mirror of
https://github.com/captbaritone/webamp.git
synced 2026-07-21 09:09:01 +00:00
Correctly parse command opcodes
This moves to using a node Buffer to hold the command bytecode which resolves a character encoding issue we were having
This commit is contained in:
Jordan Eldredge
parent
59e41c87d6
commit
000f369751
3 changed files with 73 additions and 66 deletions
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@ -8,40 +8,26 @@ class Variable {
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}
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}
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function decodeUInt32(code) {
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// prettier-ignore
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return (
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(code.charCodeAt(3) << 24) +
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(code.charCodeAt(2) << 16) +
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(code.charCodeAt(1) << 8) +
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code.charCodeAt(0)
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);
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}
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function decodeInt32(code) {
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let num = decodeUInt32(code);
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if (num > 0x7fffffff) {
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num = num - 0xffffffff - 1;
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}
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return num;
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}
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class Command {
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constructor({
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functionsCode,
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commandsBuffer,
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pos,
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types,
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variables,
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functionNames,
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localFunctions
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}) {
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const opcode = functionsCode.charCodeAt(pos);
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const opcode = commandsBuffer.readInt8(pos);
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this.pos = pos;
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this.opcode = opcode;
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this.arguments = [];
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this.command = COMMANDS[opcode];
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this.size = 1;
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if (this.command == null) {
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// I don't think this ever happens in a real .maki file
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// throw new Error(`Unknown opcode "${opcode}"`);
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// But the decompiler tries to do something...
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this.command = {
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name: `unknown ${opcode}`,
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in: 0,
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@ -59,22 +45,22 @@ class Command {
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let arg = null;
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switch (argType) {
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case "var": {
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const variable = decodeInt32(functionsCode.substr(pos + 1, 4));
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const variable = commandsBuffer.readUInt32LE(pos + 1);
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if (variables[variable] != null) {
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arg = variables[variable];
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} else {
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arg = new Variable(-1, -0, "unknown");
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}
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this.name = `Unknown ${variable}`;
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arg.name = `Unknown ${variable}`;
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break;
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}
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case "line": {
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const variable = decodeInt32(functionsCode.substr(pos + 1, 4)) + 5;
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const variable = commandsBuffer.readUInt32LE(pos + 1) + 5;
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arg = { name: variable, line: variable };
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break;
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}
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case "objFunc": {
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const variable = decodeInt32(functionsCode.substr(pos + 1, 4));
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const variable = commandsBuffer.readUInt32LE(pos + 1);
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if (functionNames[variable] != null) {
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arg = functionNames[variable].function;
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} else {
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@ -88,28 +74,23 @@ class Command {
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}
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case "func": {
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// Note in the perl code here: "todo, something strange going on here..."
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const variable = decodeInt32(functionsCode.substr(pos + 1, 4)) + 5;
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const s = functionsCode.substr(pos + 1, 1);
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console.log(functionsCode.length);
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console.log(s.charCodeAt(0));
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const variable = commandsBuffer.readUInt32LE(pos + 1) + 5;
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const offset = variable + pos;
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arg = {
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name: `func${variable + pos}`,
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name: `func${offset}`,
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code: [],
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offset: variable + pos
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offset
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};
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if (opcode === 25) {
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// console.log(variable);
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}
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if (localFunctions[variable + pos] == null) {
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localFunctions[variable + pos] = {
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if (localFunctions[offset] == null) {
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localFunctions[offset] = {
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function: arg,
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offset: variable + pos
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offset
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};
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}
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break;
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}
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case "obj": {
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const variable = decodeInt32(functionsCode.substr(pos + 1, 4));
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const variable = commandsBuffer.readUInt32LE(pos + 1);
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arg = types[variable];
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break;
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}
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@ -118,14 +99,14 @@ class Command {
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this.arguments = [arg];
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this.size = 5;
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/*
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# look forward for a stack protection block
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# (why do I have to look FORWARD. stupid nullsoft)
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if( length($code) > $pos+5+4 &&
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decodeUInt32( substr( $code, $pos+5, 4 ) ) >= 0xffff0000 ) {
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$self->{size} += 4;
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// From perl: look forward for a stack protection block
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// (why do I have to look FORWARD. stupid nullsoft)
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if (
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commandsBuffer.length > pos + 5 + 4 &&
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commandsBuffer.readUInt32LE(pos + 5) >= 0xffff0000
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) {
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this.size += 4;
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}
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*/
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if (opcode === 112) {
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this.size += 1;
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@ -1,7 +1,7 @@
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const { COMMANDS } = require("./constants");
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const Command = require("./command");
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const MAGIC = "FG";
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const ENCODING = "ascii";
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const ENCODING = "binary";
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class Parser {
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_readMagic() {
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@ -125,11 +125,6 @@ class Parser {
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}
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}
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_readFunctionsCode() {
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const code = this._readStringOfLength(this._readUInt32LE());
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return code;
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}
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_readUInt32LE() {
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const int = this._buffer.readUInt32LE(this._i);
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this._i += 4;
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@ -158,15 +153,17 @@ class Parser {
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return this._readStringOfLength(this._readUInt16LE());
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}
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_decodeCode({ functionsCode, types, variables, functionNames, functions }) {
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_decodeCode({ types, variables, functionNames, functions }) {
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const length = this._readUInt32LE();
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const commandsBuffer = this._buffer.slice(this._i, this._i + length);
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this._i += length;
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let pos = 0;
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const localFunctions = {};
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const results = [];
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const poss = [];
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while (pos < functionsCode.length) {
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poss.push(pos);
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while (pos < commandsBuffer.length) {
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const command = new Command({
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functionsCode,
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commandsBuffer,
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pos,
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types,
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variables,
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@ -201,22 +198,18 @@ class Parser {
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const variables = this._readVariables();
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const constants = this._readConstants();
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const functions = this._readFunctions();
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const functionsCode = this._readFunctionsCode();
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const decoding = this._decodeCode({
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functionsCode,
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types,
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variables,
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functionNames,
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functions
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});
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this._readCommands(functionsCode);
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return {
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magic,
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types,
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functionNames,
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variables,
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constants,
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functionsCode,
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functions,
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decoding
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};
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@ -67,15 +67,48 @@ describe("standardframe.maki", () => {
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]);
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});
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test("can read function code", () => {
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expect(maki.functionsCode.length).toBe(1004);
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});
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test("can read function code", () => {
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expect(maki.functionsCode.length).toBe(1004);
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});
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// [opcode, size] as output by the Perl decompiler
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// prettier-ignore
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const expectedCommands = [
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[1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5],
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[1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [1, 5], [1, 5],
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[1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1],
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[2, 1], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [1, 5],
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[1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1],
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[2, 1], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [1, 5],
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[1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [33, 1], [3, 5], [3, 5], [1, 5], [1, 5], [8, 1],
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[16, 5], [1, 5], [25, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5],
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[9, 1], [16, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [8, 1], [1, 5], [1, 5],
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[8, 1], [81, 1], [16, 5], [1, 5], [1, 5], [9, 1], [16, 5], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1],
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[1, 5], [1, 5], [8, 1], [16, 5], [1, 5], [1, 5], [9, 1], [16, 5], [1, 5], [1, 5], [1, 5], [64, 1], [1, 5],
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[24, 5], [2, 1], [18, 5], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [33, 1],
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[3, 5], [3, 5], [3, 5], [3, 5], [1, 5], [1, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5],
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[1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [8, 1], [1, 5], [1, 5], [8, 1], [81, 1], [1, 5],
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[1, 5], [8, 1], [81, 1], [1, 5], [1, 5], [8, 1], [81, 1], [16, 5], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5],
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[33, 1], [3, 5], [1, 5], [1, 5], [1, 5], [24, 5], [48, 1], [2, 1], [1, 5], [1, 5], [8, 1], [16, 5], [1, 5], [1, 5],
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[1, 5], [1, 5], [1, 5], [1, 5], [64, 1], [1, 5], [64, 1], [24, 5], [2, 1], [1, 5], [33, 1], [1, 5], [1, 5], [1, 5],
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[24, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [1, 5], [1, 5],
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[24, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5],
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[1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5], [1, 5], [24, 5], [2, 1], [1, 5],
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[33, 1]
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];
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test("can read decoding", () => {
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maki.decoding.forEach((command, i) => {
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const [expectedOpcode, expectedSize] = expectedCommands[i];
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if (expectedOpcode !== command.opcode) {
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throw new Error(
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`Command ${i} reported opcode ${
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command.opcode
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}. Expected ${expectedOpcode}`
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);
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}
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if (expectedSize !== command.size) {
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throw new Error(
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`Command ${i} reported size ${command.size}. Expected ${expectedSize}`
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);
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}
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});
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expect(maki.decoding.length).toBe(256);
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});
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});
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