Arduino read all serial data

uint8_t buffer[1024];
size_t bufferSize = 0;
unsigned long lastSerialReadTime = 0;

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

void loop() {
  if (Serial1.available() > 0) {
    unsigned long currentTime = millis();
    unsigned long timeDifference = currentTime - lastSerialReadTime;
    lastSerialReadTime = currentTime;

    // For serial communication, each byte typically consists of 10 bits
    // 1 start bit, 8 data bits, and 1 stop bit.
    // Here baud rate is 2400.
    // time = 10/2400 => 4.1667ms
    // So it would take approximately (5ms) to receive one byte of data
    if (timeDifference <= 5) {
      if (bufferSize < sizeof(buffer)) {
        buffer[bufferSize++] = Serial1.read();
      }
    } else {
      if (bufferSize > 0) {
        Serial.write(buffer, bufferSize);
        bufferSize = 0;
      }
    }
  }
}


// Optimized Version:
//-----------------------------------------------------------------------------

const uint16_t BUFFER_SIZE = 256;
uint8_t buffer[BUFFER_SIZE];
size_t bytesRead = 0;
unsigned long lastReadTime = 0;

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

void loop() {
  while (Serial1.available()) {
    uint8_t byte = Serial1.read();

    if (bytesRead >= BUFFER_SIZE || (bytesRead > 0 && millis() > lastReadTime)) {
      Serial.write(buffer, bytesRead);
      bytesRead = 0;
    }

    buffer[bytesRead++] = byte;

    // For serial communication, each byte typically consists of 10 bits
    // 1 start bit, 8 data bits, and 1 stop bit.
    // Here baud rate is 2400.
    // time = 10/2400 => 4.1667ms
    // So it would take approximately (5ms) to receive one byte of data
    lastReadTime = millis() + 5;
  }
}