__umulh

Microsoft Specific

Return the high 64 bits of the product of two 64-bit unsigned integers.

Syntax

unsigned __int64 __umulh(
   unsigned __int64 a,
   unsigned __int64 b
);

Parameters

a
[in] The first number to multiply.

b
[in] The second number to multiply.

Return value

The high 64 bits of the 128-bit result of the multiplication.

Requirements

Header file <intrin.h>

Remarks

These routines are only available as intrinsics.

Example

// umulh.cpp
// processor: X64
#include <cstdio>
#include <intrin.h>

int main()
{
    unsigned __int64 i = 0x10;
    unsigned __int64 j = 0xFEDCBA9876543210;
    unsigned __int64 k = i * j; // k has the low 64 bits
                                // of the product.
    unsigned __int64 result;
    result = __umulh(i, j); // result has the high 64 bits
                            // of the product.
    printf_s("0x%016I64x * 0x%016I64x = 0x%016I64x_%016I64x \n", i, j, result, k);
    return 0;
}

0x0000000000000010 * 0xfedcba9876543210 = 0x000000000000000f_edcba98765432100

END Microsoft Specific

See also

Compiler intrinsics