"Feike Boomstra" <f.p.boomstra@xxxxxxxxx> writes: > I didn't get it from the source code. I found it here: > http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/namespace____gnu__cxx.html > and that looked to me as an interface description. > > The build-in bit_scan_forward function implements the bsf instruction of the > X386 instructionset. It is in the intel c-compiler and the ms c-compiler. This is a reason that I personally don't like doxygen documentation. It isn't clearly separated into interface functions and internal functions. Take my word for it: don't call that function. Now, if you look at the definition of the function, you will see that it is this: inline size_t _Bit_scan_forward(size_t __num) { return static_cast<size_t>(__builtin_ctzl(__num)); } So how about just calling __builtin_ctzl instead? That is documented here: http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Other-Builtins.html Ian
