Add phaser.

audio/dsp_filter.c

@@ -224,11 +224,13 @@ static bool create_filter_graph(rarch_dsp_filter_t *dsp, float sample_rate)
 extern const struct dspfilter_implementation *panning_dspfilter_get_implementation(dspfilter_simd_mask_t mask);
 extern const struct dspfilter_implementation *iir_dspfilter_get_implementation(dspfilter_simd_mask_t mask);
 extern const struct dspfilter_implementation *echo_dspfilter_get_implementation(dspfilter_simd_mask_t mask);
+extern const struct dspfilter_implementation *phaser_dspfilter_get_implementation(dspfilter_simd_mask_t mask);
 
 static const dspfilter_get_implementation_t dsp_plugs_builtin[] = {
    panning_dspfilter_get_implementation,
    iir_dspfilter_get_implementation,
    echo_dspfilter_get_implementation,
+   phaser_dspfilter_get_implementation,
 };
 
 static bool append_plugs(rarch_dsp_filter_t *dsp)

audio/filters/Phaser.dsp

@@ -0,0 +1,11 @@
+filters = 1
+filter0 = phaser
+
+# Defaults.
+# lfo_freq = 0.4
+# lfo_start_phase = 0.0
+# feedback = 0.0
+# depth = 0.4
+# dry_wet = 0.5
+# stages = 2
+

audio/filters/phaser.c

@@ -0,0 +1,143 @@
+/*  RetroArch - A frontend for libretro.
+ *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
+ *  Copyright (C) 2014 - Brad Miller
+ *
+ *  RetroArch is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ *  PURPOSE.  See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with RetroArch.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "dspfilter.h"
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define phaserlfoshape 4.0
+#define lfoskipsamples 20
+
+struct phaser_data
+{
+   float freq;
+   float startphase;
+   float fb;
+   float depth;
+   float drywet;
+   float old[2][24];
+   float gain;
+   float fbout[2];
+   float lfoskip;
+   float phase;
+
+   int stages;
+   unsigned long skipcount;
+};
+
+static void phaser_free(void *data)
+{
+   free(data);
+}
+
+static void phaser_process(void *data, struct dspfilter_output *output,
+      const struct dspfilter_input *input)
+{
+   unsigned i, c;
+   int s;
+   float m[2], tmp[2];
+   struct phaser_data *ph = (struct phaser_data*)data;
+
+   output->samples = input->samples;
+   output->frames  = input->frames;
+   float *out = output->samples;
+
+   for (i = 0; i < input->frames; i++, out += 2)
+   {
+      float in[2] = { out[0], out[1] };
+
+      for (c = 0; c < 2; c++)
+         m[c] = in[c] + ph->fbout[c] * ph->fb * 0.01f;
+
+      if ((ph->skipcount++ % lfoskipsamples) == 0)
+      {
+         ph->gain = 0.5 * (1.0 + cos(ph->skipcount * ph->lfoskip + ph->phase));
+         ph->gain = (exp(ph->gain * phaserlfoshape) - 1.0) / (exp(phaserlfoshape) - 1);
+         ph->gain = 1.0 - ph->gain * ph->depth;
+      }
+
+      for (s = 0; s < ph->stages; s++)
+      {
+         for (c = 0; c < 2; c++)
+         {
+            tmp[c] = ph->old[c][s];
+            ph->old[c][s] = ph->gain * tmp[c] + m[c];
+            m[c] = tmp[c] - ph->gain * ph->old[c][s];
+         }
+      }
+
+      for (c = 0; c < 2; c++)
+      {
+         ph->fbout[c] = m[c];
+         out[c] = m[c] * ph->drywet + in[c] * (1.0f - ph->drywet);
+      }
+   }
+}
+
+static void *phaser_init(const struct dspfilter_info *info,
+      const struct dspfilter_config *config, void *userdata)
+{
+   struct phaser_data *ph = (struct phaser_data*)calloc(1, sizeof(*ph));
+   if (!ph)
+      return NULL;
+
+   float lfo_freq, lfo_start_phase;
+
+   config->get_float(userdata, "lfo_freq", &lfo_freq, 0.4f);
+   config->get_float(userdata, "lfo_start_phase", &lfo_start_phase, 0.0f);
+   config->get_float(userdata, "feedback", &ph->fb, 0.0f);
+   config->get_float(userdata, "depth", &ph->depth, 0.4f);
+   config->get_float(userdata, "dry_wet", &ph->drywet, 0.5f);
+   config->get_int(userdata, "stages", &ph->stages, 2);
+
+   if (ph->stages < 1)
+      ph->stages = 1;
+   else if (ph->stages > 24)
+      ph->stages = 24;
+
+   ph->lfoskip = lfo_freq * 2.0 * M_PI / info->input_rate;
+   ph->phase   = lfo_start_phase * M_PI / 180.0;
+
+   return ph;
+
+error:
+   free(ph);
+   return NULL;
+}
+
+static const struct dspfilter_implementation phaser_plug = {
+   phaser_init,
+   phaser_process,
+   phaser_free,
+
+   DSPFILTER_API_VERSION,
+   "Phaser",
+   "phaser",
+};
+
+#ifdef HAVE_FILTERS_BUILTIN
+#define dspfilter_get_implementation phaser_dspfilter_get_implementation
+#endif
+
+const struct dspfilter_implementation *dspfilter_get_implementation(dspfilter_simd_mask_t mask)
+{
+   (void)mask;
+   return &phaser_plug;
+}
+
+#undef dspfilter_get_implementation
+