my_double2ulonglong.h

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#ifndef MY_DOUBLE2ULONGLONG_INCLUDED
#define MY_DOUBLE2ULONGLONG_INCLUDED

/**
  @file include/my_double2ulonglong.h
  Utility functions for converting between ulonglong and double.
*/

#include "my_inttypes.h"

#ifdef _WIN32
inline unsigned long long my_double2ulonglong(double d) {
  const double t = d - (double)0x8000000000000000ULL;

  if (t >= 0) return ((unsigned long long)t) + 0x8000000000000000ULL;
  return (unsigned long long)d;
}
#define double2ulonglong my_double2ulonglong
#endif /* _WIN32 */

#ifndef ulonglong2double
#define ulonglong2double(A) ((double)(ulonglong)(A))
#define my_off_t2double(A) ((double)(my_off_t)(A))
#endif
#ifndef double2ulonglong
#define double2ulonglong(A) ((ulonglong)(double)(A))
#endif

// The largest longlong that will fix into a double (LLONG_MAX is not
// exactly convertible to double, so for large double x, the test
// x <= LLONG_MAX does not guarantee x will fit in a longlong,
// and may give a compiler warning). LLONG_MIN is exact.
static constexpr double LLONG_MAX_DOUBLE = 9223372036854774784.0;

// Similar, for ulonglong.
static constexpr double ULLONG_MAX_DOUBLE = 18446744073709549568.0;

// The largest and smallest integer that is guaranteed to fix exactly into a
// double (there are 53 mantissa bits).
static constexpr int64_t MAX_EXACT_INTEGER_DOUBLE = (1ULL << 53);
static constexpr int64_t MIN_EXACT_INTEGER_DOUBLE = -MAX_EXACT_INTEGER_DOUBLE;

// Same, for float.
static constexpr int64_t MAX_EXACT_INTEGER_FLOAT = (1ULL << 23);
static constexpr int64_t MIN_EXACT_INTEGER_FLOAT = -MAX_EXACT_INTEGER_FLOAT;

#endif  // MY_DOUBLE2ULONGLONG_INCLUDED