SolCalc VS Code Extension

Mixed-Decimal Calculator for evm Audits

SolCalc is a developer utility that helps smart contract auditors and evm developers verify arithmetic operations with explicit decimal tracking. It mimics evm's integer-only arithmetic while showing precision loss, rounding behavior, and decimal propagation.

Why SolCalc?

evm doesn't have floating-point types. All token amounts are stored as integers with an implied decimal place. For example:

• 1 USDC (6 decimals) = 1000000
• 1 ETH (18 decimals) = 1000000000000000000

SolCalc helps you verify calculations across different decimal precisions without manual conversion, catching precision loss bugs before they make it to production.

Features

Core Functionality

• BigInt-Only Arithmetic: No floating-point operations, matching evm exactly
• Mixed-Decimal Support: Work with values of different decimal precisions (USDC 6, WETH 18, etc.)
• Floor/Ceil Rounding: Choose rounding mode and see the impact on results
• Loss Calculation: See exactly how much value is lost due to rounding
• Scale Constants: Support for 1e18, 1e6, 10 ** n patterns common in DeFi
• Variable Support: Define variables with explicit values and decimals

Built-in Guidelines

38 comprehensive guidelines covering:

• DeFi patterns (ERC4626, WAD/RAY math, BPS)
• Audit pitfalls to watch for
• Common bugs and how to avoid them
• Best practices for decimal arithmetic

Privacy & Security

• 100% Local: All calculations run locally in VS Code
• No Network Access: No data is sent anywhere
• No Telemetry: No usage tracking or analytics
• Open Source: Full source code available on GitHub

How to Use

1. Open SolCalc: Click the calculator icon in the Activity Bar (left sidebar)
2. Enter Expression: Type your arithmetic expression (e.g., (price * amount) / 1e18)
3. Define Variables: If your expression has variables, enter their values and decimal precision
4. View Results: See the result in raw, human-readable, and wvm formats, plus any precision loss

Example Use Cases

Verify vault share conversions:

shares * totalAssets / totalShares

Check price calculations:

(1500 * 1e18) * (10 * 1e18) / 1e18

Test division rounding:

(3 * 1e18) / 7

Architecture

SolCalc consists of three components:

1. Core Engine (@solcalc/core): Pure TypeScript arithmetic engine using BigInt
2. React UI: Calculator interface with theme support
3. VS Code Extension: Webview host for the calculator

The webview contains a pre-built React application (bundled JavaScript and CSS) that provides the calculator interface. No dynamic code execution or external resources are loaded.

Development

Building the Extension

From the project root:

# Install all dependencies
npm run install:all

# Build everything (core, UI, extension)
npm run build

Or build individually:

# Build core engine
npm run build:core

# Build UI for extension
npm run build:ui

# Compile extension
npm run build:extension

Testing the Extension

1. Open the extension directory in VS Code
2. Press F5 to launch the Extension Development Host
3. In the new VS Code window, open Command Palette and run "Open SolCalc Calculator"

Alternatively, you can:

• Run > Start Debugging (F5)
• Or use the "Run Extension" configuration from the Debug panel

Debugging

• Set breakpoints in src/extension.ts or src/webviewProvider.ts
• Press F5 to start debugging
• Check the Debug Console for logs

Extension Structure

extension/
├── package.json          # Extension manifest
├── tsconfig.json         # TypeScript config
├── src/
│   ├── extension.ts      # Entry point
│   └── webviewProvider.ts # Webview manager
├── dist/                 # Compiled extension code
└── webview/              # Built React UI
    ├── index.html
    └── assets/

Publishing

To package the extension for distribution:

cd extension
npm run package

This creates a .vsix file that can be installed or published to the marketplace.

License

MIT