krkind / circularbuffer

This repository contains a circular buffer or a ring buffer implementation in C code suitable for embedded systems.

Circular Buffer

This repository contains a circular buffer or a ring buffer implementation in C code suitable for embedded systems. The implementation using a single empty cell to detect the buffer "full" case; for supporting a single producer thread and single consumer thread without OS lock primitive. For use of efficient algorithms the maximum number of elements in the circular buffer must be a power of 2. The code follows the Google C++ Style Guide with one exception that instead of 2 spaces it use 4 spaces.

Unittest

The added unittest uses the googletest framework and the SCons build system.

Follow the steps below for building the unittest

1. Install the scons, if you run on an Ubuntu machine:

   sudo apt install scons

2. Go to https://github.com/google/googletest and clone the git repo besides the circularbuffer repo.

3. Create a directory called build_gtest beside the circularbuffer and googletest repos.

4. Now you shall have the following directory structure:

  <your path>
      | build_gtest
      | circularbuffer
      | googletest

5. Change directory to the new directory build_gtest.

6. Build the google test framework:

   <your path>/build_gtest$ cmake ../googletest/

   <your path>/build_gtest$ make

7. Change directory to <your path>/circularbuffer.

8. Build, run and clean the units test with the scons command:

   <your path>/circularbuffer$ scons test

   <your path>/circularbuffer$ scons test -c

9. Optional build, run and clean the units test with the commands:

   <your path>/circularbuffer$ scons

   <your path>/circularbuffer$ ./build/circularbuffer-gtest

   <your path>/circularbuffer$ scons -c

Follow the steps below for generate code coverage report

1. Install the lcov, if you run on an Ubuntu machine:

   sudo apt install lcov

2. Generate report:

   <your path>/circularbuffer$ ./gen_test_report.sh

3. Html output result is found here

   <your path>/circularbuffer/build/out$

4. Delete report:

   <your path>/circularbuffer$ ./gen_test_report.sh -c

circularbuffer's Issues

bug when size of buffer not a power of 2

circularbuffer/circularbuffer.c

Line 87 in ab84593

const size_t write_pos = (ctx->write_pos + 1) & ctx->max_size;

May be to roll the pointers back use % buf size rather than &. This will work for any size of buffer.