mingw-w64-crt/intrincs/_rotl64.c

#include <_mingw.h>

unsigned __int64 __cdecl _rotl64 (unsigned __int64 _val, int _Shift);

unsigned __int64 __cdecl _rotl64 (unsigned __int64 _val, int _Shift)
{
  /* Make sure we don't rotate over scalar width.  */
  _Shift &= 63;
  if (!_Shift)
    return _val;
  return (_val >> (64 - _Shift)) | (_val << _Shift);
}