Programming :: Traverse Byte Array In Assembly Using Nasm As Assembler?

Jun 16, 2010

I am trying to learn assembly using nasm as assembler. I did not found example related to string operation. I had following example code,

global asm_strlen
section .data
section .bss
section .text


my problem is at highlighted line, I am not getting how to copy a byte into 4 byte reg. rather what is syntax of mov instruction to mov byte to WORD DWORD etc.

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Programming :: How To Convert Negative Integer To Byte Array?

Oct 26, 2010

I need to convert an integer to a byte array of size 2 and vice versa. The code shown below works well for positive values but not for negative values. Also, using an array of size four makes the conversion works. However, I am limited to an array of size 2.

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Programming :: Memcpy Fails To Copy Data / But Byte By Byte Assignment Work

Jul 6, 2011

I got across a peculiar problem with memcpy.History:writing a code which do flash/Read functionality for SPI Parts.

1.memory map the Flash chip registers to userspace. - fine
2.Issue block read command
3.Just print the data I got, using the memory mapped address - fine I got the correct data.
4.Copy the data to a local buffer from memory mapped address using memcpy - FAIL

on SUSE 11.3 -32 bit the above code worked perfectly, but on SUSE 11.4 - 64bit , Ubantu, Fedora it failed.
I am using gcc compiler obviously. I am using i386/x86_64 OS. Processor: Intel core 2 duo, SNB after step 4 , when I dump the data from local buffer every thing is FF.But step 4, if i implement byte by byte copy using assignment operator, it there any known bug with memcpy? am I missing anything?

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Programming :: Traverse Through The XML Nodes?

Jul 12, 2011

I have a xml file and I read it within a php file with XML dom. This is the node structure of my xml file :



In the comment line, I've got the parent node of the current node. Parent node is "User" node. I would like to obtain the children of this parent node, say "name","surname " etc. How can I do this? Is there any function such as : "$parent_nodes->bringChildren('name')".

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Programming :: NASM Compiling With An IDE?

Sep 21, 2010

I am searching for the IDE that can compile and debug a NASM code. I am using ubuntu 10.04 and I can make compile via terminal but I must view registers for educational purposes.

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Programming :: Use Absolute Sections In Gnu Assembler?

Feb 14, 2011

how to use absolute sections in gnu assembler?

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Programming :: Debugging Nasm Source Code ?

Dec 5, 2010

I found on the Internet a rough suggestion to debug code which says to add a line:

An example shows this lists the lines of source that do work.

I do not know where these lines are supposed to go and whether the "notdeadyet" should be a call to a subroutine or what. I only found that "%define" is used to link to external files, so I am confused because what I tried did not work.

(I am unable to use (and learn) any debugging tool for another few weeks and I'd like to progress on this If I can.)

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Programming :: Convert Code From MASM To NASM

Jul 2, 2010

convert the following code from MASM to NASM


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Programming :: Write A Module In Pure Assembler?

Jan 16, 2010

I need to write a module in pure assembler.Now the linker needs symbols out of the kernel library to link to ( module_init, module_exit, printk).Does anybody know the kernel library name, or are these symbols only in the compressed kernel image (vmlinuz) ?And if, how can I link to a compressed kernel image ?

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Programming :: An Assembler Directive To Interpret All Constants In Hexa?

Jul 9, 2011

GNU assembler 2.17 And without having to prefix them. I'm skimming through as info page and can't find any pseudo operator or assembler directive of this type. E.g. 74 would be a decimal number. But I want it to be hexa 74 without the need to write 0x74.

NOTE: as is the GNU assembler.

EDIT: Google led me to discover this:


If you write numbers without an explicit indication of the base, the most recent `.RADIX S' command determines how they are interpreted. However, on the one hand, it says the most recent and, on the other one, it applies to GASP, the GNU assembler preprocessor. IDK if it is the same as as (the GNU assembler).

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Programming :: GCC Inline Assembler Doesn't Even Support Local Variable?

Jul 3, 2010

It's good that GCC support intel inline disassembly syntax, but it cannot even simply address local variables/parameters properly, making itself stupid and essentially useless, look at the following:

int myfunc(float f){
int x;
float fa[8];
asm(".intel_syntax noprefix
"mov eax, [x]


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Programming :: Write A Simple Character Printing Program Using NASM?

Jul 27, 2010

i tried a code to accept a character and print the same ! i can accept it with following code but its not working with printing that character i use NASM version 2.07


segment .data
msg1: db 'Enter a key',10
msg1len: equ $-msg1


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Programming :: Linking The Assembly And C?

Apr 29, 2010

I have a C code and assembly (nasm) code and I am not able to find how to link them each other. Here are the codes :
NASM side:


section .text


I am using ubuntu 9.10 and my NASM version 2.05.01 compiled on Nov 5 2008.

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Programming :: What's Relationship Btw C Hex And Assembly?

Jul 12, 2011

Could you please explain the relationship between the languages?For one, is C writing assembly when you compile, does every piece of code end up assembly/hex? Is there a way to convert (?port?) between them?I don't understand much at all of them yet, but I've seen examples where it looks like they are interacting, and an understanding of all of them looks to be important?

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Debian Programming :: How Can Use Chmod In Assembly X86

Aug 3, 2014

i wanna use chmod() in linux x86 [debian 3.7.2 x86] but i have some problem in function argv

look at this function:
Code: Select all int chmod(const char *path, mode_t mode);

and mode_t modes:
Code: Select all       S_ISUID  (04000)  set-user-ID  (set  process  effective  user   ID   on

       S_ISGID  (02000)  set-group-ID  (set  process  effective  group  ID  on
                         execve(2);  mandatory  locking,   as   described   in
                         fcntl(2);  take a new file's group from parent direcق
                         tory, as described in chown(2) and mkdir(2))


i know there is some problem in ecx and mode_t value/

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Programming :: Code To Add 5 Numbers In Assembly?

Mar 28, 2011

Looking for code to add 5 numbers in assembly? I want to use array for input of those 5 numbers. No problem if the output is 1 digit(0....9).

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Programming :: Converting C Code To Assembly

May 17, 2011

I've been converting some C code to assembly for my homework; it was going well but I'm having trouble with a for loop for hours. I could not understand where is the problem and decided to ask. I'm posting the part where I'm having trouble of my C-code and assembly-code; every other part of codes act same and the variable values are same. I'm waiting this two codes to act same, but they don't.

mov ebx, [result]
mov eax, [i]
mov ecx, [ebx+eax]
mov [j], ecx
mov [ebx+eax], byte '.'

mov ebx, [result]
mov eax, [i]
inc eax
mov cl, [ebx+eax]
cmp cl, 'Z'
je _continue

mov ebx,[result]
mov eax,[i]
inc eax
mov ecx, [ebx+eax]
mov [k], ecx
mov ebx, [result]
mov eax, [i]
inc eax
mov ecx, [j]
mov [ebx+eax], ecx
mov ecx, [k]
mov [j], ecx
inc dword [i]
jmp _loop


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Programming :: X86 Syntax - Understanding Assembly Instruction

Jan 6, 2011

I'm reading "Understanding the Linux Kernel" and came upon this assembly instruction:
movl $(__KERNEL_CS << 16), %eax
I am curious as to what "<<" means/does. I tried to gooogle, but google doesn't search for "<<".

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Programming :: Convert Gigabyte To Byte?

Nov 24, 2010

I'm learning C and trying to write a program to convert gigabyte into byte. It will take 50% of the value given and then convert that value into byte. But the problem is the output goes into minus / negative value. Like, if I enter 22, I get output: -2147483648.


#include <stdio.h>
#include <math.h>
main (int argc, char* argv[])


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Programming :: Byte At Memory Location 45 With Immediate Value 03

Jul 10, 2011

As 2.17
I want to code this:
and byte[45],03

In words, AND the byte at memory location 45 with immediate value 03. As reports "Ambiguous operand size for and". How could I code the instruction such that as understands my intention?

john: .byte 45
and byte[john],03
gives the same error.

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Programming :: Assembly - Structure References To Members - Get The Values 403004h And 4

Jul 9, 2011


if the address of stWndClass is 403000h, WHY it would be compile as mov eax,[esi+403004] and the first one would be mov eax,[esi+4]? I know how to get the values 403004h and 4,but do not know why.

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Programming :: Can Bash Commands Be Converted To Assembly Like C Source Code?

Nov 30, 2010

I have read where C is first converted to Assembly before its final compilation to binary. Is there a way to do this with Bash commands? I would like the understanding that Assembly allows to Bash somehow.

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Programming :: Calculate The Number Of - Necessary - Bits In A Byte ?

Jun 11, 2010

E.g. 98 is represented as 1100010 (number of valid bits is 7)

What is the formula to calculate the number of valid bits in a byte ?

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Programming :: C Realloc Resize Array / Delete And Add Information Into The Array?

Mar 6, 2011

I am trying to dynamically delete and add information into the array "blah"

int blahsize = 1;
char** blah = (char**) calloc(blahsize+1,sizeof(char*));
Adding information:

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Programming :: C Function To Reverse The Byte Order In A Double?

Aug 12, 2010

I'm trying to write an extension to PHP which means coding in C. I'm really really rusty at C coding and was never very good at it.

Can anyone propose an efficient, safe, and [hopefully] future-proof way of reversing a double? Keep in mind that it should work on as many systems as possible and on 32- and 64-bit systems (and on ???-bit systems in the future?). Will the size of a 'double' ever change or will it always be 8 bytes?

I've tried this and it doesn't work...the compiler complains about "invalid operands to binary" because I'm trying bitwise shiftw on a non-integer.

x = (x>>56) |
((x<<40) & 0x00FF000000000000) |
((x<<24) & 0x0000FF0000000000) |
((x<<8) & 0x000000FF00000000) |


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Programming :: Convert Short Array To Char Array?

Jun 7, 2010

I have trouble converting a short array to a char array


short pShort[4] = { 0x41, 0x42, 0x43, 0x44 };

How to convert this to a char array?

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Debian Programming :: How To Find Total Size Of A List Object In Byte

Jan 11, 2013

Assuming there are two list objects a1, a2.

a1 = ['
a2 =['hi

len() built-in function gives total number of elements in the list object.
len(a1) gives 1. len(a2) gives 1 also.

Code: Select all$ python
Python 2.7.3 (default, Sep  9 2012, 17:41:34)
[GCC 4.7.1] on linux2


I thought there exists a built-in function that gives total size of a list object in byte. So using the function produces 1 for a1, 3 for a2. I haven't found such function or module yet.

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Programming :: Converting A PHP Array Into An HTML Array?

Aug 9, 2009

I'm writing a PHP program. I've encountered a problem; in the following code I try to pass $_POST['delete'] which is an array as the value of a hidden input to some form, but it doesn't do so.there's something wrong with converting PHP array into HTML array. I'm sure that $_POST['delete'] is not null and is a real array.

echo '<input type="hidden" name="delete[]" value="'.$_POST['delete'].'" />';

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Programming :: Serial Port Communication Program Always Lose One Byte Data: 0x00?

Dec 13, 2009

I wrote a serial port communication program to access a equipment.

int main(void)
int fd = 0;
int nread = 0,i = 0,nwrite = 0, tmpread = 0, m = 0, n = 0 ;


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Programming :: Filling 2D Array With 1D Array In C?

May 26, 2010

(I am using vector() and matrix() functions from "Numerical recipes in C".)There are 100 numbers to be stored in 2D array of 10 rows and 10 columns.100 numbers are stored in a 1D array.I get "segmentation fault" at the line indicated in the segment of my code below:


#define size 100
#define nl 1


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