new STM32 programs

arduino/v5.3/prime_logging_STM32F103C8T6/prime_logging_STM32F103C8T6.ino

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+/* Prime numbers in Arduino C v5.4 2023/12/14 for STM32F103C8T6 */
+#include <time.h>
+#include <math.h>
+#include <EEPROM.h>
+
+double start;
+int column = 10;
+int found = 4;   // we already know 2, 3, 5, 7
+int divisors = found;
+uint32_t primes[3550] = {3, 5, 7}; // limit due to RAM on F103
+int led = PC13; // LED_BUILTIN
+
+int is_prime(uint32_t number) {
+  int prime = 1;
+  for (int divider = 3; divider < (int)(sqrt(number)) + 1; divider += 2)
+  {
+    if (number % divider == 0)
+    {
+      prime = 0;
+      break;
+    }
+  }
+  return prime;
+}
+
+int find_primes(uint32_t limit) {
+  for(uint32_t number=11; number < limit + 1; number += 2) { 
+    if( is_prime(number) == 1) {
+      primes[found - 1] = number;
+      found++;
+    }
+  }
+  primes[found - 1] = limit;
+  divisors = found - 1;
+  return 1;
+}
+
+int is_prime_fast(uint32_t number) {
+  uint32_t largest_divider = (int)(sqrt(number));
+  int flag_prime = 1;
+  for(int i=0; i < divisors; i++)
+  {
+    if(number % primes[i] == 0) 
+    {
+      flag_prime = 0;
+      break;
+    }
+    if(primes[i] > largest_divider)
+    {
+      break;
+    }
+  }
+  return flag_prime;
+}
+
+void elapsed_time(int seconds) {
+  int hours = (int)seconds/3600;
+  int minutes = (int)(seconds/60 - hours*60);
+  int sec = (int)(seconds - minutes*60 - hours*3600);
+  Serial.print(" ");
+  Serial.print(hours);
+  Serial.print("h ");
+  Serial.print(minutes);
+  Serial.print("min ");
+  Serial.print(sec);
+  Serial.print("s ");
+}
+
+void setup() {
+  Serial.begin(74880);
+  pinMode(led, OUTPUT);
+  digitalWrite(led,LOW);
+  for (int i = 0; i < 3; i++) {
+    Serial.print(".");
+    delay(1000);
+  }
+  const uint32_t scope[] = {100, 1000, 10000, 100000, 1000000, 10000000, 25000000, 100000000, 1000000000, 2147483647, 4294967295 };
+  const int reference[] = {25, 168, 1229, 9592, 78498, 664579, 1565927, 5761455, 50847534, 105097564, 200000000};
+
+  // previous run
+  Serial.print("\nGet previous results for this STM32F103C8T6:\n");
+  Serial.print("    last        seconds   \n");
+  for(int i = 0; i < 11; i++) {
+    int spaces = 12 - (int)log10(scope[i]);
+    for(int j = 0; j < spaces; j++) {
+      Serial.print(" ");
+    }
+    Serial.print(scope[i]);
+    Serial.print("    ");
+    float last_time;
+    EEPROM.get(i * 4 + 1, last_time);
+    Serial.print(last_time, 6);
+    Serial.print("\n");
+  }
+
+  // start calculating
+  for (int i = 0; i < 11; i++) 
+  {
+    int last = scope[i];
+    found = 4;   // we already know 2, 3, 5, 7
+    Serial.println("\n\nPrime v5.4 in Arduino C - 2023/12/16");
+    Serial.print("Calculating prime numbers until ");
+    Serial.println(last);
+    start = millis();      
+//    start = micros();        // use micros() for more precision in runtimes < 70 minutes
+    int largest_divider = (int)(sqrt(last)); 
+    if(largest_divider % 2 == 0)
+    {
+      largest_divider += 1;
+    }
+    find_primes(largest_divider);
+    Serial.print("Found ");
+    Serial.print(found);
+    Serial.print(" primes until ");
+    Serial.print(largest_divider);
+    Serial.print(" to use as divisors.\n");
+    int dot = millis();
+    int column = 0;
+    for(uint32_t number = largest_divider + 2; number < last; number += 2)
+    {
+      found += is_prime_fast(number);
+      if((millis() - dot) > 1000) {
+        Serial.print(".");
+        dot = millis();
+        column += 1;
+        if(column % 2 == 0) {
+          digitalWrite(led, HIGH);
+        }
+        else
+        {
+          digitalWrite(led, LOW);
+        }
+        if(column > 40) {
+          column = 0;
+          elapsed_time((millis()-start)/1000);
+          Serial.print(" - ");
+          Serial.print(number);
+          Serial.print(" ");
+          Serial.print((int)(number / (last / 100)));
+          Serial.print("% \n");
+        }
+      }
+    }
+    float duration = (millis() - start)/1000;
+//    float duration = (micros() - start)/1000000; // use micros() for more precision in runtimes < 70 minutes
+    if(duration > 2) {
+      Serial.print("\n");
+    }    
+    Serial.print("Found ");
+    Serial.print(found);
+    Serial.print(" prime numbers. It should be ");
+    Serial.print(reference[i]);
+    Serial.print(".\nThis took ");
+    Serial.print(duration, 6);
+    Serial.print(" seconds.");
+    elapsed_time(duration);
+    EEPROM.put(i * 4 + 1, duration);
+  }
+  Serial.print("\n");
+}
+
+void loop() {  // program finished, just keep printing some dots
+  for(int i = 0; i < 80; i++) {
+    Serial.print(".");
+    for(int x = 0; x < 100; x++) {
+      digitalWrite(led, HIGH);
+      delay(20);     
+      digitalWrite(led, LOW); 
+      delay(30);   
+    }
+  }
+  Serial.print(".\n");
+}