C4KE - C4 Kernel Experiment

c4 was "An exercise in minimalism."

C4KE is "an exploration in over-extending minimalism." It provides a multitasking kernel, shell, compiler, and utilities.

C4KE runs under a modified c4 interpreter called c4m, which itself can be run be in an unmodified c4 interpreter. It does however run much faster under a natively compiled c4m.

Architecture

C4KE is a pre-emptive multitasking operating system. It uses a cycle-based trap to switch between tasks automatically, or custom opcodes that can manually switch tasks (cooperative multitasking.)

c4m can trap on unknown opcodes, and this feature is used to implement C4KE's extended opcodes. All registers, including return addresses, can be modified inside these trap handlers. By swapping register values from one task with those from another, task switching is accomplished transparently to running tasks.

C4KE uses a custom executable format, the "C4 Relocatable." This format contains symbols and runtime patch information.

Running

To run under the extended c4m interpreter, use:

make run

To run under the original c4 interpreter, use:

make run-c4

Once in C4KE, type help for a command listing, or ls to display runnable programs.

Try bench or innerbench to test out how fast C4KE runs on your system.

Interesting files

• c4ke.c - The C4 Kernel Experiment, main source file.

• load-c4r.c - The "C4 Relocatable" executable loader and runner.

• c4cc.c - A compiler for C4 - see also asm-c4r.c, for compiling to C4R format, or asm-js.c for compiling to JavaScript.

• c4le.c - A C4 Line Editor.

• c4m.c - An updated C4 interpreter with new opcodes and support for traps. Can be run under C4.

• c4.c - The original C4 interpreter, with only enough modifications to compile portably.

• u0.c - User runtime for C4KE programs, interfaces with C4KE via extended opcodes.

Other experiments

• asm-js.c - A module for C4CC that compiles to files than can run under C4JS.

• libjs/ - A JavaScript port of C4. Incomplete, slow, and cannot run C4KE.