Re: Is this ground dead? Also, info on Mach that's more recent

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Mark said

<<The C language has provided a syntax for bit fields since the late 70's.
The disadvantage of C's syntax viz Ada's is that you have to explicitly
insert dummy fields in the record if you want non-contiguous fields.
Conversely, C lacks the strong type checking that can make it more
difficult to work with bit fields in Ada.  I write these lines based in
personal experience:  without careful type definition, unchecked conversions
become rampant when Ada is used at the bit level.
>>

The C facilities are far more primitive. In particular the bit fields in
C can only be applies to integral types (you cannot use them for float
types, or even for enumeration types). Yes, you can rig things up with
bit fields, but it is often complex and implementation dependent to do so.


As for what can happen without careful type definition, rampant unchecked
conversions are the least of the problems. If there is one place where
care is needed (and good training and design sense counts for a lot) it
is in proper design of types.

Properly written low level code in Ada is cleaner and easier to read
than corresponding low level code in C, for the simple reason that Ada
provides more extensive facilities in this area.