[sdcc-devel] [ sdcc-Bugs-717503 ] Certain breakpoints produce memory fault in s51

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Bugs item #717503, was opened at 2003-04-08 15:14
Message generated for change (Comment added) made by maartenbrock
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Category: msc51(8051) target
Group: fixed
Status: Pending
Resolution: Fixed
Priority: 5
Submitted By: Vladimir Támara Patiño (vtamara)
Assigned to: Borut Razem (borutr)
Summary: Certain breakpoints produce memory fault in s51

Initial Comment:
/* This program  (s51cell.c) just increments a counter
in
  each tick interruption.  The following sequence
produces
  a memory fault with the CVS version of s51:

$ sdcc s51cell.c
$ s51 s51cell.ihx 
uCsim 0.4.1-pre5, Copyright (C) 1997 Daniel Drotos,
Talker Bt.
uCsim comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.
This is free software, and you are welcome to
redistribute it
under certain conditions; type `show c' for details.
193 words read from s51cell.ihx
0> b 0xb
Breakpoint 1 at 0x00000b: LJMP  0038
0> r
Simulation started, PC=0x000000
Stop at 0x00000b: (104) Breakpoint
0x00 00 00 00 00 00 00 00 00 ........
000000 00 .  ACC= 0x00   0 .  B= 0x00   DPTR= 0x0000
@DPTR= 0x00   0 .
000000 00 .  PSW= 0x00 CY=0 AC=0 OV=0 P=0
F? 0x000b 02 00 38 LJMP  0038
F 0x00000b
0> s
0x00 00 00 00 00 00 00 00 00 ........
000000 00 .  ACC= 0x00   0 .  B= 0x00   DPTR= 0x0000
@DPTR= 0x00   0 .
000000 00 .  PSW= 0x00 CY=0 AC=0 OV=0 P=0
 ? 0x0038 c0 e0    PUSH  ACC
0> b s w 0x88
0> r
Simulation started, PC=0x000038
Memory fault (core dumped) 

*/

sbit at 0xAF EA;  /* Enable/Disable all interrupts */
sfr at 0x8C TH0;  /* T0 counter high byte */
sfr at 0x8A TL0;  /* T0 counter low byte */
sfr at 0x89 TMOD; /* Timer mode */
sbit at 0xA9 ET0; /* Enable/Disable timer 0
interruption */
sbit at 0xB9 PT0; /* Priority of timer 0 interruption
*/
sbit at 0x88 IT0; /* Trigger condition */
sbit at 0x8C TR0; /* Enable/Disable timer */

long c=0;
void tickISR() interrupt 1 _naked {
_asm
        ar2 = 0x02
        ar3 = 0x03
        ar4 = 0x04
        ar5 = 0x05
        ar6 = 0x06
        ar7 = 0x07
        ar0 = 0x00
        ar1 = 0x01
        push    acc
        push    b
        push    dpl
        push    dph
        push    ar0
        push    ar1
        push    ar2
        push    ar3
        push    ar4
        push    ar5
        push    ar6
        push    ar7
        push    psw
        mov     psw,#0x00
_endasm;
        c++;
_asm
        pop psw
        pop     ar7
        pop     ar6
        pop     ar5
        pop     ar4
        pop     ar3
        pop     ar2
        pop     ar1
        pop     ar0
        pop     dph
        pop     dpl
        pop     b
        pop     acc
        reti
_endasm;
}

void main() {

        EA=0;   /* Disable all interruptions */
        TH0=0x00; /* Initial count */
        TL0=0x00;
        TMOD=0x01; /* Mode 16 bits. */
        ET0=1; /* Enable t0 overflow interruption */
        PT0=1; /* High Priority */
        IT0=0; /* Low level triggered */
        TR0=1; /* Enable timer */
        EA=1;  /* Enable interruptions */
label:
        goto label;
}



----------------------------------------------------------------------

>Comment By: Maarten Brock (maartenbrock)
Date: 2006-01-29 14:12

Message:
Logged In: YES 
user_id=888171

Borut,

I followed the above sequence and got no memory fault. The 
line "b s w 0x88" was not recognized, but "b sfr w 0x88" 
was. Unfortunately I know close to nothing about the 
simulator.

But the OP also filed a patch (756476) to fix this bug 3 
months after the bug report ! And it took us developers 
almost 3 years to implement? I feel ashamed.

I hope we can close this one soon.
Maarten

----------------------------------------------------------------------

Comment By: Borut Razem (borutr)
Date: 2006-01-28 14:39

Message:
Logged In: YES 
user_id=568035

The uninitialized variable problem was solved 5.11.2005 in
sdcc version 1147.
Vladimir and bronson, can you please verify if the problem
is solved?

Borut

----------------------------------------------------------------------

Comment By: Luc_Claeys (luc_claeys)
Date: 2006-01-28 13:42

Message:
Logged In: YES 
user_id=1438374

I had also s51 simulator memory fault when starting after
setting breakpoints.  It was caused by a non-initialized
variable in s51.  The patch for sdcc-2.5.0 / uCsim 0.5.4 is
very simple and is listed  below.

*** sdcc.orig/sim/ucsim/sim.src/mem.cc  2004-07-27
15:42:52.000000000 +0200
--- sdcc/sim/ucsim/sim.src/mem.cc       2006-01-25
15:31:33.000000000 +0100
***************
*** 430,435 ****
--- 430,436 ----
    flags= CELL_NON_DECODED;
    width= 8;
    *data= 0;
+   operators= 0;
  
  #ifdef STATISTIC
    nuof_writes= nuof_reads= 0;


----------------------------------------------------------------------

Comment By: Scott Bronson (bronson)
Date: 2003-07-13 13:22

Message:
Logged In: YES 
user_id=30977

s51 also often dies if you try to set a breakpoint at
location 0.
Even when it doesn't die, it won't stop there when you hit run
immediately after reset.

----------------------------------------------------------------------

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