mirror/kissfft
1
0
Fork 0
mirror of https://github.com/mborgerding/kissfft.git synced 2025-07-18 04:54:20 -04:00
Code Issues Packages Projects Releases Wiki Activity

slight code cleanup, comments

Browse Source
This commit is contained in:
Mark Borgerding
2003-10-18 01:39:36 +00:00
parent bca7fd5151
commit c239ba2c1c
1 changed files with 16 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
kiss_fft.c
View File

@ -16,26 +16,20 @@ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
#include <stdio.h> #include <stdio.h>
#include <math.h> #include <math.h>
#include <memory.h> #include <memory.h>
/* kiss_fft.h
defines kiss_fft_scalar as either short or a float type
and defines
typedef struct { kiss_fft_scalar r; kiss_fft_scalar i; }kiss_fft_cpx; */
#include "kiss_fft.h" #include "kiss_fft.h"
/*try this, you might get a speed improvement*/ /* Try static inline. Who knows? You might get a speed improvement. I didn't. YMMV */
#if 0 #if 0
# define FUNCDECL static inline # define FUNCDECL static inline
#else #else
# define FUNCDECL # define FUNCDECL
#endif #endif
/*
* kiss_fft.h
* defines kiss_fft_scalar as either short or a float type
* and defines
* typedef struct {
* kiss_fft_scalar r;
* kiss_fft_scalar i;
* }kiss_fft_cpx;
*/
typedef struct { typedef struct {
int nfft; int nfft;
int inverse; int inverse;
@ -46,20 +40,20 @@ typedef struct {
}kiss_fft_state; }kiss_fft_state;
#ifdef FIXED_POINT #ifdef FIXED_POINT
# define C_MUL(m,a,b) \ # define C_MUL(m,a,b) \
do{ (m).r = ( ( (a).r*(b).r - (a).i*(b).i) + (1<<14) ) >> 15;\ do{ (m).r = ( ( (a).r*(b).r - (a).i*(b).i) + (1<<14) ) >> 15;\
(m).i = ( ( (a).r*(b).i + (a).i*(b).r) + (1<<14) ) >> 15;\ (m).i = ( ( (a).r*(b).i + (a).i*(b).r) + (1<<14) ) >> 15;\
}while(0) }while(0)
# define C_FIXDIV(c,div) \ # define C_FIXDIV(c,div) \
do{ (c).r /= div; (c).i /=div; }while(0) do{ (c).r /= div; (c).i /=div; }while(0)
#define C_MUL_SCALAR(m,s) \ #define C_MUL_SCALAR(m,s) \
do{ (m).r = ( (m).r * (s) + (1<<14) ) >> 15;\ do{ (m).r = ( (m).r * (s) + (1<<14) ) >> 15;\
(m).i = ( (m).i * (s) + (1<<14) ) >> 15;\ (m).i = ( (m).i * (s) + (1<<14) ) >> 15;\
}while(0) }while(0)
#else /* not FIXED_POINT*/ #else /* not FIXED_POINT*/
#define C_MUL_SCALAR(m,s) \ #define C_MUL_SCALAR(m,s) \
do{ (m).r *= (s);\ do{ (m).r *= (s);\
(m).i *= (s);\ (m).i *= (s);\
@ -68,6 +62,7 @@ typedef struct {
#define C_MUL(m,a,b) \ #define C_MUL(m,a,b) \
do{ (m).r = (a).r*(b).r - (a).i*(b).i;\ do{ (m).r = (a).r*(b).r - (a).i*(b).i;\
(m).i = (a).r*(b).i + (a).i*(b).r; }while(0) (m).i = (a).r*(b).i + (a).i*(b).r; }while(0)
#endif #endif
#define C_ADD( res, a,b)\ #define C_ADD( res, a,b)\
@ -80,9 +75,9 @@ typedef struct {
do { (res).r -= (a).r; (res).i -= (a).i; }while(0) do { (res).r -= (a).r; (res).i -= (a).i; }while(0)
#define C_ROTADDTO(sum,c,q) \ #define C_ROTADDTO(sum,c,q) \
do{ switch (q) {\ do{ switch (q) {\
case 0: (sum).r += (c).r; (sum).i += (c).i; break;\ case 0: C_ADDTO(sum,c); break;\
case 1: (sum).r += (c).i; (sum).i -= (c).r; break;\ case 1: (sum).r += (c).i; (sum).i -= (c).r; break;\
case 2: (sum).r -= (c).r; (sum).i -= (c).i; break;\ case 2: C_SUBFROM(sum,c); break;\
case 3: (sum).r -= (c).i; (sum).i += (c).r; break;\ case 3: (sum).r -= (c).i; (sum).i += (c).r; break;\
} }while(0) } }while(0)
@ -157,9 +152,9 @@ void bfly3(
scratch[4].r = scratch[5].r - scratch[6].i; scratch[4].r = scratch[5].r - scratch[6].i;
scratch[4].i = scratch[5].i + scratch[6].r; scratch[4].i = scratch[5].i + scratch[6].r;
C_ADD( *Fout1, scratch[0] , scratch[4] ); C_ADD( *Fout1, scratch[0] , scratch[4] );
scratch[4].r = scratch[5].r + scratch[6].i; *Fout2 = *Fout1;
scratch[4].i = scratch[5].i - scratch[6].r; Fout2->r += 2*scratch[6].i;
C_ADD( *Fout2, scratch[0] , scratch[4] ); Fout2->i -= 2*scratch[6].r;
++Fout0;++Fout1;++Fout2; ++Fout0;++Fout1;++Fout2;
} }
} }
@ -326,7 +321,8 @@ void * kiss_fft_alloc(int nfft,int inverse_fft)
} }
while (nfft>1) { while (nfft>1) {
const int primes[] = {4,2,3,5,7,11,13,17,-1}; /* If you add a new radix, don't forget to put it here */
const int primes[] = {4,2,3,-1};
int p=nfft; int p=nfft;
i=0; i=0;
while ( primes[i] != -1 ) { while ( primes[i] != -1 ) {
@ -342,22 +338,6 @@ void * kiss_fft_alloc(int nfft,int inverse_fft)
++nstages; ++nstages;
} }
/* reverse the factors list so that the 2s are packed to the back*/
nfft=st->nfft;
for ( i=0 ; i< nstages ;i+=2 ) {
int p;
p = st->factors[i];
st->factors[i] = st->factors[ 2*nstages-i-2];
st->factors[2*nstages-i-2 ] = p;
}
for ( i=0 ; i< nstages*2 ;i+=2 ) {
nfft /= st->factors[i];
st->factors[i+1] = nfft;
}
memset(st->tmpbuf,0,sizeof(kiss_fft_cpx)*nfft);
return st; return st;
} }