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libtgvoip/webrtc_dsp/modules/third_party/fft/fft.c
Grishka 5caaaafa42 Updated WebRTC APM 
I'm now using the entire audio processing module from WebRTC as opposed to individual DSP algorithms pulled from there before. Seems to work better this way.
2018-11-23 04:02:53 +03:00

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/*
* Copyright(c)1995,97 Mark Olesen <olesen@me.QueensU.CA>
* Queen's Univ at Kingston (Canada)
*
* Permission to use, copy, modify, and distribute this software for
* any purpose without fee is hereby granted, provided that this
* entire notice is included in all copies of any software which is
* or includes a copy or modification of this software and in all
* copies of the supporting documentation for such software.
*
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR QUEEN'S
* UNIVERSITY AT KINGSTON MAKES ANY REPRESENTATION OR WARRANTY OF ANY
* KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS
* FITNESS FOR ANY PARTICULAR PURPOSE.
*
* All of which is to say that you can do what you like with this
* source code provided you don't try to sell it as your own and you
* include an unaltered copy of this message (including the
* copyright).
*
* It is also implicitly understood that bug fixes and improvements
* should make their way back to the general Internet community so
* that everyone benefits.
*
* Changes:
* Trivial type modifications by the WebRTC authors.
*/
/*
* File:
* WebRtcIsac_Fftn.c
*
* Public:
* WebRtcIsac_Fftn / fftnf ();
*
* Private:
* WebRtcIsac_Fftradix / fftradixf ();
*
* Descript:
* multivariate complex Fourier transform, computed in place
* using mixed-radix Fast Fourier Transform algorithm.
*
* Fortran code by:
* RC Singleton, Stanford Research Institute, Sept. 1968
*
* translated by f2c (version 19950721).
*
* int WebRtcIsac_Fftn (int ndim, const int dims[], REAL Re[], REAL Im[],
* int iSign, double scaling);
*
* NDIM = the total number dimensions
* DIMS = a vector of array sizes
* if NDIM is zero then DIMS must be zero-terminated
*
* RE and IM hold the real and imaginary components of the data, and return
* the resulting real and imaginary Fourier coefficients. Multidimensional
* data *must* be allocated contiguously. There is no limit on the number
* of dimensions.
*
* ISIGN = the sign of the complex exponential (ie, forward or inverse FFT)
* the magnitude of ISIGN (normally 1) is used to determine the
* correct indexing increment (see below).
*
* SCALING = normalizing constant by which the final result is *divided*
* if SCALING == -1, normalize by total dimension of the transform
* if SCALING < -1, normalize by the square-root of the total dimension
*
* example:
* tri-variate transform with Re[n1][n2][n3], Im[n1][n2][n3]
*
* int dims[3] = {n1,n2,n3}
* WebRtcIsac_Fftn (3, dims, Re, Im, 1, scaling);
*
*-----------------------------------------------------------------------*
* int WebRtcIsac_Fftradix (REAL Re[], REAL Im[], size_t nTotal, size_t nPass,
* size_t nSpan, int iSign, size_t max_factors,
* size_t max_perm);
*
* RE, IM - see above documentation
*
* Although there is no limit on the number of dimensions, WebRtcIsac_Fftradix() must
* be called once for each dimension, but the calls may be in any order.
*
* NTOTAL = the total number of complex data values
* NPASS = the dimension of the current variable
* NSPAN/NPASS = the spacing of consecutive data values while indexing the
* current variable
* ISIGN - see above documentation
*
* example:
* tri-variate transform with Re[n1][n2][n3], Im[n1][n2][n3]
*
* WebRtcIsac_Fftradix (Re, Im, n1*n2*n3, n1, n1, 1, maxf, maxp);
* WebRtcIsac_Fftradix (Re, Im, n1*n2*n3, n2, n1*n2, 1, maxf, maxp);
* WebRtcIsac_Fftradix (Re, Im, n1*n2*n3, n3, n1*n2*n3, 1, maxf, maxp);
*
* single-variate transform,
* NTOTAL = N = NSPAN = (number of complex data values),
*
* WebRtcIsac_Fftradix (Re, Im, n, n, n, 1, maxf, maxp);
*
* The data can also be stored in a single array with alternating real and
* imaginary parts, the magnitude of ISIGN is changed to 2 to give correct
* indexing increment, and data [0] and data [1] used to pass the initial
* addresses for the sequences of real and imaginary values,
*
* example:
* REAL data [2*NTOTAL];
* WebRtcIsac_Fftradix ( &data[0], &data[1], NTOTAL, nPass, nSpan, 2, maxf, maxp);
*
* for temporary allocation:
*
* MAX_FACTORS >= the maximum prime factor of NPASS
* MAX_PERM >= the number of prime factors of NPASS. In addition,
* if the square-free portion K of NPASS has two or more prime
* factors, then MAX_PERM >= (K-1)
*
* storage in FACTOR for a maximum of 15 prime factors of NPASS. if NPASS
* has more than one square-free factor, the product of the square-free
* factors must be <= 210 array storage for maximum prime factor of 23 the
* following two constants should agree with the array dimensions.
*
*----------------------------------------------------------------------*/
#include <stdlib.h>
#include <math.h>
#include "modules/third_party/fft/fft.h"
/* double precision routine */
static int
WebRtcIsac_Fftradix (double Re[], double Im[],
size_t nTotal, size_t nPass, size_t nSpan, int isign,
int max_factors, unsigned int max_perm,
FFTstr *fftstate);
#ifndef M_PI
# define M_PI 3.14159265358979323846264338327950288
#endif
#ifndef SIN60
# define SIN60 0.86602540378443865 /* sin(60 deg) */
# define COS72 0.30901699437494742 /* cos(72 deg) */
# define SIN72 0.95105651629515357 /* sin(72 deg) */
#endif
# define REAL double
# define FFTN WebRtcIsac_Fftn
# define FFTNS "fftn"
# define FFTRADIX WebRtcIsac_Fftradix
# define FFTRADIXS "fftradix"
int WebRtcIsac_Fftns(unsigned int ndim, const int dims[],
double Re[],
double Im[],
int iSign,
double scaling,
FFTstr *fftstate)
{
size_t nSpan, nPass, nTotal;
unsigned int i;
int ret, max_factors, max_perm;
/*
* tally the number of elements in the data array
* and determine the number of dimensions
*/
nTotal = 1;
if (ndim && dims [0])
{
for (i = 0; i < ndim; i++)
{
if (dims [i] <= 0)
{
return -1;
}
nTotal *= dims [i];
}
}
else
{
ndim = 0;
for (i = 0; dims [i]; i++)
{
if (dims [i] <= 0)
{
return -1;
}
nTotal *= dims [i];
ndim++;
}
}
/* determine maximum number of factors and permuations */
#if 1
/*
* follow John Beale's example, just use the largest dimension and don't
* worry about excess allocation. May be someone else will do it?
*/
max_factors = max_perm = 1;
for (i = 0; i < ndim; i++)
{
nSpan = dims [i];
if ((int)nSpan > max_factors)
{
max_factors = (int)nSpan;
}
if ((int)nSpan > max_perm)
{
max_perm = (int)nSpan;
}
}
#else
/* use the constants used in the original Fortran code */
max_factors = 23;
max_perm = 209;
#endif
/* loop over the dimensions: */
nPass = 1;
for (i = 0; i < ndim; i++)
{
nSpan = dims [i];
nPass *= nSpan;
ret = FFTRADIX (Re, Im, nTotal, nSpan, nPass, iSign,
max_factors, max_perm, fftstate);
/* exit, clean-up already done */
if (ret)
return ret;
}
/* Divide through by the normalizing constant: */
if (scaling && scaling != 1.0)
{
if (iSign < 0) iSign = -iSign;
if (scaling < 0.0)
{
scaling = (double)nTotal;
if (scaling < -1.0)
scaling = sqrt (scaling);
}
scaling = 1.0 / scaling; /* multiply is often faster */
for (i = 0; i < nTotal; i += iSign)
{
Re [i] *= scaling;
Im [i] *= scaling;
}
}
return 0;
}
/*
* singleton's mixed radix routine
*
* could move allocation out to WebRtcIsac_Fftn(), but leave it here so that it's
* possible to make this a standalone function
*/
static int FFTRADIX (REAL Re[],
REAL Im[],
size_t nTotal,
size_t nPass,
size_t nSpan,
int iSign,
int max_factors,
unsigned int max_perm,
FFTstr *fftstate)
{
int ii, mfactor, kspan, ispan, inc;
int j, jc, jf, jj, k, k1, k2, k3, k4, kk, kt, nn, ns, nt;
REAL radf;
REAL c1, c2, c3, cd, aa, aj, ak, ajm, ajp, akm, akp;
REAL s1, s2, s3, sd, bb, bj, bk, bjm, bjp, bkm, bkp;
REAL *Rtmp = NULL; /* temp space for real part*/
REAL *Itmp = NULL; /* temp space for imaginary part */
REAL *Cos = NULL; /* Cosine values */
REAL *Sin = NULL; /* Sine values */
REAL s60 = SIN60; /* sin(60 deg) */
REAL c72 = COS72; /* cos(72 deg) */
REAL s72 = SIN72; /* sin(72 deg) */
REAL pi2 = M_PI; /* use PI first, 2 PI later */
fftstate->SpaceAlloced = 0;
fftstate->MaxPermAlloced = 0;
// initialize to avoid warnings
k3 = c2 = c3 = s2 = s3 = 0.0;
if (nPass < 2)
return 0;
/* allocate storage */
if (fftstate->SpaceAlloced < max_factors * sizeof (REAL))
{
#ifdef SUN_BROKEN_REALLOC
if (!fftstate->SpaceAlloced) /* first time */
{
fftstate->SpaceAlloced = max_factors * sizeof (REAL);
}
else
{
#endif
fftstate->SpaceAlloced = max_factors * sizeof (REAL);
#ifdef SUN_BROKEN_REALLOC
}
#endif
}
else
{
/* allow full use of alloc'd space */
max_factors = fftstate->SpaceAlloced / sizeof (REAL);
}
if (fftstate->MaxPermAlloced < max_perm)
{
#ifdef SUN_BROKEN_REALLOC
if (!fftstate->MaxPermAlloced) /* first time */
else
#endif
fftstate->MaxPermAlloced = max_perm;
}
else
{
/* allow full use of alloc'd space */
max_perm = fftstate->MaxPermAlloced;
}
/* assign pointers */
Rtmp = (REAL *) fftstate->Tmp0;
Itmp = (REAL *) fftstate->Tmp1;
Cos = (REAL *) fftstate->Tmp2;
Sin = (REAL *) fftstate->Tmp3;
/*
* Function Body
*/
inc = iSign;
if (iSign < 0) {
s72 = -s72;
s60 = -s60;
pi2 = -pi2;
inc = -inc; /* absolute value */
}
/* adjust for strange increments */
nt = inc * (int)nTotal;
ns = inc * (int)nSpan;
kspan = ns;
nn = nt - inc;
jc = ns / (int)nPass;
radf = pi2 * (double) jc;
pi2 *= 2.0; /* use 2 PI from here on */
ii = 0;
jf = 0;
/* determine the factors of n */
mfactor = 0;
k = (int)nPass;
while (k % 16 == 0) {
mfactor++;
fftstate->factor [mfactor - 1] = 4;
k /= 16;
}
j = 3;
jj = 9;
do {
while (k % jj == 0) {
mfactor++;
fftstate->factor [mfactor - 1] = j;
k /= jj;
}
j += 2;
jj = j * j;
} while (jj <= k);
if (k <= 4) {
kt = mfactor;
fftstate->factor [mfactor] = k;
if (k != 1)
mfactor++;
} else {
if (k - (k / 4 << 2) == 0) {
mfactor++;
fftstate->factor [mfactor - 1] = 2;
k /= 4;
}
kt = mfactor;
j = 2;
do {
if (k % j == 0) {
mfactor++;
fftstate->factor [mfactor - 1] = j;
k /= j;
}
j = ((j + 1) / 2 << 1) + 1;
} while (j <= k);
}
if (kt) {
j = kt;
do {
mfactor++;
fftstate->factor [mfactor - 1] = fftstate->factor [j - 1];
j--;
} while (j);
}
/* test that mfactors is in range */
if (mfactor > FFT_NFACTOR)
{
return -1;
}
/* compute fourier transform */
for (;;) {
sd = radf / (double) kspan;
cd = sin(sd);
cd = 2.0 * cd * cd;
sd = sin(sd + sd);
kk = 0;
ii++;
switch (fftstate->factor [ii - 1]) {
case 2:
/* transform for factor of 2 (including rotation factor) */
kspan /= 2;
k1 = kspan + 2;
do {
do {
k2 = kk + kspan;
ak = Re [k2];
bk = Im [k2];
Re [k2] = Re [kk] - ak;
Im [k2] = Im [kk] - bk;
Re [kk] += ak;
Im [kk] += bk;
kk = k2 + kspan;
} while (kk < nn);
kk -= nn;
} while (kk < jc);
if (kk >= kspan)
goto Permute_Results_Label; /* exit infinite loop */
do {
c1 = 1.0 - cd;
s1 = sd;
do {
do {
do {
k2 = kk + kspan;
ak = Re [kk] - Re [k2];
bk = Im [kk] - Im [k2];
Re [kk] += Re [k2];
Im [kk] += Im [k2];
Re [k2] = c1 * ak - s1 * bk;
Im [k2] = s1 * ak + c1 * bk;
kk = k2 + kspan;
} while (kk < (nt-1));
k2 = kk - nt;
c1 = -c1;
kk = k1 - k2;
} while (kk > k2);
ak = c1 - (cd * c1 + sd * s1);
s1 = sd * c1 - cd * s1 + s1;
c1 = 2.0 - (ak * ak + s1 * s1);
s1 *= c1;
c1 *= ak;
kk += jc;
} while (kk < k2);
k1 += inc + inc;
kk = (k1 - kspan + 1) / 2 + jc - 1;
} while (kk < (jc + jc));
break;
case 4: /* transform for factor of 4 */
ispan = kspan;
kspan /= 4;
do {
c1 = 1.0;
s1 = 0.0;
do {
do {
k1 = kk + kspan;
k2 = k1 + kspan;
k3 = k2 + kspan;
akp = Re [kk] + Re [k2];
akm = Re [kk] - Re [k2];
ajp = Re [k1] + Re [k3];
ajm = Re [k1] - Re [k3];
bkp = Im [kk] + Im [k2];
bkm = Im [kk] - Im [k2];
bjp = Im [k1] + Im [k3];
bjm = Im [k1] - Im [k3];
Re [kk] = akp + ajp;
Im [kk] = bkp + bjp;
ajp = akp - ajp;
bjp = bkp - bjp;
if (iSign < 0) {
akp = akm + bjm;
bkp = bkm - ajm;
akm -= bjm;
bkm += ajm;
} else {
akp = akm - bjm;
bkp = bkm + ajm;
akm += bjm;
bkm -= ajm;
}
/* avoid useless multiplies */
if (s1 == 0.0) {
Re [k1] = akp;
Re [k2] = ajp;
Re [k3] = akm;
Im [k1] = bkp;
Im [k2] = bjp;
Im [k3] = bkm;
} else {
Re [k1] = akp * c1 - bkp * s1;
Re [k2] = ajp * c2 - bjp * s2;
Re [k3] = akm * c3 - bkm * s3;
Im [k1] = akp * s1 + bkp * c1;
Im [k2] = ajp * s2 + bjp * c2;
Im [k3] = akm * s3 + bkm * c3;
}
kk = k3 + kspan;
} while (kk < nt);
c2 = c1 - (cd * c1 + sd * s1);
s1 = sd * c1 - cd * s1 + s1;
c1 = 2.0 - (c2 * c2 + s1 * s1);
s1 *= c1;
c1 *= c2;
/* values of c2, c3, s2, s3 that will get used next time */
c2 = c1 * c1 - s1 * s1;
s2 = 2.0 * c1 * s1;
c3 = c2 * c1 - s2 * s1;
s3 = c2 * s1 + s2 * c1;
kk = kk - nt + jc;
} while (kk < kspan);
kk = kk - kspan + inc;
} while (kk < jc);
if (kspan == jc)
goto Permute_Results_Label; /* exit infinite loop */
break;
default:
/* transform for odd factors */
#ifdef FFT_RADIX4
return -1;
break;
#else /* FFT_RADIX4 */
k = fftstate->factor [ii - 1];
ispan = kspan;
kspan /= k;
switch (k) {
case 3: /* transform for factor of 3 (optional code) */
do {
do {
k1 = kk + kspan;
k2 = k1 + kspan;
ak = Re [kk];
bk = Im [kk];
aj = Re [k1] + Re [k2];
bj = Im [k1] + Im [k2];
Re [kk] = ak + aj;
Im [kk] = bk + bj;
ak -= 0.5 * aj;
bk -= 0.5 * bj;
aj = (Re [k1] - Re [k2]) * s60;
bj = (Im [k1] - Im [k2]) * s60;
Re [k1] = ak - bj;
Re [k2] = ak + bj;
Im [k1] = bk + aj;
Im [k2] = bk - aj;
kk = k2 + kspan;
} while (kk < (nn - 1));
kk -= nn;
} while (kk < kspan);
break;
case 5: /* transform for factor of 5 (optional code) */
c2 = c72 * c72 - s72 * s72;
s2 = 2.0 * c72 * s72;
do {
do {
k1 = kk + kspan;
k2 = k1 + kspan;
k3 = k2 + kspan;
k4 = k3 + kspan;
akp = Re [k1] + Re [k4];
akm = Re [k1] - Re [k4];
bkp = Im [k1] + Im [k4];
bkm = Im [k1] - Im [k4];
ajp = Re [k2] + Re [k3];
ajm = Re [k2] - Re [k3];
bjp = Im [k2] + Im [k3];
bjm = Im [k2] - Im [k3];
aa = Re [kk];
bb = Im [kk];
Re [kk] = aa + akp + ajp;
Im [kk] = bb + bkp + bjp;
ak = akp * c72 + ajp * c2 + aa;
bk = bkp * c72 + bjp * c2 + bb;
aj = akm * s72 + ajm * s2;
bj = bkm * s72 + bjm * s2;
Re [k1] = ak - bj;
Re [k4] = ak + bj;
Im [k1] = bk + aj;
Im [k4] = bk - aj;
ak = akp * c2 + ajp * c72 + aa;
bk = bkp * c2 + bjp * c72 + bb;
aj = akm * s2 - ajm * s72;
bj = bkm * s2 - bjm * s72;
Re [k2] = ak - bj;
Re [k3] = ak + bj;
Im [k2] = bk + aj;
Im [k3] = bk - aj;
kk = k4 + kspan;
} while (kk < (nn-1));
kk -= nn;
} while (kk < kspan);
break;
default:
if (k != jf) {
jf = k;
s1 = pi2 / (double) k;
c1 = cos(s1);
s1 = sin(s1);
if (jf > max_factors){
return -1;
}
Cos [jf - 1] = 1.0;
Sin [jf - 1] = 0.0;
j = 1;
do {
Cos [j - 1] = Cos [k - 1] * c1 + Sin [k - 1] * s1;
Sin [j - 1] = Cos [k - 1] * s1 - Sin [k - 1] * c1;
k--;
Cos [k - 1] = Cos [j - 1];
Sin [k - 1] = -Sin [j - 1];
j++;
} while (j < k);
}
do {
do {
k1 = kk;
k2 = kk + ispan;
ak = aa = Re [kk];
bk = bb = Im [kk];
j = 1;
k1 += kspan;
do {
k2 -= kspan;
j++;
Rtmp [j - 1] = Re [k1] + Re [k2];
ak += Rtmp [j - 1];
Itmp [j - 1] = Im [k1] + Im [k2];
bk += Itmp [j - 1];
j++;
Rtmp [j - 1] = Re [k1] - Re [k2];
Itmp [j - 1] = Im [k1] - Im [k2];
k1 += kspan;
} while (k1 < k2);
Re [kk] = ak;
Im [kk] = bk;
k1 = kk;
k2 = kk + ispan;
j = 1;
do {
k1 += kspan;
k2 -= kspan;
jj = j;
ak = aa;
bk = bb;
aj = 0.0;
bj = 0.0;
k = 1;
do {
k++;
ak += Rtmp [k - 1] * Cos [jj - 1];
bk += Itmp [k - 1] * Cos [jj - 1];
k++;
aj += Rtmp [k - 1] * Sin [jj - 1];
bj += Itmp [k - 1] * Sin [jj - 1];
jj += j;
if (jj > jf) {
jj -= jf;
}
} while (k < jf);
k = jf - j;
Re [k1] = ak - bj;
Im [k1] = bk + aj;
Re [k2] = ak + bj;
Im [k2] = bk - aj;
j++;
} while (j < k);
kk += ispan;
} while (kk < nn);
kk -= nn;
} while (kk < kspan);
break;
}
/* multiply by rotation factor (except for factors of 2 and 4) */
if (ii == mfactor)
goto Permute_Results_Label; /* exit infinite loop */
kk = jc;
do {
c2 = 1.0 - cd;
s1 = sd;
do {
c1 = c2;
s2 = s1;
kk += kspan;
do {
do {
ak = Re [kk];
Re [kk] = c2 * ak - s2 * Im [kk];
Im [kk] = s2 * ak + c2 * Im [kk];
kk += ispan;
} while (kk < nt);
ak = s1 * s2;
s2 = s1 * c2 + c1 * s2;
c2 = c1 * c2 - ak;
kk = kk - nt + kspan;
} while (kk < ispan);
c2 = c1 - (cd * c1 + sd * s1);
s1 += sd * c1 - cd * s1;
c1 = 2.0 - (c2 * c2 + s1 * s1);
s1 *= c1;
c2 *= c1;
kk = kk - ispan + jc;
} while (kk < kspan);
kk = kk - kspan + jc + inc;
} while (kk < (jc + jc));
break;
#endif /* FFT_RADIX4 */
}
}
/* permute the results to normal order---done in two stages */
/* permutation for square factors of n */
Permute_Results_Label:
fftstate->Perm [0] = ns;
if (kt) {
k = kt + kt + 1;
if (mfactor < k)
k--;
j = 1;
fftstate->Perm [k] = jc;
do {
fftstate->Perm [j] = fftstate->Perm [j - 1] / fftstate->factor [j - 1];
fftstate->Perm [k - 1] = fftstate->Perm [k] * fftstate->factor [j - 1];
j++;
k--;
} while (j < k);
k3 = fftstate->Perm [k];
kspan = fftstate->Perm [1];
kk = jc;
k2 = kspan;
j = 1;
if (nPass != nTotal) {
/* permutation for multivariate transform */
Permute_Multi_Label:
do {
do {
k = kk + jc;
do {
/* swap Re [kk] <> Re [k2], Im [kk] <> Im [k2] */
ak = Re [kk]; Re [kk] = Re [k2]; Re [k2] = ak;
bk = Im [kk]; Im [kk] = Im [k2]; Im [k2] = bk;
kk += inc;
k2 += inc;
} while (kk < (k-1));
kk += ns - jc;
k2 += ns - jc;
} while (kk < (nt-1));
k2 = k2 - nt + kspan;
kk = kk - nt + jc;
} while (k2 < (ns-1));
do {
do {
k2 -= fftstate->Perm [j - 1];
j++;
k2 = fftstate->Perm [j] + k2;
} while (k2 > fftstate->Perm [j - 1]);
j = 1;
do {
if (kk < (k2-1))
goto Permute_Multi_Label;
kk += jc;
k2 += kspan;
} while (k2 < (ns-1));
} while (kk < (ns-1));
} else {
/* permutation for single-variate transform (optional code) */
Permute_Single_Label:
do {
/* swap Re [kk] <> Re [k2], Im [kk] <> Im [k2] */
ak = Re [kk]; Re [kk] = Re [k2]; Re [k2] = ak;
bk = Im [kk]; Im [kk] = Im [k2]; Im [k2] = bk;
kk += inc;
k2 += kspan;
} while (k2 < (ns-1));
do {
do {
k2 -= fftstate->Perm [j - 1];
j++;
k2 = fftstate->Perm [j] + k2;
} while (k2 >= fftstate->Perm [j - 1]);
j = 1;
do {
if (kk < k2)
goto Permute_Single_Label;
kk += inc;
k2 += kspan;
} while (k2 < (ns-1));
} while (kk < (ns-1));
}
jc = k3;
}
if ((kt << 1) + 1 >= mfactor)
return 0;
ispan = fftstate->Perm [kt];
/* permutation for square-free factors of n */
j = mfactor - kt;
fftstate->factor [j] = 1;
do {
fftstate->factor [j - 1] *= fftstate->factor [j];
j--;
} while (j != kt);
kt++;
nn = fftstate->factor [kt - 1] - 1;
if (nn > (int) max_perm) {
return -1;
}
j = jj = 0;
for (;;) {
k = kt + 1;
k2 = fftstate->factor [kt - 1];
kk = fftstate->factor [k - 1];
j++;
if (j > nn)
break; /* exit infinite loop */
jj += kk;
while (jj >= k2) {
jj -= k2;
k2 = kk;
k++;
kk = fftstate->factor [k - 1];
jj += kk;
}
fftstate->Perm [j - 1] = jj;
}
/* determine the permutation cycles of length greater than 1 */
j = 0;
for (;;) {
do {
j++;
kk = fftstate->Perm [j - 1];
} while (kk < 0);
if (kk != j) {
do {
k = kk;
kk = fftstate->Perm [k - 1];
fftstate->Perm [k - 1] = -kk;
} while (kk != j);
k3 = kk;
} else {
fftstate->Perm [j - 1] = -j;
if (j == nn)
break; /* exit infinite loop */
}
}
max_factors *= inc;
/* reorder a and b, following the permutation cycles */
for (;;) {
j = k3 + 1;
nt -= ispan;
ii = nt - inc + 1;
if (nt < 0)
break; /* exit infinite loop */
do {
do {
j--;
} while (fftstate->Perm [j - 1] < 0);
jj = jc;
do {
kspan = jj;
if (jj > max_factors) {
kspan = max_factors;
}
jj -= kspan;
k = fftstate->Perm [j - 1];
kk = jc * k + ii + jj;
k1 = kk + kspan - 1;
k2 = 0;
do {
k2++;
Rtmp [k2 - 1] = Re [k1];
Itmp [k2 - 1] = Im [k1];
k1 -= inc;
} while (k1 != (kk-1));
do {
k1 = kk + kspan - 1;
k2 = k1 - jc * (k + fftstate->Perm [k - 1]);
k = -fftstate->Perm [k - 1];
do {
Re [k1] = Re [k2];
Im [k1] = Im [k2];
k1 -= inc;
k2 -= inc;
} while (k1 != (kk-1));
kk = k2 + 1;
} while (k != j);
k1 = kk + kspan - 1;
k2 = 0;
do {
k2++;
Re [k1] = Rtmp [k2 - 1];
Im [k1] = Itmp [k2 - 1];
k1 -= inc;
} while (k1 != (kk-1));
} while (jj);
} while (j != 1);
}
return 0; /* exit point here */
}
/* ---------------------- end-of-file (c source) ---------------------- */
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