Target Audience

Welcome to the 1.0.1 release of the Yasm Modular Assembler. Its target audience includes people who want to:

use a mature NASM-syntax x86 and AMD64 assembler that can target Win32, Win64, MacOS X, and Unix derivatives;
use a GAS-syntax assembler other than GAS;
have assembly source-level debugging using either DWARF2 or CodeView 8.0 (Visual Studio 2005 and later);
have a free software assembler that supports Win32/Win64 structured exception handling (SEH) and ELF32/ELF64 thread local storage (TLS);
target the latest AMD XOP/FMA4/CVT16 or Intel AVX instruction sets;
have a free assembler highly integrated into the Visual Studio 2010 IDE;
keep track of Yasm’s progress in terms of stability and feature set;
contribute to Yasm development from a new release.

Download Yasm 1.0.1

A number of download formats are available. For Windows and DOS users, we recommend downloading the prebuilt binaries. The source tarball contains all sources needed to build Yasm on UNIX-compatible systems, Windows, and DOS. If you use Visual Studio 2010, we highly recommend downloading the appropriate vsyasm zip file and following its readme.txt directions for integration of yasm into the Visual Studio IDE.

Source .tar.gz
Win32 VS2010 .zip (for use with VS2010 on 32-bit Windows)
Win64 VS2010 .zip (for use with VS2010 on 64-bit Windows)
Win32 .exe (for general use on 32-bit Windows)
Win64 .exe (for general use on 64-bit Windows)
DOS .exe (for use on pure DOS or for use with DJGPP)

A TASM-like frontend is also available. It defaults to the “tasm” parser and provides TASM-like command line options.

Win32 Win64 DOS

Features

Changes from 1.0.0 to 1.0.1:

Fix ELF32 shared object relocations (#202).
Ignore [warning] directive (#201).

Features also include:

Object and debugging format support:

Full support for ELF, including support for both AMD64 and 32-bit x86 static and shared objects and thread local storage.
Support for Mach-O object format used in MacOS X, including both the 32-bit (x86) and 64-bit (AMD64) versions (contributed by Henryk Richter).
Full support for COFF (DJGPP) and Win32 (PE32) and Win64 (PE32+) object formats.
Support for structured exception handling on Win64 and Win32.
Support for RDOFF2 (.rdf) object format.
XDF object format (64-bit basic format, similar in spirit to NASM’s RDF).
Multi-section binary support (compatible but slightly more advanced than NASM’s).
STABS, DWARF2, and CodeView 8 debugging formats (enable with “-g …”).

Assembler syntax support:

Full NASM-compatible parser, including the “real” NASM preprocessor (imported from NASM tree).
GAS parser and preprocessor.
Basic support for TASM syntax, based on the NASM parser and preprocessor.

Architecture support:

Support for AMD64 instruction set, registers, and addressing modes. This is enabled in one of three ways: using the [BITS 64] directive, using a 64-bit object format such as win64 or elf64, or setting the machine to “amd64”. Only the last two will actually generate a 64-bit object file.
Full support for AMD64 RIP-relative addressing; the forms supported in NASM syntax are [rip+val] (direct index) and [sym wrt rip] or [rel sym] (relocated relative).

Other features:

Fast and efficient “virtual multi-pass” optimizer that automatically generates much smaller code for jumps and immediates.
Full warnings for integer overflow.
NASM-like list format.
Most code licensed under 2-clause BSD license, although some portions are still LGPL-licensed (NASM preprocessor module).
Support for the -I option to specify include directories, with a search pattern essentially identical to most C compilers.
Support for CALL/JMP FAR, including proper handling of location EQU seg:off; jmp far location.
Man pages: yasm(1), yasm_objfmts(7), yasm_dbgfmts(7), and yasm_arch(7).

Important Differences from NASM

A number of command line options are different. Run “yasm –help” for a quick command line option summary, or read the full yasm(1) manpage for detailed descriptions of all command line options.
Include files with relative paths are not searched in the same way. Yasm’s search behavior is essentially that of most C compilers.

Known Issues

As Yasm is still under development, there are some caveats and features that do not yet work or are not yet fully functional. See the Tickets area of Yasm’s website for a list of active issues.

Compiling Yasm from source

On UNIX-compatible operating systems, Yasm builds using the standard “./configure; make; make install” commands. GNU make is not required. While Yasm development requires a larger toolchain (see the HACKING file), building Yasm should not require more than just a C compiler.

For Windows and DOS systems, we recommend simply downloading the prebuilt executables. However, for those that want to build YASM directly using DJGPP, CygWin, or Visual Studio, Makefiles and all required specialized files are provided in the Mkfiles/ directory of the distribution tarball.

Running Yasm

Version Information:

yasm --version

Command Line Option Help:

yasm --help

Assemble test.asm to Win32 object file test.obj with CodeView 8.0 (VS2005) source debug info:

yasm -f win32 -g cv8 test.asm

Assemble test2.asm to Win64 object file test.obj with CodeView 8.0 source debug info:

yasm -f win64 -g cv8 test2.asm

Assemble test3.asm to AMD64 ELF object file test3.o with DWARF2 debugging information:

yasm -f elf64 -g dwarf2 test3.asm

Alternative to above:

yasm -f elf -m amd64 -g dwarf2 test3.asm

Assemble test4.s (GAS syntax file) to 32-bit x86 ELF object file testo.o with DWARF2 debugging information:

yasm -p gas -f elf32 -g dwarf2 -o testo.o test4.s

Yasm 1.0.1 Release Notes