Standart VHDL function that rounds down numbers

[shaiko]

Hello,

Is there a standard VHDL function that accepts real numbers and rounds them down?
For example:

signal x : real
x <= 14.6 ;

A function that when applied on X will return 14.0

 

[ads-ee]

function FLOOR (X : real ) return real;

There is also a corresponding CEIL function

 

[TrickyDicky]

and the trunc function too.

x <= trunc(14.6);

 

[shaiko]

What's the functional deference between "floor" and "trunc"?

 

[ads-ee]

without looking at the actual package body the fucntion descriptions seems to indicate semantically different but identical behavior.

 

[mrflibble]

Presumably floor() and trunc() will give different results for negative numbers.

floor(-42.42) = -43

trunc(-42.42) = -42

 

[shaiko]

Different result for negatives and same result for positives?

 

[mrflibble]

Yes. From the man pages:

floor(x)
... return the largest integral value that is not greater than x.

trunc(x)
... round x to the nearest integer not larger in absolute value.