patterns: Added pattern for PopCap's Lua bytecode (#458)

* patterns: Added PopCap's proprietary Lua bytecode pattern.

* updated README to include new pattern

* fixed README link

* patterns/popcap_luc.hexpat: fixed comments and sources

* patterns/popcap_luc.hexpat: Changed datatype of filename to be more clear about its structure

* patterns/popcap_luc.hexpat: fixed improper handling of Nil type and added test file

README.md

@@ -105,6 +105,7 @@ Everything will immediately show up in ImHex's Content Store and gets bundled wi
 | Java Class | `application/x-java-applet` | [`patterns/java_class.hexpat`](patterns/java_class.hexpat) | Java Class files |
 | JPEG | `image/jpeg` | [`patterns/jpeg.hexpat`](patterns/jpeg.hexpat) | JPEG Image Format |
 | LOC | | [`patterns/loc.hexpat`](patterns/loc.hexpat) | Minecraft Legacy Console Edition Language file |
+| LUC | | [`patterns/popcap_luc.hexpat`](patterns/popcap_luc.hexpat) | PopCap's proprietary Lua bytecode |
 | Lua 5.1 | | [`patterns/lua51.hexpat`](patterns/lua51.hexpat) | Lua 5.1 bytecode |
 | Lua 5.2 | | [`patterns/lua52.hexpat`](patterns/lua52.hexpat) | Lua 5.2 bytecode |
 | Lua 5.3 | | [`patterns/lua53.hexpat`](patterns/lua53.hexpat) | Lua 5.3 bytecode |

patterns/popcap_luc.hexpat

@@ -0,0 +1,174 @@
+#pragma author gluecia
+#pragma description PopCap's proprietary Lua bytecode (.luc)
+#pragma endian little
+#pragma magic [ 1B 4C 75 61 56 ] @ 0x00;
+
+import std.io;
+import std.sys;
+
+using PLChunk;
+using PLConst;
+using PLLocal;
+using PLOp;
+using PLStr;
+using cType;
+
+
+struct PLHeader {
+    char magic[5];
+    padding[18];
+
+    // *technically* this is a part of the first top level chunk, though
+    // it is essentially just a part of the header since it only appears there.
+   PLStr filename [[name("Source Name")]];
+};
+
+
+// LOCALS
+fn fmtLocal(PLLocal l) {
+    return l.name;
+};
+
+struct PLLocal {
+    u32 nameLength [[hidden]];
+    char16 name[nameLength] [[name("Local")]];
+    u32 begin [[name("Begin")]];
+    u32 end [[name("End")]];
+} [[format("fmtLocal")]];
+
+
+// CONSTANTS
+// constant types
+fn fmtCType(cType t) {
+    match (t) {
+        (cType::Nil): return "nil";
+        (cType::Int): return "int";
+        (cType::Float): return "float";
+        (cType::Str): return "str";
+        (_): return "unknown";
+    }
+};
+
+enum cType : u8 {
+    Nil,
+    Float = 3,
+    Int,
+    Str
+} [[format("fmtCType")]];
+
+// lua strings
+fn fmtStr(PLStr s) {
+    return std::format("\"{}\"", s.val);
+};
+
+
+struct PLStr {
+    u32 len [[hidden]];
+    if (len > 0)
+        char16 val[len];
+} [[format("fmtStr"), sealed]];
+
+// constants struct
+fn fmtConst(PLConst c) {
+    if (c.type == cType::Nil) {
+        return c.type;
+    } else {
+        return std::format("{} ({})", c.val, c.type);
+    }
+};
+
+struct PLConst {
+    cType type;
+    match (type) {
+        (cType::Float): double val;
+        (cType::Int): s32 val;
+        (cType::Str): PLStr val;
+        // theres definitely a better way to handle the Nil case        
+        (cType::Nil): u8 val = 0;
+        (_): std::error("unknown cType given");
+    }
+} [[format("fmtConst"), sealed]];
+
+
+// PROTOTYPES
+struct PLPrototype {
+    padding[4];
+    PLChunk chunk;
+} [[inline]];
+
+
+// UPVALUES
+struct PLUpvalue {
+    u32 len [[hidden]];
+    char name[len] [[name("Upvalue")]];
+} [[inline]];
+
+
+// OPERANDS
+fn fmtPLOp(PLOp o) {
+    return o.opcode;
+};
+
+// source: https://github.com/wxarmstrong/PopLua-Disassembler/blob/master/popOp.cpp
+enum PLOpType : u8 {
+    MOVE, LOADK, LOADBOOL, LOADNIL, GETUVPVAL,
+    GETGLOBAL, GETTABLE, SETGLOBAL, SETUPVAL,
+    SETTABLE, NEWTABLE, SELF, ADD, SUB, MUL,
+    DIV, MOD, POW, UNM, NOT, SIZ, CONCAT, JMP,
+    EQ, LT, LE, TEST, CALL, TAILCALL, RETURN,
+    FORLOOP, TFORLOOP, TFORPREP, SETLIST,
+    SETLISTO, CLOSE, ALTSELF, CONSTGLOBAL,
+    CONSTTABLE, DEFGLOBAL, DEFTABLE,
+    SETSELFORGLOBAL, GETSELFORGLOBAL,
+    SELFORGLOBAL, CALLSELFORGLOBAL,
+    TAILCALLSELFORGLOBAL, INT, BREAK,
+    CLOSURE
+};
+
+// this is for a different version of lua and its bytecode, but helped a LOT
+// https://archive.org/details/a-no-frills-intro-to-lua-5.1-vm-instructions
+struct PLOp {
+    u32 raw [[hidden]];
+    PLOpType opcode = raw & 0x3F [[name("Opcode"), hidden, export]];
+    u32 rawOperands = raw >> 6;
+    u8 opA = rawOperands & 0xFF [[name("Operand A"), export]];
+
+    match(opcode) {
+        (PLOpType::LOADK | PLOpType::CLOSURE): u32 Bx = (rawOperands >> 8) [[name("Operand Bx"), export]];
+        // 131071 is the bias for sBx to make it signed, formed from (2^18 - 1) >> 1
+        // where 2^18 - 1 is the maximum value for an 18 bit number
+        (PLOpType::JMP | PLOpType::FORLOOP | PLOpType::TFORLOOP): s32 opSBx = (rawOperands >> 8) - 131071 [[name("Operand sBx"), comment("Signed displacement added to the PC."), export]];
+        (_): {
+            u16 opB = (rawOperands >> 8) & 0xFF01 [[name("Operand B"), export]];
+            u16 opC = (rawOperands >> 17) & 0xFF01 [[name("Operand C"), export]];
+        }
+    }
+} [[format("fmtPLOp")]];
+
+// CHUNKS
+struct PLChunk {
+    char intro[0xC] [[name("Chunk Intro"), comment("Holds information on the function, but the format is unknown.")]];
+
+    u32 sizecode [[name("Instructions Count")]];
+    u32 linesArray[sizecode] [[name("Line Numbers"), comment("The line numbers for the given operations, this should be interpreted with the operations array.")]];
+
+    u32 sizelocvars [[name("Locals Count")]];
+    PLLocal localsArray[sizelocvars] [[name("Locals")]];
+
+    u32 sizeupvalues [[name("Upvalues Count")]];
+    PLUpvalue upvalsArray[sizeupvalues] [[name("Upvalues")]];
+
+    u32 sizek [[name("Constants Count")]];
+    PLConst constsArray[sizek] [[name("Constants")]];
+
+    u32 sizep [[name("Prototype Count")]];
+    PLPrototype protoArray[sizep] [[name("Prototypes")]];
+
+    u32 sizecodeVerify [[hidden]];
+    std::assert(sizecode == sizecodeVerify, std::format("sizecode ({}) did not match sizecodeVerify ({})!", sizecode, sizecodeVerify));
+
+    PLOp opsArray[sizecode] [[name("Instructions"), comment("The raw bytes for operations, should be interpreted with the line numbers array.")]];
+};
+
+PLHeader Header @ 0x0;
+PLChunk Body @ $;