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From: forgeas@swinjm.UUCP (Jean-Michel Forgeas)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Problem with SetFunction()
Message-ID: <18d9ce4e.ARN0bdc@swinjm.UUCP>
Date: 19 Mar 91 13:08:30 GMT
References: <13531@darkstar.ucsc.edu>
Reply-To: forgeas@swinjm.UUCP (Jean-Michel Forgeas)
Followup-To: comp.sys.amiga.programmer
Organization: The Software Winery
Lines: 41

In article <13531@darkstar.ucsc.edu>, Dave Schreiber writes:

> APTR __regargs newAllocMem(ULONG size,ULONG types);
> [...]
>    oldAllocMem=SetFunction(ExecBase,NEG_AM_OFFSET,newAllocMem);
> [...]
> APTR __regargs newAllocMem(ULONG size,ULONG types)
> {
>    return(oldAllocMem(size,types));
> }

Just an idea: when it sees __regargs, the compiler assigns registers
to parameters, and in your case should use D0/D1. But did you verify
it with a small disassembly of newAllocMem() ?

> temp=(APTR)AllocMem(1000,0L); /*Goes to my routine & allocates*/
>                               /*the memory without a problem*/

How are you sure that 'temp' is something valid ?

> If I change newAllocMem() so that it just returns NULL, the call to
> AllocMem() in main() returns NULL; i.e. I know that calls to AllocMem() are
> being routed to my module.  newAllocMem() as it is above also works without
> a hitch.  But when I printf() an '\n' (or when I Permit() without undoing the
> patch), it crashes.  Any suggestions?  BTW, I'm using a 3000 under 2.02
> (under 1.3 it crashes as well, but it gives a 8000 0003 error).

Seems that it crashes every time newAllocMem() calls oldAllocMem().
1 - Either you call oldAllocMem with bad values into registers,
    don't forget that the a6 register must stay with ExecBase value.
2 - Either you don't call oldAllocMem() at all but jump into
    the 5th dimension.

Best regards,
    Jean-Michel
--
                                     \___/
Jean-Michel Forgeas                   \-/
cbmvax!cbmehq!cbmfra!swinjm!forgeas    |    The Software Winery
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                           And, where is the universe ?