src/jitcs_int_power2funcs.h

   1 #ifndef _JITCS_INT_POWER2FUNCS_H_
   2 #define _JITCS_INT_POWER2FUNCS_H_
   3
   4 #include "jitcs_base.h"
   5
   6 namespace jitcs {
   7
   8 // compile time functions
   9 template <size_t t>
  10 struct IsPowerOf2OrZeroCT { static const bool Val = (t & (t - 1)) == 0; };
  11 template <size_t t>
  12 struct IsPowerOf2CT { static const bool Val = t != 0 && IsPowerOf2OrZeroCT<t>::Val; };
  13
  14 template <size_t t>
  15 struct Log2CT { static const size_t Val = t > 1 ? (Log2CT<(t>>1)>::Val + 1) : 0; };
  16 template <>
  17 struct Log2CT<0> { static const size_t Val = 0; };
  18
  19 template <size_t t, size_t u>
  20 struct RoundUpToPowerOf2CT {
  21   static_assert(IsPowerOf2CT<u>::Val, "expected power of 2");
  22   static const size_t Val = (t + u - 1) & (~u + 1);
  23 };
  24
  25 // runtime functions
  26 inline bool IsPowerOf2OrZero(size_t t) { return (t & (t - 1)) == 0; }
  27 inline bool IsPowerOf2(size_t t) { return t != 0 && IsPowerOf2OrZero(t); }
  28
  29 template <size_t u>
  30 inline size_t RoundUpToPowerOf2(size_t t) {
  31   static_assert(IsPowerOf2CT<u>::Val, "expected power of 2");
  32   return (t + u - 1) & (~u + 1);
  33 }
  34 template <size_t u>
  35 inline size_t DivRoundedUpByPowerOf2(size_t t) {
  36   static_assert(IsPowerOf2CT<u>::Val, "expected power of 2");
  37   return (t + u - 1) / u;
  38 }
  39
  40 inline size_t RoundUpToPowerOf2(size_t t, size_t u) {
  41   assert(IsPowerOf2(u));
  42   return (t + u - 1) & (~u + 1);
  43 }
  44
  45 } // end of namespace jitcs
  46 #endif
  47 // _JITCS_INT_POWER2FUNCS_H_