C/C++ :: Read And Write Datatypes To Memory Array
Oct 5, 2014
I decided I wanted to make a proper programming language with a virtual machine and bytecode. I used this tutorial: [URL] .....
As a starting point for my project. So far I have modified it to allow for 32-bit addressing so that I can theoretically use 4GB in my programs. Now the problem I'm having is creating the memory.
Question:
I'm not sure if I should do this with malloc or a char array. What I need to do is create 4 methods to read and 4 to write to memory like this (and it has to be fast):
char GetByte(char* memory, int offset);
uint16 GetInt16(char* memory, int offset);
uint32 GetInt32(char* memory, int offset);
char[] GetString(char* memory, int offset);
So basically memory is the malloced memory and the offset is the position I want to read at.
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Oct 5, 2014
I'm not sure if I should do this with malloc or a char array. What I need to do is create 4 methods to read and 4 to write to memory like this (and it has to be fast):
Code:
char GetByte(char* memory, int offset);
uint16 GetInt16(char* memory, int offset);
uint32 GetInt32(char* memory, int offset);
char[] GetString(char* memory, int offset);
So basically memory is the malloced memory and the offset is the position I want to read at.
I'm not sure if there's already a way to do this and maybe I'm overlooking something.
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Sep 5, 2013
I am doing a project which I have to read, write and erase data from a NorFlash Memory. Then, I have to compare those data files in order to find errors.
Besides, I would like to know which is the best way to TEST errors in this kind of memories.
I am using NetBeans 7.3.1 for writting the code and Cygwin running on Windows XP Virtual Machine. The Memory Flash (S29JL064J 64 Megabit) is incorporated on an external board which is connected to an adapter board (using HDMI cable). This adapter is connected to the Laptop (using an USB).
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Mar 30, 2014
I have two from in visual studio 2010 with C#. In form1 I have one combobox and one button .In form2 I have Reportviewer . When Button in form1 is clicked form2 is shown. Now my problem is when I click button to show form2 on the line Form2.Show(); this error appear : Attempted to read or write protected memory. This is often an indication that other memory is corrupt. What can i do? In form1 I have one combobox that combo fill with Database with this code in the Form Load:
private void DocReportOnlyAlalhesabSearch_Load(object sender, EventArgs e) {
//fill shahrestan Combo
if (Class.Global.CurrentYear.Length != 0) {
OleDbConnection conn1;
OleDbCommand cmd1;
cmd1 = new OleDbCommand();
[Code] ....
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Mar 17, 2013
I have CAN Dll program for my application,which was separately used.Now I have included the Drivers program into my application Program and I am having this error System Access Violation Exception:Attempted to read or write protected memory.i am attaching the Dll code and Application code which is throwing this error.
[CODE]
The CAN Dll Code
int receive_data(unsigned char *data_output, int *MsgId, XLportHandle g_xlPortHandle){
XLstatusxlStatus, xlStatus_new;
XLevent xlEvent;
unsigned intmsgsrx=RECEIVE_EVENT_SIZE;
char *local_data ="11111111";
DWORD status;
xlStatus_new = xlSetNotification(g_xlPortHandle, &h, 1);
[code]...
My Application Code which is the receiver thread for accessing the messages got onto the CAN bus.
DWORD WINAPI Rcv_Msg(LPVOID param){
int*MsgId = new int;//msg id from CAN
intRcvVal;//0 = there is data in the queue; 1 = there is no data
unsigned int uMsgId;
*MsgId = 0;
unsigned char CanData[8];
[code]...
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Jan 29, 2014
I have a complex program, around 25.000 code lines. It is quite stable, but I have a bug which only happens from time to time, and when in online-mode, so it is quite difficult for me to reproduce it. I have put lot of efforts to see where the problem is, and I have seen where the code crash, but that line is not the culprit, it only refers to read a memory location where it is supposed to be good data, and it is not. The real bug has happens before in execution. That data is read-only, I mean, I only compute it at program start-up, and then never write into it again, but my bug write to it doring code run, maybe because bad pointers address in any place, and look ramdom (different snapshots execution write at different memory locations).
My question is, is there a way to know when my code 'write' into that 'to me protected memory'? I thinking if there is a method to make a hash of all variables and arrays in that memory section, or any way to 'assert' when that big memory section is written, taking into accound that when I refer to that memory section it could be any of the lots of variables and arrays I precompute at start-up.
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Apr 8, 2014
Writing bytes to external process to remove a detour that the program does
this is what im trying it fails
HANDLE Handle = OpenProcess(PROCESS_ALL_ACCESS, false, ProcessId);
BYTE btLdrLoadDll[] = { 0x8B, 0xFF, 0x55, 0x8B, 0xEC };
if (!WriteProcessMemory(Handle, (BYTE*)((DWORD)GetProcAddress(GetModuleHandle("ntdll.dll"), "LdrLoadDll")), &btLdrLoadDll, sizeof(btLdrLoadDll), NULL)) {
CloseHandle(Handle);
std::cout << "
Failed to write Bytes to memory. Press enter to exit.";
[Code] ....
an also using the right address like this fails
WriteProcessMemory(Handle, (BYTE*)0x77C64F9F, &btLdrLoadDll, sizeof(btLdrLoadDll), NULL)
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Mar 3, 2013
How can I erase the data stored in /tmp/a.txt after every run of this code?
Code:
#include <stdio.h> // IO operations
#include <unistd.h> //for pid, ppid, fork functions
#include <sys/types.h> //for pid_t type, kill function
#include <stdlib.h> //for exit function
#include <signal.h> //for kill function
#include <sys/types.h>
#include <sys/stat.h>
[Code]...
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Dec 22, 2013
My program needs to receive data continuously from one process and the received data is read continuously by another process.But when I am trying to create a pipe using mknod on fat32 file system in linux , it throws an error saying "mknod: operation not permitted".
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Sep 8, 2013
I receive a telegram in XML format and I need to parse it and send my data in the same format back. My main problem is that I'm not allowed to use any open source software or other 3rd party software except VS2010. I have to write it in C++.
Now my question: is there any good tutorial for such a parser? I was hoping that I could write something which can be used similar to the GEtPrivateProfil-functions which are handy for ini-files.
My XML telegram looks like hat:
Code:
<Tag0 cmdId=“254“ version=“1“ ID=“87951“ action=“doing1“>
<!—comment1 -->
<Tag1 lId=“31“ type=“12“ index=“100“ state=“open“ />
<Tag1 lId=“31“ type=“12“ index=“135“ state=“open" />
<!—comment2 -->
<Tag2 lId=“42“ type=“32“ index=“2“ state=“open" >
<param key=“pos“ value=“center“ />
<param key=“car“ />
</epr>
</Tag0>
I was hoping to find a way to get to know how many tag1 and tag2 are in tag0 and then get for each tag the attributes and sub-tags like param in tag2
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Jan 20, 2014
I have a C program. Within it, I would like to embed either a file or a pre-assigned variable. I would prefer a method that is platform independent.
I am using the data type "RSA" from <openssl/rsa.h>. I have a key file in PEM format, but I would like to embed an RSA object in the program instead. I tried creating a char array and then casting the pointer, but that caused some sort of illegal casting issue. I tried using memcpy but I haven't been able to get it working that way. What is the best way of going about this? Is it possible to read a file directly from a memory buffer?
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Jun 27, 2014
I have trouble reading the last element in a struct.I do get the correct value for the first two elements. In my example that is:
a = 11 and c = H
however I get:
b = 0
but I am expecting b=2
I got two files to handle this.The first one is writing data to memory -
Code:
#include <sys/shm.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
}
[code]....
why I cannot get correct value for the third element in my struct?In the second file where I'm reading from memory I allocate some space. Is this incorrect in some way? I'm running this on a Linux machine.
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Jan 16, 2013
i want to write a program that can access to variables and methods of another program. I ques for access to variables need to read memory, but about methods?how i can use methods and call them?
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Aug 5, 2013
this is my read/write functions based the read from the last post! then went nuts with it! used the %19s%*s on the write to the file, solved all the probs on the read side! but any refining on this would be great. This is another program that i started with the forums, and started going my own direction!
Code:
void WriteAccount(int account,char *a[])
{
FILE *fptr;
char Memo[20];
char buff[20];
double Amount;
struct tm *sTm;
}
[code]....
the a[] is a string array with bank account names, and Account is the number on the menu based list.
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Jan 6, 2014
I have two designs for reading/writing my classes to XML. Which do you think is better:
This is my structure (Attributes are single class members, Elements are std::vector< T > members
Structure:
+ Calibrator
+ Attrib: readLabel (string)
+ Attrib: saveLabel (string)
+ Element: Device
+ Attrib: sourceLabel (string)
+ Attrib: destLabel (string)
+ Element: CalPoint
+ Attrib: sourceVal (double)
+ Attrib: destVal (double)
1. Design 1: Have an independent class to handle everything and "friend" it with the users.
Pro: Only 1 interface needed and we can switch interface easily.
Con: There is a lot of inter-class data which destroys encapsulation
class CalibratorXML;
class Device{
string sourceLabel;
string destLabel;
vector<CalPoint> calPoints;
friend class CalibratorXML;
[Code] .....
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Feb 4, 2013
I am planning to use this mostly to copy binary files, but why won't this work with text???
input.txt
int main(int argc, char* argv[]) {
// open file
std::ifstream ifs;
ifs.open("./input.txt", std::ios::binary);
[Code] ....
output.txt
310^?z^@^@^@^@^@300367346^A^@
Will this method always work to copy a file?
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Dec 10, 2014
I'm looking to write a program in C/C++ to traverse a Fasta file formatted like:
>ID and header information
SEQUENCE1
>ID and header information
SEQUENCE2
and so on
in order to find all unique sequences (check if subset of any other sequence) and write unique sequences (and all headers) to an output file.
My approach was:
Prep: Copy all sequences to an array/list at the beginning (more efficient way to do this?)
Grab header, append it to output file, compare sequence for that header to everything in the list/array. If unique, write it under the header, if not, go on.
However, I'm a little unsure as to how to approach reading the lines in properly. I need to read the top line for the header, and then "return?" to the next line to read the sequence. Sometimes the sequence spans more then two lines, so would I use > (from the example above) as a delimiter? If I use C++, I imagine I'd use iostreams to do the reading.
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Oct 12, 2014
How to read some characters from file, I know we can move a pointer to some position using seekg() & seekp() function, get current position of the pointer through tellg() & tellp() functions. By moving the pointer to appropriate position using seekg(), we can read the whole line using getline() function. But is there any function which read certain characters from the current position of the pointer and write certain characters from current position of the pointer.
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Oct 12, 2014
How to read some characters from file, I know we can move a pointer to some position using seekg() & seekp() function, get current position of the pointer through tellg() & tellp() functions. By moving the pointer to appropriate position using seekg(), we can read the whole line using getline() function. But is there any function which read certain characters from the current position of the pointer and write certain characters from current position of the pointer.
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Feb 19, 2014
#include <stdio.h>
#include <stdlib.h>
int main () {
FILE * pFile;
long lSize;
char * buffer;
size_t result;
pFile = fopen ( "myfile.bin" , "rb" );
[Code] .....
How to open binary for read and write? Why the buffer is char * buffer? i mean in binary u cant read chars . How can it be? how the data is represented? just like txt file? What the buffer will contain how to print this buffer???
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Nov 17, 2014
reading and writing 2D arrays I've been trying out a few tutorials using FileStream but I couldn't get any of them to work.
Anyway what I'm trying to do is save the playerArray to a .txt file and then read from that .txt into the fields within the GUI. This is supposed to act as a database.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
[Code]....
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Sep 22, 2012
the output of the password text file contains like this:
username
776655443322 (password encoded)
How to write the value in last line (3rd row) of the file. after that read and write or alter 3rd row value. I need logic using "C" language.
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Mar 25, 2013
I need do read a text file from memory card using threading.
I am able to do it with out using thread but because of some limitations, i have to do it with threading only.
Here is the code to read file from memory card with out thread:
Code: ##########################################
#include <stdio.h>
#include <stdlib.h>
#include <XMC4500.h> /* SFR declarations of the selected device */
#include <DAVE3.h> /* Declarations from DAVE3 Code
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
[Code]...
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Dec 29, 2013
Explain me a working code to read and write a file using serial communication.and i need to store that file.I know normal file handling in C, but how it is through serial port i am not getting.
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Sep 27, 2014
called object 'fptr_in' is not a function or function pointer
called object 'fptr_out' is not a function or function pointer
what can i do for the errors?(i mustn't use loop and arrays for the code)
Code:
#include <stdio.h>
void sum_of_2nd_and_3nd( FILE* fptr_in, FILE* fptr_out);
int main()
return 0;
}
void sum_of_2nd_and_3nd( FILE* fptr_in, FILE* fptr_out){
}
[code].....
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Jan 30, 2014
So I've been turning my programs into classes and I run into errors.
So this program is supposed to allow the user to open the file and either read or write to it.
I've omitted the read part from it as I want to attempt that on my own .
I get these compile errors:
fileclass.cpp:13: error: ISO C++ forbids declaration of ‘choice’ with no type
fileclass.cpp:21: error: ISO C++ forbids declaration of ‘choice’ with no type
fileclass.cpp: In member function ‘int file::choice()’:
[Code] .....
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