MASM/NASM Differences

45
votes

What are the syntax differences between the NASM and MASM assemblers?

2
assemblyx86nasmmasm
Related: How to know if an assembly code has particular syntax (emu8086, NASM, TASM, ...)? shows some syntax diff examples. – Peter Cordes

2 Answers

48
votes

Section 2.2 of the NASM documentation is titled Quick Start for MASM Users which lists the important differences between NASM and MASM.

-3
votes

What an interesting question. The difference between them is, they are not compatible! But then again, nasm assemblers are not compatible amongst themselves, it seems. Learned it the hard way, while compiling libvpx. I think this single example says it all:

ml64.exe (MSVC 2019) -> throws

nasm for windows -> compiles some *.asm files, throws on some

invalid combination of opcode and operands

Huh?

yasm for windows -> works

llvm assembler (debian) -> throws:

    /usr/lib/llvm-13/bin/llvm-as

https://packages.debian.org/experimental/llvm-13

yasm (debian) -> works

nasm (debian) -> works

GNU assembler -> ???

https://manpages.debian.org/experimental/binutils-common/as.1.en.html