How to replace this switch with preprocessor code

[Rohit]

Hi,

I am working on a switch module which after reading voltage through a
port pin and caterogizing it into three ranges(open,low or high),
passes this range to a function switch_status() with parameters value
and signal ID. Signal Id is used to get a user configurable parameter
inside a configuration file, which depends on the type of switch.

I have implemented it as under. Please ignore those magic numbers as I
have mimized logic to simplify it. Now I want to optimize it. Somebody
told me that the logical connection between variables: value,
switchconfTable[signal_id].contact and the return value(TRUE or FALSE)
should be solved via preprocessor not code.

I am unclear about what it means. Can anybody suggest an insight what
it means ?

.h file

typedef enum
{
Switch_Low, /*!< 0 - value of digital Input is low */
Switch_High, /*!< 1 - value of digital Input is high */
Switch_Open /*!< 2 - value of digital input being not
connected (break) */
} Switch_value_t;

.c file
/* This function is called after determining that value
is in one of the ranges defined by Switch_value_t */
int static switch_status(Switch_value_t value, signal_id)
{
int retval = 0;
switch(value)
{
case Switch_Low:
{
if(switchconfTable[signal_id].contact==0x01)
retval = 1;

else
retval = 2;

}

case Switch_High:
/* Similar code as Switch_Low case*/

case Switch_Open:
/* Similar code as Switch_Low case*/
}

return retval;
}

Cheers
Rohit
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[Jasen Betts]

On 2008-07-04, Rohit <papak...@gmail.com> wrote:
> Hi,
>
> I am working on a switch module which after reading voltage through a
> port pin and caterogizing it into three ranges(open,low or high),
> passes this range to a function switch_status() with parameters value
> and signal ID. Signal Id is used to get a user configurable parameter
> inside a configuration file, which depends on the type of switch.
>
> I have implemented it as under. Please ignore those magic numbers as I
> have mimized logic to simplify it. Now I want to optimize it. Somebody
> told me that the logical connection between variables: value,
> switchconfTable[signal_id].contact and the return value(TRUE or FALSE)
> should be solved via preprocessor not code.

I can't see how that's possible unless the configueation file is
compile-time configuration.

Bye.
Jasen