Decoding i386 opcodes to instructions

Question

I'm trying to Is there any good resource available to learn 'decoding' of i386 opcodes? Most of the websites talk about how to encode instructions, but I don't find anywhere something telling as to how to decode opcodes to instructions.

I've looked at the source code of some disassemblers, but I want some documentation as to how to decode opcodes to instructions.

Thanks and Regards,
Hrishikesh Murali

Read http://www.intel.com/products/processor/manuals/ – user786653 Aug 04 '11 at 13:25 — user786653, Aug 04 '11 at 13:25

score 2 · Answer 1 · edited May 23 '17 at 12:15

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Read the processor manuals, they have it described, though maybe not in complete details:

Intel Manuals, in particular see Chapter 2 in Volume 2A and Appendix A in Volume 2B.
AMD Manuals, see Programmer's Manual Volume 3.

See also How to interpret the opcode manually?

edited May 23 '17 at 12:15

Community

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answered Aug 04 '11 at 13:28

Igor Skochinsky

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score 0 · Answer 2 · answered Aug 04 '11 at 13:35

if you want to lean at a more programmatic level, olly's old disasm engine is a very simple disassembler to learn from (written in C), and if you want to cover the more recent opcodes (and hidden/aliased opcodes), bea-engine is a great open-source disassem engine.

Decoding i386 opcodes to instructions

2 Answers2