Arduino - Dual Servo Control

#include <Servo.h>

Servo servo_base, servo_joint;

int servo_base_output = 120;
int servo_joint_output = 90;

int servo_pin_base = 10;
int servo_pin_joint = 11;

String stream, stream_base, stream_joint;
char charBuf[50];

char *i;

char ascii_table[] = {' ', '!', '"', '#', '$', '%', '&', '\'', '(', ')', '*',
                    '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5',
                    '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@',
                    'A', 'B', 'C', 'D', 'E', 'F', 'G','H', 'I', 'J', 'K', 'L',
                    'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
                    'Y', 'Z', '[', '\\', ']', '^', '_', '`', 'a', 'b', 'c', 'd',
                    'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
                    'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{',
                    '|', '}', '~'};

char ascii_to_char(int ascii){
  return ascii_table[ascii - 32];
}

String capture_stream(){
  int input;
  String output;
  boolean flag = false;
  while((input = Serial.read()) != -1){
    output += String(ascii_to_char(input));
    flag = true;
  }
  if(flag){
    Serial.println(String(output));
    return output;
  }else{
    Serial.println(String("-1"));
    return "-1";
  }
}

void setup(){
  Serial.begin(9600);
  Serial.println("starting up");
  servo_base.attach(servo_pin_base);
  servo_joint.attach(servo_pin_joint);
}

void loop(){
  if((stream = capture_stream()) != "-1"){
    stream.toCharArray(charBuf, 50);
    stream_base = strtok_r(charBuf, ":", &i);
    stream_joint = strtok_r(NULL, ":", &i);

    if(stream_base == "-") stream_base = String(servo_base_output);
    if(stream_joint == "-") stream_joint = String(servo_joint_output);

    servo_base_output = stream_base.toInt();
    servo_joint_output = stream_joint.toInt();

    Serial.println("Base Servo:  " + String(servo_base_output));
    Serial.println("Joint Servo: " + String(servo_joint_output));

    if(servo_base_output != -1){
      if(servo_base_output > 180){
        servo_base_output = 180;
      }else if(servo_base_output < 0){
        servo_base_output = 0;
      }
      servo_base.write(servo_base_output);
    }

    if(servo_joint_output != -1){
      if(servo_joint_output > 180){
        servo_joint_output = 180;
      }else if(servo_joint_output < 0){
        servo_joint_output = 0;
      }
      servo_joint.write(servo_joint_output);
    }
  }
  delay(500);
}