Casm Assembly Language Documentation

Casm is a low-level assembly language designed for programming a custom CPU architecture. The language features basic operations, conditional jumps, function definitions, and custom operations like arithmetic and bitwise shifts.

Table of Contents

1. Introduction
2. Instructions
   • Control Flow Instructions
   • Arithmetic Instructions
   • Shift Instructions
   • Comparison Instructions
   • Input/Output Instructions
   • Function Definitions
3. Operands
4. Creating Binaries
5. Examples

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Introduction

Casm is designed to provide a simple yet powerful assembly language for custom CPU implementations. The language allows direct manipulation of registers, memory, and control flow to achieve a variety of tasks, such as computation, input/output operations, and conditional execution.

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Instructions

x/XY	0Y	1Y	2Y	3Y	4Y	5Y	6Y	8Y	9Y	AY	BY	CY	DY	EY	FY
X0	Jump	Return	Exit	Read	Write	P==P?	P==0?	R==R	P==0?	Nop	None	None	None	None	None
X1	Left bitshft	Right bitshft	Add	Sub	Mult	Div	Reg1 += 1	None	None	Reg left shft	Reg right shft	Reg add	Reg Sub	Reg Mult	Reg Div

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Operands

Casm uses several types of operands:

• Registers: Denoted by rX, where X is the register number (e.g., r0, r1).
• Pointers: Denoted by pX, where X is the address (e.g., p10).
• Line Pointers: Denoted by plX, where Xis the line number (e.g., pl4, pl7)
• Ram Pointers: Denoted by prX, where Xis the address starting in ram (e.g., pr70, pr8)
• Labels/Functions: Functions are defined with the def keyword, and run instructions can target them.

Operands for instructions must be provided in the correct order as per the instruction format.

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Creating Binaries

To compile your Casm code into binary form, use the following Python script:

python3 compiler.py <filename>

This will take the Casm source code file, convert it to binary, and save it with a .bin extension.

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Examples

Example 1: Simple Addition

add r0 r1 r2

This instruction adds the values in r0 and r1 and stores the result in r2.

Example 2: Function Definition and Call

def my_function
    add r0 r1 r2
    return

run my_function

This code defines a function my_function that adds r0 and r1, stores the result in r2, and then returns. The run instruction calls my_function.

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For more information, consult the Casm source code.