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Happy New Month to you all.
However, l am playing with Createfile, WriteFile and ReadFile functions, Createfile and Writefile works well but my problem is ReadFile.
l want to read the data written to a buffer "szBuffer", by using "ReadFile" to read the data in the szBuffer into another buffer szBuf. But it doesn't work.
When l check the return value like error=ReadFile(hfile,szBuffer,10,&in,NULL), it returns 0 but when l use GetLastError() to check for the return value, it gives me 998. l learnt that the second parameter to ReadFile() is the address to store the data read.
Code snippet below:
<pre
lang="c++">hfile=CreateFile("C:\file.txt",GENERIC_READ|GENERIC_WRITE,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,CREATE_NEW,FILE_ATTRIBUTE_NORMAL,NULL);// this works well
<pre>
WriteFile(hfile,szBuffer,256,&in,NULL);//this works well
ReadFile(hfile,szBuf,256,&in,NULL);//this does not read data
CloseHandle(hfile);
hdc=GetDC(hwnd);
TextOut(hdc,50,300,szerror,wsprintf(szerror,"%i",GetLastError()));//check return value
ReleaseDC(hwnd,hdc);</pre>
Can someone help me to overcome this?
Thanks.
modified 4-Apr-16 9:59am.
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After writing to the file, the file pointer is at the actual end of the file when the file has been created. If you then try to read from the file, there is nothing to read at that position (the end of the file).
If you want to read the data that has just been written, you must set the file pointer using SetFilePointer function (Windows)[^]:
SetFilePointer(hFile, 0, 0, FILE_BEGIN);
A return value of zero (FALSE) indicates that the function failed (see ReadFile function (Windows)[^]). Error code 998 is ERROR_NOACCESS / " Invalid access to memory location."
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Thanks. But l have made necessary corrections but the ReadFile is still not working and GetLasterror still returns 998. Also, direct check of ReadFile also returns 0. Help please.
<blockquote class="quote"><div class="op">Quote:</div>hfile=CreateFile("C:\\file.txt",GENERIC_READ|GENERIC_WRITE,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,CREATE_NEW,FILE_ATTRIBUTE_NORMAL,NULL);
<pre>
WriteFile(hfile,szBuffer,256,&in,NULL); SetFilePointer(hfile,0,0,FILE_BEGIN);
ReadFile(hfile,szBuf,256,&in,NULL); CloseHandle(hfile);
hdc=GetDC(hwnd);
TextOut(hdc,50,300,szerror,wsprintf(szerror,"%i",GetLastError())); ReleaseDC(hwnd,hdc);</blockquote></pre>
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You should check the return value from all system calls to see whether the function succeeded or failed. Without that information you are just guessing.
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A probable error source is szBuf being NULL.
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Use double slashes in your file name.
ReadFile() will read from the file pointer's current position. Perhaps you need to call SetFilePointer(FILE_BEGIN) in between write and read.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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I made following program to use opencl library supplied with Nvidia cuda 7.5.
As result I obtained:
Num of devices=1
Device name= quadro K600
Device vendor=NVIDIA Corporation
Device Version=OPENCL 1.2 CUDA
Driver Version= 353.90
DEVICE_MAX_COMPUTE_UNITS = 1 !!!!!!!!!!!!!!!!!!!!!!!!!!
DEVICE_MAX_CLOCK_FREQUENCY = 875 MHZ
DEVICE_GLOBAL_MEM_SIZE= 1073741824
Only 1 compute unit at 875 Mhz????
I read that K600 has 192
#include <stdlib.h>
#define __CL_ENABLE_EXCEPTIONS
#pragma warning(disable:4996)
#include <CL/cl.hpp>
#include <fstream>
#include <iostream>
#include <time.h>
#include <cmath>
#define LOCAL_SIZE 512
#define WIDTH_A (4096*2)
#define HEIGHT_A (4096*2)
float *matrix_A;
float *vector_B;
float *result_vector;
float *result_vector_host;
#define MAX_SOURCE_SIZE (0x100000)
int main()
{
cl_platform_id platform_id = NULL;
cl_device_id device_id = NULL;
cl_context context = NULL;
cl_command_queue command_queue = NULL;
cl_mem Amobj = NULL;
cl_mem Bmobj = NULL;
cl_mem Cmobj = NULL;
cl_program program = NULL;
cl_kernel kernel = NULL;
cl_uint ret_num_devices;
cl_uint ret_num_platforms;
cl_int ret;
int i, j;
ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);
ret = clGetDeviceIDs(platform_id, CL_DEVICE_TYPE_DEFAULT, 1, &device_id, &ret_num_devices);
context = clCreateContext(NULL, 1, &device_id, NULL, NULL, &ret);
char buffer[10240];
cl_uint buf_uint;
cl_ulong buf_ulong;
printf("Num of devices=%i", ret_num_devices);
for (i = 0; i < ret_num_devices; i++)
{
printf(" -- %d --\n", i);
clGetDeviceInfo(device_id, CL_DEVICE_NAME, sizeof(buffer), buffer, NULL);
printf(" DEVICE_NAME = %s\n", buffer);
clGetDeviceInfo(device_id, CL_DEVICE_VENDOR, sizeof(buffer), buffer, NULL);
printf(" DEVICE_VENDOR = %s\n", buffer);
clGetDeviceInfo(device_id, CL_DEVICE_VERSION, sizeof(buffer), buffer, NULL);
printf(" DEVICE_VERSION = %s\n", buffer);
clGetDeviceInfo(device_id, CL_DRIVER_VERSION, sizeof(buffer), buffer, NULL);
printf(" DRIVER_VERSION = %s\n", buffer);
clGetDeviceInfo(device_id, CL_DEVICE_MAX_COMPUTE_UNITS, sizeof(buf_uint), &buf_uint, NULL);
printf(" DEVICE_MAX_COMPUTE_UNITS = %u\n", (unsigned int)buf_uint);
clGetDeviceInfo(device_id, CL_DEVICE_MAX_CLOCK_FREQUENCY, sizeof(buf_uint), &buf_uint, NULL);
printf(" DEVICE_MAX_CLOCK_FREQUENCY = %u\n", (unsigned int)buf_uint);
clGetDeviceInfo(device_id, CL_DEVICE_GLOBAL_MEM_SIZE, sizeof(buf_ulong), &buf_ulong, NULL);
printf(" DEVICE_GLOBAL_MEM_SIZE = %llu\n", (unsigned long long)buf_ulong);
}
}
modified 31-Mar-16 11:32am.
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How is this:
printf(" DEVICE_MAX_CLOCK_FREQUENCY = %u\n", (unsigned int)buf_uint);
printing this:
DEVICE_MAX_CLOCK_FREQUENCY = 875 MHZ
Perhaps the code you are using and the code you pasted are not the same?
Have you tried asking your question here?
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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I edited it after reading to make it more easy to understand.
I have seen that the old video card is not very good improving the performance of the CPU.
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I used angle arc to divide circle into 8 segments, when i extend an angle of one angle arc then the other dissappears , it does not overwrites what to do?
What I have tried:
i used the below code
MoveToEx(hMemDC,50,50 , (LPPOINT) NULL);
AngleArc(hMemDC, 50 , 50 , 47, 0, 45);
SetArcDirection(m_hMemDC, AD_CLOCKWISE);
LineTo(hMemDC,50,50);
EndPath(hMemDC);
StrokeAndFillPath(hMemDC);
then
MoveToEx(hMemDC,50,50 , (LPPOINT) NULL);
AngleArc(hMemDC, 50 , 50 , 47, 45, 45);
SetArcDirection(m_hMemDC, AD_CLOCKWISE);
LineTo(hMemDC,50,50);
EndPath(hMemDC);
StrokeAndFillPath(hMemDC);
and so on..
now if i want to increase the angle of 2nd segment to 55 degrees then the 3rd segment dissappears. how to solve it ?
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You should decide where to ask this question...Re-posting here (after the QA) will not gain you any advantage, but maybe some who thing you are annoying them...
Skipper: We'll fix it.
Alex: Fix it? How you gonna fix this?
Skipper: Grit, spit and a whole lotta duct tape.
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Hi, Good day everyone.
l have some difficulties in the following which l need some help. Am a learner in win32 programming.
l created an application with a button "LogOut", which l want, when the user clicks the LogOut button, the application starts afresh. Just like in a standard program(eg. MSWORD) where when "New" is clicked, a new workspace pops out. So l need help in making my program to start afresh when LogOut button is clicked.
MY TRIAL:
l had done the following, and it worked but it only run the codes in WM_CREATE and l still had sent messages to other cases like WM_PAINT, WM_NOTIFY etc, still only the code in WM_CREATE runs.
case IDC_LOGOUTBTN:
SendMessage(hWnd,WM_CREATE, 0,(LPARAM)lpcs)break;
At some point in my program, l generate random numbers using srand((unsigned)time(&t)) and rand() functions when NEXT button is clicked. But l want to know if there is anyway to get the previous random number(s) when PREVIOUS button is clicked?
Thanks.
modified 30-Mar-16 3:27am.
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Member 12139442 wrote: Just like in a standard program(eg. MSWORD) where when "New" is clicked, a new workspace pops out.
Word simply creates a new document. It does not start over.
Member 12139442 wrote: So l need help in making my program to start afresh when LogOut button is clicked.
I would consider ShellExecute() or CreateProcess() for this.
Member 12139442 wrote: But l want to know if there is anyway to get the previous random number(s) when PREVIOUS button is clicked?
Store them in a container (e.g., array).
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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I have a problem when i have being composed a compiler program for my processor. A system operation( windows, linux ...), how can it run on another processor AMD or Intel? While AMD processors and Intel processors have instructions set different. Can someone answer my question?
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Every compiler has options to specify the target processor type and version (the supported commands). If such options are not used, the compilers will generate code that can run on all Intel and AMD CPUs limited to a minimum processor generation depending on the compiler and version.
For GCC see i386 and x86-64 Options - Using the GNU Compiler Collection (GCC)[^].
For Visual C/C++ there is only one option: /arch (x86)[^].
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Thank you very much! Jochen Arndt,
Regarding GPU, I know that, graphic module in a program can be run by CPU. Also, I know that GPU's instruction set of ATI (or Nvidia) and CPU's instruction set (Intel, AMD) are different. Is it that, insider a operation system has be exiting a dynamic compiler or a normal compiler compile a program to all machine architecture targets?
Newest Ubuntu 64 bits have about 1GB size. If it was compiled to specify one machine architecture, Its size would be smaller ? And how many about size?
Regards!
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GPU's are complete different. They are accessed by operation system dependant drivers for normal operation. While it is possible to perform calculations on modern GPU's, these use their own compilers (e.g. The LLVM Compiler Infrastructure Project[^]).
Intel and AMD have basically the same instruction set. The same applies to other x86 based CPUs (VIA, Cyrix). There are only a very few manufacturer specific instructions. Compilers will not use these instructions by default and might even not provide options to use them. But even then compiling for a specific manufacturer would result only in marginal decreased code size. See also Differences between AMD64 and Intel 64 at x86-64 - Wikipedia, the free encyclopedia[^]
The code size can be slightly decreased (together with slightly increased performance) when generating code for newer processor generations. This is mainly achieved by enabling Streaming SIMD Extensions - Wikipedia, the free encyclopedia[^] for older processors and Advanced Vector Extensions - Wikipedia, the free encyclopedia[^] and the FMA instruction set - Wikipedia, the free encyclopedia[^] for newer ones.
Operating system distributions should run on all systems matching the minimum requirements. Therefore, they are usually build to support also older CPU's. However, they (and also applications) may detect the CPU and use modern instructions when supported. While this increases the code size it will also increase performance.
I can't tell you how much the size decreases when compiling a Linux kernel for a more recent CPU. If you really want to know it, you have to do it.
But reducing the code size should be not necessary nowadays where systems have a lot of storage (RAM and drives).
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Hi Jochen Arndt,
I am trying to develop a processor ( you can think it is a IP ). It will be a IP module beside ARM core and the other IPs into a SoC ( example Snapdragon 820 etc... ). My processor can't running a program which were compiled for ARM architecture. And it only can run one program at a time. It was used to boost up the speed of a program when user need. The ISA for my processor is difference ARM's ISA. I want to make a driver/compiler for my IP, which can compile machine code of a program for the ARM core to machine code for my processor. Have you ever seem a driver/compiler like that? And It has ability to do?
Thank for your responds!
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I have not seen such a compiler (which does not mean they do not exist). But the behaviour of a "driver" is similar to an emulator or the virtual execution system for intermediate languages like CIL used with .Net languages.
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Hi Jochen Arndt,
Actually, I want to invite you for my project( processor that i am trying to make compiler/driver for it ). I will send project's material for you so that you clearly understand.
Are you ok ?
Regards!
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Thank you for your invitation. But I have not enough free time to be engaged in such a project.
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I have a problem when i have being composed a compiler program for my processor. A system operation( windows, linux ...), how can it run on another processor AMD or Intel? While AMD processors and Intel processors have instructions set different. Can someone answer my question?
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With MFCm I am trying to create an OpenGL control on a split form the uses the splitter class to create the panes. My problem is I don't know where to put the OnInitDialog() function or how to wire it up. I have a main form CMainFrame and 2 child forms CFormRight and CFormLeft but don't see any place for the OnInitDialog function. The OnCreateClient function in MainForm calls m_splitter.CreateView but not OnInitDialog.
Any Suggestions?
John C
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