Patent ID: 7895414
Filing Date: 2011-02-22
Classification: G06F

Abstract:
1. An instruction length determination device for using concatenate bits to determine an instruction length in a multi-mode processor, wherein the multi-mode processor executes an m×N-bit instruction formed of m N-bit data, each said N-bit data having at least one concatenate bit, where m, N are positive integers, the instruction length determination device comprising: an instruction input unit, which has a memory space to store a plurality of N-bit data; an instruction fetch unit, which fetches the plurality of N-bit data from the instruction input unit; an instruction length determination logic, for determining an instruction length according to the concatenate bit of a first N-bit data fetched by the instruction fetch unit; and an instruction concatenate unit, which selectively concatenates a number of successive N-bit data based on the instruction length determination logic for output; wherein, when the concatenate bit of the first N-bit data is not equal to a predetermined value, the instruction length determination logic determines that the first N-bit data is a complete instruction and the instruction concatenate unit outputs the N-bit data, otherwise, the N-bit data is reserved and the instruction fetch unit fetches a second N-bit data; when the concatenate bit of the second N-bit data is equal to the predetermined value, the instruction length determination logic determines that the first N-bit data and the second N-bit data form the complete instruction and the instruction concatenate unit concatenates the first and second N-bit data to output, otherwise, the second N-bit data is reserved and the instruction fetch unit fetches a third N-bit data until a last N-bit data is fetched and its concatenate bit equals to the predetermined value for determining that the complete instruction is formed of the last N-bit data finally fetched and all N-bit previously reserved; and the instruction concatenate unit concatenates the last N-bit data and all N-bit previously fetched for output.