ASM-TOP

A lightweight system monitoring tool written in pure x86-64 assembly for Linux. Displays real-time CPU and RAM usage statistics similar to the top command.

=== ASM-TOP - localhost @ 09:56:14 ===
uptime: 21h 59m  load: 0.96 1.23 1.37 
Tasks: 1662 total, 2 running
CPU:  [######..................................] 16%
RAM:  [############################............] 71% (5 GB/7 GB)
SWAP: [###.....................................] 8% (1 GB/16 GB)

Press 'q' to exit

Features

• CPU Monitoring: Real-time CPU usage percentage
• Memory Monitoring: Real-time RAM and Swap usage percentage with detailed stats
• System Stats: Uptime, Load Average, and Task breakdown
• Visual Progress Bars: Text-based bars showing resource utilization
• System Info Display: Shows hostname and current time (HH:MM:SS)
• Interactive Controls: Press 'q' to quit
• Minimal Dependencies: Pure assembly, no external libraries
• Lightweight: Extremely small binary size (~21KB) and minimal resource usage

Quick install (x86_64 GNU/Linux)

wget https://github.com/c0m4r/asm-top/releases/download/0.3.1/asm-top
echo "67d659d6748fe1528c6559e9c31a5f622ca7184485bcddd4cf9b9fe9304026bf  asm-top" | sha256sum -c || rm -f asm-top
sudo mv asm-top /usr/local/bin/
sudo chmod +x /usr/local/bin/asm-top
asm-top

Building

Prerequisites

• GNU Assembler (as) - part of binutils
• GNU Linker (ld) - part of binutils
• Linux kernel with /proc filesystem

Compile

./configure
make

This will create the asm-top executable.

Clean Build

make clean

Install

make install

Usage

Simply run the executable:

./asm-top

The display will update every second showing:

• Hostname and current time in the header
• System Uptime, Load Average, and Task counts
• CPU usage percentage with a visual progress bar
• RAM usage percentage with a visual progress bar and size details
• Swap usage percentage with a visual progress bar and size details

Press q to quit gracefully.

Technical Details

Architecture

• Platform: x86-64 (64-bit)
• Syntax: Intel syntax
• OS: Linux (requires /proc filesystem)

System Calls Used

• open(2): Open /proc/stat, /proc/meminfo, and /proc/sys/kernel/hostname
• read(0): Read file contents
• write(1): Output to stdout
• close(3): Close file descriptors
• nanosleep(35): Sleep between updates
• poll(7): Non-blocking keyboard input detection
• time(201): Get current time
• exit(60): Program termination

Data Sources

• CPU: /proc/stat - Parses total CPU time including user, nice, system, idle, iowait, irq, and softirq
• Memory/Swap: /proc/meminfo - Extracts MemTotal, MemAvailable, SwapTotal, and SwapFree
• Load/Tasks: /proc/loadavg - Load averages and running/total tasks
• Uptime: /proc/uptime - System uptime
• Hostname: /proc/sys/kernel/hostname - System hostname
• Time: time() syscall - Current Unix timestamp converted to HH:MM:SS

CPU Calculation

Total = user + nice + system + idle + iowait + irq + softirq
Idle = idle + iowait
NonIdle = Total - Idle

CPU% = ((NonIdle_now - NonIdle_prev) / (Total_now - Total_prev)) × 100

Memory and Swap Calculation

MemUsed = MemTotal - MemAvailable
Memory% = (MemUsed / MemTotal) × 100

SwapUsed = SwapTotal - SwapFree
Swap% = (SwapUsed / SwapTotal) × 100

Project Structure

asm-top/
├── main.asm       - Program entry point and main loop
├── cpu.asm        - CPU monitoring functions
├── memory.asm     - Memory monitoring functions
├── syscalls.asm   - System call wrappers
├── utils.asm      - Utility functions (string/number conversion)
├── display.asm    - Display formatting and output
├── input.asm      - Non-blocking keyboard input
├── sysinfo.asm    - Hostname and time retrieval
├── Makefile       - Build configuration
├── .gitignore     - Git ignore file
└── README.md      - This file

License

Public domain - use freely for any purpose.

Author

Created with pure assembly by Gemini 3 Pro (High) for maximum performance and minimal overhead.