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From: dbl7201@ttardis.UUCP (David B Lightstone)
Newsgroups: comp.lang.ada
Subject: calling Ada from C
Keywords: ADA, C, Telesoft
Message-ID: <2690@ttardis.UUCP>
Date: 23 Feb 91 16:01:15 GMT
Organization: self employed
List-Id: <comp.lang.ada>

There is a possible backdoor strategy which may be used. I previously 
discussed this with Telesoft tech support cerca their version 1.3 and
version 1.5 (Motorola 68000 target, Vax host). 

The problem arose when I needed an interrupt handler, but needed
a response time on the order of 10 - 20 micro seconds. 

The strategy was never implemented, so I can not say if it will be 
successful. It was straight forward. When the assembler interrupt was
ready to complete  spin off another interrupt handler by changing
machine priority, restoring the registers, enabling interrupts and 
branching to a standard Ada Interrupt.

What prevents the C program from calling a software interrupt which
will be fielded by Ada? There will be logistical problem relatable to
exchanging data, so conventions will have to be established.

I don't consider this a clean solution.

When I discussed this approach with Telesoft is was not rejected out
of hand. Their implementation has changed substancially since then, so
there should be a much better solution somewhere.