Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!gatech!udel!mmdf
From: gay%CLSEPF51.BITNET@cunyvm.cuny.edu (David Gay)
Newsgroups: comp.sys.amiga
Subject: Re: 80286- er, 68000 memory models
Message-ID: <2672@louie.udel.EDU>
Date: 22 May 88 19:46:52 GMT
Sender: mmdf@udel.EDU
Lines: 47


Let's try & clear this all up :

1) There are never any problems calling the shareable libraries (the
interface is (& was recently) precisely described). They don't use any
of the small, tiny, large ... you name it models.
   When you call them from C, you go through a stub (except if you use
Lattice's pragmas) which transfers the arguments from the stack to the
registers (*).

In C:

2) The pointers are *always* 32 bits.

3) The differnt "models" are only used "internally" by the C compilers
(that is, to refer to their own code & data). Thus the *C* libraries
must come in several versions (in Lattice V4, you have short & long int's
plus some rarely used ones which use "large" data internally).

4) The PC-relative/absolute code methods can be mixed freely.

5) absolute data modules can refer to all the data, "small" code only
to that in the __MERGED hunk (in Lattice)

6) I repeat, all this only affects your C code, and in no way impedes
access to the ROM.

I hope this doesn't generate even more confusion :-)

David Gay              EPFL, Ecole Polytechnique Federale de Lausanne
GAY@CLSEPF51.bitnet    Switzerland

Glorf !

Disclaimer: They don't even know I exist. I'm hiding away in the
computer room.


(*) I once followed a call to an intuition routine: this was what was
happening:
  C calculates the parameters (in registers), stuffs them on the stack
  Calls the stub routine
  stub routine puts them in the registers, calls intuition
  In the rom, the parameters are put back on the stack (:-))
  The actual routine is called ... and reads some of the stack into
  registers.
Fun !