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B Programming Language: Implementing a Modern Compiler from Historical Roots

高效码农

Exploring the B Programming Language: A Journey into Modern Compiler Implementation

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Project Status: Compiler not fully implemented (currently in development)

Logo Design: Strawberry 🍓

What is the B Programming Language?

B is the historical predecessor to the C language, originally developed by Ken Thompson and Dennis Ritchie at Bell Labs in 1969. This project implements a modern compiler using Crust, aiming to recreate the essence of this historically significant language. Below we explore its implementation details and practical usage.

1. Environment Setup & Quick Start

Essential Dependencies

Tool Purpose
Rust Implementation language
fasm Compiler backend assembler

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Note: Additional environment setup may be required for different target platforms (e.g., Windows)

4-Step Quick Start Guide

  1. Clone the repository
  2. Execute build command: 
    $ make
  3. Run sample program: 
    $ ./build/b -run ./examples/hello_world.b
  4. Explore more examples: 
    $ ls ./examples/

2. Testing Framework Deep Dive

The built-in btest utility provides powerful test matrix functionality located in the ./tests/ directory.

Key Testing Features

  • Automatic building: Compiled automatically when running make
  • Cross-platform support: Tests all target platforms simultaneously
  • Error tolerance: Continues execution after errors and generates comprehensive reports

Test Matrix Slicing Techniques

Platform-Specific Testing

$ ./build/btest -t fasm-x86_64-linux

Multi-platform testing:

$ ./build/btest -t fasm-x86_64-linux -t uxn

Test Case Filtering

Single test case:

$ ./build/btest -c upper

Multiple test cases:

$ ./build/btest -c upper -c vector

Combined Filtering

$ ./build/btest -c upper -c vector -t fasm-x86_64-linux -t uxn

3. Technical Implementation Insights

Core Architecture Components

  1. Frontend processing: Lexical/parsing implementation in Rust
  2. Intermediate representation: Optimized intermediate code generation
  3. Backend compilation: Machine code generation via fasm

Cross-Platform Support Mechanism

graph LR
    B[.b source] -->|Rust frontend| C[Intermediate code]
    C -->|fasm backend| D[Linux executable]
    C -->|fasm backend| E[Windows executable]
    C -->|uxn backend| F[Uxn VM bytecode]

4. Practical Code Examples

Classic Hello World

// hello_world.b
main() {
    putstr("Hello, B World!");
    return 0;
}

Execution result:

Hello, B World!

Memory Operations

// memory_demo.b
alloc ptr[100];
ptr[0] = 65;
putchar(ptr[0]);  // Outputs 'A'

5. Reference Resource Guide

  1. B Language Wikipedia
  2. Dennis Ritchie’s Original Documentation
  3. Compiler Design Reference
  4. x86 Instruction Manual
  5. ARM64 Architecture Guide

6. Frequently Asked Questions (FAQ)

Q1: Why choose fasm as the backend?

fasm (Flat Assembler) is renowned for its lightweight efficiency. Its direct machine code generation makes it ideal for compiler backends, especially in educational projects.

Q2: How does btest achieve cross-platform testing?

By abstracting compilation pipelines and generating platform-specific build commands:

  • Linux: fasm -m64
  • Uxn: uxnasm target.rom

Q3: What are key differences between B and modern C?

While syntax details aren’t specified in the documentation, historical records indicate:

  • No type system (all data is “word”)
  • Simpler memory model
  • Limited standard library

Q4: How to handle “Compiler not fully implemented” status?

This indicates normal development progress:

  1. Prioritize verified examples in /examples/
  2. Use btest -c to select implemented features
  3. Monitor project update logs

Q5: How to contribute to the project?

While not explicitly documented, the project structure suggests:

  1. Core code resides in /src/
  2. Test cases in /tests/
  3. Validate changes using btest

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Project Note: The compiler is under active development. Regularly execute git pull for updates and verify compatibility with btest. All implementations strictly follow original design documents to recreate authentic 1970s language characteristics.

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