Lpc2000

I am impressed GCC for ARM looks to use genuine jump tables.

This is how the code worked in an assembly listing.

A branch to a jump table was made if the value passed in was between 
the minimum and maximum case values. This took only three instructions:
sub...  ;subtract minimum from value passed in
cmp...  ;compare result with maximum-minimun constant value
ldrls pc,...   ;if result is less than maximum-minimum then use result 
as as an index value into a table to determine where to branch to next

The size of the jump table is the difference between the maximum and 
minimum case values + 1. The jump table contained one of two values: a 
location to branch to corresponding to the action to take if any of the 
case values was satisfied or a location to branch to if there was no 
case match between the minumum and maximum case values.

John Heenan



--- In lpc2000@yahoogroups.com, "Gus" <gus_is_working@y...> wrote:
>
> I think you are right! It generats a 240 byte jump table! Still seem 
> to be overkill
> 
> Gus