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+---- Thread: MISRA C - Rule 12.12 (/showthread.php?tid=983)
MISRA C - Rule 12.12 - Akhil - 18-09-2013
Just wanted to know if Line 3 in the following case is a violation for Rule 12.12 ...??
1. int i;
2. float f=2.1;
3. i=(int)f >>2; //Typecasting should actually take care of the bit implementation of floats
Also, If its a violation to Rule 12.12..Does that mean all typecasts (from float to any other type) should also be considered as violationg this rule..?
Re: MISRA C - Rule 12.12 - Steve Montgomery - 01-10-2013
In my opinion, Rule 12.12 intends to prevent direct access to the representation of floating-point values. This might typically be achieved using either a union or pointer casts, for example:
Code:
unsigned int tmp = *(unsigned int *)&f; /* get the float as 32-bit int */
tmp = tmp ^ 0x80000000; /* flip the sign bit */
f = *(float *)&tmp; /* store the result back */I don't think that casting a floating-point value to int violates Rule 12.12 because there is no direct access to the representation of the value. In addition, the conversion is well-defined in that the floating point value is truncated towards zero with the result being undefined only if the truncated value won't fit in the integer type.
Re: MISRA C - Rule 12.12 - misra-c - 13-12-2013
This example does not violate rule 12.12 as there is no access to the underlying floating representation as discussed by Steve in a previous post.