support more src formats: 565, 888

GCC's from_888() isn't nearly as good as Clang's,
but they both work and all other stages are very
similar across compilers.

and...
 - add some tests now that I can do something interesting
 - small tweak to the API to take an unsigned npixels

Change-Id: I9432832c96b10e38052d3cc0560f650f9bdc600e
3 files changed
tree: 877ada21ab90d421dda432d8e39a6cc7d9523f55
  1. src/
  2. .gitignore
  3. CMakeLists.txt
  4. LICENSE
  5. skcms.c
  6. skcms.h
  7. tests.c