From c29ae7a65c636b8d1fa37c6589278dcdee97658f Mon Sep 17 00:00:00 2001
From: Dennis Brentjes <d.brentjes@gmail.com>
Date: Mon, 19 Sep 2016 17:38:23 +0200
Subject: Started working on a x86 emulator.

---
 emulate/emulator.hpp | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 emulate/emulator.hpp

(limited to 'emulate/emulator.hpp')

diff --git a/emulate/emulator.hpp b/emulate/emulator.hpp
new file mode 100644
index 0000000..e894042
--- /dev/null
+++ b/emulate/emulator.hpp
@@ -0,0 +1,113 @@
+#pragma once
+
+#include "cpustate.hpp"
+
+#include "le_parse_util.hpp"
+
+#include <distorm.h>
+#include <mnemonics.h>
+
+#include <fstream>
+#include <iomanip>
+
+class Emulator {
+public:
+	CpuState cpu;
+	
+	std::map<int, std::function<void(_DInst)>> opcode_handlers;
+	
+	
+	
+	void handle_I_JMP(_DInst inst) {
+		if(inst.ops[0].type == O_PC || inst.ops[0].type == O_PTR || inst.ops[0].type == O_DISP) {
+			binparse::Offset32 target = binparse::Offset32(INSTRUCTION_GET_TARGET(&inst));
+			cpu.eip() = target;
+		} else if (inst.ops[0].type == O_SMEM) {
+			throw UnhandledInstruction();
+		} else {
+			throw UnrecognizedInstruction();
+		}
+	}
+	void handle_I_STI(_DInst) {
+		cpu.intf() = 1;
+	}
+	
+	void handle_I_AND(_DInst inst) {
+		std::cout << inst.ops[0].size << std::endl;
+		//get_op(0, inst) &= get_op(1, inst);
+	}
+	
+public:
+	Emulator(binparse::Offset32 init_eip, binparse::Offset32 init_esp) 
+	: cpu() 
+	{
+		cpu.eip() = init_eip;
+		cpu.esp() = init_esp;
+	
+		#define REGISTER_HANDLER(OPCODE) opcode_handlers[OPCODE] = std::bind(&Emulator::handle_##OPCODE, this, std::placeholders::_1)
+		
+		REGISTER_HANDLER(I_JMP);
+		REGISTER_HANDLER(I_STI);
+		REGISTER_HANDLER(I_AND);
+		
+		#undef REGISTER_HANDLER
+	}
+	
+	struct UnhandledInstruction : public std::runtime_error {
+		UnhandledInstruction()
+		: std::runtime_error("Encountered unhandled instruction")
+		{}
+	};
+	
+	struct UnrecognizedInstruction : public std::runtime_error {
+		UnrecognizedInstruction()
+		: std::runtime_error("Encountered unhandled instruction")
+		{}
+	};
+	
+	void handle_instruction(_DInst inst) {
+		opcode_handlers.at(inst.opcode)(inst);
+	}
+	
+};
+
+void emulate(std::string file_path) {
+	std::ifstream file_stream(file_path, std::ios::binary);
+	file_stream.unsetf(std::ios::skipws);
+	auto file = le::parse_file(file_stream);
+	auto binary = load_binary(file);
+	
+	_CodeInfo ci;
+	_DecodeType dt = Decode32Bits;
+	
+	auto code_object = file.object_table.entries.at(file.le_header.EIP_object);
+	auto initial_eip = code_object.reloc_base_address + file.le_header.EIP;
+	
+	auto data_object = file.object_table.entries.at(file.le_header.ESP_object);
+	auto initial_esp = data_object.reloc_base_address + file.le_header.ESP;
+	
+	Emulator emulator(initial_eip, initial_esp);
+	
+	unsigned int decodedInstructionsCount;
+	
+	bool run = true;
+	while(run) {
+		ci.code = binary.data() + emulator.cpu.eip();
+		ci.nextOffset = emulator.cpu.eip();
+		ci.codeLen = binary.size() - emulator.cpu.eip();
+		ci.codeOffset = emulator.cpu.eip();
+		ci.dt = dt;
+		ci.features = DF_NONE;
+	
+		_DInst decinst;
+		distorm_decompose(&ci, &decinst, 1, &decodedInstructionsCount);
+		
+		emulator.cpu.eip() += decinst.size;
+		
+		_DecodedInst inst;
+		distorm_format64(&ci, &decinst, &inst);
+		std::cout << "CurrentInstruction: " << std::hex << std::setw(8) << std::setfill('0') << inst.offset << ":\t" << inst.mnemonic.p << " " << inst.operands.p << std::endl;
+		
+		emulator.handle_instruction(decinst);
+	}
+}
-- 
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