Brandeis Operating Systems MiniASM Interpreter and Visualizer

Demo(TODO)

Visualizer

Interpreter

Features

• Easily upload assembly files using drag and drop
• Aids in visualization via single step and continue. Or jump to the end if thats not for you.
• Get fast feedback to program changes. Casm detects changes to your assembly source file and automatically reloads file
• Find syntax errors quickly with descriptive error messages
• Pleasing to the eyes with smooth animations
• Easy to use. Power and simplicity don't have to be mutually exclusive

Getting Started

1. Install precompiled binaries from releases
   Run on the command line ./casm [assembly_program]

2. Build from source

	git clone https://github.com/ArcherHeffern/casm.git
	make [macos|windows|linux]
	./main [assembly_program]

NOTE: I have not yet tested the windows and linux targets. Let me know if you run into any issues running these

Instruction Set Overview

Syntax Definitions

<label>: One or more letters postfixed with a colon (e.g., LOOP:, END:)
<label_ref>: One of more letters (e.g., START, ACCUMULATE)
<register>: R<number> (e.g., R1, R2).
<- : Assignment
address : An address must be a multiple of 4 (since each cell is 4 bytes), and can be an expression of numbers and the values of registers
M[address]: Memory access at address (Can be used on either side of assignment)

Load Instructions

Direct Load

• Syntax: LOAD <register:Ri>, <register:Rj>
• Description: Loads data from the memory address stored in register Rj into register Ri.
• Formal Definition: Ri <- M[Rj]

Immediate Load

• Syntax: LOAD <register>, =<number>
• Description: Loads <number> directly into <register>.
• Formal Definition: register <- number

Relative Load

• Syntax: LOAD <register:Ri>, $<register:Rj>
• Description: Loads data from the memory address located at pc+Rj into Ri.
• Formal Definition: Ri <- M[pc+Rj]

Index Load

• Syntax: LOAD <register:Ri>, [<number>, <register:Rj>]
• Description: Loads data from the memory address located at number+Rj into Ri.
• Formal Definition: Ri <- M[number+Rj]

Indirect Load

• Syntax: LOAD <register:Ri>, @<register:Rj>
• Description: Read the formal definition ;-;
• Formal Definition: Ri <- M[M[Rj]]

Store Instructions

Direct Store

• Syntax: STORE <register:Ri>, <register:Rj>
• Formal Definition: M[Rj] = Ri

Index Store

• Syntax: STORE <register:Ri>, [<number>, <register:Rj>]
• Formal Definition: M[number+Rj] = Ri

Relative Store

• Syntax: STORE <register:Ri>, $<register:Rj>
• Formal Definition: M[Rj+pc] = ri

Read Instructions

Direct Read

• Syntax: READ <register:Ri>, <register:Rj>
• Formal Definition: Ri = S[Rj]

Index Read

• Syntax: READ <register:Ri>, [<number>, <register:Rj>]
• Formal Definition: Ri = S[number+Rj]

Write Instructions

Direct Write

• Syntax: WRITE <register:Ri>, <register:Rj>
• Formal Definition: S[Rj] = Ri

Index Write

• Syntax: WRITE <register:Ri>, [<number>, <register:Rj>]
• Formal Definition: S[number+Rj] = Ri

Math Instructions

Note: This language only supports positive integers.

Addition

• Syntax: ADD <register:Ri>, <register:Rj>
• Description: Stores Ri+Rj in Ri.

Subtraction

• Syntax: SUB <register:Ri>, <register:Rj>
• Description: Stores Max(Ri - Rj, 0) in Ri.

Multiplication

• Syntax: MUL <register:Ri>, <register:Rj>
• Description: Stores Ri * Rj in Ri.

Division

• Syntax: DIV <register:Ri>, <register:Rj>
• Description: Performs Integer Division and Modulus.
  1. Stores Ri // Rj in Ri.
  2. Stores Max(Ri % Rj), 0) in Rj.

Branch Instructions

Unconditional Branch

• Syntax: BR <label_ref>
• Description: Jumps to the specified label unconditionally.

Branch if Less Than

• Syntax: BLT <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri < Rj

Branch if Greater Than

• Syntax: BGT <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri > Rj

Branch if Less Than or Equal

• Syntax: BLEQ <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri <= Rj

Branch if Greater Than or Equal

• Syntax: BGEQ <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri >= Rj

Branch if Equal

• Syntax: BEQ <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri == Rj

Branch if Not Equal

• Syntax: BNEQ <register:Ri>, <register:Rj>, <label_ref>
• Description: Jumps to <label> if Ri != Rj