70 lines
2.5 KiB
C++
70 lines
2.5 KiB
C++
/*
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PrimeNos: by Nick Gammon
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Maple Mini port m. ray burnette: Compiled under Arduino 1.6.0rc1
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Sketch uses 13,644 bytes (12%) of program storage space. Maximum is 108,000 bytes.
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Global variables use 2,656 bytes of dynamic memory.
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PUBLIC DOMAIN EXAMPLE
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*/
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#define BAUD 9600
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// just add more primes to the prime table for larger search
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// byte data type to save memory - use a larger datatype with prime table entries above 255 :)
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byte primes[]={
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2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101,
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102, 107, 109, 113, 127, 131, 137 , 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197,
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199, 211, 223, 227, 229, 233, 239, 241, 251 };
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// if you change the datatype of primes array to int, change next line to
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// "const int TopPrimeIndex = (sizeof(primes)/2) - 1;"
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const unsigned int TopPrimeIndex = sizeof(primes) - 1;
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const unsigned long TopPrimeSquared = (long)primes[TopPrimeIndex] * (long)primes[TopPrimeIndex];
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int primeFlag;
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void setup()
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{
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// initialize the digital pin as an output.
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pinMode(33, OUTPUT);
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Serial.begin(BAUD); // BAUD has no effect on USB serial: placeholder for physical UART
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// wait for serial monitor to be connected.
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while (!Serial)
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{
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digitalWrite(33,!digitalRead(33));// Turn the LED from off to on, or on to off
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delay(100); // fast blink
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}
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Serial.println("Prime Number Generator");
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Serial.print("Number of primes in prime table = ");
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Serial.println(TopPrimeIndex);
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Serial.println();
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Serial.print("Last prime in table = ");
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Serial.println((unsigned int)primes[TopPrimeIndex]);
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Serial.println();
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Serial.print("Calculating primes through ");
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Serial.println(TopPrimeSquared);
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Serial.println();
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}
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void loop() // run over and over again
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{
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for (long x = 1; x < TopPrimeSquared; x+=2){ // skips even numbers, including 2, which is prime, but it makes algorithm tad faster
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for (long j=0; j < TopPrimeIndex; j++){
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primeFlag = true;
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if (x == primes[j]) break;
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if (x % primes[j] == 0){ // if the test number modolo (next number from prime table) == 0
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primeFlag = false; // then test number is not prime, bailout and check the next number
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break;
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}
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}
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if (primeFlag == true){ // found a prime - print it
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Serial.println(x);
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}
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}
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}
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