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https://github.com/libretro/RetroArch
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Add new FFT implementation.
To be used for EQ implementation.
This commit is contained in:
Themaister
parent
a56d57c615
commit
8f913e8e9b
226
audio/fft/fft.c
Normal file
226
audio/fft/fft.c
Normal file
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/* RetroArch - A frontend for libretro.
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* Copyright (C) 2010-2014 - Hans-Kristian Arntzen
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*
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* RetroArch is free software: you can redistribute it and/or modify it under the terms
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* of the GNU General Public License as published by the Free Software Found-
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* ation, either version 3 of the License, or (at your option) any later version.
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*
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* RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the 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 along with RetroArch.
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "fft.h"
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#include <math.h>
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#include <stdlib.h>
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#ifndef M_PI
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#define M_PI 3.14159265
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#endif
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struct rarch_fft
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{
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rarch_fft_complex_t *interleave_buffer;
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rarch_fft_complex_t *phase_lut;
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unsigned *bitinverse_buffer;
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unsigned size;
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};
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static unsigned bitswap(unsigned x, unsigned size_log2)
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{
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unsigned i;
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unsigned ret = 0;
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for (i = 0; i < size_log2; i++)
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ret |= ((x >> i) & 1) << (size_log2 - i - 1);
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return ret;
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}
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static void build_bitinverse(unsigned *bitinverse, unsigned size_log2)
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{
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unsigned i;
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unsigned size = 1 << size_log2;
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for (i = 0; i < size; i++)
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bitinverse[i] = bitswap(i, size_log2);
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}
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static rarch_fft_complex_t exp_imag(double phase)
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{
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rarch_fft_complex_t out = { cos(phase), sin(phase) };
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return out;
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}
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static void build_phase_lut(rarch_fft_complex_t *out, int size)
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{
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int i;
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out += size;
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for (i = -size; i <= size; i++)
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out[i] = exp_imag((M_PI * i) / size);
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}
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static void interleave_complex(const unsigned *bitinverse,
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rarch_fft_complex_t *out, const rarch_fft_complex_t *in,
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unsigned samples)
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{
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unsigned i;
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for (i = 0; i < samples; i++)
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out[bitinverse[i]] = in[i];
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}
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static void interleave_float(const unsigned *bitinverse,
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rarch_fft_complex_t *out, const float *in,
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unsigned samples)
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{
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unsigned i;
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for (i = 0; i < samples; i++)
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{
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unsigned inv_i = bitinverse[i];
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out[inv_i].real = in[i];
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out[inv_i].imag = 0.0f;
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}
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}
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static void resolve_float(float *out, const rarch_fft_complex_t *in, unsigned samples, float gain)
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{
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unsigned i;
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for (i = 0; i < samples; i++)
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out[i] = gain * in[i].real;
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}
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rarch_fft_t *rarch_fft_new(unsigned block_size_log2)
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{
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rarch_fft_t *fft = (rarch_fft_t*)calloc(1, sizeof(*fft));
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if (!fft)
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return NULL;
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unsigned size = 1 << block_size_log2;
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fft->interleave_buffer = (rarch_fft_complex_t*)calloc(size, sizeof(*fft->interleave_buffer));
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fft->bitinverse_buffer = (unsigned*)calloc(size, sizeof(*fft->bitinverse_buffer));
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fft->phase_lut = (rarch_fft_complex_t*)calloc(2 * size + 1, sizeof(*fft->phase_lut));
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if (!fft->interleave_buffer || !fft->bitinverse_buffer || !fft->phase_lut)
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goto error;
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fft->size = size;
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build_bitinverse(fft->bitinverse_buffer, block_size_log2);
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build_phase_lut(fft->phase_lut, size);
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return fft;
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error:
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rarch_fft_free(fft);
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return NULL;
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}
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void rarch_fft_free(rarch_fft_t *fft)
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{
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if (!fft)
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return;
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free(fft->interleave_buffer);
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free(fft->bitinverse_buffer);
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free(fft->phase_lut);
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free(fft);
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}
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static inline rarch_fft_complex_t complex_mul(rarch_fft_complex_t a, rarch_fft_complex_t b)
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{
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rarch_fft_complex_t out = {
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a.real * b.real - a.imag * b.imag,
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a.imag * b.real + a.real * b.imag,
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};
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return out;
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}
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static inline rarch_fft_complex_t complex_add(rarch_fft_complex_t a, rarch_fft_complex_t b)
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{
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rarch_fft_complex_t out = {
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a.real + b.real,
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a.imag + b.imag,
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};
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return out;
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}
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static inline rarch_fft_complex_t complex_sub(rarch_fft_complex_t a, rarch_fft_complex_t b)
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{
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rarch_fft_complex_t out = {
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a.real - b.real,
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a.imag - b.imag,
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};
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return out;
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}
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static void butterfly(rarch_fft_complex_t *a, rarch_fft_complex_t *b, rarch_fft_complex_t mod)
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{
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mod = complex_mul(mod, *b);
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*b = complex_sub(*a, mod);
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*a = complex_add(*a, mod);
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}
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static void butterflies(rarch_fft_complex_t *butterfly_buf,
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const rarch_fft_complex_t *phase_lut,
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int phase_dir, unsigned step_size, unsigned samples)
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{
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unsigned i, j;
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for (i = 0; i < samples; i += step_size << 1)
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{
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int phase_step = (int)samples * phase_dir / (int)step_size;
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for (j = i; j < i + step_size; j++)
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butterfly(&butterfly_buf[j], &butterfly_buf[j + step_size], phase_lut[phase_step * (int)(j - i)]);
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}
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}
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void rarch_fft_process_forward_complex(rarch_fft_t *fft,
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rarch_fft_complex_t *out, const rarch_fft_complex_t *in)
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{
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unsigned step_size;
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unsigned samples = fft->size;
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interleave_complex(fft->bitinverse_buffer, out, in, fft->size);
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for (step_size = 1; step_size < samples; step_size <<= 1)
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{
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butterflies(out,
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fft->phase_lut + samples,
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-1, step_size, samples);
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}
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}
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void rarch_fft_process_forward(rarch_fft_t *fft,
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rarch_fft_complex_t *out, const float *in)
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{
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unsigned step_size;
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unsigned samples = fft->size;
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interleave_float(fft->bitinverse_buffer, out, in, fft->size);
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for (step_size = 1; step_size < fft->size; step_size <<= 1)
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{
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butterflies(out,
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fft->phase_lut + samples,
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-1, step_size, samples);
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}
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}
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void rarch_fft_process_inverse(rarch_fft_t *fft,
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float *out, const rarch_fft_complex_t *in)
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{
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unsigned step_size;
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unsigned samples = fft->size;
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interleave_complex(fft->bitinverse_buffer, fft->interleave_buffer, in, fft->size);
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for (step_size = 1; step_size < samples; step_size <<= 1)
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{
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butterflies(fft->interleave_buffer,
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fft->phase_lut + samples,
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1, step_size, samples);
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}
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resolve_float(out, fft->interleave_buffer, fft->size, 1.0f / fft->size);
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}
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43
audio/fft/fft.h
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43
audio/fft/fft.h
Normal file
@ -0,0 +1,43 @@
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/* RetroArch - A frontend for libretro.
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* Copyright (C) 2010-2014 - Hans-Kristian Arntzen
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*
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* RetroArch is free software: you can redistribute it and/or modify it under the terms
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* of the GNU General Public License as published by the Free Software Found-
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* ation, either version 3 of the License, or (at your option) any later version.
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*
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* RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
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* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the 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 along with RetroArch.
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef RARCH_FFT_H__
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#define RARCH_FFT_H__
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typedef struct rarch_fft rarch_fft_t;
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// C99 <complex.h> would be nice.
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typedef struct
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{
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float real;
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float imag;
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} rarch_fft_complex_t;
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rarch_fft_t *rarch_fft_new(unsigned block_size_log2);
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void rarch_fft_free(rarch_fft_t *fft);
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void rarch_fft_process_forward_complex(rarch_fft_t *fft,
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rarch_fft_complex_t *out, const rarch_fft_complex_t *in);
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void rarch_fft_process_forward(rarch_fft_t *fft,
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rarch_fft_complex_t *out, const float *in);
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void rarch_fft_process_inverse(rarch_fft_t *fft,
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float *out, const rarch_fft_complex_t *in);
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#endif
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