initial working example

arduino/v5.3/prime_ArduinoMega_tft_480x320/prime_ArduinoMega_tft_480x320.ino

@@ -0,0 +1,270 @@
+/* Prime numbers in Arduino C v5.3 2024/01/16 for Arduino Mega 2560 */
+// Put results onto the 480x320 TFT screen
+
+#include <time.h>
+#include <math.h>
+#include <EEPROM.h>
+#include <Adafruit_GFX.h>    // Core graphics library
+#include <MCUFRIEND_kbv.h>   // Hardware-specific library for 3.5" 480x320 lcd
+
+// Assign human-readable names to some common 16-bit color values:
+#define	BLACK   0x0000
+#define	BLUE    0x001F
+#define	RED     0xF800
+#define	GREEN   0x07E0
+#define CYAN    0x07FF
+#define MAGENTA 0xF81F
+#define YELLOW  0xFFE0
+#define WHITE   0xFFFF
+
+MCUFRIEND_kbv tft;
+
+double start;
+int column = 10;
+long found = 4;   // we already know 2, 3, 5, 7
+int divisors = found;
+int missing = 0;  // not yet calculated values
+uint16_t primes[350] = {3, 5, 7}; // only 3402 primes to 31623 = sqrt(1000000000)
+const int led = LED_BUILTIN; // LED_BUILTIN
+const uint32_t scope[]     = {100, 1000, 10000, 100000, 1000000, 10000000, 25000000, 100000000, 1000000000, 2147483647, 4294967295};
+const uint32_t nr_primes[] = {25, 168, 1229, 9592, 78498, 664579, 1565927, 5761455, 50847534, 105097564, 203280221}; 
+const char*    label[]     = {"100", "1,000", "10,000", "100,000", "1,000,000", "10,000,000", "25,000,000", "100,000,000", "1,000,000,000", "2,147,483,647", "4,294,967,295"};
+
+void setup(void) {
+  Serial.begin(9600);
+  Serial.println(F("Calculating primes with output on 480x320 lcd"));
+  uint16_t ID = tft.readID();
+  tft.begin(ID);
+  tft.setRotation(2);
+  recentResults();
+  delay(10000);
+  Serial.print("calculating missing");
+  // start calculating
+  for (int i = missing; i < 9; i++) // limit of 9 instead of 11 for RAM limit of Mega 2560
+  {
+    long last = scope[i];
+    found = 4;   // we already know 2, 3, 5, 7
+    Serial.println("\n\nPrime v5.3");
+    Serial.print("Primes until ");
+    Serial.println(last);
+    start = millis();      // use micros() for more precision
+    // Serial.println(start/1000000, 6);
+    long largest_divider = (long)(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");
+    long dot = millis();
+    int column = 0;
+    for(long 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(dot/1000);
+          Serial.print(" - ");
+          Serial.print(number);
+          Serial.print(" ");
+          Serial.print((int)(number / (last / 100)));
+          Serial.print("% \n");
+        }
+      }
+    }
+    const float duration = (millis() - start)/1000;
+    if(duration > 2) {
+      Serial.print("\n");
+    }    
+    Serial.print("Found ");
+    Serial.print(found);
+    Serial.print(" prime numbers. It should be ");
+    Serial.print(nr_primes[i]);
+    Serial.print(".\nThis took ");
+    Serial.print(duration, 3);
+    Serial.print(" seconds.");
+    elapsed_time(duration);
+    EEPROM.put(i * 4 + 1, duration);
+  }
+  Serial.print("\n");
+}
+
+void loop(void) {
+}
+
+void recentResults() {
+  // previous run
+  Serial.print("\nGet previous results for this Arduino Uno:\n");
+  Serial.print(" calculated to    time in seconds   \n");
+  tft.fillScreen(BLACK);
+  tft.setCursor(0, 0);
+  tft.setTextColor(GREEN); tft.setTextSize(2);
+  tft.println("Prime calculations");
+  tft.setTextColor(WHITE);  tft.setTextSize(1);
+  tft.println("Algorithm v5.0 in C on Arduino Uno\n");
+  tft.setTextColor(RED); tft.setTextSize(2);
+  tft.println("Recent results:\n");
+  tft.setTextColor(YELLOW);
+  tft.println("    last       seconds\n");
+  tft.setTextColor(WHITE);
+  float last_time_seconds = 0;
+  for(int i = 0; i < 9; i++) {  // 9 is 1 billion and will take 120 days
+    int spaces = 13 - strlen(label[i]);
+    for(int j = 0; j < spaces; j++) { Serial.print(" "); }
+    tft.setCursor(spaces * 12, 96 + i * 16);
+    EEPROM.get(i * 4 + 1, last_time_seconds);
+    if (last_time_seconds > 0) { missing++; }
+    Serial.print(label[i]);
+    Serial.print("    ");
+    Serial.println(last_time_seconds, 3);
+    tft.print(label[i]);
+    tft.print("  ");
+    tft.println(last_time_seconds, 3);
+  }
+  delay(10000);
+}
+
+int is_prime(long number) {
+  int prime = 1;
+  for (long divider = 3; divider < (long)(sqrt(number)) + 1; divider += 2)
+  {
+    if (number % divider == 0)
+    {
+      prime = 0;
+      break;
+    }
+  }
+  return prime;
+}
+
+int find_primes(long limit) {
+  for(long 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(long number) {
+  long largest_divider = (long)(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(long 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 ");
+}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+unsigned long testText() {
+  tft.fillScreen(BLACK);
+  unsigned long start = micros();
+  tft.setCursor(0, 0);
+  tft.setTextColor(WHITE);  tft.setTextSize(1);
+  tft.println("Hello World!");
+  tft.setTextColor(YELLOW); tft.setTextSize(2);
+  tft.println(1234.56);
+  tft.setTextColor(RED);    tft.setTextSize(3);
+  tft.println(0xDEADBEEF, HEX);
+  tft.println();
+  tft.setTextColor(GREEN);
+  tft.setTextSize(5);
+  tft.println("Groop");
+  tft.setTextSize(2);
+  tft.println("I implore thee,");
+  tft.setTextSize(1);
+  tft.println("my foonting turlingdromes.");
+  tft.println("And hooptiously drangle me");
+  tft.println("with crinkly bindlewurdles,");
+  tft.println("Or I will rend thee");
+  tft.println("in the gobberwarts");
+  tft.println("with my blurglecruncheon,");
+  tft.println("see if I don't!");
+  return micros() - start;
+
+
+  // unsigned long start = micros();
+
+
+  tft.setTextColor(WHITE);  tft.setTextSize(1);
+  tft.println("Hello World!");
+  tft.setTextColor(YELLOW); tft.setTextSize(2);
+  tft.println(1234.56);
+  tft.setTextColor(RED);    tft.setTextSize(3);
+  tft.println(0xDEADBEEF, HEX);
+  tft.println();
+  tft.setTextColor(GREEN);
+  tft.setTextSize(5);
+  tft.println("Groop");
+  tft.setTextSize(2);
+  tft.println("I implore thee,");
+  tft.setTextSize(1);
+  tft.println("my foonting turlingdromes.");
+  return micros() - start;
+}
+
+
+
+
+
+
+
+

arduino/v5.3/results_ArduinoUno.txt

@@ -7,8 +7,8 @@ Arduino Uno with 16 MHz and only 2kByte RAM
         1,000         0.153     
        10,000         1.789       
       100,000        30.901 
-    1,000,000        
-   10,000,000           or  3h 28min 44s
+    1,000,000       595.123 
+   10,000,000     12448.568      or  3h 27min 28s
    25,000,000         nan
   100,000,000         nan
 1,000,000,000         nan