Re: [gforth] Gforth image files and shared c librarys! How to access?

[Bernd Paysan]

Am Montag, 2. September 2013, 14:10:46 schrieb Philip Smith:
> Hi fellow Gforthers
> I need to understand how to use a shared library in Gforth with a Gforth
> image!  I Think this is possible because
> i can access a c shared library in gforth from the command line or from
> code that is accessed in gforth via the #! method as a script.
> I can not however access the c shared library from an image though.  I
> think this is because i do not understand some part of gforthmi
> or perhaps gforth itself i am missing some part of the puzzle.  The issue
> seems to be a linkage issue to the shared library but i present the
> steps i took to test this below.  Note the "#####" indicates a file or
> screen capture.
> This is all done on a Raspberry pi running Debian Wheezy.  I am using
> gforth version 0.7.2 but have also tried 0.7.0 with same results.
> I am just looking for some input if a c shared library can be assessed in a
> gforth image or not and if so how is it done correctly!

At the moment, this does not work, and we know that (i.e. a known bug); this 
is a valid feature request.

> ##### someclib.c
> #include <stdio.h>
> 
> int mytest(void)
> {
>   printf("Hello world");
>   return 99 ;
> }
> #####
> 
> ##### someclib.h
> #include <stdio.h>
> 
> int mytest(void);
> #####
> 
> Now i compile the c and make it a shared library as follows:
> 
> ##### from the raspberry pi ssh session
> address@hidden ~/git/gforth_testing $ gcc -c -fPIC someclib.c -o someclib.o
> address@hidden ~/git/gforth_testing $ ar rcs libsomeclib.a someclib.o
> address@hidden ~/git/gforth_testing $ gcc -shared
> -W1,-soname,libsomeclib.so.1 -o libsomeclib.so.1.0.1 someclib.o
> address@hidden ~/git/gforth_testing $ sudo cp libsomeclib.so.1.0.1 /usr/lib/
> address@hidden ~/git/gforth_testing $ sudo ln -sf
> /usr/lib/libsomeclib.so.1.0.1 /usr/lib/libsomeclib.so
> address@hidden ~/git/gforth_testing $ sudo ln -sf
> /usr/lib/libsomeclib.so.1.0.1 /usr/lib/libsomeclib.so.1
> address@hidden ~/git/gforth_testing $ sudo ldconfig -n /usr/lib/
> address@hidden ~/git/gforth_testing $ sudo cp someclib.h
> /usr/include/someclib.h
> #####
> 
> The library is now a shared library and the system sees it and i can link
> to it with other c code.
> Now i want to link to it with a wrapper function in gforth to allow usage
> of c library functions in gforth
>  but ultimately i want the gforth as fast as it can be so i would like to
> make an image for gforth to use.
>  I find this does not work!  The steps are show below.
> 
> ##### mywrapper.fs
> clear-libs
> c-library mybugtest
> s" someclib" add-lib
> 
> \c #include "someclib.h"
> \c int thecfunction(void) { return (mytest()); }
> 
> c-function forthword thecfunction -- n
> 
> end-c-library
> ######
> 
> ###### mytest.fs
> include mywrapper.fs
> 
> variable myvar
> 
> 5 myvar !
> 
> : testword myvar @ . cr threading-method . cr version-string type cr
> 
> forthword cr . cr ;
> 
> :noname testword bye ; is bootmessage
> 
> ######
> 
> Now if i use gforthmi as follows then run the code as shown below it fails!
> 
> ###### this is from the raspberry pi ssh session
> address@hidden ~/git/gforth_testing $ sudo gforthmi mytest mytest.fs
> data offset=-2AF20
> code offset=-5CEF98
>   xt offset=-5CEFA8
>        30         B69A7000         B697C000
>        34         B69AC000         B6981000
>        38         B69B1000         B6986000
>        3C         B69B6000         B698B000
>      1CCC         B69AB000         B6980000
>      1CD0         B69B4C00         B6989C00
>      1CD4         B69B0000         B6985000
>      1CDC         B69B4B98         B6989B98
>      1CE0         B69B4B94         B6989B94
>      1CEC          1099128           ACA128
>      2D40         B6F1A5E0         B6EEF5E0
>      2D60         B6F1A680         B6EEF680
>      970C         BED8B5D8         BED475D8
>      9748         BED8B80C         BED4780C
>      9F88          10885A8           AB95A8
>      B1AC          10999E0           ACA9E0
>     10460          1090490           AC1490
>     104C0          1088A00           AB9A00
>     16D20          1090A20           AC1A20
>     19048          1090B90           AC1B90
>     22304          1082166           AB3166
>     22358          1098D18           AC9D18
>     227B0          1099330           ACA330
>     28800          10992F8           ACA2F8
> address@hidden ~/git/gforth_testing $ sudo gforth -i mytest
> 5
> 0
> 0.7.2
> 
> :0: Invalid memory address
> 
> Backtrace:
> $B69EA770 lib-sym
> $B69EA8C0 link-wrapper-function
> $B69EE978 forthword
> $B69EE9A8 testword
> ########
> 
> But if i simply do the following from command line the code with the shared
> library works!
> Why does this work when it is compiled into the standard gforth image but
> not precompiled as an image?
> I know from testing that i can use my own images made with gforthmi but i
> can not seem to have access to anything other then gforth code
> in those images.  How then can i have access to shared c library and yet
> get the performance of an precompiled image in gforth at the same time?
> 
> ######## this is from the raspberry pi ssh session
> address@hidden ~/git/gforth_testing $ sudo gforth mytest.fs
> 5
> 0
> 0.7.2
> Hello world
> 99
> 
> address@hidden ~/git/gforth_testing $
> 
> ########
> 
> Any help would be appreciated!  PKS
-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://bernd-paysan.de/

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