CODEWITHSUNDEEP
floating-pointx86-64nasminline-assembly
user1050632
user1050632

Reputation: 668

nasm x86-64 bit division

I'm trying to divide in assembly language

I can't find a good example online on how to divide in 64 bit.

So far I have 2 values in two variabbles

input
input2

which where read in

I'm able to multiply fine, but i'm stuck on the division

so if i wan't to divide the two integers, i'm doing

mov rcx, [input]

mov rdi, [input2]

idiv rcx, rdi

that automatically give sme an error, because the division is suppose to be only one register, so i'm assuming that when using idiv, it automatically divides some register, by the one you specify, so i tried 

idiv rcx

but i'm getting "floating point error"

ideas?

Upvotes: 0

Views: 6670

Answers (1)

Carl Norum
Carl Norum

Reputation: 224904

A quick look in the documentation shows two possibilities for division involving 64-bit numbers:

IDIV r/m32

Signed divide EDX:EAX by r/m32, with result stored in EAX ← Quotient, EDX ← Remainder.

IDIV r/m64

Signed divide RDX:RAX by r/m64, with result stored in RAX ← Quotient, RDX ← Remainder.

It's going to be integer division though. Your question is tagged floating point - if you want floating point division, you'll need one of the variants of the FDIV instruction.

Upvotes: 4

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