Nish-19 / Two_Pass_Assembler_Emulator

Two Pass Assembler and Emulator for compiling and running assembly language

Two_Pass_Assembler_Emulator

Assembler and Emulator implementation in C Language for the given Assembly Language. Project as a part of CS321-CS322 Computer Architecture Course IIT-Patna.

Rules of the given Assembly Language

• Two registers, A & B, arranged as an internal stack
• A program counter, PC
• A stack pointer, SP
• These registers are 32 bits in size
• Instructions have either no operands or a single operand
• The operand is a signed 2's complement value.
• The encoding uses the bottom 8 bits for opcode and the upper 24 bits for operand.
• Comments are denoted using ';' (semicolon)
• An operand is either a label or a number, the number can be decimal, hex or octal.
• Label definitions consist of the label name followed by a ':'
• Label Name is alpha_numberic
• Label used to calculate displacement in case of branch instructions.
• An operand is either a label or a number, the number can be decimal, hex or octal.

Assembler

• Has two data structures to store respectively labels and mnemonic table with expected operands.
• Reads the file once, converts to internal format using linked list and then parses.
• detects label errors.
• consistent and sensible formatting with sensible program structure.
• sensible variable, function & type names with explanatory comments.
• advanced listing file.
• assembles ALL test programs.
• CAN IMPLEMENT and demonstrates the instruction SET.

Emulator

• Three data structures are used to store respectively memory, mnemonic table with expected operands and a linked list structure code.
• loads object file,
• Does automatic trace i.e at each step displays the value of PC, SP, reg A, and Reg B
• Does automatic memory dump, before and after the program to show the state of memory elements.

TestCases

Test cases consists of sample programs written in the simple assembly language. There are a total of 10 such programs. Test cases are present in the folder cs33testcases. The listing and object file obtained after execution from the assembler is also provided.

Compiling and Running

1. For assembler gcc asm.c -o asm

2. For emulator gcc emu.c -o emu

Running on given test cases

Assembler - ./asm cs33testcases/filename.asm

Emulator - ./emu cs33testcases/filename_obj.o

Sample Execution

Compiling and linking the bubble sort program written in the assembly Language

./asm cs33bubble.asm ./emu cs33bubble_obj.o

Before sorting (numbers in random order)

After soring (numbers in sorted order)