> Encodings with bits \[15:0\] all zeros are defined as illegal instructions. These instructions are considered to be of minimal length: 16 bits if any 16-bit instruction-set extension is present, otherwise 32 bits. The encoding with bits \[ILEN-1:0\] all ones is also illegal; this instruction is considered to be ILEN bits long. https://riscv.github.io/riscv-isa-manual/snapshot/unprivileged/#\_base_instruction_length_encoding {width=900 height=34}