Ada array vs C pointer (call by reference)

[Adrian Hoe <abyhoe@gmail.com>]

Hi,

I have a C library function which takes a float * as a parameter. The
function is as below:

   int pwmRead (int pwmCount, float * data);

where data is an array of float which size is determined by pwmCount.

In Ada, I have:

   PWM_Count : Integer := No_Of_Components_Intended;
   PWM_Data : array (1 .. PWM_Count) of Float;

My concern is how safe to pass an Ada array to a C function as a
pointer (call by reference)? I presume Ada will allocate contiguous
memory for array, but what if it does not? How can we establish a
deterministic allocation and to make sure float * is accessed
contiguously? Is there any "safe" way to do this?

Thanks.
--
Adrian Hoe
http://adrianhoe.com