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    1: \ libcc.fs	foreign function interface implemented using a C compiler
    2: 
    3: \ Copyright (C) 2006 Free Software Foundation, Inc.
    4: 
    5: \ This file is part of Gforth.
    6: 
    7: \ Gforth is free software; you can redistribute it and/or
    8: \ modify it under the terms of the GNU General Public License
    9: \ as published by the Free Software Foundation; either version 2
   10: \ of the License, or (at your option) any later version.
   11: 
   12: \ This program is distributed in the hope that it will be useful,
   13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
   14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15: \ GNU General Public License for more details.
   16: 
   17: \ You should have received a copy of the GNU General Public License
   18: \ along with this program; if not, write to the Free Software
   19: \ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
   20: 
   21: 
   22: \ What this implementation does is this: if it sees a declaration like
   23: 
   24: \ libc dlseek int dlong int (dlong) lseek ( fd doffset whence -- doffset2 )
   25: 
   26: \ it genererates C code similar to the following:
   27: 
   28: \ #include <gforth.h>
   29: \ 
   30: \ void gforth_call_dl_i_dl_i(void)
   31: \ {
   32: \   Cell *sp = gforth_SP;
   33: \   Float *fp = gforth_FP;
   34: \   long (*func)(int, long, int);
   35: \   int arg1;
   36: \   long arg2;
   37: \   int arg3;
   38: \   long result;
   39: \   func = (char *)((Cell *)sp)[0];
   40: \   arg3 = ((Cell *)sp)[1];
   41: \   arg2 = gforth_d2ll(sp[3],sp[2]);
   42: \   arg1 = ((Cell *)sp)[4];
   43: \   result = func(arg1, arg2, arg3);
   44: \   gforth_ll2d(result, sp[4], sp[3]);
   45: \   gforth_SP += 3;
   46: \ }
   47: 
   48: \ Then it compiles this code and dynamically links it into the Gforth
   49: \ system (batching and caching are future work).  It also dynamically
   50: \ links lseek.  Performing DLSEEK then puts the function pointer of
   51: \ lseek() on the stack, the function pointer of
   52: \ gforth_call_del_i_dl_i, and calls CALL-C.
   53: 
   54: 
   55: s" Library not found" exception constant err-nolib
   56: 
   57: : library ( "name" "file" -- ) \ gforth
   58: \G Dynamically links the library specified by @i{file}.  Defines a
   59: \G word @i{name} ( -- lib ) that starts the declaration of a
   60: \G function from that library.
   61:     create parse-name open-lib dup 0= err-nolib and throw ,
   62:   does> ( -- lib )
   63:     @ ;
   64: 
   65: