Rand: Replacing rand() for portable tests

In order to keep tests simple with respect to signal processing code, a portable
Pseudo Random Number Generator was built.
This will ensure that the sequence of random numbers from a given seed are
identical from platform to platform.
As this is not a cryptographic application, this behavior should not be an
issue.
Basic statistics of random source verified.

For source of magic numbers, see glibc.

src/DSP/Unison.h

@@ -22,7 +22,7 @@
 #ifndef UNISON_H
 #define UNISON_H
 #include <stdlib.h>
-#include "../globals.h"
+#include "../Misc/Util.h"
 
 #define UNISON_FREQ_SPAN 2.0f
 //how much the unison frequencies varies (always >= 1.0f)

src/Effects/EffectLFO.cpp

@@ -20,11 +20,11 @@
 
 */
 
-#include <cstdlib>
-#include <cmath>
-
 #include "EffectLFO.h"
+#include "../Misc/Util.h"
 
+#include <cstdlib>
+#include <cmath>
 
 EffectLFO::EffectLFO()
 {

src/Misc/Util.cpp

@@ -35,9 +35,10 @@
 #include <sched.h>
 
 
-int SAMPLE_RATE = 44100;
+int SAMPLE_RATE       = 44100;
 int SOUND_BUFFER_SIZE = 256;
-int OSCIL_SIZE  = 1024;
+int OSCIL_SIZE        = 1024;
+prng_t prng_state     = 0x1234;
 
 Config    config;
 float *denormalkillbuf;

src/Misc/Util.h

@@ -25,6 +25,7 @@
 
 #include <string>
 #include <sstream>
+#include <stdint.h>
 #include "Config.h"
 #include "../globals.h"
 
@@ -86,6 +87,33 @@ T limit(T val, T min, T max)
     return (val < min ? min : (val > max ? max : val));
 }
 
+//Random number generator
+
+typedef uint32_t prng_t;
+extern prng_t prng_state;
+
+// Portable Pseudo-Random Number Generator
+inline prng_t prng_r(prng_t &p)
+{
+    return (p = p * 1103515245 + 12345);
+}
+
+inline prng_t prng(void)
+{
+    return prng_r(prng_state)&0x7fffffff;
+}
+
+inline void sprng(prng_t p)
+{
+    prng_state = p;
+}
+
+/*
+ * The random generator (0.0f..1.0f)
+ */
+# define INT32_MAX		(2147483647)
+#define RND (prng() / (INT32_MAX * 1.0f))
+
 
 #endif
 

src/Output/DSSIaudiooutput.cpp

@@ -27,10 +27,11 @@
 //this file contains code used from trivial_synth.c from
 //the DSSI (published by Steve Harris under public domain) as a template.
 
-#include <string.h>
 #include "DSSIaudiooutput.h"
 #include "../Misc/Config.h"
 #include "../Misc/Bank.h"
+#include "../Misc/Util.h"
+#include <string.h>
 #include <limits.h>
 
 using std::string;
@@ -603,7 +604,7 @@ DSSIaudiooutput::DSSIaudiooutput(unsigned long sampleRate)
 
     config.init();
 
-    srand(time(NULL));
+    sprng(time(NULL));
     denormalkillbuf=new float [SOUND_BUFFER_SIZE];
     for (int i=0;i<SOUND_BUFFER_SIZE;i++) denormalkillbuf[i]=(RND-0.5f)*1e-16;
 

src/Params/FilterParams.cpp

@@ -20,10 +20,11 @@
 
 */
 
+#include "FilterParams.h"
+#include "../Misc/Util.h"
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include "FilterParams.h"
 
 FilterParams::FilterParams(unsigned char Ptype_,
                            unsigned char Pfreq_,

src/Synth/ADnote.cpp

@@ -93,7 +93,7 @@ ADnote::ADnote(ADnoteParameters *pars,
         NoteGlobalPar.Punch.Enabled = 0;
 
     for(int nvoice = 0; nvoice < NUM_VOICES; ++nvoice) {
-        pars->VoicePar[nvoice].OscilSmp->newrandseed(rand());
+        pars->VoicePar[nvoice].OscilSmp->newrandseed(prng());
         NoteVoicePar[nvoice].OscilSmp = NULL;
         NoteVoicePar[nvoice].FMSmp    = NULL;
         NoteVoicePar[nvoice].VoiceOut = NULL;
@@ -275,7 +275,7 @@ ADnote::ADnote(ADnoteParameters *pars,
         if(pars->VoicePar[nvoice].Pextoscil != -1)
             vc = pars->VoicePar[nvoice].Pextoscil;
         if(!pars->GlobalPar.Hrandgrouping)
-            pars->VoicePar[vc].OscilSmp->newrandseed(rand());
+            pars->VoicePar[vc].OscilSmp->newrandseed(prng());
         int oscposhi_start =
             pars->VoicePar[vc].OscilSmp->get(NoteVoicePar[nvoice].OscilSmp,
                                              getvoicebasefreq(nvoice),
@@ -478,7 +478,7 @@ void ADnote::legatonote(float freq, float velocity, int portamento_,
         if(pars->VoicePar[nvoice].Pextoscil != -1)
             vc = pars->VoicePar[nvoice].Pextoscil;
         if(!pars->GlobalPar.Hrandgrouping)
-            pars->VoicePar[vc].OscilSmp->newrandseed(rand());
+            pars->VoicePar[vc].OscilSmp->newrandseed(prng());
 
         pars->VoicePar[vc].OscilSmp->get(NoteVoicePar[nvoice].OscilSmp,
                                          getvoicebasefreq(nvoice),
@@ -605,7 +605,7 @@ void ADnote::legatonote(float freq, float velocity, int portamento_,
         /* Voice Modulation Parameters Init */
         if((NoteVoicePar[nvoice].FMEnabled != NONE)
            && (NoteVoicePar[nvoice].FMVoice < 0)) {
-            partparams->VoicePar[nvoice].FMSmp->newrandseed(rand());
+            partparams->VoicePar[nvoice].FMSmp->newrandseed(prng());
 
             //Perform Anti-aliasing only on MORPH or RING MODULATION
 
@@ -614,7 +614,7 @@ void ADnote::legatonote(float freq, float velocity, int portamento_,
                 vc = partparams->VoicePar[nvoice].PextFMoscil;
 
             if(!partparams->GlobalPar.Hrandgrouping)
-                partparams->VoicePar[vc].FMSmp->newrandseed(rand());
+                partparams->VoicePar[vc].FMSmp->newrandseed(prng());
 
             for(int i = 0; i < OSCIL_SMP_EXTRA_SAMPLES; ++i)
                 NoteVoicePar[nvoice].FMSmp[OSCIL_SIZE + i] = 
@@ -777,7 +777,7 @@ void ADnote::initparameters()
 
         /* Voice Modulation Parameters Init */
         if((vce.FMEnabled != NONE) && (vce.FMVoice < 0)) {
-            param.FMSmp->newrandseed(rand());
+            param.FMSmp->newrandseed(prng());
             vce.FMSmp = new float[OSCIL_SIZE + OSCIL_SMP_EXTRA_SAMPLES];
 
             //Perform Anti-aliasing only on MORPH or RING MODULATION
@@ -793,7 +793,7 @@ void ADnote::initparameters()
                 tmp = getFMvoicebasefreq(nvoice);
 
             if(!partparams->GlobalPar.Hrandgrouping)
-                partparams->VoicePar[vc].FMSmp->newrandseed(rand());
+                partparams->VoicePar[vc].FMSmp->newrandseed(prng());
 
             for(int k = 0; k < unison_size[nvoice]; ++k)
                 oscposhiFM[nvoice][k] = (oscposhi[nvoice][k]

src/Synth/LFO.cpp

@@ -20,13 +20,13 @@
 
 */
 
+#include "LFO.h"
+#include "../Misc/Util.h"
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
 
-#include "LFO.h"
-
-
 LFO::LFO(LFOParams *lfopars, float basefreq)
 {
     if(lfopars->Pstretch == 0)

src/Synth/OscilGen.cpp

@@ -852,8 +852,8 @@ short int OscilGen::get(float *smps, float freqHz, int resonance)
 
     //Harmonic Amplitude Randomness
     if((freqHz > 0.1f) && (!ADvsPAD)) {
-        unsigned int realrnd = rand();
-        srand(randseed);
+        unsigned int realrnd = prng();
+        sprng(randseed);
         float power     = Pamprandpower / 127.0f;
         float normalize = 1.0f / (1.2f - power);
         switch(Pamprandtype) {
@@ -872,7 +872,7 @@ short int OscilGen::get(float *smps, float freqHz, int resonance)
                     * normalize;
             break;
         }
-        srand(realrnd + 1);
+        sprng(realrnd + 1);
     }
 
     if((freqHz > 0.1f) && (resonance != 0))

src/Tests/AdNoteTest.h

@@ -118,26 +118,26 @@ class AdNoteTest:public CxxTest::TestSuite
 #endif
             sampleCount += SOUND_BUFFER_SIZE;
 
-            TS_ASSERT_DELTA(outL[255], 0.3019f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], 0.254609f, 0.0001f);
 
             note->relasekey();
 
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], -0.1382f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.102197f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], -0.0334f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.111422f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], -0.1329f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.021375f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], 0.2690f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], 0.149882f, 0.0001f);
 
             while(!note->finished()) {
                 note->noteout(outL, outR);

src/Tests/CMakeLists.txt

@@ -21,3 +21,4 @@ target_link_libraries(EchoTest       ${test_lib})
 target_link_libraries(MicrotonalTest ${test_lib})
 target_link_libraries(OscilGenTest   ${test_lib})
 target_link_libraries(XMLwrapperTest ${test_lib})
+target_link_libraries(RandTest       ${test_lib})

src/Tests/OscilGenTest.h

@@ -74,10 +74,10 @@ class OscilGenTest:public CxxTest::TestSuite
         void testOutput(void)
         {
             oscil->get(outL, freq);
-            TS_ASSERT_DELTA(outL[23],  -0.014717f, 0.0001f);
-            TS_ASSERT_DELTA(outL[129], -0.567502f, 0.0001f);
-            TS_ASSERT_DELTA(outL[586], -0.030894f, 0.0001f);
-            TS_ASSERT_DELTA(outL[1023], -0.080001f, 0.0001f);
+            TS_ASSERT_DELTA(outL[23],  -0.044547f, 0.0001f);
+            TS_ASSERT_DELTA(outL[129], -0.018169f, 0.0001f);
+            TS_ASSERT_DELTA(outL[586], 0.045647f, 0.0001f);
+            TS_ASSERT_DELTA(outL[1023], -0.038334f, 0.0001f);
         }
 
         void testSpectrum(void)

src/Tests/RandTest.h

@@ -20,7 +20,7 @@
 
 */
 
-#include "../globals.h"
+#include "../Misc/Util.h"
 
 #include <cstdlib>
 #include <cstdio>
@@ -31,11 +31,11 @@ class RandTest:public CxxTest::TestSuite
     public:
         void testPRNG(void) {
             //verify RND returns expected pattern when unseeded
-            TS_ASSERT_DELTA(RND, 0.840188f, 0.00001f);
-            TS_ASSERT_DELTA(RND, 0.394383f, 0.00001f);
-            TS_ASSERT_DELTA(RND, 0.783099f, 0.00001f);
-            TS_ASSERT_DELTA(RND, 0.798440f, 0.00001f);
-            TS_ASSERT_DELTA(RND, 0.911647f, 0.00001f);
+            TS_ASSERT_DELTA(RND, 0.607781, 0.00001);
+            TS_ASSERT_DELTA(RND, 0.591761, 0.00001);
+            TS_ASSERT_DELTA(RND, 0.186133, 0.00001);
+            TS_ASSERT_DELTA(RND, 0.286319, 0.00001);
+            TS_ASSERT_DELTA(RND, 0.511766, 0.00001);
         }
 };
 

src/Tests/SubNoteTest.h

@@ -111,19 +111,19 @@ class SubNoteTest:public CxxTest::TestSuite
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], 0.0022f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], 0.0016f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], -0.0020f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.0000f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], 0.0010f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.0013f, 0.0001f);
 
             note->noteout(outL, outR);
             sampleCount += SOUND_BUFFER_SIZE;
-            TS_ASSERT_DELTA(outL[255], 0.0005f, 0.0001f);
+            TS_ASSERT_DELTA(outL[255], -0.0002f, 0.0001f);
 
             while(!note->finished()) {
                 note->noteout(outL, outR);

src/globals.h

@@ -24,6 +24,7 @@
 
 #ifndef GLOBALS_H
 #define GLOBALS_H
+#include <stdint.h>
 
 /**Sampling rate*/
 extern int SAMPLE_RATE;
@@ -171,11 +172,6 @@ extern int OSCIL_SIZE;
 #define dB2rap(dB) ((expf((dB) * LOG_10 / 20.0f)))
 #define rap2dB(rap) ((20 * logf(rap) / LOG_10))
 
-/*
- * The random generator (0.0f..1.0f)
- */
-#define RND (rand() / (RAND_MAX * 1.0f))
-
 #define ZERO(data, size) {char *data_ = (char *) data; for(int i = 0; \
                                                            i < size; \
                                                            i++) \

src/main.cpp

@@ -194,7 +194,7 @@ int main(int argc, char *argv[])
     OSCIL_SIZE  = config.cfg.OscilSize;
     swaplr      = config.cfg.SwapStereo;
 
-    srand(time(NULL));
+    sprng(time(NULL));
     //produce denormal buf
     denormalkillbuf = new float [SOUND_BUFFER_SIZE];
     for(int i = 0; i < SOUND_BUFFER_SIZE; ++i)