From: Waldemar Schultz <schultzma AT ma DOT tum DOT de>
Newsgroups: comp.os.msdos.djgpp
Subject: MINGW vs DJGPP
Date: Tue, 17 Apr 2001 16:29:25 +0200
Organization: [posted via] Leibniz-Rechenzentrum, Muenchen (Germany)
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

I'm trying to port a DJGPP C-Program to MINGW32.
Problem: reading binary data into structures.

example:
 
typedef unsigned long   ulg;
typedef unsigned int    uint;
typedef          double real;
typedef          float  sreal;
typedef     long double lreal;
typedef unsigned char   byte;
typedef   signed char   sbyte;
typedef   signed char   bool;
typedef struct vp
{
  short  vpi;   /*Variablen-Index*/
  char   kenn;  /*Kennung 'P'aram | 'K'onst | 'H'? */
  short  bs;    /*zugeordnet zu Modul 'bs'*/
  short  opt;   /*fuer BS-Option*/
  short  nr;    /*als 'nr'*/
  short  me;    /*Masseinheit*/
  char * nam;   /*Name*/
  char * dsc;   /*Beschreibung*/
  real   min;   /*Minimalwert*/
  real   dft;   /*default*/
  real   max;   /*Maximalwert*/
  ulg    src;   /*Herkunft aus Modul (bitcodiert)*/
  ulg    dst;   /*Verwendung in Modul (bitcodiert)*/
  ulg    typ;   /*findet Anwendung bei Knotentyp 'typ' (bitcodiert)*/
  ulg    kmb;   /*findet Anwendung bei Modul-Kombination 'kmb'
(bitcodiert)*/
  short  brch;  /*findet Anwendung bei Bereich 'brch' (bitcodiert)*/

  short  otyp;  /**/
  short  omod;  /**/
  short  odat;  /**/
  short  olam;  /**/
  short  ower;  /**/

  short  imen;  /**/
  short  imod;  /**/
  short  idat;  /**/

  short  na;    /**/      /* dta -> alt */
}VP;

...
if(fread(vorp[i],sizeof(struct vp),nel=1,fp)!=nel) return ERROR
...

this leads to vorp[] containing garbage, because of some alignment(?)
issue:
printing `sizeof(struct vp)' gives me _80_ under DJGPP, but _88_ under
MINGW32.

Does anybody know how to force the MINGW-gcc to use the same 
structure alignment / data storage scheme as DJGPP_GCC does, please?

-- 
 Gruss Waldemar Schultz.
 Technische Universität München, Zentrum Mathematik M1, D 80290 München
 Tel: +49 (0)89 2892 8226        FAX: +49 (0)89 2892 8228