Hi, 2010/7/14 vicente.botet <vicente.botet@wanadoo.fr>
Murillo, please don't top post. ----- Original Message ----- From: "Murilo Adriano Vasconcelos" <muriloufg@gmail.com> To: <boost@lists.boost.org> Sent: Wednesday, July 14, 2010 10:43 PM Subject: Re: [boost] Bits and Ints: Intention Request
But maybe it can be a good point to use enable_if<> to for 8 and 16-bit integrals specializations and use the correct __builtin for the others
like:
template <typename T> inline int count_leading_zeros(T value) { #ifndef BOOST_HAS_NO_INT64_T return __builtin_clzll(value) - (64 - (sizeof(T) << 3)); #else return __builtin_clz(value) - (32 - (sizeof(T) << 3)); #endif }
I gess the above code should be replace by the following one, when GNUC is defined, isn't it?
template<> inline int count_leading_zeros(unsigned int value) { return __builtin_clz(value); }
template<> inline int count_leading_zeros(unsigned long int value) { return __builtin_clzl(value); }
template<> inline int count_leading_zeros(unsigned long long int value) { return __builtin_clzll(value); }
What do you think?
Instead of function template specialization you can just use overloading. So the you can remove the 'template<>'
If `value` don't matches exacly with the parameter type (for example uint8_t or uint16_t) we will receive one error because calling `count_leading_zeros` with this parameter type is ambiguous. So we can do something like this: https://svn.boost.org/trac/boost/browser/sandbox/SOC/2010/bits_and_ints/boos... 32 to 51) Or create overloads for uint8_t and uint16_t. inline int count_leading_zeros(uint8_t value); inline int count_leading_zeros(uint16_t value);
Best, Vicente
Best, -- Murilo Adriano Vasconcelos http://murilo.wordpress.com