__umulh
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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
[in] a
The first number to multiply.
[in] b
The second number to multiply.
Return Value
The high 64 bits of the 128-bit result of the multiplication.
Requirements
| Intrinsic | Architecture |
|---|---|
__umulh |
x64 |
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%I64x * 0x%I64x = 0x%I64x%I64x \n", i, j, result, k);
return 0;
}
0x10 * 0xfedcba9876543210 = 0xfedcba98765432100