https://github.com/davidbuchanan314/p65a

Pythonic 6502 Assembler: An experimental alternative to traditional assemblers.
https://github.com/davidbuchanan314/p65a

6502 6502-assembler 6502-assembly assembler python3 python310

Last synced: 2 months ago
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Pythonic 6502 Assembler: An experimental alternative to traditional assemblers.

• Host: GitHub
• URL: https://github.com/davidbuchanan314/p65a
• Owner: DavidBuchanan314
• License: mit
• Created: 2022-07-11T23:19:18.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2022-07-12T14:39:25.000Z (over 2 years ago)
• Last Synced: 2024-03-14T16:22:56.399Z (9 months ago)
• Topics: 6502, 6502-assembler, 6502-assembly, assembler, python3, python310
• Language: Python
• Homepage: https://pypi.org/project/p65a/
• Size: 11.7 KB
• Stars: 17
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# p65a

Pythonic 6502 Assembler: An experimental alternative to traditional assemblers.

At this point I'm unsure whether it's a useful concept or not, but I quite enjoy

writing code this way. Consider the API to be unstable.

See the `examples/` directory for examples of code written using this library.

Here's a snippet from `examples/bootloader.py`, which showcases a few nice features:

```python

[...,

	lbl.CRC_LUT_HI,

		Db([crc16(bytes([i])) >> 8 for i in range(0x100)]),

	lbl.CRC_LUT_LO,

		Db([crc16(bytes([i])) & 0xff for i in range(0x100)]),

	lbl.crc_update, # input: A, clobbers: A, Y

		A <= A ^ zp.crc_hi,

		Y <= A,

		A <= zp.crc_lo,

		A <= A  ^ lbl.CRC_LUT_HI[Y],

		zp.crc_hi <= A,

		A <= lbl.CRC_LUT_LO[Y],

		zp.crc_lo <= A,

		RTS(),

...]

```

This snippet implements a CRC16 checksum function. The lookup tables are generated

automagically by Python list comprehensions.

Each "line" of assembly is an expression contained within a Python list. The

`<=` operator is overloaded to express assignment.

It is possible to make forward-references to labels. They are treated as symbolic

expressions until the layout of code is known (and thus, their concrete value),

and then the machine code can finally be finally emitted.

## TODO

- Refactor - there's a lot of code in places it shouldn't be

- Documentation