초록 ▼

In a method for fetching instructions in an embedded system, a predicted one of a set of the instructions stored in a memory device is fetched and is subsequently stored in an instruction buffer when a system bus is in a data access phase. When a processor generates an access request for the memory

In a method for fetching instructions in an embedded system, a predicted one of a set of the instructions stored in a memory device is fetched and is subsequently stored in an instruction buffer when a system bus is in a data access phase. When a processor generates an access request for the memory device, the predicted one of the instructions stored in the instruction buffer is provided to the system bus for receipt by the processor upon determining that the predicted one of the instructions stored in the instruction buffer hits the access request from the processor. An embedded system with an instruction prefetching device is also disclosed.

대표청구항 ▼

What is claimed is: 1. An instruction prefetching device adapted for use in an embedded system that comprises a system bus, a processor coupled to the system bus, at least one peripheral controller coupled to the system bus, and a memory device, said instruction prefetching device comprising: a mem

What is claimed is: 1. An instruction prefetching device adapted for use in an embedded system that comprises a system bus, a processor coupled to the system bus, at least one peripheral controller coupled to the system bus, and a memory device, said instruction prefetching device comprising: a memory controller coupled to said memory device for serving as an input/output interface of said instruction prefetching device and said memory device and for fetching an instruction from said memory device; an instruction buffer coupled to said memory controller, for storing the instruction fetched by said memory controller; and a prefetching controller coupled to said system bus, for monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not, wherein when said system bus is in the data access phase, the prefetching controller enables the memory controller to prefetch the instruction from said memory device and store the prefetched instruction into said instruction buffer without utilizing said system bus. 2. The instruction prefetching device as claimed in claim 1, wherein the prefetched instruction is predicted by said prefetching controller according to an instruction previously accessed by said processor. 3. The instruction prefetching device as claimed in claim 1, wherein said prefetching controller determines whether said system bus is in the data access phase or not through monitoring the target address of signal transmitted through said system bus. 4. The instruction prefetching device as claimed in claim 1, wherein when said processor requests an instruction to be fetched, said prefetching controller first determines whether the instruction stored in said instruction buffer hits the request of said processor; if the instruction stored in said instruction buffer hits the request of said processor, said prefetching controller directly fetched the instruction from said instruction buffer and then send the fetched instruction to said processor; and if the instruction stored in said instruction buffer does not hit the request of said processor, said prefetching controller controls said memory controller to fetch the requested instruction from said memory device and then send the fetched instruction to said processor. 5. An embedded system comprising: a system bus for signaling and data transactions; a processor coupled to said system bus; a memory device; and an instruction prefetching device coupled to said system bus and said memory device, for monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not, wherein when said system bus is in the data access phase, the instruction prefetching device prefetches an instruction from said memory device and store the prefetched instruction into the instruction prefetching device without utilizing said system bus. 6. The embedded system as claimed in claim 5, wherein said instruction prefetching device comprises: a memory controller serving as an input/output interface of said instruction prefetching device and said memory device and for fetching the instruction from said memory device; an instruction buffer for storing the instruction fetched by said memory controller; and a prefetching controller coupled to said system bus, for monitoring signal transaction on said system bus and for receiving requests from said processor through said system bus, wherein when said system bus is in the data access phase, the prefetching controller controls the memory controller to prefetch the instruction from said memory device and store the prefetched instruction into the instruction buffer. 7. The embedded system as claimed in claim 5, wherein the prefetched instruction is predicted by said instruction prefetching device according to an instruction previously accessed by said processor. 8. The embedded system as claimed in claim 5, wherein said instruction prefetching device determines whether said system bus is in the data access phase or not through monitoring the target address of signal transmitted through said system bus. 9. The embedded system as claimed in claim 5, wherein when said processor requests an instruction to be fetched, said instruction prefetching device first determines whether the instruction stored in said instruction prefetching device hits the request of said processor; if the instruction stored in said instruction prefetching device hits the request of said processor, said instruction prefetching device directly sends the instruction stored in said instruction prefetching device to said processor; and if the instruction stored in said instruction prefetching device does not hit the request of said processor, said instruction prefetching device fetches the requested instruction from said memory device and then send the fetched instruction to said processor. 10. A method for fetching instructions in an embedded system that comprises a system bus, a processor, a memory device, and an instruction fetching device, said method comprising the steps of: a) monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not; and b) performing an instruction prefetching procedure without utilizing said system bus when said system bus is in the data access phase, and performing an instruction fetching procedure when said system bus is not in the data access phase. 11. The method as claimed in claim 10, wherein said instruction prefetching procedure comprises: predicting an instruction that will possibly be fetched in the future according to an instruction previously accessed by said processor; prefetching the predicted instruction from said memory device; and storing the prefetched instruction into said instruction fetching device. 12. The method as claimed in claim 10, wherein said instruction fetching procedure comprises: receiving an instruction fetching request from said processor; determining whether the instruction stored in said instruction fetching device hits the instruction fetching request received from said processor; if the instruction stored in said instruction fetching device hits the instruction fetching request received from said processor, directly sending the stored instruction to said processor; and if the instruction stored in said instruction fetching device misses the instruction fetching request received from said processor, fetching the requested instruction from said memory device according to the instruction fetching request received from said processor, and then sending the fetched instruction to said processor. 13. The method as claimed in claim 10, wherein whether said system bus is in the data access phase or not is determined through monitoring the target address of signal transaction on said system bus. 14. The method as claimed in claim 10, wherein when said processor requests an instruction to be fetched, the instruction fetching device performs a determining procedure, and said determining procedure comprises: determining whether the instruction stored in said instruction fetching device hits the request of said processor; if the instruction stored in said instruction fetching device hits the request of said processor, directly sending the stored instruction to said processor; and if the instruction stored in said instruction fetching device misses the request of said processor, fetching the requested instruction from said memory device according to the request of said processor, and then sending the fetched instruction to said processor. 15. An instruction prefetching device adapted for use in an embedded system that comprises a system bus, a processor coupled to the system bus, at least one peripheral controller coupled to the system bus, and a memory device, said instruction prefetching device comprising: a memory controller coupled to said memory device for serving as an input/output interface of said instruction prefetching device and said memory device and for fetching an instruction from said memory device; an instruction buffer coupled to said memory controller, for storing the instruction fetched by said memory controller; and a prefetching controller coupled to said system bus, for monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not, wherein said prefetching controller determines whether said system bus is in the data access phase or not through monitoring the target address of signal transmitted through said system bus, and when said system bus is in the data access phase, the prefetching controller enables the memory controller to prefetch the instruction from said memory device and store the prefetched instruction into said instruction buffer. 16. An embedded system comprising: a system bus for signaling and data transactions; a processor coupled to said system bus; a memory device; and an instruction prefetching device coupled to said system bus and said memory device, for monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not, wherein said instruction prefetching device determines whether said system bus is in the data access phase or not through monitoring the target address of signal transmitted through said system bus, and when said system bus is in the data access phase, the instruction prefetching device prefetches an instruction from said memory device and store the prefetched instruction into the instruction prefetching device. 17. A method for fetching instructions in an embedded system that comprises a system bus, a processor, and a memory device, said method comprising: a) monitoring signal transaction on said system bus so as to determine whether said system bus is in a data access phase or not; and b) performing an instruction prefetching procedure when said system bus is in the data access phase, and performing an instruction fetching procedure when said system bus is not in the data access phase; wherein whether said system bus is in the data access phase or not is determined through monitoring the target address of signal transaction on said system bus. 18. An instruction prefetching device adapted for use in an embedded system that comprises a system bus, a processor coupled to the system bus, at least one peripheral controller coupled to the system bus, and a memory device, said instruction prefetching device comprising: a memory controller coupled to said memory device for serving as an input/output interface of said instruction prefetching device and said memory device and for fetching an instruction from said memory device; an instruction buffer coupled to said memory controller, for storing the instruction fetched by said memory controller; and a prefetching controller coupled to said system bus, for monitoring signal transaction on said system bus so as to determine whether said memory controller is idle while said system bus is occupied, wherein when said memory controller is idle and said system bus is occupied, the prefetching controller enables the memory controller to prefetch the instruction from said memory device and store the prefetched instruction into said instruction buffer. 19. An embedded system comprising: a system bus for signaling and data transactions; a processor coupled to said system bus; a memory device; and an instruction prefetching device coupled to said system bus and said memory device, for monitoring signal transaction on said system bus so as to determine whether said memory controller is idle while said system bus is occupied, wherein when said memory controller is idle and said system bus is occupied, the instruction prefetching device prefetches an instruction from said memory device and store the prefetched instruction into the instruction prefetching device. 20. A method for fetching instructions in an embedded system that comprises a system bus, a processor, a memory device, and a memory controller, said method comprising: a) monitoring signal transaction on said system bus so as to determine whether said memory controller is idle while said system bus is occupied; and b) performing an instruction prefetching procedure when it is determined that said memory controller is idle while said system bus is occupied, and performing an instruction fetching procedure when said memory controller is not idle and said system bus is occupied.