From SnesLab
Jump to: navigation, search

Asar (not asar) is a 65c816, SPC700, and Super FX assembler made by Alcaro. Asar is an intended replacement for xkas.


Asar is more user-friendly than xkas. It can be run two ways:

  • Double-click Asar.
    • You will be prompted for the name of the patch. Enter (or copy-paste) the path to a patch you want to apply.
    • You will be prompted for the name of your ROM. Enter (or copy-paste) the path to the ROM you want to apply the patch to.
  • Run it from the command line, like xkas.
    • >asar [Path to patch] [Path to ROM]


Asar has many features which make life easier.

  • freecode and freedata automatically find freespace for you. The difference is that freedata prefers ROM areas where RAM mirrors don't exist, while freecode refuses to put anything there.
  • autoclean automatically detects where a JSL, JML, or dl in a ROM points to and deletes its RATS tag when you re-apply a patch. This prevents freespace leaks.
  • arch assembles for another architecture. Valid values are the following:
    • 65816 is the default, the one you want in most circumstances
    • spc700-raw assembles SPC700 code. Acts as you'd expect; org $0010 stores to PC 0x0010 in the "ROM". Don't mix it with 65816 code, it won't make sense.
    • spc700-inline also assembles SPC700 code. However, org is weirder here: It doesn't edit where it'll store the data; instead, it implements the standard upload system (16bit length, then location). It also adds a terminator at the end. If you're uploading an SPC engine, you can set the entry point with "startpos $1234". The location in the ROM is where the surrounding 65816 code tells it to be.
    • superfx assembles code for the Super FX chip.

Additional Libraries

Asar comes with the following library:

  • asar.dll; wrappers for C and C# are included with the library.

This library allows programmers to use Asar from their code without calling an external application.