Inverse assembly method and apparatus

Abstract

An inverse assembly method for converting binary executable microprocessor code into corresponding assembly language mnemonics provides for the storage of all the possible binary codes and corresponding assembly language mnemonics in a plurality of tables set up in a decision tree form which corresponds to the format of a user document provided by the manufacturer of a target microprocessor. The instructions and data information contained within the executable code acquired from the taret microprocessor are distinguishably tagged prior to being stored in an acquisition memory. The code from the acquisition memory, in binary or hex form, indexes a primary table which contains a plurality of entries containing a binary value which may have a mask portion, each entry containing a plurality of actions having an optional string to be displayed, optional parameter masks and an optional table to call. The unmasked portion of the binary value is compared with the code from the acquisition memory and, if a match occurs, this entry is used for further processing, otherwise the comparison process moves on to the next entry in the table. Once a match is found a character string is displayed, parameter bits are picked off to be passed to another table, and another table is called within the decision tree. This continues until all actions are completed, including calls to additional tables which are similarly processed. After the processing of each called, or current, table is completed, a return to the calling table is made, and if there is no calling table then disassembly for the current code from the acquisition memory is completed. In like manner all the acquired executable code is processed to obtain the corresponding assembly language mnemonic.