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Home » MIDRANGE-L » May 1999

RE: *PSSR subroutine and the call stack



fixed

At 12:07 05/09/1999 , Albert York wrote:
>Now I'm curious. In my experience, a subroutine call involved saving the
>current address (usually on a stack), branching to the subroutine, and
>branching back to the saved address ( plus 1 instruction) at the end of the
>subroutine. If RPG doesn't do it this way, how does it do it?

Several years ago, I had a program that did something like this:

mainline calls Sub A
Sub A calls Sub B
Sub B calls Sub C
Sub C calls Sub A
Sub A returns to mainline (not Sub C) - this was not the desired behavior

>From this experience, I surmise that subroutine returns are implemented as
branches to a program counter address which is set at the time the
subroutine is first invoked. RPG doesn't complain about recursion either.
It just doesn't work.
Pete Hall
pbhall@execpc.com
http://www.execpc.com/~pbhall
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