Re: Generic function-calling code

From	Bartc <bc@freeuk.com>
Newsgroups	comp.lang.c
Subject	Re: Generic function-calling code
Date	2015-07-22 11:50 +0100
Organization	A noiseless patient Spider
Message-ID	<monse0$ctq$1@dont-email.me> (permalink)
References	(1 earlier) <momc30$p1p$1@dont-email.me> <351d1a19-292c-48c2-8b09-d9ab7f45e414@googlegroups.com> <momm4p$t3l$1@dont-email.me> <mon9oa$f62$1@news.albasani.net> <6dd18c80-54f0-48a9-bd0d-ab6519b03694@googlegroups.com>

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On 22/07/2015 10:37, Rick C. Hodgin wrote:
> Bart,
>
> Why are you passing parameters at all? Pass
> pointers to structs you've built which convey
> all of that information which you've manually
> built from what you know at runtime.  Why
> does it have to go through parameters?
>
> If it's a call into C from another language then
> use three functions:
>
>      int mydllfunction_getHandle(void);
>      int mydllfunction_accumulateParam(int handle, int type, void* value);
>      int mydllfunction_dispatch(int handle);
>
> You could use an optional 4th to release the
> handle, but given the nature, the dispatch()
> function could do it.

It's difficult to put across the problem although luser seemed to grasp 
it instantly.

But suppose you create an interpreter for a language which can access 
external DLL functions. You write the interpreter in C, and build it in 
July 2014.

A year later in July 2015, someone writes a program which wants to 
access a DLL function with a dozen assorted parameters (eg. 
'CreateWindowEx' from library 'user32.dll').

Now, the interpreter can't anticipate which of tens of thousands of 
possible functions in hundreds of different libraries could be called; 
it has to work with any possibility.

So how will it work? It can get the function address, it knows the 
number and types of the parameters, it knows the return value, and it 
knows the arguments the user's program will supply. But the call must 
somehow be accomplished inside the interpreter.

It can be done by dropping into assembly or using all sorts of dodgy 
techniques (generating and compiling C at runtime for example). But I'm 
interested in a solution in normal code.

(I'm looking at Kenny's link to FFCALL, which looks as though it 
understands the issues involved, but it looks very complicated, and it 
might not be fully updated for x64 (possibly it has come across the same 
problem I have!).)

-- 
Bartc

Thread

Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-21 21:21 +0100
  Re: Generic function-calling code jacobnavia <jacob@jacob.remcomp.fr> - 2015-07-21 23:04 +0200
    Re: Generic function-calling code luser droog <luser.droog@gmail.com> - 2015-07-21 14:45 -0700
      Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-22 00:56 +0100
        Re: Generic function-calling code BGB <cr88192@hotmail.com> - 2015-07-22 00:25 -0500
          Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 02:37 -0700
            Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-22 11:50 +0100
              Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 04:29 -0700
                Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-22 13:04 +0100
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 05:44 -0700
              AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-22 12:50 +0000
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 06:07 -0700
                Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-22 13:30 +0000
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 07:42 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) David Brown <david.brown@hesbynett.no> - 2015-07-22 17:07 +0200
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 08:16 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Keith Thompson <kst-u@mib.org> - 2015-07-22 08:41 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Keith Thompson <kst-u@mib.org> - 2015-07-22 08:47 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 08:53 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) David Brown <david.brown@hesbynett.no> - 2015-07-22 18:09 +0200
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) David Kleinecke <dkleinecke@gmail.com> - 2015-07-22 16:38 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Richard Heathfield <rjh@cpax.org.uk> - 2015-07-22 18:28 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) James Kuyper <jameskuyper@verizon.net> - 2015-07-22 13:37 -0400
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) BGB <cr88192@hotmail.com> - 2015-07-22 15:04 -0500
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 10:39 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Richard Heathfield <rjh@cpax.org.uk> - 2015-07-22 19:10 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 11:39 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Richard Heathfield <rjh@cpax.org.uk> - 2015-07-22 20:01 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 12:06 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Richard Heathfield <rjh@cpax.org.uk> - 2015-07-22 20:51 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) guinness.tony@gmail.com - 2015-07-22 17:48 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) raltbos@xs4all.nl (Richard Bos) - 2015-07-22 19:50 +0000
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 13:15 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Richard Heathfield <rjh@cpax.org.uk> - 2015-07-22 21:28 +0100
                Re: Let's see who can be the most off-topic Gareth Owen <gwowen@gmail.com> - 2015-07-22 21:44 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Morris Dovey <mrdovey@iedu.com> - 2015-07-22 16:35 -0500
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 15:17 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Morris Dovey <mrdovey@iedu.com> - 2015-09-05 15:20 -0500
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-05 23:01 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) wssimms@gmail.com - 2015-09-06 01:58 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-06 02:28 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Keith Thompson <kst-u@mib.org> - 2015-09-06 12:48 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-06 07:08 -0700
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Keith Thompson <kst-u@mib.org> - 2015-07-22 13:50 -0700
                Re: Let's see who can be the most off-topic Gareth Owen <gwowen@gmail.com> - 2015-07-22 21:43 +0100
                Re: Let's see who can be the most off-topic guinness.tony@gmail.com - 2015-07-22 17:43 -0700
                Re: Let's see who can be the most off-topic James Kuyper <jameskuyper@verizon.net> - 2015-07-24 10:41 -0400
                Re: Let's see who can be the most off-topic Richard Heathfield <rjh@cpax.org.uk> - 2015-07-24 16:01 +0100
                Re: Let's see who can be the most off-topic raltbos@xs4all.nl (Richard Bos) - 2015-07-25 19:20 +0000
                Re: Let's see who can be the most off-topic Gareth Owen <gwowen@gmail.com> - 2015-07-24 20:25 +0100
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) Rosario19 <Ros@invalid.invalid> - 2015-07-23 20:41 +0200
                Re: Let's see who can be the most off-topic (Was: AVCALL ...) Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 12:00 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-22 17:43 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-22 19:36 +0000
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-22 23:19 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-22 15:43 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-22 23:47 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 04:44 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-23 13:14 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 06:26 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-23 15:00 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 07:13 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-23 18:02 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 10:05 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-23 18:19 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 10:37 -0700
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) Bartc <bc@freeuk.com> - 2015-07-23 23:29 +0100
                Re: AVCALL (from the 'ffcall' package) really is the answer! (Was: Generic function-calling code) gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-23 16:18 +0000
              Re: Generic function-calling code Richard Damon <Richard@Damon-Family.org> - 2015-07-24 01:21 -0400
          Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-22 13:23 +0100
            Re: Generic function-calling code Ian Collins <ian-news@hotmail.com> - 2015-07-23 07:44 +1200
              Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-22 22:24 +0100
      Re: Generic function-calling code luser droog <luser.droog@gmail.com> - 2015-07-22 10:29 -0700
      Re: Generic function-calling code luser droog <luser.droog@gmail.com> - 2015-07-22 10:32 -0700
    Re: Generic function-calling code Keith Thompson <kst-u@mib.org> - 2015-07-21 15:38 -0700
  Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-21 17:26 -0700
  Re: Generic function-calling code Ian Collins <ian-news@hotmail.com> - 2015-07-22 14:27 +1200
  Re: Generic function-calling code gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-22 02:39 +0000
  Re: Generic function-calling code Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-07-23 09:28 +0200
  Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-23 19:04 -0700
  Re: Generic function-calling code owen.jacobson@grimoire.ca - 2015-07-24 08:32 -0700
    Re: Generic function-calling code gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-24 18:48 +0000
    Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-24 20:22 +0100
      Re: Generic function-calling code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 03:03 -0700
  Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-25 13:32 -0700
    Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-25 23:28 +0100
      Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-26 06:18 -0700
        Re: Generic function-calling code gazelle@shell.xmission.com (Kenny McCormack) - 2015-07-26 13:39 +0000
          Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-26 07:33 -0700
            Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-07-26 16:21 +0100
              Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-07-26 08:39 -0700
  Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-26 05:37 -0700
    Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-08-26 14:36 +0100
      Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-26 06:46 -0700
        Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-08-26 16:11 +0100
          Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-26 08:20 -0700
  Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-27 16:53 -0700
    Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-08-28 01:03 +0100
      Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 05:36 -0700
        Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 06:35 -0700
          Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 06:43 -0700
          Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-08-30 15:10 +0100
            Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 08:59 -0700
              Re: Generic function-calling code Geoff <geoff@invalid.invalid> - 2015-08-30 10:54 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 10:57 -0700
                Re: Generic function-calling code Geoff <geoff@invalid.invalid> - 2015-08-30 11:13 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 11:16 -0700
                Re: Generic function-calling code Geoff <geoff@invalid.invalid> - 2015-08-30 11:59 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 12:15 -0700
                Re: Generic function-calling code Geoff <geoff@invalid.invalid> - 2015-08-30 12:57 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 13:40 -0700
                Re: Generic function-calling code Geoff <geoff@invalid.invalid> - 2015-08-30 11:15 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-08-30 11:28 -0700
                Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-08-30 20:11 +0100
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-08-30 22:28 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-01 01:13 -0700
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 00:40 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 01:26 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 11:34 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 03:15 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 03:21 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 13:07 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 04:30 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 13:39 +0200
                Re: Generic function-calling code Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-09-03 07:20 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 20:25 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 11:30 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 11:44 -0700
                Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-09-03 11:21 +0100
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 13:19 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 04:51 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 14:31 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 05:57 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 04:56 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 14:53 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 06:08 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 15:18 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 06:30 -0700
                Re: Generic function-calling code Martin Shobe <martin.shobe@yahoo.com> - 2015-09-03 10:09 -0500
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 08:59 -0700
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 08:37 -0700
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 08:31 -0700
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 09:07 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 20:42 +0200
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 11:49 -0700
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 08:25 -0700
                Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-09-03 16:46 +0100
                Re: Generic function-calling code "Rick C. Hodgin" <rick.c.hodgin@gmail.com> - 2015-09-03 09:02 -0700
                Re: Generic function-calling code glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-09-04 04:04 +0000
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 00:36 -0700
                Re: Generic function-calling code Bartc <bc@freeuk.com> - 2015-09-03 16:29 +0100
                Re: Generic function-calling code Philip Lantz <prl@canterey.us> - 2015-09-03 08:45 -0700
                Re: Generic function-calling code David Brown <david.brown@hesbynett.no> - 2015-09-03 22:33 +0200

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