white noise generator

Makefile

@@ -2,7 +2,7 @@ DISTNAME = crap
 VERSION = git
 
 EXE = design
-SHOBJ = crap_eq.so crap_eq_const.so
+SHOBJ = crap_eq.so crap_eq_const.so crap_noise.so
 MID =
 HEADERS = crap_util.h crap_util_def.h ladspa.h
 

crap_noise.c

@@ -0,0 +1,84 @@
+#include "ladspa.h"
+#include "crap_util.h"
+
+typedef unsigned long ulong;
+
+#define PLUG_INPUT  0
+#define PLUG_OUTPUT 1
+#define PCOUNT      2
+
+const LADSPA_PortDescriptor p_discs[PCOUNT] = {
+    LADSPA_PORT_INPUT | LADSPA_PORT_AUDIO,
+    LADSPA_PORT_OUTPUT | LADSPA_PORT_AUDIO
+};
+const LADSPA_PortRangeHint p_hints[PCOUNT] = {
+    {.HintDescriptor = 0},
+    {.HintDescriptor = 0}
+};
+const char *p_names[PCOUNT] = {"Input", "Output"};
+
+typedef struct {
+	LADSPA_Data *input;
+	LADSPA_Data *output;
+	LADSPA_Data fs;
+} plug_t;
+
+static void
+plug_cleanup(LADSPA_Handle instance) {
+	free(instance);
+}
+
+static void
+plug_connect(LADSPA_Handle instance, ulong port, LADSPA_Data *data) {
+	plug_t *plug = (plug_t *)instance;
+	if (port == PLUG_INPUT)
+		plug->input = data;
+	else if (port == PLUG_OUTPUT)
+		plug->output = data;
+}
+
+static LADSPA_Handle
+plug_instantiate(const LADSPA_Descriptor *descriptor, ulong s_rate) {
+	plug_t *plug = (plug_t *) calloc(1, sizeof(plug_t));
+	plug->fs = s_rate;
+	return (LADSPA_Handle) plug;
+}
+
+static void
+plug_run(LADSPA_Handle instance, ulong sample_count) {
+	plug_t *plug = (plug_t *) instance;
+	//const LADSPA_Data *input = plug->input;
+	LADSPA_Data *output = plug->output;
+
+	for (ulong pos = 0; pos < sample_count; pos++)
+		output[pos] = whitenoise();
+}
+
+static const LADSPA_Descriptor eqDescriptor = {
+	.UniqueID = 0xEC57A71C,
+	.Label = "crap_noise",
+	.Properties = 0,
+	.Name = "crap noise generator",
+	.Maker = "Connor Olding",
+	.Copyright = "MIT",
+	.PortCount = PCOUNT,
+	.PortDescriptors = p_discs,
+	.PortRangeHints = p_hints,
+	.PortNames = p_names,
+
+	.activate = NULL,
+	.cleanup = plug_cleanup,
+	.connect_port = plug_connect,
+	.deactivate = NULL,
+	.instantiate = plug_instantiate,
+	.run = plug_run,
+	.run_adding = NULL,
+	.set_run_adding_gain = NULL
+};
+
+const LADSPA_Descriptor *
+ladspa_descriptor(ulong index) {
+	if (index != 0)
+		return NULL;
+	return &eqDescriptor;
+}

crap_util.h

@@ -23,6 +23,9 @@ typedef struct {
 	double b0, b1, b2, a0, a1, a2;
 } biquad_interim;
 
+static float
+whitenoise();
+
 static void
 biquad_init(biquad *bq);
 

crap_util_def.h

@@ -2,6 +2,20 @@
 #include <math.h>
 #include <stdint.h>
 
+/* via http://www.rgba.org/articles/sfrand/sfrand.htm */
+static unsigned int mirand = 1;
+
+static float
+whitenoise() {
+    union either {
+        float f;
+        unsigned int i;
+    } white;
+    mirand *= 16807;
+    white.i = (mirand & 0x007FFFFF) | 0x40000000;
+    return white.f - 3;
+}
+
 /* used to resemble https://github.com/swh/ladspa/blob/master/util/biquad.h */
 
 static void