; Author : Jeff Duntemann
; Description : A simple program in assembly for Linux,using NASM 2.05,
; demonstrating simple text file I/O (through redirection) for reading an
; input file to a buffer in blocks, forcing lowercase characters to
; uppercase, and writing the modified buffer to an output file.
;
; Run it this way:
; uppercaser2 > (output file) < (input file)
;
; Build using these commands:
; nasm -f elf -g -F stabs uppercaser2.asm
; ld -o uppercaser2 uppercaser2.o
;
SECTION .bss ; Section containing uninitialized data
BUFFLEN equ 1024 ; Length of buffer
Buff: resb BUFFLEN ; Text buffer itself
SECTION .data ; Section containing initialised data
SECTION .text ; Section containing code
global _start ; Linker needs this to find the entry point!
_start:
; This no-op keeps gdb happy...
nop
; Read a buffer full of text from stdin:
read:
mov eax,3 ; Specify sys_read call
mov ebx,0 ; Specify File Descriptor 0: Standard Input
mov ecx,Buff ; Pass offset of the buffer to read to
mov edx,BUFFLEN ; Pass number of bytes to read at one pass
int 80h ; Call sys_read to fill the buffer
mov esi,eax ; Copy sys_read return value for safekeeping
cmp eax,0 ; If eax=0, sys_read reached EOF on stdin
je Done ; Jump If Equal (to 0, from compare)
; Set up the registers for the process buffer step:
mov ecx,esi ; Place the number of bytes read into ecx
mov ebp,Buff ; Place address of buffer into ebp
dec ebp ; Adjust count to offset
; Go through the buffer and convert lowercase to uppercase characters:
Scan:
cmp byte [ebp+ecx],61h ; Test input char against lowercase 'a’
jb Next ; If below 'a’ in ASCII, not lowercase
cmp byte [ebp+ecx],7Ah ; Test input char against lowercase 'z’
ja Next ; If above 'z’ in ASCII, not lowercase
; At this point, we have a lowercase char
sub byte [ebp+ecx],20h ; Subtract 20h to give uppercase...
Next: dec ecx ; Decrement counter
jnz Scan ; If characters remain, loop back
; Write the buffer full of processed text to stdout:
Write:
mov eax,4 ; Specify sys_write call
mov ebx,1 ; Specify File Descriptor 1: Standard output
mov ecx,Buff ; Pass offset of the buffer
mov edx,esi ; Pass the # of bytes of data in the buffer
int 80h ; Make sys_write kernel call
jmp read ; Loop back and load another buffer full
; All done! Let’s end this party:
Done:
mov eax,1 ; Code for Exit Syscall
mov ebx,0 ; Return a code of zero
int 80H ; Make sys_exit kernel call
this is the error I get when running the code (NASM is the assembler ). Thanks.
cat@cat-laptop:~/Desktop$ sudo ./uppercase2 >toUpper.txt <fromLow.txt
./uppercase2: 1: �f�f�f�tf�̀f��f=t?f��f�tfMg�: not found./uppercase2: 1:
arg�: not found
: not found2: 1:
that looks like LINUX NASM code
we are a windows masm forum - so it looks a little strange :P
there are 2 things that look odd
mov ebp,Buff
not sure about NASM syntax
but, that might move the contents (the first 4 bytes) of Buff into EBP
in masm syntax, we would use
mov ebp,offset Buff
this moves the address of Buff into EBP
the other thing is that EBP is used
again - i don't know about LINUX
but EBP may not be the best register to use, as it references the SS segment, not the DS segment
Hi,
NASM differentiates between Buff and [Buff] to avoid the use
of OFFSET. So that should not be the problem.
Regards,
Steve N.
Does the error message appear in your terminal in the same human unreadable form ?
It seems like the program didn't like one of the command line arguments .
yes, it shows like that In the Terminal in human unreadable form. Copied from the Terminal
This is a Linux(Ubuntu) problem and the code is an example from "Step by step assembly" by Jeff Dunteman. The book was written in 2009 though.
it looks like older linux code (int 80h)
i think they have API functions now, somewhat similar to windows
Hi silvercats,
please tell us your command line. It should look like that:
nasm -f elf32 uppercaser.asm -o uppercaser.obj
I'm not sure, if the linker command line is valid. Anyway, which example in the book is it? I've Jeff's booklet and can check it tomorrow evening, if that is fast enough for you. At the moment I'm not at home.
Gunther
Quote'a’ 'z’ Let’s
:dazzled:
don't you find it strange in your code ::)
your compiler probably don't understand Martian language :greensml:
try
NASA instead of
NASM :bgrin:
Quote from: habran on June 06, 2014, 02:29:07 PM
your compiler probably don't understand Martian language :greensml:
Some compilers understand Martian language, but internally they call it "UTF-8" 8)
that compiler thinks probably that this is UFO-8 :biggrin:
it might be unicode text ?
displayed with the wrong codepage, maybe ?
that's why NASM spat this garbage:
Quotecat@cat-laptop:~/Desktop$ sudo ./uppercase2 >toUpper.txt <fromLow.txt
./uppercase2: 1: �f�f�f�tf�̀f��f=t?f��f�tfMg�: not found./uppercase2: 1:
arg�: not found
:greenclp:
Jochen, Habran, Dave,
now the fun should stop. That's not a joke thread, but a serious question.
Gunther
we were just pointing out that silvercats is using either wrong assembler or wrong codepage :shock:
Quote from: habran on June 07, 2014, 05:50:48 AM
we were just pointing out that silvercats is using either wrong assembler or wrong codepage :shock:
The assembler is the right one. It's NASM syntax. The code page could be, but in that case he would see always garbage at the screen by typing any text or command.
Gunther
Hi silvercats,
it was a misunderstanding. I don't have the book by Jeff Duntemann. I have confused it with the book by James Leiterman (http://books.google.de/books/about/32_64_bit_80x86_assembly_language_archit.html?id=avDkMnuhakkC&redir_esc=y). Apologies, but I was with my students on the road and therefore some days not at home. I therefore had no access to my big computer and only the laptop with me.
I've finished for you an example for assembling with NASM or YASM (version number is not critical). I've linked it wit gcc, because that saves a lot of trouble. It's inside the archive hello.zip, wich contains hello.tar.gz. The source is well commented and the program should run with any Linux distribution and under BSD.
By the way, I don't know if Duntemann's book is good, but for learning purposes is Dr. Carter's book (http://drpaulcarter.com/pcasm/) an excellent choice. It's free, available in different translations via net, covers Windows and Linux and the examples are working well.
In the meantime, I'll take a look at your code and see what I can do for you.
Gunther
Quote from: habran on June 06, 2014, 02:29:07 PM
Quote'a’ 'z’ Let’s
:dazzled:
don't you find it strange in your code ::)
your compiler probably don't understand Martian language :greensml:
try NASA instead of NASM :bgrin:
A funny guy, aren't you?
The unreadable strange chars you see on the Source code that is posted here, are not REALLY on the original source file(.asm file) in the local computer. Don't know how it happened here. (but command line output's strange chars were there, on the original Terminal.)
Found the problem thanks to Gunter! Thanks a lot for other people too.
Here is what happened. I use Geany for editing the source codes(a powerful tool for editing text and a lot more features and functions are there) . It has a button called "compile". When i went to check the linker commands as Gunter wanted me to recheck them, i realized that i actually used the button on the Geany to compile the code. So no commands were used. The program worked fine after using the proper stuff. Thanks!!
.
Thanks. I will take a look at James Leiterman's book too
hey silvercats :biggrin:
I CONFESS that I poses a certain amount of humor (and that is I suppose a crime these days) but you have to confess that I was right:
you gave to NASM source that it can't read (garbage) and that's what I was trying to point out to
you ;)
Quote from: habran on June 08, 2014, 11:09:32 PM
hey silvercats :biggrin:
I CONFESS that I poses a certain amount of humor (and that is I suppose a crime these days) but you have to confess that I was right:
you gave to NASM source that it can't read (garbage) and that's what I was trying to point out to
you ;)
did I tell you that you were funny? (hmm...is there a word called 'irony' in English).
1. It wasn't the NASM that I gave the source to exactly.
2. If you read my post correctly, you would read that there were no "garbage" in the actual source code for real.
We do appreciate real opinions and replies rather than wrong humor here.
Thank you
Quotethis is the error I get when running the code (NASM is the assembler ). Thanks.
cat@cat-laptop:~/Desktop$ sudo ./uppercase2 >toUpper.txt <fromLow.txt
./uppercase2: 1: �f�f�f�tf�̀f��f=t?f��f�tfMg�: not found./uppercase2: 1:
arg�: not found
: not found2: 1:
Quote from: habran on June 09, 2014, 12:17:43 AM
Quotethis is the error I get when running the code (NASM is the assembler ). Thanks.
cat@cat-laptop:~/Desktop$ sudo ./uppercase2 >toUpper.txt <fromLow.txt
./uppercase2: 1: �f�f�f�tf�̀f��f=t?f��f�tfMg�: not found./uppercase2: 1:
arg�: not found
: not found2: 1:
the terminal output text yes....
Hi silvercats,
fine to hear that things work well. A few remarks:
- I would use local labels with NASM. These are starting with a dot.
- Give Dr. Paul Carter a try. The Leiterman book won't help you much.
And always remember: The funny guys are Windows coders. Do they really know what a terminal output is? (With irony tags, in case anyone is in doubt. :lol: :lol: :lol:)
Gunther
Alright! Thanks for the help.It is really appreciated.......
Quote from: silvercats on June 09, 2014, 11:10:34 PM
Alright! Thanks for the help.It is really appreciated.......
You're welcome.
Gunther