__mul128
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Microsoft Specific**
Multiplies two 64-bit integers passed in as the first two arguments and puts the high 64 bits of the product in the 64-bit integer pointed to by HighProduct and returns the low 64 bits of the product.
Syntax
__int64 _mul128(
__int64 Multiplier,
__int64 Multiplicand,
__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
| Intrinsic | Architecture |
|---|---|
__mul128 |
x64 |
Header file <intrin.h>
Example
// mul128.c
// processor: x64
#include <stdio.h>
#include <intrin.h>
#pragma intrinsic(_mul128)
int main()
{
__int64 a = 0x0fffffffffffffffI64;
__int64 b = 0xf0000000I64;
__int64 c, d;
d = _mul128(a, b, &c);
printf_s("%#I64x * %#I64x = %#I64x%I64x\n", a, b, c, d);
}
0xfffffffffffffff * 0xf0000000 = 0xeffffffffffffff10000000