Nut upsdev - Oct 2011 - [PATCH] Fix logic error in rhino driver

The if() statement always evaluated to true.
Detected by "cppcheck", not tested on real hardware.

Signed-off-by: Thomas Jarosch <thomas.jarosch at intra2net.com>
---
 drivers/rhino.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/rhino.c b/drivers/rhino.c
index ca66169..e478bcb 100644
--- a/drivers/rhino.c
+++ b/drivers/rhino.c
@@ -187,7 +187,7 @@ AutonomyCalc( int ia ) /* all models */
     {
       currin = ( UtilPowerOut + ConstInt ) *1.0 / Vin;
       auton = ( ( ( AmpH *1.0 / currin ) * 60 * ( ( BattVoltage - VbatMin ) *
1.0 /( VbatNom - VbatMin ) ) * FM ) + FA );
-      if(  ( BattVoltage > 129 ) || ( BattVoltage < 144 ) )
+      if(  ( BattVoltage > 129 ) && ( BattVoltage < 144 ) )
 	result = 133;
       else
 	result = (int) auton;
-- 
1.7.4.4

On Fri, 14 Oct 2011, Thomas Jarosch wrote:
> The if() statement always evaluated to true.
> Detected by "cppcheck", not tested on real hardware.
> --- a/drivers/rhino.c
> +++ b/drivers/rhino.c
> @@ -187,7 +187,7 @@ AutonomyCalc( int ia ) /* all models */
>     {
>       currin = ( UtilPowerOut + ConstInt ) *1.0 / Vin;
>       auton = ( ( ( AmpH *1.0 / currin ) * 60 * ( ( BattVoltage - VbatMin )
* 1.0 /( VbatNom - VbatMin ) ) * FM ) + FA );
> -      if(  ( BattVoltage > 129 ) || ( BattVoltage < 144 ) )
> +      if(  ( BattVoltage > 129 ) && ( BattVoltage < 144 ) )
> 	result = 133;
>       else
> 	result = (int) auton;
Good catch on the bad logic, however, I thought the original intent would
have been:

       if(  ( BattVoltage < 129 ) || ( BattVoltage > 144 ) )
 	result = 133;
       else
 	result = (int) auton;

The idea being that the auton calculation was only valid within the 
defined range.  Also, I've found that range checks are more readable when
coded this way:

       if(  ( 129 < BattVoltage ) && ( BattVoltage < 144 ) )
 	result = (int) auton;
       else
 	result = 133;

(or the other way round if the auton calculation is actually only 
valid outside the range).

--
 	      Stuart D. Gathman <stuart at bmsi.com>
     Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song
for
a Microsoft sponsored "Where do you want to go from here?" commercial.

--- On Fri, 10/14/11, Stuart D. Gathman <stuart at bmsi.com>
> range checks are more readable when coded this way:
>
>      if(  ( 129 < BattVoltage ) && ( BattVoltage < 144 ) )
>          result = (int) auton;
>      else
>          result = 133;
I second this one, but read further.

--- On Fri, 10/14/11, Thomas Jarosch <thomas.jarosch at intra2net.com>
wrote:
> The if() statement always evaluated to true.
> Detected by "cppcheck", not tested on real hardware.
> 
> -      if(  ( BattVoltage > 129 ) || ( BattVoltage < 144 ) )
> +      if(  ( BattVoltage > 129 ) && ( BattVoltage < 144 ) )
  I think the current, ||, logic is fine.  I can't see in what 
circumstances it would yield the wrong decision.  Can anyone point a
scenario where I am wrong?
  I don't know the cppcheck tool.  I wonder weather the modified,
&&, case
should not always evaluated to true, just like the original || case. 
Assuming the tool is correct, my C is not good enough to say what is the exact
problem.  It could be that there is a problem with the types involved.
Leaving aside Stuart, and mine, preferred presentation, can Thomas try 
statements like:

         if(  ( BattVoltage > 129.0 ) || ( BattVoltage < 144.0 ) )
and
         if(  ( (int)BattVoltage > 129 ) || ( (int)BattVoltage < 144 ) )