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Initial commit. Shows in the LCD the FFT
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‎include/README‎

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This directory is intended for project header files.
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A header file is a file containing C declarations and macro definitions
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to be shared between several project source files. You request the use of a
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header file in your project source file (C, C++, etc) located in `src` folder
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by including it, with the C preprocessing directive `#include'.
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```src/main.c
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#include "header.h"
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int main (void)
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{
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...
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}
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```
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Including a header file produces the same results as copying the header file
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into each source file that needs it. Such copying would be time-consuming
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and error-prone. With a header file, the related declarations appear
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in only one place. If they need to be changed, they can be changed in one
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place, and programs that include the header file will automatically use the
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new version when next recompiled. The header file eliminates the labor of
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finding and changing all the copies as well as the risk that a failure to
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find one copy will result in inconsistencies within a program.
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In C, the usual convention is to give header files names that end with `.h'.
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It is most portable to use only letters, digits, dashes, and underscores in
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header file names, and at most one dot.
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Read more about using header files in official GCC documentation:
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* Include Syntax
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* Include Operation
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* Once-Only Headers
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* Computed Includes
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https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html

‎include/_kiss_fft_guts.h‎

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/*
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* Copyright (c) 2003-2010, Mark Borgerding. All rights reserved.
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* This file is part of KISS FFT - https://github.com/mborgerding/kissfft
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*
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* SPDX-License-Identifier: BSD-3-Clause
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* See COPYING file for more information.
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*/
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/* kiss_fft.h
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defines kiss_fft_scalar as either short or a float type
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and defines
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typedef struct { kiss_fft_scalar r; kiss_fft_scalar i; }kiss_fft_cpx; */
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#include "kiss_fft.h"
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#include <limits.h>
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#define MAXFACTORS 32
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/* e.g. an fft of length 128 has 4 factors
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as far as kissfft is concerned
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4*4*4*2
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*/
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struct kiss_fft_state{
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int nfft;
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int inverse;
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int factors[2*MAXFACTORS];
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kiss_fft_cpx twiddles[1];
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};
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/*
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Explanation of macros dealing with complex math:
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C_MUL(m,a,b) : m = a*b
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C_FIXDIV( c , div ) : if a fixed point impl., c /= div. noop otherwise
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C_SUB( res, a,b) : res = a - b
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C_SUBFROM( res , a) : res -= a
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C_ADDTO( res , a) : res += a
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* */
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#ifdef FIXED_POINT
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#if (FIXED_POINT==32)
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# define FRACBITS 31
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# define SAMPPROD int64_t
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#define SAMP_MAX 2147483647
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#else
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# define FRACBITS 15
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# define SAMPPROD int32_t
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#define SAMP_MAX 32767
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#endif
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#define SAMP_MIN -SAMP_MAX
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#if defined(CHECK_OVERFLOW)
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# define CHECK_OVERFLOW_OP(a,op,b) \
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if ( (SAMPPROD)(a) op (SAMPPROD)(b) > SAMP_MAX || (SAMPPROD)(a) op (SAMPPROD)(b) < SAMP_MIN ) { \
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fprintf(stderr,"WARNING:overflow @ " __FILE__ "(%d): (%d " #op" %d) = %ld\n",__LINE__,(a),(b),(SAMPPROD)(a) op (SAMPPROD)(b) ); }
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#endif
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# define smul(a,b) ( (SAMPPROD)(a)*(b) )
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# define sround( x ) (kiss_fft_scalar)( ( (x) + (1<<(FRACBITS-1)) ) >> FRACBITS )
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# define S_MUL(a,b) sround( smul(a,b) )
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# define C_MUL(m,a,b) \
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do{ (m).r = sround( smul((a).r,(b).r) - smul((a).i,(b).i) ); \
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(m).i = sround( smul((a).r,(b).i) + smul((a).i,(b).r) ); }while(0)
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# define DIVSCALAR(x,k) \
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(x) = sround( smul( x, SAMP_MAX/k ) )
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# define C_FIXDIV(c,div) \
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do { DIVSCALAR( (c).r , div); \
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DIVSCALAR( (c).i , div); }while (0)
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# define C_MULBYSCALAR( c, s ) \
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do{ (c).r = sround( smul( (c).r , s ) ) ;\
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(c).i = sround( smul( (c).i , s ) ) ; }while(0)
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#else /* not FIXED_POINT*/
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# define S_MUL(a,b) ( (a)*(b) )
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#define C_MUL(m,a,b) \
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do{ (m).r = (a).r*(b).r - (a).i*(b).i;\
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(m).i = (a).r*(b).i + (a).i*(b).r; }while(0)
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# define C_FIXDIV(c,div) /* NOOP */
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# define C_MULBYSCALAR( c, s ) \
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do{ (c).r *= (s);\
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(c).i *= (s); }while(0)
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#endif
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#ifndef CHECK_OVERFLOW_OP
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# define CHECK_OVERFLOW_OP(a,op,b) /* noop */
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#endif
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#define C_ADD( res, a,b)\
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do { \
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CHECK_OVERFLOW_OP((a).r,+,(b).r)\
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CHECK_OVERFLOW_OP((a).i,+,(b).i)\
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(res).r=(a).r+(b).r; (res).i=(a).i+(b).i; \
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}while(0)
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#define C_SUB( res, a,b)\
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do { \
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CHECK_OVERFLOW_OP((a).r,-,(b).r)\
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CHECK_OVERFLOW_OP((a).i,-,(b).i)\
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(res).r=(a).r-(b).r; (res).i=(a).i-(b).i; \
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}while(0)
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#define C_ADDTO( res , a)\
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do { \
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CHECK_OVERFLOW_OP((res).r,+,(a).r)\
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CHECK_OVERFLOW_OP((res).i,+,(a).i)\
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(res).r += (a).r; (res).i += (a).i;\
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}while(0)
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#define C_SUBFROM( res , a)\
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do {\
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CHECK_OVERFLOW_OP((res).r,-,(a).r)\
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CHECK_OVERFLOW_OP((res).i,-,(a).i)\
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(res).r -= (a).r; (res).i -= (a).i; \
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}while(0)
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#ifdef FIXED_POINT
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# define KISS_FFT_COS(phase) floor(.5+SAMP_MAX * cos (phase))
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# define KISS_FFT_SIN(phase) floor(.5+SAMP_MAX * sin (phase))
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# define HALF_OF(x) ((x)>>1)
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#elif defined(USE_SIMD)
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# define KISS_FFT_COS(phase) _mm_set1_ps( cos(phase) )
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# define KISS_FFT_SIN(phase) _mm_set1_ps( sin(phase) )
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# define HALF_OF(x) ((x)*_mm_set1_ps(.5))
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#else
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# define KISS_FFT_COS(phase) (kiss_fft_scalar) cos(phase)
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# define KISS_FFT_SIN(phase) (kiss_fft_scalar) sin(phase)
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# define HALF_OF(x) ((x)*.5)
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#endif
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#define kf_cexp(x,phase) \
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do{ \
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(x)->r = KISS_FFT_COS(phase);\
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(x)->i = KISS_FFT_SIN(phase);\
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}while(0)
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/* a debugging function */
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#define pcpx(c)\
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fprintf(stderr,"%g + %gi\n",(double)((c)->r),(double)((c)->i) )
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#ifdef KISS_FFT_USE_ALLOCA
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// define this to allow use of alloca instead of malloc for temporary buffers
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// Temporary buffers are used in two case:
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// 1. FFT sizes that have "bad" factors. i.e. not 2,3 and 5
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// 2. "in-place" FFTs. Notice the quotes, since kissfft does not really do an in-place transform.
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#include <alloca.h>
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#define KISS_FFT_TMP_ALLOC(nbytes) alloca(nbytes)
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#define KISS_FFT_TMP_FREE(ptr)
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#else
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#define KISS_FFT_TMP_ALLOC(nbytes) KISS_FFT_MALLOC(nbytes)
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#define KISS_FFT_TMP_FREE(ptr) KISS_FFT_FREE(ptr)
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#endif

‎include/kiss_fft.h‎

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/*
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* Copyright (c) 2003-2010, Mark Borgerding. All rights reserved.
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* This file is part of KISS FFT - https://github.com/mborgerding/kissfft
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*
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* SPDX-License-Identifier: BSD-3-Clause
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* See COPYING file for more information.
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*/
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#ifndef KISS_FFT_H
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#define KISS_FFT_H
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include <string.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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ATTENTION!
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If you would like a :
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-- a utility that will handle the caching of fft objects
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-- real-only (no imaginary time component ) FFT
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-- a multi-dimensional FFT
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-- a command-line utility to perform ffts
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-- a command-line utility to perform fast-convolution filtering
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Then see kfc.h kiss_fftr.h kiss_fftnd.h fftutil.c kiss_fastfir.c
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in the tools/ directory.
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*/
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#ifdef USE_SIMD
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# include <xmmintrin.h>
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# define kiss_fft_scalar __m128
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#define KISS_FFT_MALLOC(nbytes) _mm_malloc(nbytes,16)
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#define KISS_FFT_FREE _mm_free
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#else
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#define KISS_FFT_MALLOC malloc
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#define KISS_FFT_FREE free
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#endif
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#ifdef FIXED_POINT
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#include <sys/types.h>
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# if (FIXED_POINT == 32)
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# define kiss_fft_scalar int32_t
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# else
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# define kiss_fft_scalar int16_t
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# endif
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#else
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# ifndef kiss_fft_scalar
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/* default is float */
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# define kiss_fft_scalar float
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# endif
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#endif
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typedef struct {
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kiss_fft_scalar r;
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kiss_fft_scalar i;
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}kiss_fft_cpx;
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typedef struct kiss_fft_state* kiss_fft_cfg;
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/*
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* kiss_fft_alloc
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*
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* Initialize a FFT (or IFFT) algorithm's cfg/state buffer.
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*
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* typical usage: kiss_fft_cfg mycfg=kiss_fft_alloc(1024,0,NULL,NULL);
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*
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* The return value from fft_alloc is a cfg buffer used internally
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* by the fft routine or NULL.
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*
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* If lenmem is NULL, then kiss_fft_alloc will allocate a cfg buffer using malloc.
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* The returned value should be free()d when done to avoid memory leaks.
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*
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* The state can be placed in a user supplied buffer 'mem':
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* If lenmem is not NULL and mem is not NULL and *lenmem is large enough,
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* then the function places the cfg in mem and the size used in *lenmem
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* and returns mem.
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*
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* If lenmem is not NULL and ( mem is NULL or *lenmem is not large enough),
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* then the function returns NULL and places the minimum cfg
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* buffer size in *lenmem.
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* */
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kiss_fft_cfg kiss_fft_alloc(int nfft,int inverse_fft,void * mem,size_t * lenmem);
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/*
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* kiss_fft(cfg,in_out_buf)
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*
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* Perform an FFT on a complex input buffer.
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* for a forward FFT,
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* fin should be f[0] , f[1] , ... ,f[nfft-1]
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* fout will be F[0] , F[1] , ... ,F[nfft-1]
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* Note that each element is complex and can be accessed like
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f[k].r and f[k].i
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* */
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void kiss_fft(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
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/*
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A more generic version of the above function. It reads its input from every Nth sample.
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* */
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void kiss_fft_stride(kiss_fft_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout,int fin_stride);
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/* If kiss_fft_alloc allocated a buffer, it is one contiguous
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buffer and can be simply free()d when no longer needed*/
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#define kiss_fft_free KISS_FFT_FREE
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/*
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Cleans up some memory that gets managed internally. Not necessary to call, but it might clean up
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your compiler output to call this before you exit.
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*/
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void kiss_fft_cleanup(void);
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/*
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* Returns the smallest integer k, such that k>=n and k has only "fast" factors (2,3,5)
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*/
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int kiss_fft_next_fast_size(int n);
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/* for real ffts, we need an even size */
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#define kiss_fftr_next_fast_size_real(n) \
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(kiss_fft_next_fast_size( ((n)+1)>>1)<<1)
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#ifdef __cplusplus
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}
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#endif
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#endif

‎include/kiss_fftnd.h‎

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/*
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* Copyright (c) 2003-2004, Mark Borgerding. All rights reserved.
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* This file is part of KISS FFT - https://github.com/mborgerding/kissfft
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*
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* SPDX-License-Identifier: BSD-3-Clause
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* See COPYING file for more information.
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*/
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#ifndef KISS_FFTND_H
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#define KISS_FFTND_H
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#include "kiss_fft.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct kiss_fftnd_state * kiss_fftnd_cfg;
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kiss_fftnd_cfg kiss_fftnd_alloc(const int *dims,int ndims,int inverse_fft,void*mem,size_t*lenmem);
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void kiss_fftnd(kiss_fftnd_cfg cfg,const kiss_fft_cpx *fin,kiss_fft_cpx *fout);
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#ifdef __cplusplus
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}
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#endif
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#endif

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