pow_inl.h

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 *       - Christophe GONZALES(_at_AMU)                                     *
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 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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#pragma once
 

 
// To help IDE Parsers
#include <agrum/base/core/math/pow.h>
 
namespace gum {
  //@beforeMerging is this really faster ?
  // Specialized pow function with integers (faster implementation).
  INLINE unsigned long intPow(unsigned long base, unsigned long exponent) {
    if (exponent == 0) { return 1UL; }
 
    unsigned long out = base;
 
    for (unsigned long i = 1; i < exponent; i++)
      out *= base;
 
    return out;
  }
 
  //@beforeMerging is this really faster ?
  // Specialized base 2 pow function with integer.
  INLINE uint64_t int2Pow(uint64_t exponent) {
    if (exponent >= 64) { GUM_ERROR(OutOfBounds, "int2Pow: exponent " << exponent << " >= 64") }
    return static_cast< uint64_t >(1) << exponent;
  }
 
  //@beforeMerging is this really faster ?
  // Given an integer, compute it's - superior - and closest power of two, i.e.
  // the number of bits necessary to represent this integer as well as the
  // maximum integer that can be represented by those bits.
  INLINE void superiorPow(unsigned long card, unsigned long& num_bits, unsigned long& new_card) {
    if (card == 0) {
      num_bits = 0;
      new_card = 1;
      return;
    }
 
    num_bits = 1;
    new_card = 2;
 
    while (new_card < card) {
      new_card *= 2;
      num_bits++;
    }
  }
 
}   // namespace gum