You can define the following types of constraints in a GCF constraint file:
Note: Only ProASIC devices support GCF Timing commands. All other GCF commands are supported by both ProASIC and ProASICPLUS devices. Use the SDC timing commands to import timing constraints for ProASICPLUS devices.
Designer supports the following GCF commands.
GCF Timing Commands |
Action |
Creates a clock and defines its period and waveform | |
Modifies the way Designer generates internal path constraints for the placer to do timing-driven placement | |
Defines false paths in the design; false paths are not considered in the timing driven place-and-route system | |
Defines the timing budget for incoming signals to reach a register | |
Constrains the maximum delay on paths | |
Defines how many clock cycles a signal has to travel through these paths | |
Defines the timing budget for outgoing signals to be clocked out | |
GCF Placement Commands |
Action |
Specifies a specific subset of critical ports on a net | |
Specifies critical nets and their relative criticality over other critical nets. | |
Identifies design I/O ports that have above-normal criticality | |
Specifies a location in which no I/O pin should be placed | |
Specifies a location in which no cell should be placed | |
Initially assigns package pins to I/O ports or sets the location of I/O ports | |
Initially sets the location of a cell instance at specified x, y coordinates | |
Either assigns package pins to I/O ports or sets the location of I/O ports at a specified location on a device | |
set_io_region |
Places specific I/O instances into a target rectangular region |
Assigns a cell instance to the specified x,y coordinates | |
Creates and assigns memory to a region | |
Places all the connected instances, driver, and all the driven instances for the net(s) into the specified rectangle | |
Global Resource Commands |
Action |
Disables the default action that automatically corrects the choice of global assignment to use only the highest fanout nets | |
Specifies the name of the constraint file containing the constraints to use | |
Specifies the maximum number of global resources to use | |
Sets the minimum fan-out a net must have to be considered for automatic promotion to a global | |
Classifies the specified nets as global nets | |
Classifies nets to avoid automatic promotion to global nets | |
Specifies a single spine (LocalClock) or a rectangle of spine region which may encompass more than one spine region | |
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Netlist Optimization Commands |
Action |
Removes buffers or inverters from the netlist | |
Enables you to selectively disable optimization of named hierarchical instances | |
Turns on all netlist optimizations (the default mode | |
Sets the maximum fan-out limit on the specified nets when optimizing buffers and inverters |