Assembler x86 download

This is the project webpage for the Netwide Assembler NASM , an asssembler for the x86 CPU architecture portable to nearly every modern platform, and with code generation for many platforms old and new. As of version 2. The details of the license are available in the documentation.

Stable 2. For users of RPM-based Linux distributions e. Peter Anvin. We will even include a section on DOS assembly language programs for historical interest. These notes are not intended to be a substitute for the documentation that accompanies the processor and the assemblers, nor is it intended to teach you assembly language.

Its only purpose is to show how to assemble and link programs using different assemblers and linkers. Regardless of the assembler, object file format, linker or operating system you use, the programming process is always the same:. Each assembly language file is assembled into an "object file" and the object files are linked with other object files to form an executable.

A "static library" is really nothing more than a collection of probably related object files. This document does not cover how to use all the different assemblers; you need to read the documentation that comes with them. We will, however, give step-by-step instructions and complete examples of all three of these assemblers for a few extremely simple programs.

Some linkers out there include. In our first example we will use system calls for writing to a file call number 1 and exiting a process call number Here it is in the NASM assembly language:. If you just enter " gcc hello. You can suppress the link step with the -c option to gcc , or do the assembly and linking in one step by telling the linker not to use the C library with -nostdlib. System Calls in bit Linux There are some systems with bit builds of Linux out there still.

Although it might be interesting to show some examples for historical reasons, this introduction is probably better kept short. Sometimes you might like to use your favorite C library functions in your assembly code. This should be trivial because the C library functions are all stored in a C library, such as libc.

Technically the code is probably in a dynamic library, like libc. Still, all we have to do is place calls to C functions in our assembly language program, and link with the static C library and we are set. So if we link with a C library, all we have to do is define main and end with a ret instruction! Here is a simple example in NASM, which illustrates calling puts. To assemble and run: ; ; nasm -fmacho64 hola. C library functions have underscores, and we had to say default rel for some strange reason, which you can read about in the NASM documentation.

MASM assumes bit addressing if a bit displacement appears alone as a memory operand. There's currently no support for bit addressing with such operands. Finally, mixing register sizes within a memory operand, as demonstrated in the following code, generates an error. Microsoft Macro Assembler Reference. Skip to main content. This browser is no longer supported.

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