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⚡️An attempt at disassembling MicroPython. Very experimental, provides an ability to view "possible" instructions.

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mdis

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An attempt at a disassembler for Micropython bytecode. Largely inspired by DC540's MicroPython Challenge.

Usage

$ python ./mdis.py -h
argument type description
-h, -help none show the help menu
-b INTEGER int to format format an integer into the micropython bytecode format
-op INTEGER int to get opcode of integer
-f FILE file supply a file to print disassembly for
-fr FROM 0 offset addr supply a from address for instruction dump. constraint: must be a 0 offset address. requires to address (-t).
-t TO 0 offset addr supply a to address for instruction dump. constraint: must be a 0 offset address. requires from address (-fr).

Contributing

There are not too many contribution guidelines. Contributions should follow a decent code style and documentation style, and should be verbose with the changes.

Source Tree

  • cmd - cli commands
  • core - disassembler core
  • mio - base io / file io
  • logger - logging
  • parser - file parsing
  • reader - file reading

Dependencies

  • hexdump [3.3]
  • termcolor [1.1.0]
  • six [1.16.0]

Some Notes

There are a few things that are important to know with this very experimental project!

  • Aforementioned 0-offset addresses are addresses that have no offset. Similar to the addresses seen in an xxd dump.
  • The bytes parsed are big-endian
  • Sometimes it won't dump an entire file.
  • MicroPython deals with strings as shown here on page 139. This is unsupported as of currently.
  • There is a hidden parser feature that is not utilised but prints out EVERY SINGLE HEX BYTE in the file, without addresses.
  • This project essentially provides a level of "pseudocode", but with the actual MicroPython instructions. Due to previously listed, things, they are not the most accurate, but relatively enough.

Outputs

./mdis.py -f ./__tests__/print.mpy

The file print.mpy is compiled through mpy-cross, and is a file with the following code:

print('hi')

Since it originates from a python file, we can look at the original disassembly:

"""
  2           0 LOAD_NAME                0 (print)
              2 LOAD_CONST               0 ('hi')
              4 CALL_FUNCTION            1
              6 POP_TOP
              8 LOAD_CONST               1 (None)
             10 RETURN_VALUE
"""

Disassembling the .mpy file, we get this output:

out

Similar, but not entirely accurate.

This output highlights each opcode's hex value as seen on the left. These values are reflected in bc0.h.

./mdis.py -op 0x40

opcode

./mdis.py -b 0x30

bytecode formatted uint

References

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⚡️An attempt at disassembling MicroPython. Very experimental, provides an ability to view "possible" instructions.

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