6502bench

6502bench is a code development "workbench" for 6502, 65C02, and 65802/65816 code. It currently features one tool, the SourceGen disassembler.

You can download the source code and build it yourself, or click the "Releases" tab near the top of the github page for pre-built downloads.

SourceGen

SourceGen converts machine-language programs to assembly-language source code. It has most of the features you will find in other 6502 disassemblers, as well as many less-common ones.

A demo video is available: https://youtu.be/dalISyBPQq8

Features

Analysis:

• Support for 6502 (including undocumented opcodes), 65C02, and 65816.
• Code flow analyzer traces execution to find all reachable instructions. Hinting mechanism allows manual specification of entry points.
• Processor status flags are tracked, allowing automatic detection of branch-always and branch-never, as well as register widths on 16-bit CPUs. The analyzer tracks these across subroutine calls and branches. Cycle counts factor these in automatically.
• Editable labels are generated for every branch and data target.
• Automatic detection and classification of ASCII strings and runs of identical bytes.
• All target-platform-specific stuff is stored in plain text files loaded at runtime. This includes symbols for ROM entry points and standard zero-page locations. Additional symbols and overrides can be specified at the project level.
• Extension scripts can be used to reformat code and identify inline data that follows JSR/JSL. Code is compiled at run time and executes in a sandbox.

UI:

• Fully interactive point-and-click GUI. Add labels and multi-line comments, change addresses, and see the changes immediately.
• Instruction operand formats (hex, decimal, etc) can be set for individual lines. Symbols that don't match the operands are automatically offset, allowing simple expressions like "address - 1".
• Full-line comments are automatically word-wrapped, and can be "boxed" for an authentic retro feel.
• Data areas can be formatted as bytes, words, addresses, and more. Several types of strings are recognized (null-terminated, length prefixed, etc).
• "Infinite" undo/redo of all actions.
• Notes can be added that aren't included in generated output. Very useful for marking up a work in progress.
• Cross-reference tables are generated for every branch and data target address, as well as for external platform symbols.
• Instruction summaries, including cpu cycles and flags modified, are shown along with a description of the opcode function.
• Display is configurable for upper/lower case, choice of pseudo-op names, expression formats, and more.

Output:

• Assembly source can be generated for multiple assemblers (currently cc65 and Merlin 32).
• Cross-assemblers can be launched directly from the generation GUI to verify output correctness.
• Optional automatic conversion of labels from global to local.
• Symbols may be exported from one project and imported into another to facilitate multi-binary disassembly.

Misc:

• Preset project attributes (CPU type, platform symbol file sets) are defined for a variety of platforms.
• Project file is stored in a text format, and only holds metadata. None of the original file is included, allowing the project file to be shared without violating copyrights (note: may vary depending on local laws).

There are a couple of significant areas where support is currently lacking:

• Poor support for multi-bank 65816 files (IIgs OMF, SNES).
• No support for alternate character sets (e.g. PETSCII).

About the Code

All of the code is written in C# .NET, using the (free to download) Visual Studio Community 2017 IDE as the primary development environment. The user interface uses the WinForms API. Efforts have been made to avoid doing anything Windows-specific, in the hope that the applications will be straightforward to port to other platforms.

The solution is called "WorkBench.sln" rather than "6502bench.sln" because some things in Visual Studio got weird when it didn't start with a letter.

The code style is closer to what Android uses than "standard" C#. Lines are folded to fit 100 columns.

The source code is licensed under Apache 2.0 (http://www.apache.org/licenses/LICENSE-2.0), which makes it free for use in both open-source programs and closed-source commercial software. The license terms are similar to BSD or MIT, but with some additional constraints on patent licensing. (This is the same license Google uses for the Android Open Source Project.)

Images are licensed under Creative Commons ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/).