Home / Questions / 303831
Accepted
davidca
Asked: 2020-10-27 07:02:27 +0800 CST 2020-10-27 07:02:27 +0800 CST

Floating point exception (generated 'core') in a division in assembler

  • 772

I have the following code:

push rbp
mov  rbp, rsp

push rax
push rcx
push rdx
push rsi
push rdi

mov rax, QWORD[indiceVector]
mov rcx, 10
div rcx
mov rsi, rax
mov rdi, rdx

... and in the "div rcx" instruction it tells me "Floating point exception (generated 'core')" and it is not a division by 0, since debugging it gives me 23 divided by 10. The funny thing is that in some other function I have almost identical code and it doesn't give me the exception. Does anyone know why it gives this error? I have another question: To divide by 10, is the way I have done it correct or is there a better one?

ensamblador

1 Answers

  1. Best Answer

    Looking at the NASM Assembly Quick Reference I see something interesting regarding div:

    Divide rax by src, and put the ratio into rax, and the remainder into rdx. Bizarrely, on input rdx must be zero, or you get a SIGFPE.

    That is, you should initialize the register that receives the rest of the division to 0, mov rdx, 0to avoid the error.

    • 0