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made the factorization a separate routine

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This commit is contained in:
Mark Borgerding
2003-11-12 01:09:35 +00:00
parent 140f106743
commit 206e28f11c
6 changed files with 156 additions and 87 deletions
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78
kiss_fft.c
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@ -45,7 +45,7 @@ typedef struct {
C_MUL(m,a,b) : m = a*b
C_FIXDIV( c , div ) : if a fixed point impl., c /= div. noop otherwise
C_SUB( res, a,b) : res = a - b
C_SUB( res, a,b) : res = a - b
C_SUBFROM( res , a) : res -= a
C_ADDTO( res , a) : res += a
* */
@ -86,7 +86,7 @@ typedef struct {
kiss_fft_cpx cexp(double phase) /* returns e ** (j*phase) */
{
kiss_fft_cpx x;
#ifdef FIXED_POINT
#ifdef FIXED_POINT
x.r = (kiss_fft_scalar) ( 32767*cos(phase) );
x.i = (kiss_fft_scalar) ( 32767*sin(phase) );
#else
@ -265,7 +265,7 @@ void bfly5(
C_SUB(*Fout1,scratch[5],scratch[6]);
C_ADD(*Fout4,scratch[5],scratch[6]);
scratch[11].r = scratch[0].r + S_MUL(scratch[7].r,y2.r) + S_MUL(scratch[8].r,y1.r);
scratch[11].i = scratch[0].i + S_MUL(scratch[7].i,y2.r) + S_MUL(scratch[8].i,y1.r);
scratch[12].r = - S_MUL(scratch[10].i,y2.i) + S_MUL(scratch[9].i,y1.i);
@ -329,7 +329,7 @@ void fft_work(
m=*factors++;
for (q=0;q<p;++q) {
if (m==1)
if (m==1)
Fout[q] = *f;
else
fft_work( Fout + m*q, f, fstride*p,factors,st);
@ -352,12 +352,51 @@ int allocsize(int nfft)
+ sizeof(kiss_fft_cpx)*nfft /* tmpbuf*/
+ sizeof(int)*nfft /* factors*/
+ sizeof(kiss_fft_cpx)*nfft; /* scratch*/
return allocsize;
return allocsize;
}
/* factors out powers of 4, powers of 2, then any remaining primes
facbuf is populated by p1,m1,p2,m2, ...
where
p[i] * m[i] = m[i-1]
m0 = n
* */
void factor(int n,int * facbuf)
{
int p;
while ( n>1 && (n&1) == 0) {
if ( (n&3) == 0)
p=4;
else
p=2;
n /= p;
*facbuf++ = p;
*facbuf++ = n;
}
if (n>1) {
int floor_sqrt = floor( sqrt( n ) );
p=3;
do{
while (n%p) {
p += 2;
if ( p>floor_sqrt )
p=n;/* no more factors, skip to end*/
}
n /= p;
*facbuf++ = p;
*facbuf++ = n;
}while ( n >1);
}
}
void init_state(kiss_fft_state * st,int nfft,int inverse_fft)
{
int nstages=0;
int i;
st->nfft=nfft;
st->inverse = inverse_fft;
@ -374,26 +413,7 @@ void init_state(kiss_fft_state * st,int nfft,int inverse_fft)
st->twiddles[i] = cexp( phase );
}
while (nfft>1) {
/* If you want a new radix, don't forget to put it here */
const int divisors[] = {
4,2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,
71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,
149,151,157,163,167,173,179,181,191,193,197,199,-1};
int p=nfft;
i=0;
while ( divisors[i] != -1 ) {
if ( nfft % divisors[i] == 0){
p = divisors[i];
break;
}
++i;
}
st->factors[2*nstages] = p;
nfft /= p;
st->factors[2*nstages+1] = nfft;
++nstages;
}
factor(nfft,st->factors);
}
/*
@ -426,7 +446,7 @@ void * kiss_fft2d_alloc(int nrows,int ncols,int inverse_fft)
st = (kiss_fft2d_state *) malloc ( sizeof(kiss_fft2d_state) + size1 + size2 + sizetmp );
if (!st)
return NULL;
st->minus2 = -2;
st->rowst = (kiss_fft_state *)(st+1); /*just beyond kiss_fft2d_state struct */
st->colst = (kiss_fft_state *)( (char*)(st->rowst) + size1 );
@ -447,7 +467,7 @@ void kiss_fft2d(const void * cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)
/*fft each column*/
for (col=0;col<ncols;++col) {
for (row=0;row< nrows ;++row)
for (row=0;row< nrows ;++row)
st->tmpbuf[row] = fin[row*ncols + col];
kiss_fft(st->colst,st->tmpbuf);
for (row=0;row< nrows ;++row) {
@ -456,7 +476,7 @@ void kiss_fft2d(const void * cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout)
}
/*fft each row */
for (row=0;row< nrows ;++row)
for (row=0;row< nrows ;++row)
kiss_fft(st->rowst , fout + row*ncols );
}