Re: API documentation--RE: RPG400-L Digest V3 #74

Thanks, Joel and Buck.  I bookmarked the web page.

Regards,

Jim Langston

Joel Fritz wrote:
> 
> Here's what I have:
> 
> From: bmorris@ca.ibm.com
> Sent: Thursday, August 19, 1999 6:23 AM
> To: RPG400-L@midrange.com
> Subject: Re: C Functions..
> 
> Even though int * is a pointer, it can be thought of as an int
> passed by reference, so it's better to prototype it in RPG as
> an int passed by reference.  My own rules for converting C
> prototypes to RPG prototypes are as follows:
> 
>       C         |       RPG
> ----------------|-------------------------------------------
>   int, long     |    10i 0 value
>   unsigned int  |    10u 0 value
>   double        |     8f   value
>   int *         |    10i 0
>   unsigned *    |    10u 0
>   double *      |     8F
>   char *        |      *   value options(*string)
>   void *        |      *   value
>                 | OR       LIKE(someStructure)
>   XXX           |          value LIKE(XXX)
>   XXX *         |          LIKE(XXX)
>   ... (ellipsis)| figure out what the ... stands for
>                 | and make one or more prototypes to
>                 | match the various combinations, possibly
>                 | with OPTIONS(*NOPASS) on some parms
> 
> Where XXX is some struct/union, defined in RPG as a data structure.
> 
> This part is for those advanced folks who know C and are creating
> RPG prototypes for homegrown C functions (i.e. not part of the C
> runtime):
>   Also, watch out for C's widening rules.  Even though
>   short = 5I 0, when it comes to passing parameters by value,
>   short=10i 0 and char=10u 0.  These differences don't always
>   cause a problem since the use of registers to pass parameters
>   can cause these differences to be hidden.  Luckily, the C
>   runtime rarely if ever has short or even char parameters
>   passed by value.  Unfortunately, C doesn't ALWAYS widen - it
>   depends on the absense of a #pragma nowiden.
>   (We have some help for this widening problem coming in a
>   future release of RPG)
> 
> Barbara Morris
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