The OpenRISC 1000 disassembler is part of the wider binutils utility set and is found in the opcodes sub-directory. It provides two versions of the disassembly function, print_insn_big_or32 and print_insn_little_or32 for use with big-endian and little-endian implementations of the architecture in or32-dis.c

The instruction decode uses a finite state automaton (FSA) in or32-opc.c. This is constructed at start-up by the function build_automata from a table describing the instruction set. This function is invoked from the _initialize_or1k_tdep function immediately after the OpenRISC 1000 architecture has been defined.

The disassembler takes advantage of any symbol table information to replace branch and jump targets by symbolic names where possible.