Simple-SIC-XE-Assembler

Introduction : final project of system programming course.

A. Basic Information

• Basic 2-pass assembler

• OS : Windows 10

• Language : Python 3.9.1

• Files : source.txt , pass1.py , pass2.py , OPTAB.py

  

B. How to Run

$ python3 pass1.py
$ python3 pass2.py

1. 執行 pass1.py

2. 輸入 source code 檔名

   

3. assembler 開始執行 PASS 1

4. PASS 1 結束後

   • 產生 SYMTAB.json 與 intermediate_file.txt

     

   • 程式自動印出 SYM_TABLE 與 Intermediate File 內容

     

5. 執行 pass2.py

6. assembler 開始執行 PASS 2

7. PASS 2 結束後

   • 產生 result_file.txt 與 object_code.txt

     

   • 程式自動印出 Result File 與 Object Code File 內容

     

C. Data Structure

Hash Table

1. OPTAB

   • assembler 內建

   • 以 Dictionary 儲存在 OPTAB.py 中

   • key : Instruction 名稱

   • value : Instruction Opcode, Length

   • example

     

2. REGTAB

   • assembler 內建

   • 以 Dictionary 儲存在 OPTAB.py 中

   • key : Register 名稱

   • value : Register 編號

   • example

     

3. SYMTAB

   • PASS 1 產生

   • 以 Dictionary 儲存在 SYMTAB.json 中

   • key : Label

   • value : Location

   • example

     

PASS 1

• Functions : write_intermediate() , process_line() , print_pass1() , print_SYMTAB() , print_intermediate()
• Read line by line from source file
• Parse each line to get lable , instruction , target
  • line.split()
  • use line length and check positions
• Determine instruction
• call process_line()
  • use write_intermediate() to write line with location imformation into intermediate file
  • add label and its location into symbol table
• Use print_pass1() to print result
  • print_SYMTAB()
  • print_intermediate()

PASS 2

• Functions : twosComplement() , get_op() , get_result_1() , get_result_2() , get_disp() , write_file() , write_record() , print_result() , print_obcode() , print_pass2()
• Read line by line from intermediate file
• Parse each line to get location , lable , instruction , target
  • line.split()
  • use line length and check positions
• Determine instruction ( flag n , flag i )
• Use get_op() to get instruction op
• Use get_disp() to get intruction disp ( flag b , flag p )
• Check for '+' in instruction, '#' or '@' in target ( flag e , flag n , flag i )
• Use get_result_1() for format 3 and get_result_2() for format 4 to generate obcode
• Use write_file() to write into result file
• Use write_record() to write into obcode file
  • if number of obcode > 9 , next T record
  • if loc between two obcode too big ( I use > 4) , next T record
• Use print_pass2() to print result
  • print_result()
  • print_obcode()

D. Copyright Claim

• This code is written by Shih-Jieh Chen.
• All rights reserved.
• Date : 2022/01/20

TODO

• Add M record.

• If your assembly is a one-pass assembly.

• If the implementation of your assembly includes “Literals”

• If the implementation of your assembly includes “Symbol-defining Statements”

• If the implementation of your assembly includes “Program Blocks”

• If the implementation of your assembly includes “Control Sections