Add wahwah DSP.

audio/dsp_filter.c

@@ -225,12 +225,14 @@ extern const struct dspfilter_implementation *panning_dspfilter_get_implementati
 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);
+extern const struct dspfilter_implementation *wahwah_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,
+   wahwah_dspfilter_get_implementation,
 };
 
 static bool append_plugs(rarch_dsp_filter_t *dsp)

audio/filters/WahWah.dsp

@@ -0,0 +1,10 @@
+filters = 1
+filter0 = wahwah
+
+# Defaults.
+# lfo_freq = 1.5
+# lfo_start_phase = 0.0
+# freq_offset = 0.3
+# depth = 0.7
+# resonance = 2.5
+

audio/filters/phaser.c

@@ -22,6 +22,10 @@
 #define phaserlfoshape 4.0
 #define lfoskipsamples 20
 
+#ifndef M_PI
+#define M_PI		3.1415926535897932384626433832795
+#endif
+
 struct phaser_data
 {
    float freq;
@@ -113,10 +117,6 @@ static void *phaser_init(const struct dspfilter_info *info,
    ph->phase   = lfo_start_phase * M_PI / 180.0;
 
    return ph;
-
-error:
-   free(ph);
-   return NULL;
 }
 
 static const struct dspfilter_implementation phaser_plug = {

audio/filters/wahwah.c

@@ -0,0 +1,139 @@
+/*  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 lfoskipsamples 30
+
+#ifndef M_PI
+#define M_PI		3.1415926535897932384626433832795
+#endif
+
+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)
+{
+   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;
+
+   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] };
+
+      if ((wah->skipcount++ % lfoskipsamples) == 0)
+      {
+         float frequency = (1.0 + cos(wah->skipcount * wah->lfoskip + wah->phase)) / 2.0;
+         frequency = frequency * wah->depth * (1.0 - wah->freqofs) + wah->freqofs;
+         frequency = exp((frequency - 1.0) * 6.0);
+
+         float omega = M_PI * frequency;
+         float sn = sin(omega);
+         float cs = cos(omega);
+         float alpha = sn / (2.0 * wah->res);
+
+         wah->b0 = (1.0 - cs) / 2.0;
+         wah->b1 = 1.0 - cs;
+         wah->b2 = (1.0 - cs) / 2.0;
+         wah->a0 = 1.0 + alpha;
+         wah->a1 = -2.0 * cs;
+         wah->a2 = 1.0 - alpha;
+      }
+
+      float 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;
+      float 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 * 2.0 * M_PI / info->input_rate;
+   wah->phase = wah->startphase * M_PI / 180.0;
+
+   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
+