Quartus II Settings File Reference Manual - Altera

6–18 Chapter 6: Fitter Assignments
AUTO_PACKED_REGISTERS_CYCLONE
AUTO_PACKED_REGISTERS_CYCLONE
Type
Allows the Compiler to automatically implement a register and a combinational
function in the same logic cell, or to implement registers using I/O cells or RAM
blocks instead of logic cells. This option controls how aggressively the Fitter combines
registers with other function blocks in order to reduce logic element count. If this
option is set to Off, the Fitter does not attempt to place a pair of logic functions in a
single logic cell; however, logic cells specified during synthesis to perform both a
combinational and a sequential function are maintained. If this option is set to
Normal, the Fitter places both a combinational and a sequential operation in a logic
cell when it is expected that the placement does not affect design performance. When
this option is set to Minimize Area, the Fitter aggressively combines unrelated
sequential and combinational functions that are not part of an arithmetic or register
cascade chain into a single logic cell in order to reduce the logic cell count, even at the
expense of design performance. When this option is set to Minimize Area with
Chains, the Fitter even more aggressively combines sequential and combinational
functions that are part of arithmetic or register cascade chains or that can be converted
to register cascade chains. When this setting is Auto, the fitter attempts to achieve the
best performance while maintaining a fit for the design in the specified device. The
fitter will combine all combinational and sequential functions that are deemed to
benefit circuit speed. In addition, more aggressive combinations of unrelated
combinational and sequential functions are performed to the extent required to
reduce the area of the design in order to achieve a fit in the specified device. If this
option is set to any value but Off, registers are merged with I/O cells to improve I/O
timing, and with RAM blocks to reduce logic cell count or improve timing when
possible.
Enumeration
■ Auto
■ Minimize Area
■ Minimize Area with Chains
■ Normal
■ Off
Device Support
This setting can be used in projects targeting the following device families:
■ Cyclone
Notes
This assignment supports wildcards.
This assignment is included in the Fitter report.
Syntax
set_global_assignment -name AUTO_PACKED_REGISTERS_CYCLONE
Quartus Settings File June 2012 Altera Corporation
Reference Manual