1. A method for decompressing instructions, the method comprising: fetching compressed instructions from a memory, wherein each compressed instruction comprises an X-index and a Y-index; fetching for each compressed instruction an X-bit pattern from an X memory using the X-index and a Y-bit pattern from a Y memory using the Y-index; and combining the X-bit pattern with the Y-bit pattern based on a mix mask associated with each compressed instruction into a decompressed instruction, wherein a format length of the decompressed instruction is determined by the associated mix mask.