Looking for an opcode generator program.

Say, I'd like to patch some 4 bytes to "movsx eax, word ptr [ebx+ecx]" and it will give me "0FBF040B" or vice versa.

Any advices?

Thanks.

Most disassembles have assemblers built in.

Ollydbg is an example Load a program into it and go to a blank area in the memory map and assemble whatever and you will see the numbers or enter the numbers and the code will appear.

Hview is another alternative (don't know if it assembles)

Hello dunno !

HIEW is a very good program, as peterg70 said. You can assemble 16-bit and 32-bit intructions in both 16-bit and 32-bit code segments. You can even search for things like "Mov ?, [EAX+?]" and it will find all intructions according to your search. HIEW has a built in disassembler and assembler and opens files in shared mode, so you're able to view many files which you cannot view else.