_umul128

The latest version of this topic can be found at _umul128.

Microsoft Specific**

Multiplies two 64-bit unsigned integers passed in as the first two arguments and puts the high 64 bits of the product in the 64-bit unsigned integer pointed to by HighProduct and returns the low 64 bits of the product.

Syntax

unsigned __int64 _umul128(   
   unsigned __int64 Multiplier,   
   unsigned __int64 Multiplicand,   
   unsigned __int64 *HighProduct   
);  

Parameters

[in] Multiplier
The first 64-bit integer to multiply.

[in] Multiplicand
The second 64-bit integer to multiply.

[out] HighProduct
The high 64 bits of the product.

Return Value

The low 64 bits of the product.

Requirements

Example

// umul128.c  
// processor: IPF, x64  
  
#include <stdio.h>  
#include <intrin.h>  
  
#pragma intrinsic(_umul128)  
  
int main()  
{  
    unsigned __int64 a = 0x0fffffffffffffffI64;  
    unsigned __int64 b = 0xf0000000I64;  
    unsigned __int64 c, d;  
  
    d = _umul128(a, b, &c);  
  
    printf_s("%#I64x * %#I64x = %#I64x%I64x\n", a, b, c, d);  
}  

0xfffffffffffffff * 0xf0000000 = 0xeffffffffffffff10000000  

END Microsoft Specific

See Also

Compiler Intrinsics