// Function to encode the RPM value for transmission to the ESP32 (Little Endian)
uint16_t encode_rpm(uint16_t actual_rpm) {
    // Multiply the RPM by 50 and then by 4
    //actual_rpm *= 50;  // commented for Simulation
    actual_rpm *= 4;
    
    // Calculate A and B for the encoded value
    uint8_t A = highByte(actual_rpm);  // Extract the most significant byte (A)
    uint8_t B = lowByte(actual_rpm);  // Extract the least significant byte (B)
    
    // Combine A and B into the encoded value
    uint16_t encoded_value = (A * 256) + B;  // Combine A and B into a 16-bit value in little-endian order

    return encoded_value;  // Return the encoded RPM value
}

// Function to decode the RPM from an encoded value ODB app (Little Endian)
uint16_t decode_rpm(uint16_t encoded_value) {
    // Extract A and B from the encoded value
    uint8_t A = highByte(encoded_value);       // Shift right by 8 bits to get the most significant byte (A)
    uint8_t B = lowByte(encoded_value);     // Mask to get the least significant byte (B)
    
    // Calculate the actual RPM using the formula: (256 * A) + B, then divide by 4
    uint16_t actual_rpm = ((256 * A) + B) / 4;  // Perform integer division

    return actual_rpm;  // Return the decoded RPM
}

void setup() {  
  Serial.begin(115200);  
}

void loop() {
  static bool input_received = false;
    
    // Ask for input RPM if input is not received yet
    if (!input_received) {
        Serial.println("Enter the RPM value (Max RPM: 16383) and press Enter:");
        input_received = true; // Set input_received to true to indicate that input has been asked for
    }
    
    // Check if input RPM is available
    if (Serial.available() > 0) {
        // Read input RPM from Serial
        uint16_t input_rpm = Serial.parseInt();
        
        // Check if a valid integer has been parsed
        if (input_rpm != 0) {
            // Reset input_received to allow asking for input again
            input_received = false;

            // Encode the RPM value
            uint16_t encoded_rpm = encode_rpm(input_rpm);

            // Decode the encoded RPM value
            uint16_t decoded_rpm = decode_rpm(encoded_rpm);

            // Print input RPM, encoded RPM, and decoded RPM
            Serial.print("Input RPM: ");
            Serial.println(input_rpm);
            Serial.print("Encoded RPM: ");
            Serial.println(encoded_rpm);
            Serial.print("Decoded RPM: ");
            Serial.println(decoded_rpm);
        }
    }
}