Path: utzoo!mnetor!uunet!husc6!hao!noao!arizona!rupley
From: rupley@arizona.edu (John Rupley)
Newsgroups: comp.sources.bugs
Subject: Re: A couple of nethack bug fixes
Message-ID: <3308@megaron.arizona.edu>
Date: 24 Dec 87 11:36:22 GMT
References: <339@gaia.UUCP>
Organization: U of Arizona CS Dept, Tucson
Lines: 45
Summary: nethack 80286-specific bug in mklev.c


In article <339@gaia.UUCP>, Jonathan Corbet writes
> I found the answer to the bug I posted the other day, wherein the dungeon
> was simply devoid of objects on Microport systems.  I'm not sure of the
> bug is in the nethack code, or in the Microport C compiler.

The bug is in the code, which is broken for 80286 machines but not for
the likes of Vaxen, where longs and ints have the same width.

> What happens
> is that the result of the somex() and somey() macros in mklev.c are "xchar"
                                                                       ^^^^^
In fact, they are longs, typed by the rand() call in the macros.

> values, while the mkgold() and mkobj_at() routines expect full integers.
> Most compilers will widen the values accordingly, but not here...

Not quite... one long on the stack is read as two integers by the 
function, garbaging both integer parameters; thus the compiler is doing 
what it should.

> The fix
> is to go into mklev.c, and change lines like
> 	mkgold (0L, somex (), somey ());
> to 
> 	mkgold (0L, (int) somex (), (int) somey);
> and similarly with the mkobj_at() calls.  I think there were only three
> that needed to be changed.

Right, but it is simpler to make the cast from long to int in the 
#defines for the somex and somey macros:

#define somex() (int )((rand()%(croom->hx-croom->lx+1))+croom->lx)
#define somey() (int )((rand()%(croom->hy-croom->ly+1))+croom->ly)

some[xy] are defined as long also in fountain.c, but they are harmlessly 
truncated to int in the code.


John Rupley
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