C examples

This repository contains my C code. A lot of it is my own versions of standard datatypes and algorithms such as my own hashset datatype. It was written for fun because I love C coding.

As some smart person once said; only the one who reinvents the wheel truly understand how it works. So there's that.

This repository consists of the following directories:

Libraries

Located in libraries are a bunch of libraries I have written to learn more about algorithms, data structures, OS APIs, etc. They are designed to be mostly self-contained and thus easy to borrow by copying the files. However, over the years I have introduced dependencies between them. Factoring out common code is just too pleasurable.

No guarantee that the libraries are -- or ever will be -- complete. They were written because I wanted to.

libraries/benchmark

Minimal library for benchmarking C code.

libraries/collectors

An object model and a bunch of garbage collectors. These were written to teach myself about garbage collection strategies.

• copying.[ch] - Bump pointer allocation and semi-space copying
• copying-opt.[ch] - Optimized version of the above
• ref-counting.[ch] - Plain reference counting
• ref-counting-cycles.[ch] - Reference counting with cycle detection
• mark-sweep.[ch] - Mark & Sweep gc

libraries/cud

Small wrapper for CUDA libraries.

libraries/datatypes

Standard datatypes for C programming like vector and hashset. There is not a lot of documentation for these datatypes because the code should be self-explanatory.

libraries/diophantine

A minimal library for solving linear Diophantine equations.

libraries/fastio

Fast IO routines accessing stdin and stdout. They are useful to minimize IO overhead in competitive programming challenges.

libraries/file3d

A library for loading 3d meshes.

libraries/ieee754

A library for explicit handling of ieee754 floating point numbers.

libraries/isect

A collection of ray/triangle intersection algorithms. These are used by my raytracer.

libraries/linalg

Trival single-precision linear algebra library. Contains things like matrix multiplication and stuff.

libraries/opencl

A library containing OpenCL utility functions. It can be tricky to compile for Intel FPGA because libraries and headers are not in standard locations. You can try:

CFLAGS=$(aocl compile-config) \
    CXXFLAGS=$(aocl compile-config) \
    LDFLAGS=$(aocl ldflags) \
    ./waf-2.0.25 build

Of course, this assumes that aocl and related programs are on the PATH. To run the built programs the OpenCL library must be linkable:

LD_LIBRARY_PATH=/path/to/opencl ./build/programs/opencl/prog

libraries/pretty

Simple pretty-printing.

libraries/random

Random number generation using www.pcg-random.org.

libraries/paths

A library for filesystem path handling.

libraries/quickfit

A memory allocator based on the Quick Fit algorithm. It's used by my garbage collectors.

libraries/tensors

A library for dealing with N-dimensional arrays (tensors).

Tests

Test suites for the various libraries.

Programs

Demo programs of all kinds:

• programs/npyread.c: Reading .npy files.
• programs/ntimes.c: See {n} times faster than C - part one.
• programs/opencl/list.c: List installed OpenCL platforms.

Compilation

The project is built using the build tool Waf like this:

./waf configure build

Windows, Linux and OS X is supported.

Design Philosophy and Coding Style

Structs are not private. I have good reasons for making them public, but I forgot what they are now.

I prefer function declarations split over multiple lines, with the return type and function attributes on a separate line. Like this:

cl_int
ocl_create_buffer_and_write(cl_context ctx, cl_command_queue queue,
                            size_t n_bytes, void *host_ptr,
                            cl_mem *mem);

Lines shouldn't be longer 73-75 characters since that is how long my side-by-side Emacs frames are.