6502 disassembler and (re)assembler
Allows disassembling any sequence of bytes to a unique disassembly text, and
reassembling the assembly text to the same bytes (fully roundtrippable). Includes
support for illegal opcodes with multiple mneumonic aliases, and truncated operands
represented by xx.
Intended for disassembling a ROM (or a part of a ROM), editing the assembly to patch it, and reassembling with the changes. See also: nes-game-genie and nes-file.
Example:
const {disasm, formatDisasm, reasm} = require('6502-reasm');
// returns an array, one element per instruction
const lines = disasm([0x78, 0xd8, 0xa9, 0x10, 0x8d, 0x00, 0x20, 0xa2, 0xff, 0x9a, 0xad, 0x02, 0x20, 0x10, 0xfb, 0xad]);
// returns a verbosely formatted text string, same as passed below
const formattedDisassembly = formatDisasm(lines);
// returns an array of bytes, identical as passed to disasm() above
reasm(`\
00000000 78 SEI
00000001 d8 CLD
00000002 a9 10 LDA #$10
00000004 8d 00 20 STA $2000
00000007 a2 ff LDX #$ff
00000009 9a TXS
0000000a ad 02 20 LDA $2002
0000000d 10 fb BPL -5
0000000f ad xx xx LDA $xxxx
`);MIT