Concurrent Noteć Calculator (Współbieżny Szesnastkator Noteć)

A concurrent, thread-safe x86_64 assembly implementation of a Reverse Polish Notation (RPN) calculator operating on 64-bit hexadecimal numbers.

Overview

Noteć is a stack-based calculator that can run N parallel instances simultaneously, each in its own thread. The calculator uses the processor's hardware stack for computations and implements thread synchronization using spinlocks.

Features

• Reverse Polish Notation: Stack-based expression evaluation
• Hexadecimal arithmetic: Operations on 64-bit numbers in base-16
• Concurrent execution: Multiple calculator instances running in parallel
• Thread synchronization: Custom spinlock implementation for the W operation
• Hardware stack: Direct use of CPU stack for calculations

Operations

Number Input

• 0-9, A-F, a-f: Hex digits (automatic number accumulation mode)
• =: Exit number input mode

Arithmetic Operations

• +: Addition
• *: Multiplication
• -: Negation (unary)

Bitwise Operations

• &: AND
• |: OR
• ^: XOR
• ~: NOT (bitwise negation)

Stack Manipulation

• Y: Duplicate top value
• X: Swap top two values
• Z: Remove top value

Special Operations

• N: Push total number of Noteć instances
• n: Push current instance number
• g: Call external debug function
• W: Thread synchronization - exchange values between two Noteć instances

API

uint64_t notec(uint32_t n, char const *calc);

• n: Instance number (0 to N-1)
• calc: ASCIIZ string containing calculation
• Returns: Value from top of stack after execution

Building

# Assemble
nasm -DN=$N -f elf64 -w+all -w+error -o notec.o notec.asm

# Compile example
gcc -DN=$N -c -Wall -Wextra -O2 -std=c11 -o example.o example.c

# Link
gcc notec.o example.o -lpthread -o example

Where $N is the number of concurrent Noteć instances.

Example

// Calculate: (~((0xab - 0x12) * 3) & 0xfff) | 0xcde09
notec(0, "6N8ZXab=12-+3*~FFF&cDe09|g");

// Exchange values between instances using thread synchronization
notec(0, "nY1^W");  // XOR instance number with 1, exchange with that instance

Technical Details

• Pure x86_64 assembly implementation
• No external libraries
• ABI-compliant register and stack usage
• Spinlock-based synchronization without bus locking
• All arithmetic modulo 2^64

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Created in 2021 for the Operating Systems course at the University of Warsaw.