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Does anybody know if the mnemonics can be derived from the opcode? (like lda). I remember I was looking for a table of a dissambler, I couldn't find one, and wa
by andi999 5y ago
Does anybody know if the mnemonics can be derived from the opcode? (like lda). I remember I was looking for a table of a dissambler, I couldn't find one, and was always wondering how this is implemented.
- dirkt 5y agoNot sure what you mean, but all 6502 disassemblers I've seen use a table to get the mnemonic (and the addressing mode) from the opcode. Mnemonics are arbitrary, there is no other way.
- ectopod 5y agoYou can convert from an opcode to an index into a lookup table of mnemonics quite efficiently, and vice versa. You can also pack a single three character mnemonic into two bytes, so the lookup table may be hard to spot. Assemblers and disassemblers running on 6502 used to do this because space was at a premium.
- vidarh 5y agoNow I want to golf a 6502 opcode -> mnemonic decoder... Not that I have any use for one.