Handling exceptions (Only Visual Project Type)
Easy Code can create an error handler for catching exceptions (errors) fired during the program execution, so you can handle errors at procedure level (or even at message level) with these two macros:
StartErrorHandler <Offset HandlerAddress>
EndErrorHandler
StartErrorHandler
starts the error
handling, specifying the effective address that will receive control
when an
error occurs, while EndErrorHandler
specifies that the error handling ends its control. You can
use these
macros in the following way:
AnyProcedure
Proc
StartErrorHandler Offset
ErrorsPlace
.........
code.....
.........
EndErrorHandler
@@: Ret
ErrorsPlace:
EndErrorHandler
.If
Error.lCode
==
0C0000005H
;Access violation read
do something
.EndIf
Jmp
@B
AnyProcedure
EndP
This error handler will be active along all code between the two sentences (StartErrorHandler and EndErrorHandler), and any other procedures called inside it (unless those other procedures have their own error handler), until EndErrorHandler is reached (in the example above, at the end of the procedure). It is very important, for a correct behavior of the application, that each StartErrorHandler matches an EndErrorHandler at the same level (usually at the end of the procedure).
You can accurate even more the error handling. For example:
.If
uMsg ==
WM_CREATE
StartErrorHandler
Offset
ErrorsPlace1
.........
code.....
.........
EndErrorHandler
@@: Ret
ErrorsPlace1:
EndErrorHandler
.If
Error.lCode
==
0C0000005H
;Access
violation read
do something
.EndIf
Jmp @B
.ElseIf
uMsg ==
WM_DESTROY
StartErrorHandler
Offset
ErrorsPlace2
.........
code.....
.........
EndErrorHandler
@@: Ret
ErrorsPlace2:
EndErrorHandler
.If
Error.lCode
==
0C0000005H
;Access
violation read
do something
.EndIf
Jmp @B
.EndIf
This type of
handling cannot be nested,
so as said before, you should write an EndErrorHandler
for
each StartErrorHandler
at the same level (take into account whether
the procedure has two or more Ret o Return sentences due to the
stack frame), so that it removes the handler address from the stack. If
you do not do that, next time the program execution enters the
procedure for processing any other message and an error
occurs, it will not work properly.
REMARKS:
All the code above is written in Masm
syntax. You will have to make the necessary modifications for other
assemblers.