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| //=====================================
/*Program
FHT.C*********************************************************************
/*
/* This program assumes a maximum array length of 2^M = N where */
/* M=9 and N=512. */
/* See Line 52 if the array length is increased. */
# include <stdio.h>
# include <math.h>
#include <conio.h>
# define M 3
# define N 8
float* myFht ( );
float* myFht()
float X;
int n, m;
{
int i, j, k, kk, _1, _10, _11, _12, _13, _14, _15, m1, n1, n2, NN, s;
int diff=0, diff2, gamma, gamma2=2, n2_2, n2_4, n_2, n_4, n_8, n_16;
int itemp, ntemp, phi, theta_by_2;
float ee, temp1, temp2, xtemp1, xtemp2;
float h_sec_b, x0, x1, x2, x3, x4, x5, xtemp;
double cc1, cc2, ss1, ss2;
double sine[256];
/***********************************************************************/
/* Digit reverse counter. */
/***********************************************************************/
int powers_of_2[16], seed[256];
int firstj, log2_n, log2_seed_size;
int group_no, nn, offset;
log2_n=m >> 1;
nn=2<<(log2_n - 1);
if ( (m % 2) ==1 )
log2_n = log2_n + 1;
seed[0] = 0; seed[1] = 1;
for (log2_seed_size = 2; log2_seed_size <= log2_n; log2_seed_size++)
{
for ( i = 0; i <2 << (log2_seed_size - 2); i++)
{
seed[i] = 2*seed[i];
for (k = 1; k < 2; k++)
seed[ i + k * (2 << (log2_seed_size - 1)>>1) ] = seed[i];
}
}
for (offset = 1; offset < nn; offset++)
{
{firstj = nn*seed[offset];
i = offset; j=firstj;
xtemp = x[i];
x[i] = x[j];
x[j] = xtemp;
for ( group_no = 1; group_no < seed[offset]; group_no++)
{
i = i + nn; j = firstj + seed[group_no];
xtemp = x[i];
x[i] = x[j];
x[j] = xtemp;
}
}
j = 0;
n1 = n - 1;
n_16 = n >> 4;
n_8 = n >> 3;
n_4 = n >> 2;
n_2 = n >> 1;
/************************************************************************/
/* Start the transform computation with 2-point butterflies. */
/************************************************************************/
for (i = 0; i < n; i += 2)
{
s = i+1;
xtemp = x[i];
x[i] += x[s];
x[s] = xtemp - x[s];
}
/************************************************************************/
/* Now, the 4-point butterflies. */
/************************************************************************/
for ( i = 0; i < n; i += 4)
{
xtemp = x[i];
x[i] += x[i+2];
x[i+2] = xtemp - x[i+2];
xtemp = x[i+1];
x[i+1] += x[i+3];
x[i+3] = xtemp - x[i+3];
}
/*******************************************************************/
/* Sine table initialization. */
/*******************************************************************/
NN = n_4;
sine[0] = 0;
sine[n_16] = 0.382683432;
sine[n_8] = 0.707106781;
sine[3*n_16] = 0.923879533;
sine[n_4] = 1.000000000;
h_sec_b = 0.509795579;
diff = n_16;
theta_by_2 = n_4 >> 3;
j = 0;
while (theta_by_2 >= 1)
{
for ( i = 0; i <= n_4; i += diff)
{
sine[j + theta_by_2] = h_sec_b * (sine[j] + sine[j + diff] );
j = j + diff;
}
j = 0;
diff = diff >> 1;
theta_by_2 = theta_by_2 >> 1;
h_sec_b = 1 / sqrt(2 + 1/h_sec_b);
}
/***********************************************************************/
/* Other butterflies. */
/***********************************************************************/
for ( i = 3; i <= m; i++ )
{
diff = 1; gamma = 0;
ntemp = 0; phi = 2 << (m-i) >> 1;
ss1 = sine[phi];
cc1 = sine[n_4 - phi];
n2 = 2 << (i-1);
n2_2 = n2 >>1;
n2_4 = n2 >> 2;
gamma2 = n2_4;
diff2 = gamma2 + gamma2 - 1;
itemp = n2_4;
k=0;
/************************************************************************/
/* Initial section of stages 3, 4, …for which sines & cosines are */
/* not required. */
/************************************************************************/
for (k = 0; k < (2 << (m-i)>>1); k++)
{
_10 = gamma;
_11 = _10 + n2_2;
_13 = gamma2;
_14 = gamma2 + n2_2;
_15 = _11 + itemp;
x0 = x[_10];
x1 = x[_11];
x3 = x[_13];
x5 = x[_15];
x1 = x0 + x1;
x[_11] = x0 - x1;
x[_13] = x3 + x5;
x[_14] = x3 - x5;
gamma = gamma + n2;
gamma2 = gamma2 + n2;
}
gamma = diff;
gamma2 = diff2;
/************************************************************************/
/* Next sections of stages 3, 4, … */
/************************************************************************/
for ( j = 1; j < 2 << (i-3); j++ )
{
for ( k = 0; k < (2 << (m-i) >> 1); k++)
{
_10 = gamma;
_11 = _10 + n2_2;
_13 = gamma2;
_14 = _13 + n2_2;
x0 = x[_10];
x1 = x[_11];
x3 = x[_13];
x4 = x[_14];
x[_10] = x0 + x1 * cc1 + x4 * ss1;
x[_11] = x0 - x1 * cc1 - x4 * ss1;
x[_13] = x3 - x4 * cc1 + x1 * ss1;
x[_14] = x3 + x4 * cc1 - x1 * ss1;
gamma = gamma + n2;
gamma2 = gamma2 + n2;
}
itemp = 0;
phi = phi + ( 2 << (m-i) >> 1 );
ntemp=(phi < n_4) ? 0 : n_4;
ss1=sine[phi - ntemp];
cc1=sine[n_4 - phi + ntemp];
diff++; diff2--;
gamma=diff;
gamma2=diff2;
}
}
}
//
//--------- Main -------------
main(X,N,M)
{
/* Read the integer values 1, …, N into the vector X[N]. */
int i;
float X[N];
for (i = 0; i < N; i++)
{
X[i] = i+1;
for (i = 0; i < N; i++)
{
printf ("%f\n", X[i]);
myFht(X, N, M);
printf ("\n");
for (i = 0; i < N; i++)
{
printf ("%d: %f\n", i, X[i]/N);
}
}
}
/* It is assumed that the user divides by the integer N. */
//-------- Stop Program !!!! -------------
getch();
printf("For Stop Program press qey [q]: \n")
return 0;
}
//========================================== |
(
