Re: how to do this in Ada?

[cet1@cl.cam.ac.uk (C.E. Thompson)]

In article <256@avocado.uucp> garym@sugar.hackercorp.com writes:
> ...
>The C compiler will probably generate a table jump.  But before it can index
>into the table it must make sure that the index is within the range 0..2, that
>takes 2 compares.  ...

A common fallacy. With any machine instruction set that you care to name,
you will find that you can test a value for being in the range a..b with 
an add/subtract and one compare (and subsequent conditional branch): usually
a subtract of 'a' and an unsigned comparison with 'b-a'. If a is zero, as
here, the subtract disappears as well.

Of course, this applies to the Ada range test as well.

Chris Thompson
JANET:    cet1@uk.ac.cam.phx
Internet: cet1%phx.cam.ac.uk@nsfnet-relay.ac.uk