flat assembler
Open source assembly language compiler.

The flat assembler (abbreviated to fasm, intentionally stylized with lowercase letters) is a fast self-assembling assembler running in a variety of operating systems, in continued development since 1999. It was designed primarily for the assembly of x86 instructions and it supports x86 and x86-64 instructions sets with MMX, 3DNow!, SSE up to SSE4, AVX, AVX2, XOP and AVX-512 extensions and can produce output in plain binary, MZ, PE, COFF or ELF format. It includes the powerful but easy to use macroinstruction support and does multiple passes to optimize the size of instruction codes. The flat assembler is self-hosting and the complete source code is included.

The only difference between the various flat assembler packages is the operating system on which they can be executed. For any given source each version is going to generate exactly the same output file, so each of the following releases can be used to compile programs for any operating system.

The flat assembler g (abbreviated to fasmg) is a new assembly engine designed to become a successor of the one used by flat assembler 1. It does not have a built-in support for x86 instructions. It is a generic assembler that can be used in place of flat assembler 1 in applications where only the pure macroinstruction engine is needed instead of x86 encoder, for example when an instruction set for a different architecture is defined through macroinstructions. However, thanks to the included set of macroinstructions implementing the x86 instruction sets, it has the ability of self-hosting. With the included macroinstructions it is capable of generating all the output formats that flat assembler 1 could and additional ones, like Mach-O or Intel HEX.

The packages listed below are the latest development snapshot of flat assembler 1. Note that these versions may not yet be thoroughly tested.

The following are some third-party products based on flat assembler, they are available to download from their respective websites.

Copyright © 2004-2017, Tomasz Grysztar.