can't input something in nasm using int 80h?
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Basically I am learning Assembly language/nasm through this book : http://www.pravaraengg.org.in/Download/MA/assembly_tutorial.pdf
In the book one of the example is to do below tasks:
- output on the screen
Please enter a number:
- ask user to input a number
- output on the screen saying:
You have entered:1234
Below is the script:
section .data ;Data segment
userMsg db 'Please enter a number: ' ;Ask the user to enter a number
lenUserMsg equ $-userMsg ;The length of the message
dispMsg db 'You have entered: '
lenDispMsg equ $-dispMsg
section .bss ;Uninitialized data
num resb 5
section .text ;Code Segment
global main
main:
;User prompt
mov eax, 4
mov ebx, 1
mov ecx, userMsg
mov edx, lenUserMsg
int 80h
;Read and store the user input
mov eax, 3
mov ebx, 2
mov ecx, num
mov edx, 5 ;5 bytes (numeric, 1 for sign) of that information
int 80h
;Output the message 'The entered number is: '
mov eax, 4
mov ebx, 1
mov ecx, dispMsg
mov edx, lenDispMsg
int 80h
;Output the number entered
mov eax, 4
mov ebx, 1
mov ecx, num
mov edx, 5
int 80h
; Exit code
mov eax, 1
mov ebx, 0
int 80h
I am compiling the script at: https://rextester.com/l/nasm_online_compiler or https://www.jdoodle.com/compile-assembler-nasm-online
but I never get to input anything, it just straight outputs: Please enter a number: You have entered:
assembly nasm
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
add a comment |
Basically I am learning Assembly language/nasm through this book : http://www.pravaraengg.org.in/Download/MA/assembly_tutorial.pdf
In the book one of the example is to do below tasks:
- output on the screen
Please enter a number:
- ask user to input a number
- output on the screen saying:
You have entered:1234
Below is the script:
section .data ;Data segment
userMsg db 'Please enter a number: ' ;Ask the user to enter a number
lenUserMsg equ $-userMsg ;The length of the message
dispMsg db 'You have entered: '
lenDispMsg equ $-dispMsg
section .bss ;Uninitialized data
num resb 5
section .text ;Code Segment
global main
main:
;User prompt
mov eax, 4
mov ebx, 1
mov ecx, userMsg
mov edx, lenUserMsg
int 80h
;Read and store the user input
mov eax, 3
mov ebx, 2
mov ecx, num
mov edx, 5 ;5 bytes (numeric, 1 for sign) of that information
int 80h
;Output the message 'The entered number is: '
mov eax, 4
mov ebx, 1
mov ecx, dispMsg
mov edx, lenDispMsg
int 80h
;Output the number entered
mov eax, 4
mov ebx, 1
mov ecx, num
mov edx, 5
int 80h
; Exit code
mov eax, 1
mov ebx, 0
int 80h
I am compiling the script at: https://rextester.com/l/nasm_online_compiler or https://www.jdoodle.com/compile-assembler-nasm-online
but I never get to input anything, it just straight outputs: Please enter a number: You have entered:
assembly nasm
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Changemov ebx, 2tomov ebx, 0.
– rkhb
Nov 16 '18 at 16:02
add a comment |
Basically I am learning Assembly language/nasm through this book : http://www.pravaraengg.org.in/Download/MA/assembly_tutorial.pdf
In the book one of the example is to do below tasks:
- output on the screen
Please enter a number:
- ask user to input a number
- output on the screen saying:
You have entered:1234
Below is the script:
section .data ;Data segment
userMsg db 'Please enter a number: ' ;Ask the user to enter a number
lenUserMsg equ $-userMsg ;The length of the message
dispMsg db 'You have entered: '
lenDispMsg equ $-dispMsg
section .bss ;Uninitialized data
num resb 5
section .text ;Code Segment
global main
main:
;User prompt
mov eax, 4
mov ebx, 1
mov ecx, userMsg
mov edx, lenUserMsg
int 80h
;Read and store the user input
mov eax, 3
mov ebx, 2
mov ecx, num
mov edx, 5 ;5 bytes (numeric, 1 for sign) of that information
int 80h
;Output the message 'The entered number is: '
mov eax, 4
mov ebx, 1
mov ecx, dispMsg
mov edx, lenDispMsg
int 80h
;Output the number entered
mov eax, 4
mov ebx, 1
mov ecx, num
mov edx, 5
int 80h
; Exit code
mov eax, 1
mov ebx, 0
int 80h
I am compiling the script at: https://rextester.com/l/nasm_online_compiler or https://www.jdoodle.com/compile-assembler-nasm-online
but I never get to input anything, it just straight outputs: Please enter a number: You have entered:
assembly nasm
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
Basically I am learning Assembly language/nasm through this book : http://www.pravaraengg.org.in/Download/MA/assembly_tutorial.pdf
In the book one of the example is to do below tasks:
- output on the screen
Please enter a number:
- ask user to input a number
- output on the screen saying:
You have entered:1234
Below is the script:
section .data ;Data segment
userMsg db 'Please enter a number: ' ;Ask the user to enter a number
lenUserMsg equ $-userMsg ;The length of the message
dispMsg db 'You have entered: '
lenDispMsg equ $-dispMsg
section .bss ;Uninitialized data
num resb 5
section .text ;Code Segment
global main
main:
;User prompt
mov eax, 4
mov ebx, 1
mov ecx, userMsg
mov edx, lenUserMsg
int 80h
;Read and store the user input
mov eax, 3
mov ebx, 2
mov ecx, num
mov edx, 5 ;5 bytes (numeric, 1 for sign) of that information
int 80h
;Output the message 'The entered number is: '
mov eax, 4
mov ebx, 1
mov ecx, dispMsg
mov edx, lenDispMsg
int 80h
;Output the number entered
mov eax, 4
mov ebx, 1
mov ecx, num
mov edx, 5
int 80h
; Exit code
mov eax, 1
mov ebx, 0
int 80h
I am compiling the script at: https://rextester.com/l/nasm_online_compiler or https://www.jdoodle.com/compile-assembler-nasm-online
but I never get to input anything, it just straight outputs: Please enter a number: You have entered:
assembly nasm
assembly nasm
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
asked Nov 16 '18 at 15:46
asdfasdfasdfasdfasdfasdf
64
64
Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Changemov ebx, 2tomov ebx, 0.
– rkhb
Nov 16 '18 at 16:02
add a comment |
Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Changemov ebx, 2tomov ebx, 0.
– rkhb
Nov 16 '18 at 16:02
Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Change
mov ebx, 2 to mov ebx, 0.– rkhb
Nov 16 '18 at 16:02
Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Change
mov ebx, 2 to mov ebx, 0.– rkhb
Nov 16 '18 at 16:02
add a comment |
1 Answer
1
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votes
Works for me when I run it in a terminal on my Linux desktop, after linking it into a 32-bit static executable.
Oh, you're reading from stderr (fd=2), not stdin (fd=0). I noticed this when I tried piping input to it with echo 123 | ./foo and it didn't exit right away. (because stderr is still the terminal.) I checked to see that's what was really happening by running it with strace ./foo.
That happens to work when they're both open on the terminal, because by tradition stderr is opened read/write.
near dup: linux x86 assembly language sys_read call should have first argument as 0 (stdin)
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
changingmov ebx, 2tomov ebx, 0seems to work, you might want to add that to your answer :)
– asdfasdfasdf
Nov 16 '18 at 17:06
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Works for me when I run it in a terminal on my Linux desktop, after linking it into a 32-bit static executable.
Oh, you're reading from stderr (fd=2), not stdin (fd=0). I noticed this when I tried piping input to it with echo 123 | ./foo and it didn't exit right away. (because stderr is still the terminal.) I checked to see that's what was really happening by running it with strace ./foo.
That happens to work when they're both open on the terminal, because by tradition stderr is opened read/write.
near dup: linux x86 assembly language sys_read call should have first argument as 0 (stdin)
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
changingmov ebx, 2tomov ebx, 0seems to work, you might want to add that to your answer :)
– asdfasdfasdf
Nov 16 '18 at 17:06
add a comment |
Works for me when I run it in a terminal on my Linux desktop, after linking it into a 32-bit static executable.
Oh, you're reading from stderr (fd=2), not stdin (fd=0). I noticed this when I tried piping input to it with echo 123 | ./foo and it didn't exit right away. (because stderr is still the terminal.) I checked to see that's what was really happening by running it with strace ./foo.
That happens to work when they're both open on the terminal, because by tradition stderr is opened read/write.
near dup: linux x86 assembly language sys_read call should have first argument as 0 (stdin)
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
changingmov ebx, 2tomov ebx, 0seems to work, you might want to add that to your answer :)
– asdfasdfasdf
Nov 16 '18 at 17:06
add a comment |
Works for me when I run it in a terminal on my Linux desktop, after linking it into a 32-bit static executable.
Oh, you're reading from stderr (fd=2), not stdin (fd=0). I noticed this when I tried piping input to it with echo 123 | ./foo and it didn't exit right away. (because stderr is still the terminal.) I checked to see that's what was really happening by running it with strace ./foo.
That happens to work when they're both open on the terminal, because by tradition stderr is opened read/write.
near dup: linux x86 assembly language sys_read call should have first argument as 0 (stdin)
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
Works for me when I run it in a terminal on my Linux desktop, after linking it into a 32-bit static executable.
Oh, you're reading from stderr (fd=2), not stdin (fd=0). I noticed this when I tried piping input to it with echo 123 | ./foo and it didn't exit right away. (because stderr is still the terminal.) I checked to see that's what was really happening by running it with strace ./foo.
That happens to work when they're both open on the terminal, because by tradition stderr is opened read/write.
near dup: linux x86 assembly language sys_read call should have first argument as 0 (stdin)
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
answered Nov 16 '18 at 15:55
Peter CordesPeter Cordes
135k19204345
135k19204345
changingmov ebx, 2tomov ebx, 0seems to work, you might want to add that to your answer :)
– asdfasdfasdf
Nov 16 '18 at 17:06
add a comment |
changingmov ebx, 2tomov ebx, 0seems to work, you might want to add that to your answer :)
– asdfasdfasdf
Nov 16 '18 at 17:06
changing
mov ebx, 2 to mov ebx, 0 seems to work, you might want to add that to your answer :)– asdfasdfasdf
Nov 16 '18 at 17:06
changing
mov ebx, 2 to mov ebx, 0 seems to work, you might want to add that to your answer :)– asdfasdfasdf
Nov 16 '18 at 17:06
add a comment |
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Online compiler don't stop for reading an input. You have to tell them beforehand what you want them to take as input. And they ignore inputs from STDERR. Use STDIN instead: stackoverflow.com/a/51308591/3512216. Change
mov ebx, 2tomov ebx, 0.– rkhb
Nov 16 '18 at 16:02