register packing Definition

This feature allows you to combine a register with a combinational function in the same logic cell, or to merge into I/O cells, RAM blocks, or DSP blocks. This option is useful for reducing logic element count in a design and improving performance.

Packing registers into the DSP blocks is essential to achieve maximum performance. Refer to the Fixed Point DSP Register Packing Summary and Fixed Point DSP Register Packing Details Compilation Reports to determine where to implement register packing improvements.

To direct the Compiler to automatically implement register packing for appropriate pairs of logic functions, you set Auto packed registers to Auto in Assignments > Assignment Editor or by clicking Assignments > Settings > Compiler Settings > Advanced Settings (Fitter).

Alternatively, you implement register packing manually by setting the global QII_AUTO_PACKED_REGISTERS logic option in your tcl script.