REM   Example to demonstrate generating an ON ERROR condition on the SBC2000-074
REM   and SBC2000-062.
REM
REM   Author: Steven R. Wheeler
REM
REM   Copyright 1998 Vesta Technology, Inc.
REM   All rights reserved.


REM   It is possible for an application to generate an ON ERROR condition. This
REM   allows you to have an error handling routine which handles not only the
REM   errors which are generated by the runtime engine, but also any errors you
REM   can make your application detect. There are two things which are required.
REM   First, you must assign unique error codes to the conditions you generate,
REM   and place those error codes where the error handler can find them. Second,
REM   you must realize that as soon as you set the bit indicating that an error
REM   condition has occurred, the runtime engine will want to vector to the
REM   error handler BEFORE THE START OF THE NEXT PCODE INSTRUCTION. The only way
REM   you can postpone the jump to the handler at all is to perform the setting
REM   of the bit within a VITAL subroutine. In this case, the runtime engine will
REM   not vector to the error handler until you exit the subroutine.


REM   Error codes can be in the range from 1 to 255. The following values have
REM   already been defined in the runtime engine:
REM
REM      0 = no error
REM     20 = divide by zero
REM     21 = invalid input to math routine
REM     22 = arithmetic overflow
REM     70 = No memory available (stack overflow)
REM     81 = No acknowledge from VAST IIC device
REM     88 = Serial port/other timeout
REM     99 = Basic internal error (stack underflow)


REM   The following two declarations are the key ones. They are made (with other
REM   names) in the monitor. If you always compile with debug, you could remove
REM   these declarations and use the names declared in the monitor. Keeping these
REM   declarations will allow your code to run when compiled with or without debug
REM   enabled.

CONSTANT Error_Code AS INTEGER = 0x3B
GLOBAL   Error_Flag AS BIT = 0x39,2


REM   This routine will set an error. If you provide an error handler in your
REM   application, it will obtain control when the return from the subroutine
REM   is executed. Call this subroutine with the error code you have assigned.
REM   Any code you add to this routine will be executed before the error is
REM   handled.

VITAL SUBROUTINE Set_Error(type AS INTEGER)
	POKE(Error_Code, type)
	Error_Flag = 1
END