3 Input Adder in Stratix II Using 1 ALM

[Altera_Forum]

There is a great link on the Altera web page explaining how to implement a 3 input parallel adder in one ALM. 

 http://www.altera.com/products/devices/stratix2/features/architecture/st2-adder.html  I used the "Parallel Add" function in the MegaWizard to try and implement this for a Stratix II GX target.   Unfortunately, it uses 2 ALMs.  Does anybody know if there is a special QII setting or coding style that must be used to get the 1 ALM implementation?  Thanks.

[Altera_Forum]

I just use assign "sum = a+b+c" in Verilog.  

 You need to be a little careful with the grouping in adder trees, matching up the bitwidths, etc. There is some discussion in this manual -  www.altera.com/literature/manual/stx_cookbook.pdf www.altera.com/literature/manual/cookbook.zip