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libtgvoip/webrtc_dsp/modules/third_party/fft/fft.c

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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.
2018-11-21 19:22:31 +01:00
/*
* 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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