kopia lustrzana https://github.com/Dsplib/libdspl-2.0
236 wiersze
8.6 KiB
C
236 wiersze
8.6 KiB
C
/*
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* Copyright (c) 2015-2020 Sergey Bakhurin
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* Digital Signal Processing Library [http://dsplib.org]
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*
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* This file is part of DSPL.
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*
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* is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* DSPL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "dspl.h"
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#ifdef DOXYGEN_ENGLISH
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/*! ****************************************************************************
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\ingroup FILTER_CONV_GROUP
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\fn int conv_fft(double* a, int na, double* b, int nb,
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fft_t* pfft, int nfft, double* c)
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\brief Real vectors fast linear convolution by using fast Fourier
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transform algorithms
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Function convolves two real vectors \f$ c = a * b\f$ length `na` and `nb`
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in the frequency domain by using FFT algorithms. This approach provide
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high-performance convolution which increases with `na` and `nb` increasing.
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The output convolution is a vector `c` with length equal to `na + nb - 1`.
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\param[in] a
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Pointer to the first vector `a`. \n
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Vector size is `[na x 1]`. \n \n
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\param[in] na
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Size of the first vector `a`. \n \n
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\param[in] b
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Pointer to the second vector `b`. \n
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Vector size is `[nb x 1]`. \n \n
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\param[in] nb
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Size of the second vector `b`. \n \n
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\param[in] pfft
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Pointer to the structure `fft_t`. \n
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Function changes `fft_t` structure fields so `fft_t` must
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be clear before program returns. \n \n
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\param[in] nfft
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FFT size. \n
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This parameter set which FFT size will be used
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for overlapped frequency domain convolution. \n
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FFT size must be more of minimal `na` and `nb` value.
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For example if `na = 10`, `nb = 4` then `nfft` parameter must
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be more than 4. \n
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\param[out] c
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Pointer to the convolution output vector \f$ c = a * b\f$. \n
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Vector size is `[na + nb - 1 x 1]`. \n
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Memory must be allocated. \n \n
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\return `RES_OK` if convolution is calculated successfully. \n
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Else \ref ERROR_CODE_GROUP "code error". \n \n
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Example:
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\include conv_fft_test.c
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Program output:
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\verbatim
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conv_fft error: 0x00000000
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conv error: 0x00000000
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c[ 0] = -0.00 d[ 0] = 0.00
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c[ 1] = -0.00 d[ 1] = 0.00
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c[ 2] = 1.00 d[ 2] = 1.00
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c[ 3] = 4.00 d[ 3] = 4.00
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c[ 4] = 10.00 d[ 4] = 10.00
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c[ 5] = 20.00 d[ 5] = 20.00
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c[ 6] = 35.00 d[ 6] = 35.00
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c[ 7] = 56.00 d[ 7] = 56.00
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c[ 8] = 77.00 d[ 8] = 77.00
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c[ 9] = 98.00 d[ 9] = 98.00
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c[ 10] = 119.00 d[ 10] = 119.00
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c[ 11] = 140.00 d[ 11] = 140.00
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c[ 12] = 161.00 d[ 12] = 161.00
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c[ 13] = 182.00 d[ 13] = 182.00
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c[ 14] = 190.00 d[ 14] = 190.00
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c[ 15] = 184.00 d[ 15] = 184.00
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c[ 16] = 163.00 d[ 16] = 163.00
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c[ 17] = 126.00 d[ 17] = 126.00
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c[ 18] = 72.00 d[ 18] = 72.00
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\endverbatim
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\author Sergey Bakhurin www.dsplib.org
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***************************************************************************** */
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#endif
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#ifdef DOXYGEN_RUSSIAN
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/*! ****************************************************************************
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\ingroup FILTER_CONV_GROUP
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\fn int conv_fft(double* a, int na, double* b, int nb,
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fft_t* pfft, double* c)
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\brief Линейная свертка двух вещественных векторов с использованием алгоритмов
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быстрого преобразования Фурье
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Функция рассчитывает линейную свертку двух векторов \f$ c = a * b\f$ используя
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секционную обработку с перекрытием в частотной области. Это позволяет сократить
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вычислительные операции при расчете длинных сверток.
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\param[in] a
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Указатель на первый вектор \f$a\f$. \n
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Размер вектора `[na x 1]`. \n \n
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\param[in] na
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Размер первого вектора. \n \n
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\param[in] b
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Указатель на второй вектор \f$b\f$. \n
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Размер вектора `[nb x 1]`. \n \n
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\param[in] nb
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Размер второго вектора. \n \n
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\param[in] pfft
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Указатель на структуру `fft_t` алгоритма
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быстрого преобразования Фурье. \n
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Функция изменит состояние полей структуры `fft_t`,
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поэтому структура должна быть очищена перед выходом из
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программы для исключения утечек памяти. \n
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\param[in] nfft
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Размер алгоритма БПФ который будет использован для расчета
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секционной свертки с перекрытием. \n
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Данный параметр должен быть больше чем минимальное значение
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размеров сворачиваемых векторов. \n
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Например если `na=10`, а `nb=4`, то параметр `nfft` должен быть больше 4. \n
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Библиотека поддерживает алгоритмы БПФ составной длины
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\f$n = n_0 \times n_1 \times n_2 \times \ldots \times n_p \times m\f$,
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где \f$n_i = 2,3,5,7\f$, а \f$m \f$ --- произвольный простой множитель
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не превосходящий 46340 (см. описание функции \ref fft_create).
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Однако, максимальное быстродействие достигается при использовании длин равных
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степени двойки.
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\param[out] c
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Указатель на вектор свертки \f$ c = a * b\f$. \n
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Размер вектора `[na + nb - 1 x 1]`. \n
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Память должна быть выделена. \n \n
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\return
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`RES_OK` если свертка рассчитана успешно. \n
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В противном случае \ref ERROR_CODE_GROUP "код ошибки".
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\note
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Данная функция наиболее эффективна при вычислении длинных сверток.
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Пример использования функции:
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\include conv_fft_test.c
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Результат работы:
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\verbatim
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conv_fft error: 0x00000000
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conv error: 0x00000000
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c[ 0] = -0.00 d[ 0] = 0.00
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c[ 1] = -0.00 d[ 1] = 0.00
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c[ 2] = 1.00 d[ 2] = 1.00
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c[ 3] = 4.00 d[ 3] = 4.00
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c[ 4] = 10.00 d[ 4] = 10.00
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c[ 5] = 20.00 d[ 5] = 20.00
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c[ 6] = 35.00 d[ 6] = 35.00
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c[ 7] = 56.00 d[ 7] = 56.00
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c[ 8] = 77.00 d[ 8] = 77.00
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c[ 9] = 98.00 d[ 9] = 98.00
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c[ 10] = 119.00 d[ 10] = 119.00
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c[ 11] = 140.00 d[ 11] = 140.00
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c[ 12] = 161.00 d[ 12] = 161.00
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c[ 13] = 182.00 d[ 13] = 182.00
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c[ 14] = 190.00 d[ 14] = 190.00
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c[ 15] = 184.00 d[ 15] = 184.00
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c[ 16] = 163.00 d[ 16] = 163.00
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c[ 17] = 126.00 d[ 17] = 126.00
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c[ 18] = 72.00 d[ 18] = 72.00
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\endverbatim
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\author Бахурин Сергей. www.dsplib.org
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***************************************************************************** */
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#endif
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int DSPL_API conv_fft(double* a, int na, double* b, int nb,
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fft_t* pfft, int nfft, double* c)
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{
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complex_t *pa = NULL, *pb = NULL, *pc = NULL;
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int err;
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if(!a || !b || !c || !pfft)
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return ERROR_PTR;
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if(na<1 || nb < 1)
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return ERROR_SIZE;
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if(nfft<2)
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return ERROR_FFT_SIZE;
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pa = (complex_t*) malloc(na*sizeof(complex_t));
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pb = (complex_t*) malloc(nb*sizeof(complex_t));
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pc = (complex_t*) malloc((na+nb-1)*sizeof(complex_t));
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re2cmplx(a, na, pa);
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re2cmplx(b, nb, pb);
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err = conv_fft_cmplx(pa, na, pb, nb, pfft, nfft, pc);
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if(err != RES_OK)
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goto exit_label;
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err = cmplx2re(pc, na+nb-1, c, NULL);
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exit_label:
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if(pa) free(pa);
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if(pb) free(pb);
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if(pc) free(pc);
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return err;
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}
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