This Assembly Project will allow us to take user input.

So far we've used the $.$ text and $.$ data sections in our programs. We will now use the $.$bss $($Block Started by Symbol$).$ It allows us to reserve space in memory for uninitialized variables. We will need these to store the user input.

We have several options for the size:

resb $-1$ byte

resw $-1$ word $(16$ bits or $2$ bytes$)$

resd $-1$ double word $(4$ bytes$)$

resq $-1$ quad word $(8$ bytes, also used for floats$)$

rest $-10$ bytes, also used for extended floats

In order to get user input, we will need to use a system call. So far, we have used two system calls:

eax $1-$ system call exit $($sys exit$)$

eax $4-$ system call write $($sys$\_$write$)$

For this lab, we will add:

eax $3-$ system call read $($sys$\_$read$)$

System calls take $3$ arguments $($we need to load three registers with values$)$ besides the register EAX.

For sys$\_$read, we need:

edx $-$ loaded with the max bytes of space in memory

ecx $-$ loaded with the address of our variable $($in the $.$bss section$)$

ebx $-$ loaded with the location we want to read from $($in our casesthiN $-$standard input $-$keyboard$)$