Re: Help on disassembler/decompilers

In article <2524@l.cc.purdue.edu> hrubin@l.cc.purdue.edu (Herman Rubin) writes:
  > > [Turning object code back into assembler is pretty straightforward, and
  > > every debugger does it. Someone else asked about disassembling into higher
  > > level languages a little while ago, but I didn't see any responses. -John]
  >
  > It is not quite that straightforward, and disassemblers can be somewhat
  > hard to get. Debuggers usually use object code set up specially for
  > debugging, with certain features available. Some debuggers even require
  > that the source code be included in such a way that this can be displayed
  > at debug time. Disassembly frequently is even ambiguous.


Moreover, debuggers know at what addresses instructions start, a disassembler
does not have knowledge about it. This gets hairy if the program uses
indirect jumps on a machine with variable sized instructions. I once wrote
a disassembler for a CDC Cyber PPU. It tried to follow all code threads,
but failed horribly in this aspect; and had to be guided.
--
dik t. winter, cwi, amsterdam, nederland
dik@cwi.nl
--

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