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#include 

/*------ 18 point xform -------*/

static float w[18];

static float w2[9];

static float coef[9][4];

static float v[6];

static float v2[3];

static float coef87;

/*

typedef struct

{

   float *w;

   float *w2;

   void *coef;

}

IMDCT_INIT_BLOCK;

static IMDCT_INIT_BLOCK imdct_info_18 =

{w, w2, coef};

static IMDCT_INIT_BLOCK imdct_info_6 =

{v, v2, &coef87};

*/

/*=============================================================*/

void imdct_init()

{

   int k, p, n;

   double t, pi;

//   IMDCT_INIT_BLOCK *addr;

//   float *w, *w2;

//   float *v, *v2, *coef87;

/*--- 18 point --*/

//   addr = imdct_init_addr_18();

//   w = addr->w;

//   w2 = addr->w2;

//   coef = addr->coef;

/*----*/

   n = 18;

   pi = 4.0 * atan(1.0);

   t = pi / (4 * n);

   for (p = 0; p < n; p++)

      w[p] = (float) (2.0 * cos(t * (2 * p + 1)));

   for (p = 0; p < 9; p++)

      w2[p] = (float) (2.0 *cos(2 * t * (2 * p + 1)));

   t = pi / (2 * n);

   for (k = 0; k < 9; k++)

   {

      for (p = 0; p < 4; p++)

	 coef[k][p] = (float) (cos(t * (2 * k) * (2 * p + 1)));

   }

/*--- 6 point */

//   addr = imdct_init_addr_6();

//   v = addr->w;

//   v2 = addr->w2;

//   coef87 = addr->coef;

/*----*/

   n = 6;

   pi = 4.0 * atan(1.0);

   t = pi / (4 * n);

   for (p = 0; p < n; p++)

      v[p] = (float) (2.0 *cos(t * (2 * p + 1)));

   for (p = 0; p < 3; p++)

      v2[p] = (float) (2.0 *cos(2 * t * (2 * p + 1)));

   t = pi / (2 * n);

   k = 1;

   p = 0;

   coef87 = (float) (cos(t * (2 * k) * (2 * p + 1)));

/* adjust scaling to save a few mults */

   for (p = 0; p < 6; p++)

      v[p] = v[p] / 2.0f;

   coef87 = (float) (2.0 * coef87);

}

/*--------------------------------------------------------------------*/

void imdct18(float f[18])	/* 18 point */

{

   int p;

   float a[9], b[9];

   float ap, bp, a8p, b8p;

   float g1, g2;

   for (p = 0; p < 4; p++)

   {

      g1 = w[p] * f[p];

      g2 = w[17 - p] * f[17 - p];

      ap = g1 + g2;		// a[p]

      bp = w2[p] * (g1 - g2);	// b[p]

      g1 = w[8 - p] * f[8 - p];

      g2 = w[9 + p] * f[9 + p];

      a8p = g1 + g2;		// a[8-p]

      b8p = w2[8 - p] * (g1 - g2);	// b[8-p]

      a[p] = ap + a8p;

      a[5 + p] = ap - a8p;

      b[p] = bp + b8p;

      b[5 + p] = bp - b8p;

   }

   g1 = w[p] * f[p];

   g2 = w[17 - p] * f[17 - p];

   a[p] = g1 + g2;

   b[p] = w2[p] * (g1 - g2);

   f[0] = 0.5f * (a[0] + a[1] + a[2] + a[3] + a[4]);

   f[1] = 0.5f * (b[0] + b[1] + b[2] + b[3] + b[4]);

   f[2] = coef[1][0] * a[5] + coef[1][1] * a[6] + coef[1][2] * a[7]

      + coef[1][3] * a[8];

   f[3] = coef[1][0] * b[5] + coef[1][1] * b[6] + coef[1][2] * b[7]

      + coef[1][3] * b[8] - f[1];

   f[1] = f[1] - f[0];

   f[2] = f[2] - f[1];

   f[4] = coef[2][0] * a[0] + coef[2][1] * a[1] + coef[2][2] * a[2]

      + coef[2][3] * a[3] - a[4];

   f[5] = coef[2][0] * b[0] + coef[2][1] * b[1] + coef[2][2] * b[2]

      + coef[2][3] * b[3] - b[4] - f[3];

   f[3] = f[3] - f[2];

   f[4] = f[4] - f[3];

   f[6] = coef[3][0] * (a[5] - a[7] - a[8]);

   f[7] = coef[3][0] * (b[5] - b[7] - b[8]) - f[5];

   f[5] = f[5] - f[4];

   f[6] = f[6] - f[5];

   f[8] = coef[4][0] * a[0] + coef[4][1] * a[1] + coef[4][2] * a[2]

      + coef[4][3] * a[3] + a[4];

   f[9] = coef[4][0] * b[0] + coef[4][1] * b[1] + coef[4][2] * b[2]

      + coef[4][3] * b[3] + b[4] - f[7];

   f[7] = f[7] - f[6];

   f[8] = f[8] - f[7];

   f[10] = coef[5][0] * a[5] + coef[5][1] * a[6] + coef[5][2] * a[7]

      + coef[5][3] * a[8];

   f[11] = coef[5][0] * b[5] + coef[5][1] * b[6] + coef[5][2] * b[7]

      + coef[5][3] * b[8] - f[9];

   f[9] = f[9] - f[8];

   f[10] = f[10] - f[9];

   f[12] = 0.5f * (a[0] + a[2] + a[3]) - a[1] - a[4];

   f[13] = 0.5f * (b[0] + b[2] + b[3]) - b[1] - b[4] - f[11];

   f[11] = f[11] - f[10];

   f[12] = f[12] - f[11];

   f[14] = coef[7][0] * a[5] + coef[7][1] * a[6] + coef[7][2] * a[7]

      + coef[7][3] * a[8];

   f[15] = coef[7][0] * b[5] + coef[7][1] * b[6] + coef[7][2] * b[7]

      + coef[7][3] * b[8] - f[13];

   f[13] = f[13] - f[12];

   f[14] = f[14] - f[13];

   f[16] = coef[8][0] * a[0] + coef[8][1] * a[1] + coef[8][2] * a[2]

      + coef[8][3] * a[3] + a[4];

   f[17] = coef[8][0] * b[0] + coef[8][1] * b[1] + coef[8][2] * b[2]

      + coef[8][3] * b[3] + b[4] - f[15];

   f[15] = f[15] - f[14];

   f[16] = f[16] - f[15];

   f[17] = f[17] - f[16];

}

/*--------------------------------------------------------------------*/

/* does 3, 6 pt dct.  changes order from f[i][window] c[window][i] */

void imdct6_3(float f[])	/* 6 point */

{

   int w;

   float buf[18];

   float *a, *c;		// b[i] = a[3+i]

   float g1, g2;

   float a02, b02;

   c = f;

   a = buf;

   for (w = 0; w < 3; w++)

   {

      g1 = v[0] * f[3 * 0];

      g2 = v[5] * f[3 * 5];

      a[0] = g1 + g2;

      a[3 + 0] = v2[0] * (g1 - g2);

      g1 = v[1] * f[3 * 1];

      g2 = v[4] * f[3 * 4];

      a[1] = g1 + g2;

      a[3 + 1] = v2[1] * (g1 - g2);

      g1 = v[2] * f[3 * 2];

      g2 = v[3] * f[3 * 3];

      a[2] = g1 + g2;

      a[3 + 2] = v2[2] * (g1 - g2);

      a += 6;

      f++;

   }

   a = buf;

   for (w = 0; w < 3; w++)

   {

      a02 = (a[0] + a[2]);

      b02 = (a[3 + 0] + a[3 + 2]);

      c[0] = a02 + a[1];

      c[1] = b02 + a[3 + 1];

      c[2] = coef87 * (a[0] - a[2]);

      c[3] = coef87 * (a[3 + 0] - a[3 + 2]) - c[1];

      c[1] = c[1] - c[0];

      c[2] = c[2] - c[1];

      c[4] = a02 - a[1] - a[1];

      c[5] = b02 - a[3 + 1] - a[3 + 1] - c[3];

      c[3] = c[3] - c[2];

      c[4] = c[4] - c[3];

      c[5] = c[5] - c[4];

      a += 6;

      c += 6;

   }

}