I'm trying to access MATLAB through Engine with MetaTrader Terminal 4( a trading software from MetaQuotes metatrader4 )
I use a DLL file to communicate between MetaTrader and MATLAB.
In the code, if I put this code in a single function, it works.
But if I separate it into two distinct functions, it runs forever/bugs out
#include "stdafx.h"
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <vector>
#include <windows.h>
#include <memory.h>
#include "engine.h"
using namespace std;
#define MT4_EXPFUNC __declspec(dllexport)
Engine *pEng = NULL;
mxArray *closev = NULL;
double *closevp = NULL;
mxArray *getPArray = NULL;
MT4_EXPFUNC void InitEngine( int dummy )
{
pEng = engOpen( NULL );
}
MT4_EXPFUNC void InitCloseBuffer( int size )
{
closev = mxCreateDoubleMatrix( 1, size, mxREAL );
if ( closev != NULL )
closevp = mxGetPr( closev );
// ------------------------------------------------------------------
// the following code bugs when separated from the code above
// and put in another function called right after this one
engPutVariable( pEng, "closev", closev );
engEvalString( pEng, "[mainNet] = PTrainInit();" );
engEvalString( pEng, "[hitrate, mainNet] = PTrain(mainNet, closev);" );
engEvalString( pEng, "outGetP = PGetPrediction(mainNet, closev)" );
getPArray = engGetVariable( pEng, "outGetP" );
double *p;
if ( getPArray != NULL )
p = mxGetPr( getPArray );
// end of the separated code
// -----------------------------------------------------------------
}
I need to separate both functions though,because I need to fill closev with values.
What am I doing wrong?
thanks
Jeff
ok, I found the answer: initially I had made a standalone MATLAB Project, that was working fine but closev was column-wise and in the DLL closev is row-wise.
Also, populating closev and then using the second, separated, function was a totally different use of the function insides than with closev not populated.
These two things made it look strange error-wise though.
Glad I could make it work.
JfLB
Related
I would like to pass a String vector into an external C function.
In a minimal example I just want to pass the String vectors (or 1D array) through the C function.
My Modelica function looks like:
function testreadstri
input String instri[2];
output String outstri[2];
external "C" test_stri(instri,, size(instri, 1), outstri);
annotation (Include="#include <ebcmysql.cpp>", Library="libmysql");
end testreadstri;
My C fucntion looks like:
void test_stri(const char* thestring, size_t nLines, const char **testresult)
{
//bout = 12.3;
size_t iLines;
//size_t nLines;
iLines = 0;
//nLines = 1;
while ( iLines <= nLines ) {
<LINE_OF_INTEREST>
iLines++;
}
}
I tried for <LINE_OF_INTEREST> the following lines:
testresult[iLines] = thestring[iLines];
strcpy(testresult[iLines], thestring[iLines]);
What works, but of course does not pass the input through as an output, is:
testresult[iLines] = "aTestString";
Is there any possibility to handle Modelica input String vectors in the external C function?
Thanks in advance!
Here's a short, self-contained and compilable example demonstrating both input string and output string handling of a pure external function in Modelica
model Model
function testreadstri
input String instri[2];
output String outstri[2];
external "C" test_stri(instri, size(instri, 1), outstri, size(outstri, 1));
annotation(Include="
#include \"ModelicaUtilities.h\"
#include <stdlib.h>
#include <string.h>
void test_stri(const char** thestring, size_t nLinesIn, const char** testresult, size_t nLinesOut)
{
size_t iLines;
// example for input string handling
for (iLines = 0; iLines < nLinesIn; iLines++) {
ModelicaFormatMessage(\"%s\\n\", thestring[iLines]);
}
// example for output string handling
for (iLines = 0; iLines < nLinesOut; iLines++) {
char* line = ModelicaAllocateStringWithErrorReturn(6);
if (line != NULL) {
strcpy(line, \"result\");
testresult[iLines] = line;
}
}
}");
end testreadstri;
String s[:] = testreadstri({"first", "second"});
end Model;
Yes, this is supported by the Modelica specification, see https://specification.modelica.org/v3.4/Ch12.html#argument-type-mapping.
I'm trying to call a dll function in matlab. I have a C++ struct as shown in sixense.h:
typedef struct _sixenseControllerData {
float pos[3];
float rot_mat[3][3];
float joystick_x;
float joystick_y;
float trigger;
...
} sixenseControllerData;
and functions I could call:
SIXENSE_EXPORT int sixenseInit( void );
SIXENSE_EXPORT int sixenseGetAllNewestData( sixenseAllControllerData * );
I can easily get this to work with calllib('sixense','sixenseInit') since there is no input, but for the function sixenseGetAllNewestData I need to have a struct pointer. I realize that libstruct is what I need to use. However, I don't seem to be doing it right.
So I tried libstruct like so:
libstruct('sixenseControllerData')
and I get the error:
??? Error using ==> feval
Undefined function or variable 'lib.sixenseControllerData'.
Error in ==> libstruct at 15
ptr=feval(['lib.' structtype]);
EDIT: here is my current unedited proto file:
http://pastebin.com/PemmmMqF
the full header file is available here:
https://github.com/rll/sixense/blob/master/include/sixense.h
For C structures, loadlibrary generates types named: s_{NAME} where {NAME} is the name of the structure. In your case we create a pointer as:
s = libstruct('s_sixenseControllerData');
We can see this fact by instructing MATLAB to generate a prototype file:
>> loadlibrary('sixense', 'sixense.h', 'proto','sixense_proto')
A prototype file is a file of MATLAB commands which we can modify and use in place of a header file. In this case, the file will contain something like:
sixense_proto.m
...
structs.s_sixenseControllerData.members = struct('pos', 'single#3', 'rot_mat', 'single#9', 'joystick_x', 'single', 'joystick_y', 'single', 'trigger', 'single', 'buttons', 'uint32', 'sequence_number', 'uint8', 'rot_quat', 'single#4', 'firmware_revision', 'uint16', 'hardware_revision', 'uint16', 'packet_type', 'uint16', 'magnetic_frequency', 'uint16', 'enabled', 'int32', 'controller_index', 'int32', 'is_docked', 'uint8', 'which_hand', 'uint8', 'hemi_tracking_enabled', 'uint8');
structs.s_sixenseAllControllerData.members = struct('controllers', 's_sixenseControllerData#4');
....
Unfortunately, a limitation of loadlibrary is that it does not support nested structure very well, especially if a structure contains a pointer to another structure (or an array in this case):
Nested structures or structures containing a pointer to a structure are
not supported. However, MATLAB can access an array of
structures created in an external library.
So you will not be able to directly create the sixenseAllControllerData structure on the MATLAB side, which is defined in the C header file as:
typedef struct _sixenseAllControllerData {
sixenseControllerData controllers[4];
} sixenseAllControllerData;
According to the following discussion, one workaround is to "unroll"/"flatten" the array into separate variables. You can either do this in a copy of the header file, or making the changes in the generated prototype file (which I think is the preferred way). You can do this without having to recompile the shared library.
In your case, change the nested structure in the generated sixense_proto.m file into:
structs.s_sixenseAllControllerData.members = struct(...
'controllers1', 's_sixenseControllerData', ...
'controllers2', 's_sixenseControllerData', ...
'controllers3', 's_sixenseControllerData', ...
'controllers4', 's_sixenseControllerData');
Now we can create a pointer to this structure, and call the C method:
s = libstruct('s_sixenseAllControllerData');
s.controllers1 = libstruct('s_sixenseControllerData');
s.controllers2 = libstruct('s_sixenseControllerData');
s.controllers3 = libstruct('s_sixenseControllerData');
s.controllers4 = libstruct('s_sixenseControllerData');
out = calllib('sixense', 'sixenseGetAllNewestData', s);
get(s)
A completely different solution is to write a MEX-function to interface with the library. It is just like any other C/C++ code, only using mxArray and the MX-API to interface with MATLAB...
Example:
To test the above, I created a simple DLL with similar structures, and implemented the above solution. Here is the code if someone wants to test it:
helper.h
#ifndef HELPER_H
#define HELPER_H
#ifdef _WIN32
#ifdef EXPORT_FCNS
#define EXPORTED_FUNCTION __declspec(dllexport)
#else
#define EXPORTED_FUNCTION __declspec(dllimport)
#endif
#else
#define EXPORTED_FUNCTION
#endif
#endif
mylib.h
#ifndef MYLIB_H
#define MYLIB_H
#include "helper.h"
typedef struct _mystruct {
int pos[3];
double value;
} mystruct;
typedef struct _mystruct2 {
mystruct arr[2];
int num;
} mystruct2;
EXPORTED_FUNCTION void myfunc(mystruct *);
EXPORTED_FUNCTION void myfunc2(mystruct2 *);
#endif
mylib.c
#define EXPORT_FCNS
#include "helper.h"
#include "mylib.h"
void myfunc(mystruct *s)
{
s->pos[0] = 10;
s->pos[1] = 20;
s->pos[2] = 30;
s->value = 4.0;
}
void myfunc2(mystruct2 *s)
{
int i;
for(i=0; i<2; i++) {
myfunc(&(s->arr[i]));
}
s->num = 99;
}
After compiling the above into a DLL, we generate the initial prototype file:
loadlibrary('./mylib.dll', './mylib.h', 'mfilename','mylib_proto')
unloadlibrary mylib
I edit the prototype file as described before:
function [methodinfo,structs,enuminfo,ThunkLibName] = mylib_proto()
MfilePath = fileparts(mfilename('fullpath'));
ThunkLibName = fullfile(MfilePath,'mylib_thunk_pcwin64');
enuminfo = [];
structs = [];
structs.s_mystruct.members = struct('pos','int32#3', 'value','double');
structs.s_mystruct2.members = struct('arr1','s_mystruct', ...
'arr2','s_mystruct', 'num','int32');
ival = {cell(1,0)};
methodinfo = struct('name',ival, 'calltype',ival, 'LHS',ival, ...
'RHS',ival, 'alias',ival, 'thunkname',ival);
methodinfo.thunkname{1} = 'voidvoidPtrThunk';
methodinfo.name{1} = 'myfunc';
methodinfo.calltype{1} = 'Thunk';
methodinfo.LHS{1} = [];
methodinfo.RHS{1} = {'s_mystructPtr'};
methodinfo.thunkname{2} = 'voidvoidPtrThunk';
methodinfo.name{2} = 'myfunc2';
methodinfo.calltype{2} = 'Thunk';
methodinfo.LHS{2} = [];
methodinfo.RHS{2} = {'s_mystruct2Ptr'};
end
Now we can finally invoke functions exposed by the DLL:
%// load library using proto file
loadlibrary('./mylib.dll', #mylib_proto)
%// call first function with pointer to struct
s = struct('pos',[0,0,0], 'value',0);
ss = libstruct('s_mystruct',s);
calllib('mylib', 'myfunc', ss)
get(ss)
%// call second function with pointer to struct containing array of struct
xx = libstruct('s_mystruct2');
xx.arr1 = libstruct('s_mystruct');
xx.arr2 = libstruct('s_mystruct');
calllib('mylib', 'myfunc2', xx)
get(xx)
%// clear references and unload library
clear ss xx
unloadlibrary mylib
As of title.
The program will wait for the first event, and then go into an infinite loop - why doesn't it just process one event at a time?
#include <stdio.h>
#include <stdlib.h>
#include <sys/inotify.h>
#include <unistd.h>
int main (int argc, char **argv)
{
int id, wd;
int a;
struct inotify_event e;
id = inotify_init ();
wd = inotify_add_watch (id, "/home/andrea/Downloads", IN_CREATE);
puts ("waiting...");
while (read (id, &e, sizeof (struct inotify_event)))
{
printf ("created %s\n", e.name);
puts ("waiting...");
}
return 0;
}
Firstly, the events reported by inotify aren't of the size inotify_event, since there is an additional name reported as well. Use ioctl with FIONREAD to get the amount of bytes available for reading.
int avail;
ioctl(id, FIONREAD, &avail);
Secondly, you used blocking I/O. If you instead use inotify_init1(O_NONBLOCK) to initialise inotify, read() will immediately return and set errno to EAGAIN if no data is available. Of course, this is optional if you first used FIONREAD to check if there is data available in the first place.
I am writing a program that allocates huge chunks of memory using mmap and then accesses random memory locations to read and write into it.
I just tried out the following code:
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
int main() {
int fd,len=1024*1024;
fd=open("hello",O_READ);
char*addr=mmap(0,len,PROT_READ+PROT_WRITE,MAP_SHARED,fd,0);
for(fd=0;fd<len;fd++)
putchar(addr[fd]);
if (addr==MAP_FAILED) {perror("mmap"); exit(1);}
printf("mmap returned %p, which seems readable and writable\n",addr);
munmap(addr,len);
return 0;
}
But I cannot execute this program, is there anything wrong with my code?
First of all, the code won't even compile on my debian box. O_READ isn't a correct flag for open() as far as I know.
Then, you first use fd as a file descriptor and the you use it as a counter in your for loop.
I don't understand what you're trying to do, but I think you misunderstood something about mmap.
mmap is used to map a file into the memory, this way you can read / write to the created memory mapping instead of using functions to access the file.
Here's a short program that open a file, map it the the memory and print the returner pointer :
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main() {
int fd;
int result;
int len = 1024 * 1024;
fd = open("hello",O_RDWR | O_CREAT | O_TRUNC, (mode_t) 0600);
// stretch the file to the wanted length, writting something at the end is mandatory
result = lseek(fd, len - 1, SEEK_SET);
if(result == -1) { perror("lseek"); exit(1); }
result = write(fd, "", 1);
if(result == -1) { perror("write"); exit(1); }
char*addr = mmap(0, len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (addr==MAP_FAILED) { perror("mmap"); exit(1); }
printf("mmap returned %p, which seems readable and writable\n",addr);
result = munmap(addr, len);
if (result == -1) { perror("munmap"); exit(1); }
close(fd);
return 0;
}
I left out the for loop, since I didn't understood its purpose. Since you create a file and you want to map it on a given length, we have to "stretch" the file to the given length too.
Hope this helps.
How to draw a currency symbol in a custom label using CGContextShowTextAtPoint method in draw rect.
Here the symbol is in string format.
Any help!!
Thanks
You have to resort to C style strings, since this is what CGContextShowTextAtPoint() requires. In order to correctly handle the locale (the currency symbol changes with the locale) you must use setlocale(), then you format your string using strfmon() and finally you pass the string created with strfmon() to CGContextShowTextAtPoint().
Documentation is available as follows from the terminal:
man 3 setlocale
man 3 strfmon
EDIT/UPDATE: For your information, strfmon() internally uses struct lconv. The structure can be retrieved with the function localeconv(). See man 3 localeconv for a detailed description of the fields available in the structure.
for instance, try the following simple C program setting different locales
#include <stdio.h>
#include <locale.h>
#include <monetary.h>
int main(void)
{
char buf[BUFSIZ];
double val = 1234.567;
/* use your current locale */
setlocale(LC_ALL, "");
/* uncomment the next line and try this to use italian locale */
/* setlocale(LC_ALL, "it_IT"); */
strfmon(buf, sizeof buf, "You owe me %n (%i)\n", val, val);
fputs(buf, stdout);
return 0;
}
The following uses localeconv():
#include <stdio.h>
#include <limits.h>
#include <locale.h>
int main(void)
{
struct lconv l;
int i;
setlocale(LC_ALL, "");
l = *localeconv();
printf("decimal_point = [%s]\n", l.decimal_point);
printf("thousands_sep = [%s]\n", l.thousands_sep);
for (i = 0; l.grouping[i] != 0 && l.grouping[i] != CHAR_MAX; i++)
printf("grouping[%d] = [%d]\n", i, l.grouping[i]);
printf("int_curr_symbol = [%s]\n", l.int_curr_symbol);
printf("currency_symbol = [%s]\n", l.currency_symbol);
printf("mon_decimal_point = [%s]\n", l.mon_decimal_point);
printf("mon_thousands_sep = [%s]\n", l.mon_thousands_sep);
printf("positive_sign = [%s]\n", l.positive_sign);
printf("negative_sign = [%s]\n", l.negative_sign);
}
I don't really get what you're asking,
checking the documentation, the method would look something like that:
CGContextRef ctx = UIGraphicsGetCurrentContext();
const char *string = "$";
CGContextShowTextAtPoint (ctx, 160, 240, string, 1);
Haven't tested it, but this should draw $ in the center of the screen.
BTW, why not use images?
~ Natanavra.