CODEWITHSUNDEEP
c
izlin
izlin

Reputation: 2138

do ... while macro/function with different conditions

I have the following code:

/* some calculation */
do {
  /* data acquire and calculation */
} while (CONDITION);

My condition looks like one of the following:

(( A || B ) && C )
( A && C )

Note that I use these conditions with different statements for A, B and C. However the pre-calculation and everything inside the loop is always the same. I use this block several times in my code and wondered if there is a possibility to put it in a define or in a function to let the code look cleaner.

Is there a nice and reasonable way to achieve the loop with different statements?

I already thought about a function call in a while loop like

while (DoMyLoop( CONDITION, calculationParams ));

But with this solution I wouldn't have the pre-calculation in my one-liner.

How can I get my code block in a nice one-liner (or more if necessary, as long as it's easy to understand and maintain)?

Some additional (maybe irrelevant) information:

In my loop I receive a byte array and depending on the situation I have to loop until a specific bit changes, therefore the A or B.

C is a timeout condition.

Here is some code with variables

unsigned char data[10] = { 0 };
long intervalMS = 0;

/* precalc */
gettimeofday( &stopTimeout, NULL );
gettimeofday( &startTimeout, NULL );

do {
  receiveCall( data );
  gettimeofday( &stopTimeout, NULL );
  intervalMS = (stopTimeout.tv_sec - startTimeout.tv_sec) * 1000 +
             (stopTimeout.tv_usec - startTimeout.tv_usec) / 1000;
} while ( (data[0] & 0x01) && intervalMS < 200);

The A part of the condition can also look like ((data[2] & 0x02) || data[3] == 0x12).

Upvotes: 0

Views: 191

Answers (2)

Lundin
Lundin

Reputation: 213266

First of all, please note that do {} while(something) is equivalent to something=true; while something{}. The former saves a bit of extra execution in case you don't want the initialization part.

How can I get my code block in a nice one-liner

There is nothing wrong with your code. } while ( (data[0] & 0x01) && intervalMS < 200); is perfectly clear to me - another C programmer.

You check if the lsb is set and you check a timer interval. The only way this code could be improved would be to explain why you check the lsb - which you can do with a comment (do you check if a number is odd or do you read a bit in bit-field etc).

Now what you can and should do, is to put the whole snippet inside a function and give it a meaningful name. There's the nice one-liner.

Upvotes: 0

Pierre Fran&#231;ois
Pierre Fran&#231;ois

Reputation: 6061

What about next solution? 

for (precalculation (); CONDITION; somethingWith (calculationParams));

precalculation () is executed once, the CONDITION is evaluated at every iteration and somethingWith (calculationParams) take the place in of the incrementation. The body of the for loop is empty.

Pure C beauty.

Obviously, precalculation and somethingWith (calculationParams) must become a new function.

Upvotes: 1

Related Questions