Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!bloom-beacon!mit-eddie!apollo!beierl_c
From: beierl_c@apollo.COM (Christopher Beierl)
Newsgroups: comp.sys.apollo
Subject: Re: Discrepancy in sio.h file?
Message-ID: <4425aca6.19050@apollo.COM>
Date: 30 Jun 89 22:01:00 GMT
References: <12447@netnews.upenn.edu>
Reply-To: beierl_c@apollo.COM (Christopher Beierl)
Distribution: na
Organization: Apollo Computer, Chelmsford, MA
Lines: 57

In article <12447@netnews.upenn.edu> lau@kings.wharton.upenn.edu (Yan K. Lau) writes:
>This is a technical question about the C compiler and the Apollo sio
>include file.  There seems to be a discrepancy between parameter lists.
>
>In /usr/apollo/include/sio.h, the sio_$control call is defined as follows:
>    extern void sio_$control(
>            stream_$id_t          &stream_id,
>            sio_$opt_t            &option,
>            void                  &value,
>            status_$t             *status
>            );

This is a bug (APR #dcb69) and is fixed in SR10.2.  The correct prototype
matches the documentation and is shown below.

    extern void sio_$control(
            stream_$id_t          &stream_id,
            sio_$opt_t            &option,
            sio_$value_t          &value,
            status_$t             *status
            );

Note that an actual object of type sio_$value_t must be used in the call,
rather than just a cast because you can't cast a constant to a union.  An
example follows:

#include <apollo/sio.h>
    stream_$id_t    stream_id;
    sio_$value_t    sio_value;
    status_$t       status;

    sio_value.i = sio_$9600;
    sio_$control(stream_id, sio_$speed, sio_value, &status);
    sio_value.b = true;
    sio_$control(stream_id, sio_$raw,   sio_value, &status);

>BTW, In /sys/ins/sio.ins.c, the call is defined simply as:
>    std_$call void sio_$control();

For a C programmer it is much preferable to use the .h header files.  If
the ins.c header files are used instead then the std_$call mechanism is
used for interlanguage calls rather than prototypes.  An example follows:

#include "/sys/ins/sio.ins.c" 

    stream_$id_t    stream_id;
    status_$t       status;

    sio_$control(stream_id, sio_$speed, (pinteger)sio_$9600, status);
    sio_$control(stream_id, sio_$raw,   true,                status);


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 Christopher T. Beierl                         Internet: beierl_c@apollo.com
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