Re: problem using INTERFACE_BUFFER

At 12:09 PM 12/23/02, [email protected] wrote:
> >
> > In several places there are "if () elseif () elseif()..." sequences that
> > can be nicely replaced by switches.  eps.c, content.c, and encode.c are
> > places where I've done this.
>
>Well, the question here becomes (for me at least; since this is a parser
>library),
>which is going to be the most efficient, or is there no difference after
>the compiler interprets the code?

Assuming sequential values (such as an enum generates by default), the 
switch statement will be a tad bit faster.  With the if statements, there 
are multiple "compare, branch" sequences.  Branching is bad for any sort of 
pipelined cpu.  With the switch statement, there's an initial bounds check 
and then a branch through a transfer vector.

The biggest effect is on readability because the structure of the switch 
and its case statements are obvious at a glance.  When I see 
if...else...if..else.., it is necessary to read every test since there is 
no homogeneity requirement.  With a switch, the conditional value is stated 
at the beginning and the values it compares against are all constants.  The 
statement can be scanned (rather than read).