Method and Apparatus for Implementing Soft Constraints in Tools Used for Designing Programmable Logic Devices

Abstract

A method for designing a system on a target device utilizing programmable logic devices (PLDs) includes generating options for utilizing resources on the PLDs in response to user specified constraints. The options for utilizing the resources on the PLDs are refined independent of the user specified constraints.

What is claimed is: 
     
         1 . A method for designing a system on a target device, comprising:
 determining a routing on the target device for a signal in response to a user specified routing constraint; and   determining an alternate routing on the target device for the signal independent of the user specified routing constraint, wherein at least one of the determining is performed by a processor.   
     
     
         2 . The method of  claim 1 , wherein determining the routing comprises identifying one or more routing resources on the target device for routing the signal from a source to a destination. 
     
     
         3 . The method of  claim 1 , wherein determining the alternate routing on the target device for routing the signals is performed in response to reaching a threshold number of attempts in determining the routing. 
     
     
         4 . The method of  claim 1 , wherein determining the alternate routing on the target device for routing the signal is performed in response to the routing not satisfying design parameters. 
     
     
         5 . The method of  claim 1 , wherein the user specified routing constraint pertains to a category of routing resources. 
     
     
         6 . The method of  claim 1 , wherein the user specified routing constraint pertains to a location of routing resources. 
     
     
         7 . The method of  claim 1 , wherein the user specified routing constraint pertains to a speed of routing resources. 
     
     
         8 . A method for designing a system on a target device, comprising:
 determining a first location on the target device to place a component in response to a user specified constraint for placement of the component; and   determining a second location to place the component independent of the user specified constraint, wherein at least one of the determining procedures is performed by a processor.   
     
     
         9 . The method of  claim 8 , wherein determining the second location to place the component is performed in response the first location not satisfying design parameters. 
     
     
         10 . The method of  claim 8 , wherein the design parameters comprise timing requirements. 
     
     
         11 . The method of  claim 8 , wherein determining the second location to place the component is performed in response to reaching a threshold number of attempts in determining the first location. 
     
     
         12 . The method of  claim 8 , wherein the user specified constraint comprises a predetermined location on the target device. 
     
     
         13 . The method of  claim 8 , wherein the user specified constraint comprises a grouping of the component with other components in a logic region, wherein the logic region includes a subset of components of the system to be placed on the target device. 
     
     
         14 . A non-transitory computer readable medium including a sequence of instructions stored thereon for causing a computer to execute a method comprising:
 determining a first location on the target device to place a component in response to a user specified constraint for placement of the component; and   determining a second location to place the component independent of the user specified constraint, wherein at least one of the determining procedures is performed by a processor.   
     
     
         15 . The non-transitory computer readable medium of  claim 14 , wherein determining the second location to place the component is performed in response the first location not satisfying design parameters. 
     
     
         16 . The non-transitory computer readable medium of  claim 14 , wherein the design parameters comprise timing requirements. 
     
     
         17 . The non-transitory computer readable medium of  claim 14 , wherein the user specified constraint comprises a predetermined location on the target device. 
     
     
         18 . The non-transitory computer readable medium of  claim 14 , wherein the method further comprises:
 determining a routing on the target device for a signal in response to a user specified routing constraint; and   determining an alternate routing on the target device for the signal independent of the user specified routing constraint, wherein at least one of the determining is performed by a processor.   
     
     
         19 . The non-transitory computer readable medium of  claim 18 , wherein determining the alternate routing on the target device for routing the signal is performed in response to the routing not satisfying design parameters. 
     
     
         20 . The non-transitory computer readable medium of  claim 18 , wherein the user specified routing constraint pertains to a category of routing resources. 
     
     
         21 . The non-transitory computer readable medium of  claim 18 , wherein the user specified routing constraint pertains to a speed of routing resources.