18x18 multipiler

[Ex-NISH2]

I got an error of using 240 multiplier out of 136 multipliers on the FPGA.  I replaced around 40 'scale by power of 2' with 'logic shift', and got the compile successful.  But the summary shows around 60 multipliers are used.  My questions:

1. Is 'scale by power of 2' using multiplier?

2. How many does it uses for I32 in I32 out 'scale by power of 2'?

3. Could the compiler got a false alarm of multiplier overloading before some optimization?

[jdigiova]

The scale by power of 2 should not be using multiplies.  They do require a lot of resources if you are using a control as the input to the power terminal. Also the bigger the control the more resources it will use. For example, an I32 control will consume much more resources than an I8.  Note however that if you use a constant for the power input then the operation is free and doesn't use any resources or time.

The compiler should not get a false alarm for overmapping multiplies.  Did you get this error in the dialog that pops up after a compile finishes?  Do you still have the code?

Regards,

Joseph D.

National Instruments