System and method for providing more logical memory ports than physical memory ports

1. For a configurable integrated circuit (IC) that implements a user design having an associated user design clock cycle, said IC operating on a sub-cycle clock that has multiple sub-cycle periods within a user period of said user design clock cycle, a method of mapping the user design to the configurable IC, the method comprising:

a) identifying accesses to multiple ports of a multi-port memory defined in the user design, said accesses being in a single user design clock cycle; and

b) mapping said accesses to the multiple ports of the multi-port memory to multiple accesses of a particular port of a physical memory in the configurable IC during multiple sub-cycles associated with the single user design clock cycle, wherein the particular port of the physical memory is for accessing the physical memory at least once per sub-cycle period, and the particular port comprises a clock input for receiving clock signals at a first frequency that is a frequency of the sub-cycle clock.

2. The method of claim 1 , wherein the user design includes a first logical port corresponding to both said particular port of the physical memory and a first sub-cycle period within the user period.

3. The method of claim 2 , wherein the user design includes a second logical port corresponding to both the particular port of the physical memory and a second sub-cycle period within the user period.

4. The method of claim 3 , wherein the first logical port is identified by a first logical port number and the second logical port is identified by a second logical port number.

5. The method of claim 4 , wherein a higher logical port number corresponds to a later sub-cycle period.

6. The method of claim 1 , wherein a second frequency is a frequency associated with said user design clock cycle.

7. The method of claim 6 , wherein a number of logical ports corresponding to the particular port of the physical memory is determined by the first frequency divided by the second frequency.

8. The method of claim 1 , wherein said physical memory is accessible by the particular port of the physical memory and by a second port of the physical memory.

9. The method of claim 8 , wherein the user design includes a first logical memory port corresponding to both said particular port of the physical memory and a first sub-cycle period within the user period and a second logical port corresponding to both said second port of the physical memory and said first sub-cycle period within the user period.

10. The method of claim 9 , wherein the user design includes multiple logical memory ports corresponding to the second port of the physical memory and to the multiple sub-cycle periods within the user period.

11. A computer readable medium storing a computer program for mapping a user design having an associated user design clock cycle to a configurable integrated circuit (IC) that implements said user design, said configurable IC operating on a sub-cycle clock that has multiple sub-cycle periods within a user period of said user design clock cycle, said computer program comprising sets of instructions for:

a) identifying multiple simultaneous accesses to a first multi-port memory defined in the user design through a particular number of ports of said first multi-port memory, said multiple simultaneous accesses being in a single user design clock cycle; and

b) mapping said multiple simultaneous accesses to said first multi-port memory to multiple sequential accesses of a second physical-port memory in the configurable IC, through a smaller number of ports than the particular number of ports, during multiple sub-cycles associated with the single user design clock cycle, wherein a first physical port of said second physical-port memory is for accessing the second physical-port memory at least once per sub-cycle period, and the first physical port comprises a clock input for receiving clock signals at a first frequency that is a frequency of the sub-cycle clock.

12. The computer readable medium of claim 11 , wherein the user design includes a first logical port corresponding to both said first physical port and a first sub-cycle period within the user period.

13. The computer readable medium of claim 12 , wherein the user design has a second logical port corresponding to both the first physical port and a second sub-cycle period within the user period.

14. The computer readable medium of claim 13 , wherein the first logical port is identified by a first logical port number and the second logical port is identified by a second logical port number.

15. The computer readable medium of claim 14 , wherein a higher logical port number corresponds to a later sub-cycle period.

16. A reconfigurable integrated circuit (IC) that implements a user design that is specified based on a user design clock cycle, said reconfigurable IC comprising:

a) a physical memory with a physical memory port that operates at a frequency of a sub-cycle clock that is higher than a frequency of the user design clock cycle, wherein the physical memory port of said physical memory is for accessing the physical memory at least once per sub-cycle period, and the physical memory port comprises a clock input for receiving clock signals at the frequency of the sub-cycle clock;

b) wherein said physical memory is accessible through said physical memory port multiple times per the user design clock cycle; and

c) wherein said multiple times during said user design clock cycle correspond to accesses during a single period of the user design clock cycle of multiple memory ports of a multi-port memory in said user design.

17. The reconfigurable IC of claim 16 , further comprising circuits for writing data to said physical memory port once per sub-cycle of said user design clock cycle.