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/* Copyright (C) 2010-2020 The RetroArch team
*
* ---------------------------------------------------------------------------------------
* The following license statement only applies to this file (wahwah.c).
* ---------------------------------------------------------------------------------------
*
* Permission is hereby granted, free of charge,
* to any person obtaining a copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <retro_miscellaneous.h>
#include <libretro_dspfilter.h>
#define WAHWAH_LFO_SKIP_SAMPLES 30
struct wahwah_data
{
float phase;
float lfoskip;
float b0, b1, b2, a0, a1, a2;
float freq, startphase;
float depth, freqofs, res;
unsigned long skipcount;
struct
{
float xn1, xn2, yn1, yn2;
} l, r;
};
static void wahwah_free(void *data)
{
if (data)
free(data);
}
static void wahwah_process(void *data, struct dspfilter_output *output,
const struct dspfilter_input *input)
{
unsigned i;
struct wahwah_data *wah = (struct wahwah_data*)data;
float *out = output->samples;
output->samples = input->samples;
output->frames = input->frames;
for (i = 0; i < input->frames; i++, out += 2)
{
float out_l, out_r;
float in[2] = { out[0], out[1] };
if ((wah->skipcount++ % WAHWAH_LFO_SKIP_SAMPLES) == 0)
{
float omega, sn, cs, alpha;
float frequency = (1.0f + cos(wah->skipcount * wah->lfoskip + wah->phase)) / 2.0f;
frequency = frequency * wah->depth * (1.0f - wah->freqofs) + wah->freqofs;
frequency = exp((frequency - 1.0f) * 6.0f);
omega = M_PI * frequency;
sn = sin(omega);
cs = cos(omega);
alpha = sn / (2.0f * wah->res);
wah->b0 = (1.0f - cs) / 2.0f;
wah->b1 = 1.0f - cs;
wah->b2 = (1.0f - cs) / 2.0f;
wah->a0 = 1.0f + alpha;
wah->a1 = -2.0f * cs;
wah->a2 = 1.0f - alpha;
}
out_l = (wah->b0 * in[0] + wah->b1 * wah->l.xn1 + wah->b2 * wah->l.xn2 - wah->a1 * wah->l.yn1 - wah->a2 * wah->l.yn2) / wah->a0;
out_r = (wah->b0 * in[1] + wah->b1 * wah->r.xn1 + wah->b2 * wah->r.xn2 - wah->a1 * wah->r.yn1 - wah->a2 * wah->r.yn2) / wah->a0;
wah->l.xn2 = wah->l.xn1;
wah->l.xn1 = in[0];
wah->l.yn2 = wah->l.yn1;
wah->l.yn1 = out_l;
wah->r.xn2 = wah->r.xn1;
wah->r.xn1 = in[1];
wah->r.yn2 = wah->r.yn1;
wah->r.yn1 = out_r;
out[0] = out_l;
out[1] = out_r;
}
}
static void *wahwah_init(const struct dspfilter_info *info,
const struct dspfilter_config *config, void *userdata)
{
struct wahwah_data *wah = (struct wahwah_data*)calloc(1, sizeof(*wah));
if (!wah)
return NULL;
config->get_float(userdata, "lfo_freq", &wah->freq, 1.5f);
config->get_float(userdata, "lfo_start_phase", &wah->startphase, 0.0f);
config->get_float(userdata, "freq_offset", &wah->freqofs, 0.3f);
config->get_float(userdata, "depth", &wah->depth, 0.7f);
config->get_float(userdata, "resonance", &wah->res, 2.5f);
wah->lfoskip = wah->freq * 2.0f * M_PI / info->input_rate;
wah->phase = wah->startphase * M_PI / 180.0f;
return wah;
}
static const struct dspfilter_implementation wahwah_plug = {
wahwah_init,
wahwah_process,
wahwah_free,
DSPFILTER_API_VERSION,
"Wah-Wah",
"wahwah",
};
#ifdef HAVE_FILTERS_BUILTIN
#define dspfilter_get_implementation wahwah_dspfilter_get_implementation
#endif
const struct dspfilter_implementation *
dspfilter_get_implementation(dspfilter_simd_mask_t mask)
{
(void)mask;
return &wahwah_plug;
}
#undef dspfilter_get_implementation
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