Quartus II Settings File Reference Manual - Altera

6–22 Chapter 6: Fitter Assignments
AUTO_PACKED_REGISTERS_STRATIX
AUTO_PACKED_REGISTERS_STRATIX
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, RAM blocks,
or DSP 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 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 combines 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 DSP blocks and 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:
■ Stratix
■ Stratix GX
Notes
This assignment supports wildcards.
This assignment is included in the Fitter report.
Syntax
set_global_assignment -name AUTO_PACKED_REGISTERS_STRATIX
Quartus Settings File June 2012 Altera Corporation
Reference Manual