CodingStyle

C

FAQ

  Q: Does OpenJPEG requires C99 compiler ?
  A: No

  Q: Are you sure OpenJPEG does not requires C99 compiler, because I see stdint.h in the source code
  A: Yes !

Description

OpenJPEG is meant to be portable. OpenJPEG should only requires ANSI C (C89) compilers.

Exceptions

Instead of re-inventing the wheel, OpenJPEG will use C99 notations in two occasions:

• fixed-type notation
• large file support

OpenJPEG uses a single build-system: cmake. It support system inspection and compiler detection. What happen is that:

• iff compiler provide a stdint.h we will use it
• iff compiler provide large file support we will use it

So in summary:

• if your compiler does not provide a stdint.h we will emulate it using compiler private extension
• if your compiler does not support Large File Support, you will not have support for LFS in OpenJPEG

Note: since we use type from stdint.h we will use the C99 notation PRIi64, PRIu64 & PRIx64 for printing the fixed 64 bits type. Again this is not a requirement on your compiler, we will use your compiler private extension as replacement if PRI?64 is not present.

Code Formating

Portability

File should be pushed to server with UNIX eol

Tabs

You should not use tab char, but instead use two white space. See uncrustify example:

• http://code.google.com/p/openjpeg/source/browse/dev-utils/scripts/opj.cfg

To see it in action:

• http://code.google.com/p/openjpeg/source/browse/dev-utils/scripts/j2k.c
• http://code.google.com/p/openjpeg/source/browse/dev-utils/scripts/tcd.c

Comment

Because OpenJPEG is written in C. One should use C style comment: /* and */

For doxygen, one should use /** and */

Charset

• What charset to use for unicode ? None !
• C does not support anything other than ASCII
• Eg: "Università" in comment should be "Universita'"
• and "Université" in comment should be "Universite"

Open Questions

• tab spaces ? indent ? uncrutify rule ?
• file type (UNIX eol would be nice)

Useful commands to clean style of cmake part

Convert CMake-language commands to lower case (Thanks to Hans Johnson)

NOTE: MUST USE GNU compliant version of sed Run the following shell code (Modified from Brad King, and used on CMake source code): #!/bin/bash cmake --help-command-list
| grep -v "cmake version"
| while read c; do

echo 's/\b'"$(echo $c | tr '[:lower:]' '[:upper:]')"'(\s**)(/'"$c"'\1(/g' done >convert.sed
&& git ls-files -z -- bootstrap '.cmake' '.cmake.in' '**CMakeLists.txt' \

| fgrep -v thirdparty
| xargs -0 gsed -i -f convert.sed
&& rm convert.sed

Remove CMake-language block-end command arguments (Thanks to Hans Johnson)

NOTE: MUST USE GNU compliant version of sed Run the following shell code:

for c in else endif endforeach endfunction endmacro endwhile; do

echo 's/\b'"$c"'(\s**)(.+)/'"$c"'\1()/' done >convert.sed
&& git ls-files -z -- bootstrap '.cmake' '.cmake.in' '**CMakeLists.txt'
| xargs -0 gsed -i -f convert.sed
&& rm convert.sed