add UUID example

libraries/UUID/examples/UUID_random_seed/UUID_random_seed.ino

@@ -0,0 +1,107 @@
+//
+//    FILE: UUID_random_seed.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo
+
+
+#include "Arduino.h"
+#include "UUID.h"
+
+
+UUID uuid;
+
+uint32_t start, stop, randomtime;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  while (!Serial);
+
+  Serial.println();
+  Serial.println("UUID_test.ino");
+  Serial.print("UUID_LIB_VERSION: ");
+  Serial.println(UUID_LIB_VERSION);
+
+  uint32_t seedling = extractEntropy();
+  Serial.println(seedling, HEX);
+
+  start = micros();
+  uuid.seed(seedling);
+  stop = micros();
+
+  Serial.print("       seed: ");
+  Serial.println(stop - start);
+  delay(100);
+
+  start = micros();
+  uuid.generate();
+  stop = micros();
+
+  Serial.print("   generate: ");
+  Serial.println(stop - start);
+  delay(100);
+
+  start = micros();
+  uuid.toCharArray();
+  stop = micros();
+
+  Serial.print("toCharArray: ");
+  Serial.println(stop - start);
+  delay(100);
+
+  Serial.print("UUID: ");
+  Serial.println(uuid);
+}
+
+
+void loop()
+{
+  uuid.generate();
+  Serial.print("UUID: ");
+  Serial.println(uuid);
+  delay(1000);
+}
+
+
+uint32_t extractEntropy()
+{
+  // GET COMPILE TIME ENTROPY
+  uint32_t r = 0;
+  uint16_t len = strlen(__FILE__);
+  for (uint16_t i = 0; i < len; i++)
+  {
+    r ^= __FILE__[i];
+    r = r * (r << 3);
+  }
+  len = strlen(__DATE__);
+  for (uint16_t i = 0; i < len; i++)
+  {
+    r ^= __DATE__[i];
+    r = r * (r << 17);
+  }
+  len = strlen(__TIME__);
+  for (uint16_t i = 0; i < len; i++)
+  {
+    r ^= __TIME__[i];
+    r = r * (r << 7);
+  }
+
+  // GET RUNTIME ENTROPY
+  Serial.println("send 8 chars");
+  uint32_t mask = 0;
+  for (int i = 0; i < 8; i++)
+  {
+    while (Serial.available() == 0);
+    if (Serial.available())
+    {
+      mask <<= 7;
+      mask ^= micros();
+      Serial.read();
+    }
+  }
+  return r ^ mask;
+}
+
+
+// -- END OF FILE --