


NDISASM(1)                                             NDISASM(1)


NAME
       ndisasm - the Netwide Disassembler, an 80x86 binary file disassembler

SYNOPSIS
       ndisasm [ -o origin ] [ -s sync-point [...]]  [ -a | -i ] [ -b bits ] [
       -u ] [ -e hdrlen ] [ -k offset,length [...]]  infile
       ndisasm -h
       ndisasm -r

DESCRIPTION
       The ndisasm command generates a disassembly listing of the binary  file
       infile and directs it to stdout.

   OPTIONS
       -h     Causes  ndisasm  to  exit immediately, after giving a summary of
              its invocation options.

       -r     Causes ndisasm to exit immediately, after displaying its version
              number.

       -o origin
              Specifies  the  notional  load address for the file. This option
              causes ndisasm to get the addresses it lists down the left  hand
              margin, and the target addresses of PC-relative jumps and calls,
              right.

       -s sync-point
              Manually specifies a synchronisation address, such that  ndisasm
              will  not output any machine instruction which encompasses bytes
              on both sides of the address. Hence the instruction which starts
              at that address will be correctly disassembled.

       -e hdrlen
              Specifies a number of bytes to discard from the beginning of the
              file before starting disassembly. This does  not  count  towards
              the  calculation  of the disassembly offset: the first disassem-
              bled instruction will  be  shown  starting  at  the  given  load
              address.

       -k offset,length
              Specifies  that  length  bytes, starting from disassembly offset
              offset, should be skipped over without  generating  any  output.
              The  skipped  bytes  still  count towards the calculation of the
              disassembly offset.

       -a or -i
              Enables automatic (or intelligent) sync mode, in  which  ndisasm
              will attempt to guess where synchronisation should be performed,
              by means of examining the target addresses of the relative jumps
              and calls it disassembles.

       -b bits
              Specifies 16-, 32- or 64-bit mode. The default is 16-bit mode.




                  The Netwide Assembler Project                 1





NDISASM(1)                                             NDISASM(1)


       -u     Specifies 32-bit mode, more compactly than using `-b 32'.

       -p vendor
              Prefers instructions as defined by vendor in case of a conflict.
              Known vendor names include intel,  amd,  cyrix,  and  idt.   The
              default is intel.


RESTRICTIONS
       ndisasm  only disassembles binary files: it has no understanding of the
       header information present in object or executable files. If  you  want
       to disassemble an object file, you should probably be using objdump(1).

       Auto-sync mode won't necessarily cure all  your  synchronisation  prob-
       lems:  a sync marker can only be placed automatically if a jump or call
       instruction is found to refer to it before ndisasm  actually  disassem-
       bles  that  part  of  the code. Also, if spurious jumps or calls result
       from disassembling non-machine-code data, sync markers may  get  placed
       in strange places. Feel free to turn auto-sync off and go back to doing
       it manually if necessary.


SEE ALSO
       objdump(1).

































                  The Netwide Assembler Project                 2


