AVR-Chat

--- In AVR-Chat@yahoogroups.com, Eric <erichards@c...> wrote:
> In C/C++ there is a "case" statement, is there such a thing
> in assembly code? and is there a example around.

There are two ways to implement the logic of a switch/case.  Which 
one is chosen depends on the circumstances.  If the case values are 
constant and are mostly contiguous, the best way is to use a jump 
table, i.e., a table of addresses of code that handles each case.  
You index the table by the selection value, load r31:r30 and do an 
ijmp (or icall).

On the other hand, if the case values are scattered or are not 
constant (think of a Basic select case statement) you probably will 
be best served by a series of tests - essentially an if/elseif/else 
chain.  Sometimes the two methods can be combined to handle the range 
of expected values.

The C compiler generates code using one or the other of these 
strategies (or a combination) depending on the nature of the switch.

Don