2) )*(c); \
  (m2) = (m2)*k2+(m1);

#define SHIFTL(x,n)   ((x)<<(n))
#define SHIFTR(x, n)  ((x)>>(n))
#define HALF(n)       (1<<((n)-1))

#define IPASS 3
#define FPASS 2
#define FIX  16

#if 1

#define ROT6_C     35468
#define ROT6_SmC   50159
#define ROT6_SpC  121095
#define ROT17_C    77062
#define ROT17_SmC  25571
#define ROT17_SpC 128553
#define ROT37_C    58981
#define ROT37_SmC  98391
#define ROT37_SpC  19571
#define ROT13_C   167963
#define ROT13_SmC 134553
#define ROT13_SpC 201373

#else

#define FX(x) ( (int)floor((x)*(1<<FIX) + .5 ) )

static const double c1 = cos(1.*M_PI/16);
static const double c2 = cos(2.*M_PI/16);
static const double c3 = cos(3.*M_PI/16);
static const double c4 = cos(4.*M_PI/16);
static const double c5 = cos(5.*M_PI/16);
static const double c6 = cos(6.*M_PI/16);
static const double c7 = cos(7.*M_PI/16);

static const int ROT6_C   = FX(c2-c6);  // 0.541
static const int ROT6_SmC = FX(2*c6);   // 0.765
static const int ROT6_SpC = FX(2*c2);   // 1.847

static const int ROT17_C   = FX(c1+c7);  // 1.175
static const int ROT17_SmC = FX(2*c7);   // 0.390
static const int ROT17_SpC = FX(2*c1);   // 1.961

static const int ROT37_C   = FX((c3-c7)/c4);  // 0.899
static const int ROT37_SmC = FX(2*(c5+c7));   // 1.501
static const int ROT37_SpC = FX(2*(c1-c3));   // 0.298

static const int ROT13_C   = FX((c1+c3)/c4);  // 2.562
static const int ROT13_SmC = FX(2*(c3+c7));   // 2.053
static const int ROT13_SpC = FX(2*(c1+c5));   // 3.072

#endif

//////////////////////////////////////////////////////////

void Skl_Dct16_C( TYPE *In )
{
  TYPE *pIn;
  int i;

  pIn = In;
  for(i=8; i>0; --i)
  {
    int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, Spill;

      // odd

    LOAD_BUTF(mm1,mm6, 1, 6, mm0, pIn);
    LOAD_BUTF(mm2,mm5, 2, 5, mm0, pIn);
    LOAD_BUTF(mm3,mm4, 3, 4, mm0, pIn);
    LOAD_BUTF(mm0,mm7, 0, 7, Spill, pIn);

    BUTF(mm1, mm2, Spill);
    BUTF(mm0, mm3, Spill);

    ROTATE(mm3, mm2, ROT6_C, ROT6_SmC, -ROT6_SpC, Spill, FIX-FPASS, HALF(FIX-FPASS));
    pIn[2] = mm3;
    pIn[6] = mm2;

    BUTF(mm0, mm1, Spill);
    pIn[0] = SHIFTL(mm0, FPASS);
    pIn[4] = SHIFTL(mm1, FPASS);


      // even

    mm3 = mm5 + mm7;
    mm2 = mm4 + mm6;
    ROTATE(mm2, mm3,  ROT17_C, -ROT17_SpC, -ROT17_SmC, mm0, FIX-FPASS, HALF(FIX-FPASS));
    ROTATE(mm4, mm7, -ROT37_C,  ROT37_SpC,  ROT37_SmC, mm0, FIX-FPASS, HALF(FIX-FPASS));
    mm7 += mm3;
    mm4 += mm2;
    pIn[1] = mm7;
    pIn[7] = mm4;

    ROTATE(mm5, mm6, -ROT13_C,  ROT13_SmC,  ROT13_SpC, mm0, FIX-FPASS, HALF(FIX-FPASS));
    mm5 += mm3;
    mm6 += mm2;
    pIn[3] = mm6;
    pIn[5] = mm5;

    pIn  += 8;
  }

  pIn = In;
  for(i=8; i>0; --i)
  {
    int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, Spill;

      // odd

    LOAD_BUTF(mm1,mm6, 1*8, 6*8, mm0, pIn);
    LOAD_BUTF(mm2,mm5, 2*8, 5*8, mm0, pIn);
    BUTF(mm1, mm2, mm0);

    LOAD_BUTF(mm3,mm4, 3*8, 4*8, mm0, pIn);
    LOAD_BUTF(mm0,mm7, 0*8, 7*8, Spill, pIn);
    BUTF(mm0, mm3, Spill);

    ROTATE(mm3, mm2, ROT6_C, ROT6_SmC, -ROT6_SpC, Spill, 0,  HALF(FIX+FPASS+3));
    pIn[2*8] = (TYPE)SHIFTR(mm3,FIX+FPASS+3);
    pIn[6*8] = (TYPE)SHIFTR(mm2,FIX+FPASS+3);

    mm0 += HALF(FPASS+3) - 1;
    BUTF(mm0, mm1, Spill);
    pIn[0*8] = (TYPE)SHIFTR(mm0, FPASS+3);
    pIn[4*8] = (TYPE)SHIFTR(mm1, FPASS+3);

      // even

    mm3 = mm5 + mm7;
    mm2 = mm4 + mm6;

    ROTATE(mm2, mm3,  ROT17_C, -ROT17_SpC, -ROT17_SmC, mm0, 0, HALF(FIX+FPASS+3));
    ROTATE2(mm4, mm7, -ROT37_C,  ROT37_SpC,  ROT37_SmC, mm0);
    mm7 += mm3;
    mm4 += mm2;
    pIn[7*8] = (TYPE)SHIFTR(mm4,FIX+FPASS+3);
    pIn[1*8] = (TYPE)SHIFTR(mm7,FIX+FPASS+3);

    ROTATE2(mm5, mm6, -ROT13_C,  ROT13_SmC,  ROT13_SpC, mm0);
    mm5 += mm3;
    mm6 += mm2;
    pIn[5*8] = (TYPE)SHIFTR(mm5,FIX+FPASS+3);
    pIn[3*8] = (TYPE)SHIFTR(mm6,FIX+FPASS+3);

    pIn++;
  }
}

//////////////////////////////////////////////////////////

void Skl_IDct16_C( TYPE *In )
{
  TYPE *pIn;
  int i;

  pIn = In;
  for (i=8; i>0; --i)
  {
    int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, Spill;

      // odd

    mm4 = (int)pIn[7];
    mm5 = (int)pIn[5];
    mm6 = (int)pIn[3];
    mm7 = (int)pIn[1];

    mm2 = mm4 + mm6;
    mm3 = mm5 + mm7;
    ROTATE2(mm2, mm3,  ROT17_C, -ROT17_SpC, -ROT17_SmC, mm1);
    ROTATE2(mm4, mm7, -ROT37_C,  ROT37_SpC,  ROT37_SmC, mm1);
    ROTATE2(mm5, mm6, -ROT13_C,  ROT13_SmC,  ROT13_SpC, mm1);

    mm4 += mm2;
    mm5 += mm3;
    mm6 += mm2;
    mm7 += mm3;

      // even

    mm3 = (int)pIn[2];
    mm2 = (int)pIn[6];

    ROTATE2(mm3, mm2, ROT6_C, ROT6_SmC, -ROT6_SpC, mm1);

    LOAD_BUTF(mm0, mm1, 0, 4, Spill, pIn);
    mm0 = SHIFTL(mm0, FIX) + HALF(FIX-IPASS);
    mm1 = SHIFTL(mm1, FIX) + HALF(FIX-IPASS);
    BUTF(mm0, mm3, Spill);
    BUTF(mm1, mm2, Spill);


    BUTF(mm0, mm7, Spill);
    pIn[0] = SHIFTR(mm0, FIX-IPASS);
    pIn[7] = SHIFTR(mm7, FIX-IPASS);
    BUTF(mm1, mm6, mm0);
    pIn[1] = SHIFTR(mm1, FIX-IPASS);
    pIn[6] = SHIFTR(mm6, FIX-IPASS);
    BUTF(mm2, mm5, mm0);
    pIn[2] = SHIFTR(mm2, FIX-IPASS);
    pIn[5] = SHIFTR(mm5, FIX-IPASS);
    BUTF(mm3, mm4, mm0);
    pIn[3] = SHIFTR(mm3, FIX-IPASS);
    pIn[4] = SHIFTR(mm4, FIX-IPASS);

    pIn += 8;
  }


  pIn = In;
  for (i=8; i>0; --i)
  {
    int mm0, mm1, mm2, mm3, mm4, mm5, mm6, mm7, Spill;

      // odd

    mm4 = (int)pIn[7*8];
    mm5 = (int)pIn[5*8];
    mm6 = (int)pIn[3*8];
    mm7 = (int)pIn[1*8];


    mm2 = mm4 + mm6;
    mm3 = mm5 + mm7;
    ROTATE2(mm2, mm3,  ROT17_C, -ROT17_SpC, -ROT17_SmC, mm1);
    ROTATE2(mm4, mm7, -ROT37_C,  ROT37_SpC,  ROT37_SmC, mm1);
    ROTATE2(mm5, mm6, -ROT13_C,  ROT13_SmC,  ROT13_SpC, mm1);

    mm4 += mm2;
    mm5 += mm3;
    mm6 += mm2;
    mm7 += mm3;

      // even

    mm3 = (int)pIn[2*8];
    mm2 = (int)pIn[6*8];

    ROTATE2(mm3, mm2, ROT6_C, ROT6_SmC, -ROT6_SpC, mm1);

    LOAD_BUTF(mm0, mm1, 0*8, 4*8, Spill, pIn);
    mm0 = SHIFTL(mm0, FIX) + HALF(FIX+IPASS+3);
    mm1 = SHIFTL(mm1, FIX) + HALF(FIX+IPASS+3);
    BUTF(mm0, mm3, Spill);
    BUTF(mm1, mm2, Spill);

    BUTF(mm0, mm7, Spill);
    pIn[8*0] = (TYPE) SHIFTR(mm0, FIX+IPASS+3);
    pIn[8*7] = (TYPE) SHIFTR(mm7, FIX+IPASS+3);
    BUTF(mm1, mm6, mm0);
    pIn[8*1] = (TYPE) SHIFTR(mm1, FIX+IPASS+3);
    pIn[8*6] = (TYPE) SHIFTR(mm6, FIX+IPASS+3);
    BUTF(mm2, mm5, mm0);
    pIn[8*2] = (TYPE) SHIFTR(mm2, FIX+IPASS+3);
    pIn[8*5] = (TYPE) SHIFTR(mm5, FIX+IPASS+3);
    BUTF(mm3, mm4, mm0);
    pIn[8*3] = (TYPE) SHIFTR(mm3, FIX+IPASS+3);
    pIn[8*4] = (TYPE) SHIFTR(mm4, FIX+IPASS+3);

    pIn++;
  }
}

void Skl_IDct16_Sparse_C( TYPE *In )
{
  TYPE *pIn;
  int i;

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