In the gcc-riscv compiler, __builtin_ffs will call ffs, and calling __builtin_ffs in ffs will cause recursion
Change ffs to an inline function, and compile ffs implemented by nuttx by default.
Only call the implementation of nuttx when the compiler cannot provide an ffs implementation.
Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>
Make use of XCHG/BSWAP on x86, REV16 and REV on ARMv6-m and above,
and whatever other optimized instructions on other platforms.
Defines extra CONFIG variables, and removes the unused functions for
endian-swapping. Fixes some oversights in using the macros.
Squashed commit of the following:
libs/libxx: Fix some confusing in naming. If the directory is called libxx, then the library must be libxx.a (unless perhaps LIBCXX is selected).
libs/: Fix paths in moved library directories.
libs: Brute force move of libc, libnx, and libxx to libs. Cannot yet build it in that configuration.
