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| -rw-r--r-- | docs/defines.txt | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/docs/defines.txt b/docs/defines.txt new file mode 100644 index 000000000..677335e2f --- /dev/null +++ b/docs/defines.txt @@ -0,0 +1,61 @@ +Feeble attempt to document the horde of #defines we deal with. +Editors, plese make your descriptions short but informative. + + + +__BEGIN_DECLS, __END_DECLS + Defined to either empty or 'extern "C" {' and '}' if included by C++. + +__USE_GNU, __USE_BSD, __USE_XOPEN[2K], __USE_SVID, __USE_POSIX... + If defined, user program which included us requests compat additions + from relevant standard or Unix flavor. See features.h for full list. + +__USE_FILE_OFFSET64 +__USE_LARGEFILE[64] +_LARGEFILE[64]_SOURCE +_FILE_OFFSET_BITS + ??? + +__NTH(fct) +__THROW +__REDIRECT(name, proto, alias) +__REDIRECT_NTH(name, proto, alias) + ??? + +__BIG_ENDIAN 4321 +__LITTLE_ENDIAN 1234 + Should be always as shown. __PDP_ENDIAN is historic, ignore? +__BYTE_ORDER, __FLOAT_WORD_ORDER + Should be defined to __BIG_ENDIAN or __LITTLE_ENDIAN. + Usage: "#if __BYTE_ORDER == __LITTLE_ENDIAN ..." + __USE_BSD adds versions without leading "__" for above four defines. +_BIG_ENDIAN, __BIG_ENDIAN__ +_LITTLE_ENDIAN, __LITTLE_ENDIAN__ + Defined (to what?) by gcc for some architectures to indicate endianness. + Seems that the fact of defined-ness is an indicator, not the value. + +__USE_EXTERN_INLINES + If defined, headers will supply some function as inlines. + uclibc itself is built with this option off and provides + out-of-line version of every inlined function in case user program + calls it instead of using an inline. +_EXTERN_INLINE + Define it to replace "extern __inline" string in inline definitions + (those enabled by __USE_EXTERN_INLINES) with something else. + A few uclibc .c files use it to create non-inlined functions + by defining it to "". + +_LIBC +UCLIBC_INTERNAL + Defined only at libc build time. _LIBC is probably from glibc, +and UCLIBC_INTERNAL is added by vda (he didn't know about _LIBC). +Both defines are physically deleted from headers (using unifdef tool) +in installed headers ("make install"). + +__UCLIBC_XXX + uclibc-internal and uclibc-specific defines. In particular: +__UCLIBC_HAS_XXX__, __UCLIBC_HAVE_XXX__ + __UCLIBC_HAS_XXX__ are booleans (defined/undefined), defined in + uClibc_config.h and generated from uclibc .config file. + __UCLIBC_HAVE_XXX__ are booleans from bits/uClibc_arch_features.h + (there are more __UCLIBC_XXX defines there) |