Move auto random seeding to hardware specific implementation files

(This is expected to increase flash size, marginally, but the effect will mostly go
away once implementation and usage are once again in the same compilation unit.)

Author: tfry-git

MozziGuts_impl_AVR.hpp

@@ -377,3 +377,49 @@ void stopMozzi() {
 // 	Timer1.isrCallback();
 // }
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+#if defined (__AVR_ATmega644P__)
+
+// a less fancy version for gizduino (__AVR_ATmega644P__) which doesn't know INTERNAL
+static long longRandom()
+{
+	return ((long)analogRead(0)+63)*(analogRead(1)+97); // added offsets in case analogRead is 0
+}
+
+#else
+
+/*
+longRandom(), used as a seed generator, comes from:
+http://arduino.cc/forum/index.php/topic,38091.0.html
+//  AUTHOR: Rob Tillaart
+// PURPOSE: Simple Random functions based upon unreliable internal temp sensor
+// VERSION: 0.1
+//       DATE: 2011-05-01
+//
+// Released to the public domain, use at own risk
+//
+*/
+static long longRandom()
+{
+	//analogReference(INTERNAL);
+	unsigned long rv = 0;
+	for (uint8_t i=0; i< 32; i++) rv |= ((analogRead(8)+1171) & 1L) << i; // added 1171 in case analogRead is 0
+	return rv;
+}
+#endif
+
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+  ADCSRA &= ~ (1 << ADIE); // adc Disable Interrupt, re-enable at end
+  // this attempt at remembering analog_reference stops it working
+  // maybe needs a delay after changing analog reference in longRandom (Arduino reference suggests this)
+  // because the analog reads return 0
+  //uint8_t analog_reference_orig = ADMUX&192; // analog_reference is high 2 bits of ADMUX, store this because longRandom sets it to internal
+  *x = longRandom();
+  *y = longRandom();
+  *z = longRandom();
+  //analogReference(analog_reference_orig); // change back to original
+  ADCSRA |= (1 << ADIE); // adc re-Enable Interrupt
+}
+
+//// END Random seeding ////////

MozziGuts_impl_ESP32.hpp

@@ -161,4 +161,12 @@ void stopMozzi() {
 }
 //// END AUDIO OUTPUT code ///////
 
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+  *x = esp_random();
+  *y = esp_random();
+  *z = esp_random();
+}
+//// END Random seeding ////////
+
 #undef ESP_SAMPLE_SIZE    // only used inside this file

MozziGuts_impl_ESP8266.hpp

@@ -136,3 +136,13 @@ void stopMozzi() {
 #endif
 
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+  *x = RANDOM_REG32;
+  // TODO: The XORs may not be needed, but for lack of documentation (that I could find), let's assume RANDOM_REG32
+  //       itself might not get updated on every read. NOTE: x, y, and z are initialized to non-zero, before this.
+  *y = *y ^ RANDOM_REG32;
+  *z = *z ^ RANDOM_REG32;
+}
+//// END Random seeding ////////

MozziGuts_impl_MBED.hpp

@@ -221,5 +221,11 @@ void stopMozzi() {
 #endif
 ////// END audio output code //////
 
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////
+
 #undef CHUNKSIZE
 #undef US_PER_AUDIO_TICK

MozziGuts_impl_RENESAS.hpp

@@ -168,3 +168,9 @@ void stopMozzi() {
 #endif
 }
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////

MozziGuts_impl_RP2040.hpp

@@ -266,5 +266,11 @@ void stopMozzi() {
 }
 ////// END audio output code //////
 
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////
+
 #undef MOZZI_RP2040_BUFFERS
 #undef MOZZI_RP2040_BUFFER_SIZE

MozziGuts_impl_SAMD.hpp

@@ -138,3 +138,9 @@ void stopMozzi() {
   interrupts();
 }
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////

MozziGuts_impl_STM32.hpp

@@ -138,3 +138,24 @@ void stopMozzi() {
 }
 
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+  // Unfortunately the internal temp sensor on STM32s does _not_ appear to create a lot of noise.
+  // Ironically, the calls to calibrate help induce some random noise. You're still fairly likely to produce two equal
+  // random seeds in two subsequent runs, however.
+  adc.enableInternalReading();
+  union {
+    float cf;
+    uint32_t ci;
+  } conv;
+  conv.cf = adc.readTemp();
+  *x=*x^conv.ci;
+  adc.calibrate();
+  conv.cf = adc.readTemp();
+  *y=*y^conv.ci;
+  adc.calibrate();
+  conv.cf = adc.readTemp();
+  *z=*z^conv.ci;
+}
+//// END Random seeding ////////

MozziGuts_impl_STM32duino.hpp

@@ -171,3 +171,9 @@ void stopMozzi() {
 }
 
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////

MozziGuts_impl_TEENSY.hpp

@@ -112,3 +112,9 @@ void stopMozzi() {
   interrupts();
 }
 //// END AUDIO OUTPUT code ///////
+
+//// BEGIN Random seeding ////////
+void autoRandomSeeds(uint32_t *x, uint32_t *y, uint32_t *z) {
+#warning Automatic random seedings is not implemented on this platform
+}
+//// END Random seeding ////////