Following Lua's source code as closely as possible

4 files changed, 118 insertions, 28 deletions

diff --git a/src/bytecodeparser.js b/src/bytecodeparser.js
deleted file mode 100644
index 595158e..0000000
--- a/src/bytecodeparser.js
+++ /dev/null
@@ -1,28 +0,0 @@
-"use strict";
-
-const DataView = require('buffer-dataview');
-
-/**
- * Parse Lua 5.3 bytecode
- */
-class BytecodeParser {
-
-    constructor(dataView) {
-        this.dataView = dataView;
-        this.offset = 0;
-    }
-
-    _read(offset, nbytes) {
-        let bytes = new Uint8Array(nbytes);
-
-        for (let i = 0; i < nbytes; i++)
-            bytes[i] = this.dataView.getUint8(offset, true);
-
-        return bytes.length === 1 ? bytes[0] : bytes;
-    }
-
-    readByte() {
-        return read(this.offset++, 1);
-    }
-
-}
\ No newline at end of file
diff --git a/src/lobject.js b/src/lobject.js
new file mode 100644
index 0000000..2e21f16
--- /dev/null
+++ b/src/lobject.js
@@ -0,0 +1,15 @@
+/*jshint esversion: 6 */
+"use strict";
+
+class LClosure {
+
+    constructor(L, n) {
+        this.p = [];
+        this.nupvalues = n;
+    }
+
+}
+
+module.exports = {
+    LClosure: LClosure
+};
\ No newline at end of file
diff --git a/src/lstate.js b/src/lstate.js
new file mode 100644
index 0000000..b0002c3
--- /dev/null
+++ b/src/lstate.js
@@ -0,0 +1,36 @@
+/*jshint esversion: 6 */
+"use strict";
+
+class lua_State {
+
+    constructor() {
+        // CommonHeader;
+        // unsigned short nci;  /* number of items in 'ci' list */
+        // lu_byte status;
+        // StkId top;  /* first free slot in the stack */
+        // global_State *l_G;
+        // CallInfo *ci;  /* call info for current function */
+        // const Instruction *oldpc;  /* last pc traced */
+        // StkId stack_last;  /* last free slot in the stack */
+        // StkId stack;  /* stack base */
+        // UpVal *openupval;  /* list of open upvalues in this stack */
+        // GCObject *gclist;
+        // struct lua_State *twups;   list of threads with open upvalues 
+        // struct lua_longjmp *errorJmp;  /* current error recover point */
+        // CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
+        // volatile lua_Hook hook;
+        // ptrdiff_t errfunc;  /* current error handling function (stack index) */
+        // int stacksize;
+        // int basehookcount;
+        // int hookcount;
+        // unsigned short nny;  /* number of non-yieldable calls in stack */
+        // unsigned short nCcalls;  /* number of nested C calls */
+        // l_signalT hookmask;
+        // lu_byte allowhook;
+    }
+
+}
+
+module.exports = {
+    lua_State: lua_State
+};
\ No newline at end of file
diff --git a/src/lundump.js b/src/lundump.js
new file mode 100644
index 0000000..69445d4
--- /dev/null
+++ b/src/lundump.js
@@ -0,0 +1,67 @@
+/*jshint esversion: 6 */
+"use strict";
+
+const DataView  = require('buffer-dataview');
+const fs        = require('fs');
+const lua_State = require('./lstate.js').lua_State;
+const LClosure  = require('./lobject.js').LClosure;
+
+/**
+ * Parse Lua 5.3 bytecode
+ * @see {@link http://www.lua.org/source/5.3/lundump.c.html|lundump.c}
+ */
+class BytecodeParser {
+
+    /**
+     * Initilialize bytecode parser
+     * @constructor
+     * @param {DataView} dataView Contains the binary data
+     */
+    constructor(dataView) {
+        this.dataView = dataView;
+        this.offset = 0;
+    }
+
+    peekByte() {
+        return this.dataView.getUint8(this.offset, true);
+    }
+
+    readByte() {
+        let byte = this.peekByte();
+        this.offset++;
+        return byte;
+    }
+
+    peekWord() {
+        return this.dataView.getUint32(this.offset, true);
+    }
+
+    readWord() {
+        let word = this.peekWord();
+        this.offset += 4;
+
+        return word;
+    }
+
+    checkHeader() {
+        if (this.readByte() !== 0x1b
+            || this.readByte() !== 0x4c
+            || this.readByte() !== 0x75
+            || this.readByte() !== 0x61)
+            throw new Error("Bad LUA_SIGNATURE, expected [1b 4c 75 61]");
+
+        if (this.readByte() !== 0x53)
+            throw new Error("Bad Lua version, expected 5.3");
+
+        if (this.readByte() !== 0)
+            throw new Error("Supports only official PUC-Rio implementation")
+    }
+
+    luaU_undump() {
+        checkHeader();
+        let cl = new LClosure(L, this.readByte());
+
+        return cl;
+    }
+
+}
\ No newline at end of file