Sub-EndSub

Source: Positron16 Compiler User Manual, PDF page 455

Syntax

Sub Label Name() BASIC commands inside the Subroutine

EndSub

Overview

Create a ‘standard’ subroutine but with a start directive (Sub) and an end directive (EndSub).

Parameters

Label Name is the name of the subroutine.

Example

' Create a subroutine to flash an LED 10 times
  Device = 24FJ64GA002
  Declare Xtal = 16
  Declare Hserial_Baud = 9600      ' UART1 Baud rate
  Declare Hrsout1_Pin = PORTB.14
                                     ' Select the pin for TX with USART1
  Dim FlashAmount as Byte
                                ' Create a variable for the amount of LED flashes
  Symbol LED = PORTB.0
                                ' Create a name for the LED’s Port and Pin
  Do
                                ' Create a loop
     FlashLED()
                                ' Call the subroutine
     DelayMs 1000
                                ' Delay for 1 second
  Loop
                                ' Loop forever
' Create a subroutine that will flash an LED
'
Sub FlashLED()
   For FlashAmount = 1 to 10
                                ' A loop for the amount of flashes
     PinHigh LED
                                ' Illuminate the LED
     DelayMs 500
                                ' Wait for half a second
     PinLow LED
                                ' Extinguish the LED
     DelayMs 500
                                ' Wait for half a second
   Next
                                ' Close the loop
EndSub
                                ' End the subroutine and return from it

The EndSub directive will produce a Return command and exit the subroutine as normal. There is also an ExitSub command that will create a Return command and return from the subroutine.

' Create a subroutine that will flash an LED and exit when required
'
Sub FlashLED()
   For FlashAmount = 1 to 100
                                ' A loop for the amount of flashes
     PinHigh LED
                                ' Illuminate the LED
     DelayMs 500
                                ' Wait for half a second
     PinLow LED
                                ' Extinguish the LED
     DelayMs 500
                                ' Wait for half a second
     If FlashAmount >= 10 Then ExitSub  ' Exit the subroutine after 10 flashes
  Next
                                ' Close the loop
EndSub
                                ' End the subroutine and return from it

Calling a sub only requires the name, and a pair of parenthesis after it. This makes a program easier to read:

MySub()
          ' Call the subroutine named MySub