Piston X86-64 Assembler (PASM) is NASM syntax based symbolic machine code compiler for X86-64 architecture - fully working in browser and in Node.js based environments. Test live demo

• X86-64 opcodes
• NASM syntax
• 16,32,64 bit modes
• R8-R13 registers
• SIB, MODR/M, RIP addressing
• EQU, TIMES
• labels, expressions
• testing framework

• It works <-- We are here
• Floating point instructions, rep, segment prefixes, MMX, macros, ...

Releases are available for download from GitHub.

Alternatively, you can install using Node Package Manager (npm):

npm install pasm

Usage:

pasm simple.asm

So far its been tested in FF12, Chrome 23 and Safari 6. Usage:

<script type="text/javascript" src="pasm.min.js"></script>
<script type="text/javascript">

    // Define where to show errors
    myError = function(err, line) {
      console.log('Error:' + err + ' in line ' + line);
    };
    window.Opcode.error = myError;
    pasm.parseError = myError;

    // Parse assembler code
    var hexString = pasm.parse('mov ax, 0x4c00');
    console.log(hexString.data);

</script>