64tass-mode.el

Major mode for working with 64tass assembly, offering column-based editing.

Features

• Context-sensitive indentation and cycling through line segments.
• Syntax highlighting/font-locking.
• Invoking 64tass for assembly from within Emacs.
• Assemble-and-launch with 64tass and VICE (x64).
• Auto-detect entry-point file for assembly/launch.
• Built in memory map as contextual eldoc (based on https://sta.c64.org/cbm64mem.html )

Related packages

This repository is a monorepo containing standalone packages for common functionality that can be used by other modes or users that require these features, but can not or do not want to depend on the full 64tass-mode.el major mode.

• 64tass-proc.el - Utility package for interacting with/invoking 64tass
• flycheck-64tass.el - Flycheck syntax checker for 64tass.
• vice-emu-proc.el - Utility package for interacting with/invoking The VICE Emulator (x64).

Commands and default keybindings

Navigation and editing

Binding	Command	Description
<tab>	64tass-align-and-cycle	Format the current line and move to the next segment
<backtab>	64tass-align-and-cycle-left	Format the current line and move to the prevous segment
s-<up>	64tass-shift-column-up	Shift the contents of the column at point upwards
s-<own>	64tass-shift-column-down	Shift the contents of the column at point downwards
C-c C-n	64tass-cycle-number-at-point	Cycle through number formats/repesentations for number at point

Insert and generate

Binding	Command	Description
C-c i h	64tass-insert-BASIC-header	Insert BASIC loader stub
C-c i b	64tass-insert-docblock	Insert docblock for the following line

Assembly / Launch

There is no canonical concept of a project in 64tass, but 64tass-mode.el provides a default implicit concept of a 64tass-project.

Binding	Command	Description
C-c C-c	64tass-assemble-project	Invoke 64tass to assemble the project associated with the current buffer
C-c C-e	64tass-assemble-and-launch-project	Assemble the project associated with the current buffer with 64tass and launch program in VICE/x64
C-c b C-c	64tass-assemble-buffer	Invoke 64tass to assemble the current buffer
C-c b C-e	64tass-assemble-and-launch-buffer	Assemble the current buffer with 64tass and launch program in VICE/x64

Custom variables

Variable	Type	Description
64tass-instruction-column-indent	20	indent-level for assembly instructions
64tass-comment-column-indent	40	indent-level for trailing/right-margin comments
64tass-default-project-resolver	<fn>	Default function to use for resolving the project associated with the current buffer
64tass-on-assembly-success-function	<fn>	Callback to invoke upon successful assembly. Defaults to 64tass--on-assembly-success.
64tass-on-assembly-error-function	<fn>	Callback to invoke upon assembly error. Defaults to 64tass--on-assembly-error.
64tass-label-format-function	<fn>	Determines label-style/format based on context. Defaults to 64tass-default-label-format-function.
64tass-xref-definition-source-order	'list	Determines in which order sources/handlers will be invoked to find xref definitions
64tass-xref-definition-source-alist	'alist	An alist containing (<source symbol> . <handler-function>) entries.

License

© 2025 Sven Johansson. GNU GPL v3.0 Licensed. See LICENSE for details.