Due to having many NOPs

VLIW(Very Long Instruction Word) exists serious code size expansion problem.As an efficient way to solve this problem

the code compression needs to deal with three key points:improving the compression ratio (CR)

simplifying decomposition operations

and relocating the branch target.According to the characteristics of VLIW on stream architecture

a two-dimension(2-D) compression scheme is put forward

where VLIW code is compressed in both vertical and horizontal directions

the horizontal decompression and code execution can be implemented in parallel

and loop entrance addresses are buffered by stack registers.The experiment results illustrate that 2-D compression scheme can resolve code expansion issue effectively.Specifically

it has achieved a 36.48% area reduction of the on-chip instruction memory and a 7.85% area reduction of the CISP system.