Method and architecture capable of accessing data and instructions using store and forward

1. An architecture capable of accessing data and instructions of an external memory device using store and forward, comprising:

a processor kernel capable of effecting a burst transfer for continuously outputting a data string having a fixed burst length for access;

a cache module for storing a portion of data and instructions sent from the memory device, the stored portion of data and instructions being available for the processor kernel to access at high speed;

a prefetch module for predicting possible data and instructions to be used by the processor kernel, so as to read the same from the memory device and store the same therein in advance;

a switch for switching a connection from the processor kernel to the cache module or the prefetch module; and

a store and forward controller for detecting access between the prefetch module and the memory device, so as to command the switch to switch the connection from the processor kernel to the prefetch module when the prefetch module transfers data by burst transfer, such that data and instructions transferred from the memory device to the prefetch module are also transferred to the processor kernel.

2. The architecture as claimed in claim 1 , wherein the switch is normally operative to switch a connection from the processor kernel to the cache module.

3. The architecture as claimed in claim 1 , wherein the processor kernel takes a single instruction or data as a unit for transfer; each of the cache module and the prefetch module takes a plurality of instructions or data as a unit for continuous transfer; and the store and forward controller is operative to output instructions and data obtained from the memory device into the processor kernel before a-completion of a unit data transfer by the prefetch module.

4. The architecture as claimed in claim 1 , wherein the memory device is a DRAM.

5. The architecture as claimed in claim 1 , wherein the memory device is a SRAM.

6. In a processor architecture having a processor kernel, a cache module and a prefetch module, a method of using store and forward for accessing data and instructions of an external memory device, the processor kernel being capable of effecting a burst transfer for continuously outputting a data string having a fixed burst length for access, the cache module storing a portion of data and instructions sent from the memory device for the processor kernel to access at a high speed, the prefetch module predicting possible data and instructions to be accessed by the processor kernel, so as to read the same from the memory device and store the same therein in advance, the method comprising the steps of:

(A) the processor kernel issuing an access request for reading data and instructions by burst transfer unit, which results in a cache miss and a prefetch hit;

(B) if all data and instructions of the burst transfer unit are transferred to the prefetch module, transferring the data and instructions in the prefetch module into the processor core;

(C) if not all data and instructions of the burst transfer unit are transferred to the prefetch module, and the data and instructions to be read are transferred into the prefetch module, transferring the data and instructions to be read in the prefetch module into the processor core; and

(D) if not all data and instructions of the burst transfer unit are transferred to the prefetch module, and the data and instructions to be read are not transferred into the prefetch module, awaiting the data and instructions until they are transferred into the prefetch module, and transferring the data and instructions in the prefetch module into the processor core.