B Compiler Collection

This repository contains compilers for the B programming language — the direct predecessor to C, created by Ken Thompson and Dennis Ritchie at Bell Labs in 1969. Two compilers are provided:

• BCause (intel64/) — runs B programs on modern x86-64 Linux and macOS.
• bbesm (besm6/) — runs B programs on the BESM-6, a Soviet mainframe computer (via the Dubna emulator).

What is the B language?

B is a simple, typeless language: every variable holds one machine-size word, with no distinction between integers and pointers. You declare local variables with auto and reference globals with extrn. Escape sequences use * instead of \ (for example, *n is a newline and *t is a tab). B was the direct ancestor of C and a fascinating snapshot of early Unix history.

Good starting points for learning B:

• A Tutorial Introduction to the Language B by B. W. Kernighan
• User's Reference to B by K. Thompson

BCause — B for modern Linux (intel64/)

BCause is a small, single-pass compiler (~2000 lines of C99). It translates B source files to x86-64 assembly, then calls the system assembler (as) and linker (ld) to produce a standalone binary. On Linux the GNU toolchain is used; on macOS the Apple toolchain is used.

Prerequisites

Linux: a standard C toolchain — gcc (or any C99 compiler), make, and binutils (as and ld). Available on any typical Linux distribution.

macOS: Xcode Command Line Tools, which provide cc, make, as, and Apple ld. Install with:

xcode-select --install

Build

cd intel64
make

This produces the bcause compiler binary and libb.a (the B standard library).

To install globally:

sudo make install   # copies bcause to /usr/local/bin and libb.a to /usr/local/lib

Usage

bcause hello.b              # compile, assemble, and link → a.out
bcause hello.b -o hello     # same, but output named hello
./hello

Additional flags:

Flag	Effect
-S	Stop after generating assembly (.s file)
-c	Stop after assembling (.o file); do not link
-o <file>	Write output to <file>
-L<dir>	Look for libb.a in <dir>
-save-temps	Keep intermediate .s and .o files

Run the tests

cd intel64
make test

The test suite uses GoogleTest (downloaded automatically by CMake on first run).

bbesm — B for BESM-6 (besm6/)

bbesm is a B compiler written in B itself, targeting the BESM-6 Soviet mainframe. It runs under the Dubna operating system emulator.

Dependencies

Install both of these first:

• dubna — BESM-6 system emulator
• besmc — BESM-6 assembler

Building bbesm

cd besm6
make

Testing bbesm

cd besm6
make test

Note: bbesm does not yet support break, continue, for, do...while, switch, the logical operators && and ||, compound assignment operators (like =+), hexadecimal literals, or the %x format in printf(). See besm6/README.md for the full list.

Example Programs

The examples/ directory contains several ready-to-run B programs:

File	Description
hello.b	Print "Hello, World!" using write()
helloworld.b	Same, using printf()
fibonacci.b	Print Fibonacci numbers
fizzbuzz.b	Classic FizzBuzz (1–100)
e-2.b	Compute e−2 to ~4000 decimal digits

Here is the simplest one:

/* The following program will print 'Hello World' to stdout. */

main() {
    write('Hello,');
    write(' World');
    write('!*n');
}

Compile and run it:

cd intel64
bcause ../examples/hello.b -o hello
./hello

Documentation

• B Runtime Library for BESM-6 — comprehensive reference for all routines in besm6/libb/
• Calling conventions for BESM-6
• User's Reference to B by K. Thompson
• A Tutorial Introduction to The Language B by B. W. Kernighan
• Users' Reference to B on MH-TSS by S. C. Johnson
• The Development of the C Language by Dennis M. Ritchie

License

Both compilers are released under the MIT License. See the LICENSE file in each subdirectory for details.