INSTRUCTION BUFFER ORGANIZATION METHOD AND SYSTEM

摘要

Variable-length instructions are prepared for simultaneous decoding and execution of a plurality of instructions in parallel by reading multiple variable-length instructions from an instruction source and determining the starting point of each instruction so that multiple instructions are presented to a decoder simultaneously for decoding in parallel. Immediately upon accessing the multiple variable-length instructions from an instruction memory, a predecoder derives predecode information for each byte of the variable-length instructions by determining an instruction length indication for that byte, assuming each byte to be an opcode byte since the actual opcode byte is not identified. The predecoder associates an instruction length to each instruction byte. The instructions and predecode information are applied to an instruction buffer circuit in a memory-aligned format. The instruction buffer circuit prepares the variable-length instructions for decoding by converting the instruction alignment from a memory alignment to an instruction alignment on the basis of the instruction length indication. The instruction buffer circuit also assists the preparation of variable-length instructions for decoding of multiple instructions in parallel by facilitating a conversion of the instruction length indication to an instruction pointer.