switch statement for ISR in Marlin firmware

excerpt.cpp

  switch(temp_state) {
  case 0: // Prepare TEMP_0
#ifdef NORMAL_OP
#if (TEMP_0_PIN > -1)
#if TEMP_0_PIN > 7
    ADCSRB = 1<<MUX5;
#endif
    ADMUX = ((1 << REFS0) | (TEMP_0_PIN & 0x07));
    ADCSRA |= 1<<ADSC; // Start conversion
#endif
#ifdef ULTIPANEL
    buttons_check();
#endif
#endif
    temp_state = 1;
    break;
  case 1: // Measure TEMP_0
#ifdef NORMAL_OP
#if (TEMP_0_PIN > -1)
    raw_temp_0_value += ADC;
#endif
#endif
#ifndef NORMAL_OP
    raw_temp_0_value += analogRead(TEMP_0_PIN);
#endif
    temp_state = 2;
    break;
  case 2: // Prepare TEMP_1
#ifdef NORMAL_OP
#if (TEMP_1_PIN > -1)
#if TEMP_1_PIN > 7
    ADCSRB = 1<<MUX5;
#endif
    ADMUX = ((1 << REFS0) | (TEMP_1_PIN & 0x07));
    ADCSRA |= 1<<ADSC; // Start conversion
#endif
#ifdef ULTIPANEL
    buttons_check();
#endif
#endif
    temp_state = 3;
    break;
  case 3: // Measure TEMP_1
#ifdef NORMAL_OP
#if (TEMP_1_PIN > -1)
    raw_temp_1_value += ADC;
#endif
#endif
#ifndef NORMAL_OP
    raw_temp_1_value += analogRead(TEMP_1_PIN);
#endif
    temp_state = 4;
    break;
  case 4: // Prepare TEMP_2
#if (TEMP_2_PIN > -1)
#if TEMP_2_PIN > 7
    ADCSRB = 1<<MUX5;
#endif
    ADMUX = ((1 << REFS0) | (TEMP_2_PIN & 0x07));
    ADCSRA |= 1<<ADSC; // Start conversion
#endif
#ifdef ULTIPANEL
    buttons_check();
#endif
    temp_state = 5;
    break;
  case 5: // Measure TEMP_2
#if (TEMP_2_PIN > -1)
    raw_temp_2_value += ADC;
#endif
    temp_state = 0;
    temp_count++;
    break;
  default:
    SERIAL_ERROR_START;
    SERIAL_ERRORLNPGM("Temp measurement error!");
    break;
  }