How to copy bytes from buffer into the managed struct?
- by Chupo_cro
I have a problem with getting the code to work in a managed environment (VS2008 C++/CLI Win Forms App). The problem is I cannot declare the unmanaged struct (is that even possible?) inside the managed code, so I've declared a managed struct but now I have a problem how to copy bytes from buffer into that struct. Here is the pure C++ code that obviously works as expected:
typedef struct GPS_point {
float point_unknown_1;
float latitude;
float longitude;
float altitude; // x10000
float time;
int point_unknown_2;
int speed; // x100
int manually_logged_point; // flag (1 --> point logged manually)
} track_point;
int offset = 0;
int filesize = 256; // simulates filesize
int point_num = 10; // simulates number of records
int main () {
char *buffer_dyn = new char[filesize]; // allocate RAM
// here, the file would have been read into the buffer
buffer_dyn[0xa8] = 0x1e; // simulates the speed data (1e 00 00 00)
buffer_dyn[0xa9] = 0x00;
buffer_dyn[0xaa] = 0x00;
buffer_dyn[0xab] = 0x00;
offset = 0x90; // if the data with this offset is transfered trom buffer
// to struct, int speed is alligned with the buffer at the
// offset of 0xa8
track_point *points = new track_point[point_num];
points[0].speed = 0xff; // (debug) it should change into 0x1e
memcpy(&points[0],buffer_dyn+offset,32);
cout << "offset: " << offset << "\r\n";
//cout << "speed: " << points[0].speed << "\r\n";
printf ("speed : 0x%x\r\n",points[0].speed);
printf("byte at offset 0xa8: 0x%x\r\n",(unsigned char)buffer_dyn[0xa8]); // should be 0x1e
delete[] buffer_dyn; // release RAM
delete[] points;
/*
What I need is to rewrite the lines 29 and 31 to work in the managed code (VS2008 Win Forms C++/CLI)
What should I have after:
array<track_point^>^ points = gcnew array<track_point^>(point_num);
so I can copy 32 bytes from buffer_dyn to the managed struct declared as
typedef ref struct GPS_point {
float point_unknown_1;
float latitude;
float longitude;
float altitude; // x10000
float time;
int point_unknown_2;
int speed; // x100
int manually_logged_point; // flag (1 --> point logged manually)
} track_point;
*/
return 0;
}
Here is the paste to codepad.org so it can be seen the code is OK.
What I need is to rewrite these two lines:
track_point *points = new track_point[point_num];
memcpy(&points[0],buffer_dyn+offset,32);
to something that will work in a managed application. I wrote:
array<track_point^>^ points = gcnew array<track_point^>(point_num);
and now trying to reproduce the described copying of the data from buffer over the struct, but haven't any idea how it should be done.
Alternatively, if there is a way to use an unmanaged struct in the same way shown in my code, then I would like to avoid working with managed struct.
