From: "ldries46" <bertus.dries@planet.nl>
Subject: Garbage Collection ???
Date: Fri, 13 Apr 2012 14:14:43 +0200
Date: 2012-04-13T14:14:43+02:00 [thread overview]
Message-ID: <4f881910$0$2652$703f8584@news.kpn.nl> (raw)
I am creating a program within GNAT Programming Studio in which I have to
create A List of the model
edges : ptr_Node;
where ptr_Node is
.....
.....
next : ptr_edge;
end record;
This structure is called throughout my program extensively with no problems
but within a declare begin ... end
part of the form
declare
stold_Points : ptr_Node;
old_Points : ptr_Node;
begin
stold_Points := new Node;
...
...
end;
This program part is run within a while loop.
Now the following occurs:
I get a segmentation fault on line 196 within the program lines:
edges := stedges;
while edges /= NULL loop
Edge_Force(edges);
line 196 edges := edges.next;
end loop;
with the fault message:
Program received signal SIGSEGV, Segmentation fault.
0x0054694c in falling.falling_ball (file_name=..., version=...) at
E:\ada\project\Cell_3D\Source Files\Falling.adb:196
At the point the program is stopped I get the following values printed
(gdb) print stedges
$9 = (access general.edge) 0x3e2dbf8
(gdb) print edges
$8 = (access general.edge) 0x0
The fault is the result of the last result that is clear edges = NULL when
edges.next is called
but as the code of Edge_Force is
procedure Edge_Force(edge1 : ptr_Edge) is
len : float;
begin
len := Length(edge1.P1.pnt, edge1.P2.pnt) - edge1.l_init;
if abs(len / edge1.l_init) < 0.00001 then
len := 0.0;
end if;
edge1.force := edge1.k_s * len;
end Edge_Force;
I don't change the value of edges so as I read it edges could not be NULL at
that point.
What also causes the changed value of edges within the loop. Can it be some
garbage problem.
At the moment the fault occurs the outer loop has run for at least serveral
hundred times
L. Dries
next reply other threads:[~2012-04-13 12:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-13 12:14 ldries46 [this message]
2012-04-13 13:20 ` Garbage Collection ??? Dmitry A. Kazakov
2012-04-13 19:27 ` ldries46
2012-04-13 20:06 ` Dmitry A. Kazakov
2012-04-13 22:49 ` Brian Drummond
2012-04-14 3:21 ` ldries46
2012-04-14 18:21 ` Robert A Duff
2012-04-18 9:07 ` Julian Leyh
2012-04-19 14:36 ` Robert A Duff
2012-04-19 20:26 ` Randy Brukardt
2012-04-20 7:11 ` Dmitry A. Kazakov
2012-04-21 0:46 ` Randy Brukardt
-- strict thread matches above, loose matches on Subject: below --
1992-04-22 18:55 Garbage collection? dog.ee.lbl.gov!overload.lbl.gov!agate!spool.mu.edu!yale.edu!jvnc.net!darw
1992-04-21 23:48 Robert I. Eachus
1992-04-21 23:02 Rick Hudson
1992-04-21 21:09 titan.ksc.nasa.gov!mcroberts
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