RISC-V Assembler

A full-stack RISC-V assembler with a modern web-based visualizer. Write assembly code, assemble it to machine code, and step through execution line by line.

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Features

• RISC-V Assembler (C++) — Translates .asm source files to .mc machine code files
• Web Visualizer (React + Vite) — Syntax-highlighted assembly editor with side-by-side machine code output
• Line-by-line Execution — Step forward/backward through instructions, or use Auto Run with adjustable speed
• Animated Progress Bar — Live execution progress with current PC address
• Copy to Clipboard — One-click copy of the full machine code output
• ISA Reference Panel — Expandable quick-reference listing all supported instructions
• Syntax Highlighting — Keywords, registers, immediates, and labels are color-coded in the editor view

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Supported Instructions

Format	Instructions
R-Type	add, sub, and, or, xor, sll, srl, sra, slt, mul, div, rem, addw, subw, mulw, divw, remw
I-Type	addi, andi, ori, addiw, lb, lh, lw, ld, jalr
S-Type	sb, sh, sw, sd
B-Type	beq, bne, blt, bge
U-Type	lui, auipc
J-Type	jal
System	ecall

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Project Structure

Assembler/
├── assembly.cpp        # RISC-V assembler source (C++)
├── assembler           # Compiled assembler binary
├── input.asm           # Input assembly file (written by server on each request)
├── output.mc           # Output machine code file
├── server/
│   └── index.js        # Express API server — runs assembler binary and returns output
├── src/
│   ├── App.jsx         # React frontend — editor, visualizer, controls
│   ├── styles.css      # Dark theme UI styles
│   └── main.jsx        # React entry point
├── package.json
└── vite.config.js

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Getting Started

Prerequisites

• Node.js v18+ and npm
• g++ (C++17) to (re)compile the assembler

1. Clone the repository

git clone https://github.com/hima1323/Assembler.git
cd Assembler

2. Install dependencies

npm install

3. (Optional) Recompile the assembler binary

The pre-built assembler binary is included. If you want to recompile from source:

g++ -std=c++17 -O2 -o assembler assembly.cpp

4. Run the development server

npm run dev

This starts both servers concurrently:

• Vite frontend → http://localhost:5173
• Express API server → http://localhost:5050

Open http://localhost:5173 in your browser.

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Usage

1. Write your RISC-V assembly code in the editor panel (left side)
2. Click Assemble — the code is sent to the server, assembled by the C++ binary, and the machine code appears on the right
3. Step through instructions using ← Prev / Next →, or use ▶ Run for automatic execution
4. Adjust speed with the Speed selector (Slow / Normal / Fast / Turbo)
5. Copy the machine code output with the Copy button
6. ISA Reference — click the button in the controls bar to toggle the instruction reference panel

Example Assembly

.text
addi x1, x0, 10
addi x2, x0, 5
add  x3, x1, x2
beq  x1, x2, end
sub  x4, x1, x2
end:
ecall

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Assembly Language Syntax

• Comments start with #
• Labels end with :
• Directives: .text, .data, .word, .space, .string, .asciiz, .align
• Registers: x0–x31, or ABI aliases (zero, ra, sp, gp, tp, t0–t6, s0–s11, a0–a7, fp)
• Immediates: decimal (42), hex (0xFF), binary (0b1010), or character ('A')
• Load/Store: lw x1, 4(x2) — offset(base) syntax
• JALR: supports both jalr rd, rs1, imm and jalr rd, imm(rs1)

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Tech Stack

Layer	Technology
Assembler backend	C++17
API server	Node.js + Express
Frontend framework	React 18 + Vite 5
Styling	Vanilla CSS (dark glassmorphism theme)
Fonts	Inter + JetBrains Mono (Google Fonts)

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License

MIT