# 期中作業報告

課程： 系統程序
學生： 史煜疏

## 使用python 使用匯編語言編寫成機器語言，最後將結果輸出到二進制的文件和輸出結果保存在文件中還有在控制臺進行輸出。
> 講解

# Define opcode and machine code mapping table
opcode_table = {
    "MOV": "8B",
    "ADD": "03",
    "SUB": "2B",
    "MUL": "0F AF",
}

### An opcode table (also called an opcode matrix) is a visual representation of all opcodes in an instruction set. It is arranged such that each axis of the table represents an upper or lower nibble, which combined form the full byte of the opcode. Additional opcode tables can exist for additional instructions created using an opcode prefix.

> 資料來源：https://en.wikipedia.org/wiki/Opcode_table

## 定義以一個'Assembler'類 這是一個自定義的類 實現滙編器功能 滙編器是將匯編語言轉換成機器碼的工具。

class Assembler:
    def __init__(self):
        self.symbol_table = {}
        self.error_report = []

### 首先先初始化兩個變量"symbol_table" 和 "error_report", 這倆分別用於儲存符號表和錯誤報告。

def assemble(self, assembly_code, output_file_name):
        # Clear symbol table and error report
        self.symbol_table.clear()
        self.error_report.clear()

        # Parse assembly code and build symbol table
        self.build_symbol_table(assembly_code)

        # Assemble instructions
        machine_code = self.assemble_instructions(assembly_code)

        # Optimize instructions
        self.optimize(machine_code)

        # Write output file
        self.write_output_file(output_file_name, machine_code)

        # Print error report
        self.print_error_report()

### 'assemble' 是整個滙編器的入口。 接受匯編代碼和輸出文件名為參考。

a    def build_symbol_table(self, assembly_code):
        current_address = 0
        lines = assembly_code.split("\n")
        for line in lines:
            if line.strip() and not line.strip().startswith(";"):
                parts = line.split()
                if parts[0].endswith(":"):
                    label = parts[0].rstrip(":")
                    if label in self.symbol_table:
                        self.error_report.append(f"Duplicated label: {label}")
                    else:
                        self.symbol_table[label] = current_address
                else:
                    current_address += 1

### 構建符號表： 'build_symbol_table'用於解析匯編代碼並構建符號表。

def assemble_instructions(self, assembly_code):
        machine_code = []
        lines = assembly_code.split("\n")
        for line in lines:
            if line.strip() and not line.strip().startswith(";"):
                parts = line.split()
                if parts[0].endswith(":"):
                    continue

                instruction = parts[0].upper()
                operands = parts[1:]

                if instruction in opcode_table:
                    opcode = opcode_table[instruction]
                    machine_code.append(bytes.fromhex(opcode))

                    for operand in operands:
                        if operand in self.symbol_table:
                            address = self.symbol_table[operand]
                            machine_code.append(address.to_bytes(4, "big"))
                        else:
                            try:
                                value = int(operand)
                                machine_code.append(value.to_bytes(4, "big"))
                            except ValueError:
                                self.error_report.append(f"Invalid operand: {operand}")
                else:
                           self.error_report.append(f"Invalid instruction: {instruction}")

        return b"".join(machine_code)

### "assemble_instructions" 用於將匯編語言轉換成機器碼。

    def optimize(self, machine_code):
        # Perform instruction optimization here
        pass

### 進行代碼優化 'optimize' 用於優化指令

    def write_output_file(self, output_file_name, machine_code):
        with open(output_file_name, "wb") as file:
            file.write(machine_code)

### 'write_output_file' 將機器碼寫入輸出文件

    def print_error_report(self):
        for error in self.error_report:
            print(error)

### 'print_error_report' 打印錯誤報告

with open(output_file_name, "rb") as file:
    machine_code = file.read()

print("Machine code:")
for i in range(0, len(machine_code), 4):
    instruction_bytes = machine_code[i:i+4]
    print(" ".join(f"{byte:02X}" for byte in instruction_bytes))

### 將生成的機器碼文件， 按照4個字節進行結構 再將 每個字節以十六進行進行打印。

## 最後輸出結果

#### 這學期的系統程序語言 多數是用C 進行編寫， 而我的C語言較爲不熟悉，所以期末期中作業多用 python進行編寫和測試 。