what is the final output of this?
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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Question
what is the final output of this?
![```assembly
section .data
msg: db 10, "You are at the start.", 10
len: equ $-msg
msg2: db "Done!", 10
len2 equ $-msg2
char: db 0
section .text
global main
print:
mov rax, 1
mov rdi, 1
syscall
ret
main:
xor rax, rax
xor r9, r9
mov r8b, 255
xor r8b, r8b
label1:
cmp r9b, 0
jae label2
mov rsi, msg
mov rdx, len
call print
jmp done
label2:
xor rsi, rsi
mov rsi, 48
add rsi, r9
mov [char], rsi
mov rsi, char
mov rdx, 1
call print
sub r8b, 1
jmp label1
done:
mov rsi, msg2
mov rdx, len2
call print
xor rax, rax
ret
```
### Explanation
This assembly program is written for an x86-64 architecture using the SysV ABI (Application Binary Interface) convention. It consists of two main sections: `.data` and `.text`.
- **.data section**:
- `msg` contains the string "You are at the start.".
- `len` calculates the length of `msg`.
- `msg2` contains the string "Done!".
- `char` is an empty byte used for character manipulation.
- **.text section**:
- Defines the main function and a subroutine for printing strings.
- **Print subroutine**:
- Uses system calls (`syscall`) to print strings to the standard output (file descriptor 1).
- **Main procedure**:
- Initializes registers and sets up loops to print the initial message and decrement a loop counter (`r8b`).
- **label1** and **label2**](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F78de2526-b393-406f-b144-213aa508c7e8%2F5bb7db2f-05f5-4fa1-9901-f38948464373%2F2bjz3f_processed.png&w=3840&q=75)
Transcribed Image Text:```assembly
section .data
msg: db 10, "You are at the start.", 10
len: equ $-msg
msg2: db "Done!", 10
len2 equ $-msg2
char: db 0
section .text
global main
print:
mov rax, 1
mov rdi, 1
syscall
ret
main:
xor rax, rax
xor r9, r9
mov r8b, 255
xor r8b, r8b
label1:
cmp r9b, 0
jae label2
mov rsi, msg
mov rdx, len
call print
jmp done
label2:
xor rsi, rsi
mov rsi, 48
add rsi, r9
mov [char], rsi
mov rsi, char
mov rdx, 1
call print
sub r8b, 1
jmp label1
done:
mov rsi, msg2
mov rdx, len2
call print
xor rax, rax
ret
```
### Explanation
This assembly program is written for an x86-64 architecture using the SysV ABI (Application Binary Interface) convention. It consists of two main sections: `.data` and `.text`.
- **.data section**:
- `msg` contains the string "You are at the start.".
- `len` calculates the length of `msg`.
- `msg2` contains the string "Done!".
- `char` is an empty byte used for character manipulation.
- **.text section**:
- Defines the main function and a subroutine for printing strings.
- **Print subroutine**:
- Uses system calls (`syscall`) to print strings to the standard output (file descriptor 1).
- **Main procedure**:
- Initializes registers and sets up loops to print the initial message and decrement a loop counter (`r8b`).
- **label1** and **label2**
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