Mismatches Between Multiplier Based MATLAB and RTL Models With Throughput One

For the multiplier-based architecture with throughput = 1 (output every clock cycle), there can be mismatches between the outputs of the MATLAB model and the RTL design for values of magnitude precision. These mismatches seem to be rounding errors for very large values.

Multiplier-based architecture of the NCO MegaCore function with throughput = 1.

The design impact is a comparison of the output values from the MATLAB model and RTL design during testing may show mismatches. However, the error margin is small in both absolute and relative terms. For example, the MATLAB model calculates -536,870,910, whereas the RTL calculates -536,870,911.

The RTL design works correctly, but comparison between the MATLAB model and the RTL cannot be done automatically.

This issue will be fixed in a future version of the NCO MegaCore function.