Method for designing a system LSI

A method for designing a system LSI comprising the steps of:

• (a) dividing a function described in an algorithm description into a hardware function part for configuring a processor and a software function part for creating an application program running on the processor;
• (b) upon designing the processor based on the divided hardware function party,
• (i) if an instruction needed for the divided hardware function part exists in an instruction set library stored in a database, extracting a corresponding instruction description from the instruction set library including therein instruction descriptions defining execution definition sections, installation of the same into the processor description, or
• (ii) if the instruction does not exist in the instruction set library, extracting a new instruction description from the instruction set library to which the new instruction description corresponding to the instruction is added, for installation of the same into the processor description;
• (c) extracting, from a behavior function library storing therein functional blocks defining contents of processings for execution definition sections, a behavior function description corresponding to the instruction description or the new instruction description extracted from the instruction set library, for installation of the same into the instruction description;
• and
• (d) synthesizing by behavior synthesis based on the processor description to which the instruction description, to which the behavior function description is installed, to thereby obtain an RTL description.