__emul, __emulu
Microsoft Specific
Performs multiplications that overflow what a 32-bit integer can hold.
__int64 __emul(
int a,
int b
);
unsigned __int64 __emulu(
unsigned int a,
unsigned int b
);
Parameters
[in] a
The first integer operand of the multiplication.[in] b
The second integer operand of the multiplication.
Return Value
The result of the multiplication.
Requirements
Intrinsic |
Architecture |
|---|---|
__emul |
x86, x64 |
__emulu |
x86, x64 |
Header file <intrin.h>
Remarks
__emul takes two 32-bit signed values and returns the result of the multiplication as a 64-bit signed integer value.
__emulu takes two 32-bit unsigned integer values and returns the result of the multiplication as a 64-bit unsigned integer value.
Example
// emul.cpp
// compile with: /EHsc
// processor: x86, x64
#include <iostream>
#include <intrin.h>
using namespace std;
#pragma intrinsic(__emul)
#pragma intrinsic(__emulu)
int main()
{
int a = -268435456;
int b = 2;
__int64 result = __emul(a, b);
cout << a << " * " << b << " = " << result << endl;
unsigned int ua = 0xFFFFFFFF; // Dec value: 4294967295
unsigned int ub = 0xF000000; // Dec value: 251658240
unsigned __int64 uresult = __emulu(ua, ub);
cout << ua << " * " << ub << " = " << uresult << endl;
}
Output
-268435456 * 2 = -536870912
4294967295 * 251658240 = 1080863910317260800