[sdcc-devel] [ sdcc-Bugs-1376320 ] sign error in datatype long

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Bugs item #1376320, was opened at 2005-12-08 15:27
Message generated for change (Comment added) made by maartenbrock
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Category: msc51(8051) target
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: sign error in datatype long

Initial Comment:
Hi,

We have found a serious bug when using 32-bit signed values for the 
8051 target. We have attached a code-snippet that can reproduce the 
problem.

When using SDCC the compiler treats the signed value as unsigned.
The code-snippet that we have attached works when compiled with KEIL, 
but not in SDCC. We are using a Nordic VLSI nRF24E1 board.

We have been using SDCC 2.5.0 #1020 (Aug 16 2005), on a Gentoo-box.
we have compiled the c-program with the command 
"sdcc -mmcs51 signed.c -o signed.hex"

There is no error-message, it just produces wrong code.

Kind Regards,

Sidsel Jensen (pu...@di...) &
Anders Egeskov (eg...@di...)

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>Comment By: Maarten Brock (maartenbrock)
Date: 2005-12-10 11:42

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Allthough sfr definition is different, that is not the 
issue. The real problem is that SDCC reduces the if 
statement to P0 = 0x00. And it happens for short int too, 
only not for char.

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Comment By: Jesus Calvino-Fraga (jesusc)
Date: 2005-12-10 09:31

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Definition of special function registers in Keil and sdcc 
is different.  Please try again using the right syntax for 
sdcc (section 3.4.1.7 of the user manual):

sfr at 0x80 P0;
sfr at 0x94 P0_DIR;

Jesus



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Comment By: Sidsel Jensen (purplehex)
Date: 2005-12-09 23:48

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here is the code-snippet that wasn't uploaded:

sfr P0 = 0x80;
sfr P0_DIR = 0x94;

void main(void) {
  signed long dat;
  unsigned long comp;
  
  P0_DIR = 0x00;
  dat = 3;
  comp = 5;
  dat -= comp;
  if(dat<0) P0 = 0xFF; else P0 = 0x00;
}

/Sidsel

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Comment By: Bernhard Held (bernhardheld)
Date: 2005-12-08 15:40

Message:
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There's no attachment!

You can't attach anything unless you're logged in to SF.

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