text: // Copyright (c) 2020 Can Boluk and contributors of the VTIL Project   
  // All rights reserved.   
  //    
  // Redistribution and use in source and binary forms, with or without   
  // modification, are permitted provided that the following conditions are met: 
  //    
  // 1. Redistributions of source code must retain the above copyright notice,   
  //    this list of conditions and the following disclaimer.   
  // 2. Redistributions in binary form must reproduce the above copyright   
  //    notice, this list of conditions and the following disclaimer in the   
  //    documentation and/or other materials provided with the distribution.   
  // 3. Neither the name of mosquitto nor the names of its   
  //    contributors may be used to endorse or promote products derived from   
  //    this software without specific prior written permission.   
  //    
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE   
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE  
  // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE   
  // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR   
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF   
  // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS   
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN   
  // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)   
  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE  
  // POSSIBILITY OF SUCH DAMAGE.        
  //
  #pragma once
  #include <stdint.h>
  
  #ifndef _MSC_VER
      inline static uint64_t _umul128( uint64_t _Multiplier, uint64_t _Multiplicand, uint64_t* _HighProduct )
      {
          uint64_t LowProduct;
          uint64_t HighProduct;
  
          __asm__( "mulq  %[b]\n"
                   :"=d"( HighProduct ), "=a"( LowProduct )
                   : "1"( _Multiplier ), [ b ]"rm"( _Multiplicand ) );
  
          *_HighProduct = HighProduct;
          return LowProduct;
      }
  
      inline static int64_t _mul128( int64_t _Multiplier, int64_t _Multiplicand, int64_t* _HighProduct )
      {
          int64_t LowProduct;
          int64_t HighProduct;
  
          __asm__( "imulq  %[b]\n"
                   :"=d"( HighProduct ), "=a"( LowProduct )
                   : "1"( _Multiplier ), [ b ]"rm"( _Multiplicand ) );
  
          *_HighProduct = HighProduct;
          return LowProduct;
      }
  
      inline static int64_t __mulh( int64_t _Multiplier, int64_t _Multiplicand )
      {
          int64_t HighProduct;
          _mul128( _Multiplier, _Multiplicand, &HighProduct );
          return HighProduct;
      }
  
      inline static uint64_t __umulh( uint64_t _Multiplier, uint64_t _Multiplicand )
      {
          uint64_t HighProduct;
          _umul128( _Multiplier, _Multiplicand, &HighProduct );
          return HighProduct;
      }
  #else
      #include <intrin.h>
  #endif