pinMode(LED_BUILTIN, OUTPUT); // Prepare built-in led pin as output

Serial.begin(115200); // Open serial port

if (Serial.available()) {

Serial.println("ready"); // Send start word to miner program

}

String startStr = Serial.readStringUntil('\n');

if (startStr == "start") { // Wait for start word, serial.available caused problems

Serial.flush(); // Clear serial buffer

String hash = Serial.readStringUntil('\n'); // Read hash

String job = Serial.readStringUntil('\n'); // Read job

unsigned int diff = Serial.parseInt() * 100 + 1; // Read difficulty

unsigned long StartTime = micros(); // Start time measurement

#ifdef REVERSE_SEARCH

for (unsigned int iJob = diff; iJob >= 0; iJob--) { // Reversed difficulty loop

#else

for (unsigned int iJob = 0; iJob < diff; iJob++) { // Difficulty loop

#endif

Sha1.init(); // Create SHA1 hasher

Sha1.print(String(hash) + String(iJob));

uint8_t * hash_bytes = Sha1.result(); // Get result

for (int i = 0; i < 10; i++) { // Cast result to array

for (int i = 0; i < 32; i++) {

buffer[2 * i] = "0123456789abcdef"[hash_bytes[i] >> 4]; // MSB to LSB (Depending on the address in hash_bytes)

// Choose that from the given array of characters

buffer[2 * i + 1] = "0123456789abcdef"[hash_bytes[i] & 0xf]; // Retreve the value from address next spot over

}

}

result = String(buffer); // Convert and prepare array

result.remove(40); // First 40 characters are good, rest is garbage

if (String(result) == String(job)) { // If result is found

unsigned long EndTime = micros(); // End time measurement

unsigned long ElapsedTime = EndTime - StartTime; // Calculate elapsed time

Serial.println(String(iJob) + "," + String(ElapsedTime)); // Send result back to the program with share time

PORTB = PORTB | B00100000; // Turn on built-in led

delay(25); // Wait a bit

PORTB = PORTB & B11011111; // Turn off built-in led

break; // Stop the loop and wait for more work

}

}

}