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/* Copyright (C) 2010-2020 The RetroArch team
*
* ---------------------------------------------------------------------------------------
* The following license statement only applies to this file (tremolo.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>
#include <string/stdstring.h>
#define sqr(a) ((a) * (a))
struct tremolo_core
{
float *wavetable;
float freq;
float depth;
int index;
int maxindex;
};
struct tremolo
{
struct tremolo_core left, right;
};
static void tremolo_free(void *data)
{
struct tremolo *tre = (struct tremolo*)data;
free(tre->left.wavetable);
free(tre->right.wavetable);
free(data);
}
static void tremolocore_init(struct tremolo_core *core,float depth,int samplerate,float freq)
{
double env;
unsigned i;
const double offset = 1. - depth / 2.;
core->index = 0;
core->maxindex = samplerate / freq;
core->wavetable = malloc(core->maxindex * sizeof(float));
memset(core->wavetable, 0, core->maxindex * sizeof(float));
for (i = 0; i < core->maxindex; i++)
{
env = freq * i / samplerate;
env = sin((M_PI*2) * fmod(env + 0.25, 1.0));
core->wavetable[i] = env * (1 - fabs(offset)) + offset;
}
}
float tremolocore_core(struct tremolo_core *core,float in)
{
core->index = core->index % core->maxindex;
return in * core->wavetable[core->index++];
}
static void tremolo_process(void *data, struct dspfilter_output *output,
const struct dspfilter_input *input)
{
unsigned i;
float *out;
struct tremolo *tre = (struct tremolo*)data;
output->samples = input->samples;
output->frames = input->frames;
out = output->samples;
for (i = 0; i < input->frames; i++, out += 2)
{
float in[2] = { out[0], out[1] };
out[0] = tremolocore_core(&tre->left, in[0]);
out[1] = tremolocore_core(&tre->right, in[1]);
}
}
static void *tremolo_init(const struct dspfilter_info *info,
const struct dspfilter_config *config, void *userdata)
{
float freq, depth;
struct tremolo *tre = (struct tremolo*)calloc(1, sizeof(*tre));
if (!tre)
return NULL;
config->get_float(userdata, "freq", &freq,4.0f);
config->get_float(userdata, "depth", &depth, 0.9f);
tremolocore_init(&tre->left,depth,info->input_rate,freq);
tremolocore_init(&tre->right,depth,info->input_rate,freq);
return tre;
}
static const struct dspfilter_implementation tremolo_plug = {
tremolo_init,
tremolo_process,
tremolo_free,
DSPFILTER_API_VERSION,
"Tremolo",
"tremolo",
};
#ifdef HAVE_FILTERS_BUILTIN
#define dspfilter_get_implementation tremolo_dspfilter_get_implementation
#endif
const struct dspfilter_implementation *dspfilter_get_implementation(dspfilter_simd_mask_t mask)
{
return &tremolo_plug;
}
#undef dspfilter_get_implementation
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