Added section on platform specific code to README.md

README.md

@@ -319,6 +319,32 @@ The EMB² team welcomes all kinds of contributions, preferably as pull requests
 or patches via the development mailing lists (see above). If possible, please
 or patches via the development mailing lists (see above). If possible, please
 refer to a current snapshot of the development branch.
 refer to a current snapshot of the development branch.
 
 
+EMB² is supposed to be easily portable to platforms unsupported so far. Almost
+all platform specific code is located in the base_c and base_cpp modules. All
+existing platform specific code is fenced by EMBB_PLATFORM_* defines.
+
+To distinguish between compilers, EMB² currently uses the following defines:
+
+  - EMBB_PLATFORM_COMPILER_GNUC
+  - EMBB_PLATFORM_COMPILER_MSVC
+  - EMBB_PLATFORM_COMPILER_UNKNOWN
+
+Different architectures are distinguished using:
+
+  - EMBB_PLATFORM_ARCH_X86
+  - EMBB_PLATFORM_ARCH_X86_32
+  - EMBB_PLATFORM_ARCH_X86_64
+  - EMBB_PLATFORM_ARCH_ARM
+  - EMBB_PLATFORM_ARCH_UNKNOWN
+
+Threading APIs are switched by:
+
+  - EMBB_PLATFORM_THREADING_WINTHREADS
+  - EMBB_PLATFORM_THREADING_POSIXTHREADS
+
+Please use these defines for new platform specific code. If additional defines
+are needed, they can be defined in the config.h or cmake_config.h.in files.
+
 
 
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