Divide and Get Remainder at the same time?

Question

Apparently, x86 (and probably a lot of other instruction sets) put both the quotient and the remainder of a divide operation in separate registers.

Now, we can proba

Answer 1

In Java (since 1.5) the class BigDecimal has the operation divideAndRemainder returning an array of 2 elements with the result and de remainder of the division.

BigDecimal bDecimal = ...
BigDecimal[] result = bDecimal.divideAndRemainder(new BigDecimal(60));

Javadoc: https://docs.oracle.com/javase/8/docs/api/java/math/BigDecimal.html#divideAndRemainder-java.math.BigDecimal-

Answer 2

    int result,rest;
    _asm
    {
        xor edx, edx // pone edx a cero; edx = 0
        mov eax, result// eax = 2AF0
        mov ecx, radix // ecx = 4
        div ecx
        mov val, eax
        mov rest, edx
    }

Answer 3

The .NET framework has Math.DivRem:

int mod, div = Math.DivRem(11, 3, out mod);
// mod = 2, div = 3

Although, DivRem is just a wrapper around something like this:

int div = x / y;
int mod = x % y;

(I have no idea whether or not the jitter can/does optimise that sort of thing into a single instruction.)

Answer 4

In C#/.NET you've got Math.DivRem: http://msdn.microsoft.com/en-us/library/system.math.divrem.aspx

But according to this thread this isn't that much an optimization.

Answer 5

As Stringer Bell mentioned there is DivRem which is not optimized up to .NET 3.5.

On .NET 4.0 it uses NGen.

The results I got with Math.DivRem (debug; release = ~11000ms)

11863
11820
11881
11859
11854

Results I got with MyDivRem (debug; release = ~11000ms)

29177
29214
29472
29277
29196

Project targeted for x86.

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Math.DivRem Usage example

int mod1;
int div1 = Math.DivRem(4, 2, out mod1);

Method signatures

DivRem(Int32, Int32, Int32&) : Int32
DivRem(Int64, Int64, Int64&) : Int64

.NET 4.0 Code

[TargetedPatchingOptOut("Performance critical to inline across NGen image boundaries")]
public static int DivRem(int a, int b, out int result)
{
    result = a % b;
    return (a / b);
}

.NET 4.0 IL

.custom instance void System.Runtime.TargetedPatchingOptOutAttribute::.ctor(string) = { string('Performance critical to inline across NGen image boundaries') }
.maxstack 8
L_0000: ldarg.2 
L_0001: ldarg.0 
L_0002: ldarg.1 
L_0003: rem 
L_0004: stind.i4 
L_0005: ldarg.0 
L_0006: ldarg.1 
L_0007: div 
L_0008: ret 

MSDN Reference

Answer 6

FWIW, Haskell has both divMod and quotRem that latter of which corresponds directly to the machine instruction (according to Integral operators quot vs. div) while divMod may not.