Overview

AVM1 (ActionScript 1/2 bytecode) support: disassemble DoAction bytecode to a mutable, strongly-typed action tree and assemble it back losslessly; dump it as p-code or best-effort AS2; and evaluate linear data scripts to a typed value tree you can edit and write back — or map them to your own records with the serializer.

Disassemble to p-code or AS2

using ShockwaveFlash;
using ShockwaveFlash.Avm1.Text;
using ShockwaveFlash.Tags.Action;

var swf = ShockwaveFlashFile.Disassemble(File.ReadAllBytes("movie.swf"));
var version = swf.Header.Version;
var tag = swf.Tags.OfType<DoActionTag>().First();

string pcode = Avm1Disassembler.Disassemble(tag.Data, version, Avm1DisassemblyKind.Pcode);
string as2 = Avm1Disassembler.Disassemble(tag.Data, version, Avm1DisassemblyKind.As2);

P-code is a faithful, complete listing — every opcode with its operands, constant-pool references resolved, and function/with/try bodies decoded and indented:

ConstantPool "VERSION", "DU", "Object", "n", "m", ...
Push "VERSION"
Push 1258
SetVariable
Push "DU"
Push 0
Push "Object"
NewObject
SetVariable

AS2 is a best-effort reconstruction over the linear subset (push literals, get/set variable and member, object/array literals, operators, new/calls, function bodies). It is not a full decompiler: control flow and registers holding complex expressions fall back to their p-code line.

VERSION = 1258;
DU = new Object();
DU[1] = {n: "Donjon Bouftou", m: new Object()};

Scope

The evaluator is a data-script interpreter: it runs the pure, branch-free operators over version-accurate value coercion — no control flow, no function calls, no host/display objects. Opcodes outside that subset are recorded in UnsupportedOpcodes (or throw when strict). AVM2 (DoABC) is out of scope and kept raw.