bcompress  rd rs1 rs2 31..25=4  14..12=6 6..2=0x0C 1..0=3
bdecompress rd rs1 rs2 31..25=36 14..12=6 6..2=0x0C 1..0=3
pack       rd rs1 rs2 31..25=4  14..12=4 6..2=0x0C 1..0=3
packh      rd rs1 rs2 31..25=4  14..12=7 6..2=0x0C 1..0=3