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Merge pull request #17 from muep/fix_msb

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Progress on fixing FindMSB implementation. Negative values and zeros remains to be done.
This commit is contained in:
Christophe Riccio 2012-09-12 06:56:44 -07:00
commit d6bbf90670
2 changed files with 9 additions and 4 deletions
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9
glm/core/func_integer.inl
View File

@ -543,7 +543,14 @@ namespace glm
genIUType const & Value
)
{
return __builtin_clz(Value);
/**
* clz returns the number or trailing 0-bits; see
* http://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/Other-Builtins.html
*
* NoteBecause __builtin_clz only works for unsigned ints, this
* implementation will not work for 64-bit integers.
*/
return 31 - __builtin_clz(Value);
}
#else

4
glm/gtx/integer.inl
View File

@ -60,10 +60,8 @@ namespace _detail
template <typename T>
GLM_FUNC_QUALIFIER T operator() (T const & Value) const
{
#if(GLM_COMPILER & GLM_COMPILER_VC)
#if(GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_GCC))
return Value <= T(1) ? T(0) : T(32) - nlz(Value - T(1));
#elif(GLM_COMPILER & GLM_COMPILER_GCC)
return Value <= T(1) ? T(0) : nlz(Value - T(1)) + 1;
#else
return T(32) - nlz(Value - T(1));
#endif