Problem converting Matlab code to C standalone executable using Matlab Coder

3 vues (au cours des 30 derniers jours)
Hank
Hank le 3 Sep 2012
Commenté : Prachi Singh le 25 Mar 2015
Hello, I am trying to convert a very simple Matlab program (connect two input strings together) to a C standalone executable using Matlab Coder.
The m file I have is:
function r = connect(a,b) %#codegen
assert(isa(a,'char'));
assert(isa(b,'char'));
r = [a,b];
The main.c I have is:
#include <stdio.h>
#include <stdlib.h>
#include "connect.h"
#include "connect_initialize.h"
#include "connect_terminate.h"
int main(int argc, char *argv[])
{
connect_initialize();
printf("Result is %s\n", connect(argv[1],argv[2]));
connect_terminate();
return 0;
}
The error message I got is:
26 C:\C\connect\main.c(16) : warning C4047: 'function' : 'char_T' differs in levels of indirection from 'char *'
27 C:\C\connect\main.c(16) : warning C4024: 'connect' : different types for formal and actual parameter 1
28 C:\C\connect\main.c(16) : warning C4047: 'function' : 'char_T' differs in levels of indirection from 'char *'
29 C:\C\connect\main.c(16) : warning C4024: 'connect' : different types for formal and actual parameter 2
I'd really appreciate it if somebody can give me a hint. Thanks.
  3 commentaires
Afficher 1 commentaire plus ancien
Hank
Hank le 3 Sep 2012
Hi Walter, thanks for the comment. The connect.h Matlab generated automatically is:
#ifndef __CONNECT_H__
#define __CONNECT_H__
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "rtwtypes.h"
#include "connect_types.h"
extern void connect(char_T a, char_T b, char_T r[2]);
#endif
Did you mean the difference between char* and char_T? I also found this in rtwtypes.h:
typedef char char_T;
typedef char_T byte_T;
This might be the problem, but I don't think I understand C well enough to solve it. Could someone please point me the direction? Thanks.
Prachi Singh
Prachi Singh le 25 Mar 2015
I am also facing a problem while matlab to c conversion. I am working on ECG Analysis using Pan-Tompkins Algorithm I have a function defined as function [ ecg_m,qrs_amp_raw,qrs_i_raw,delay]= pan_tompkin(ecg,fs,gr) but after converting to c using matlab coder I am getting a function void pan_e(const emxArray_real_T *ecg, real_T fs, real_T gr, emxArray_real_T *ecg_m, real_T *delay)
and there is no a mention of qrs_amp_raw,qrs_i_raw which are mainly needed for further processing. Can someone suggest why this problem is occurring?

Connectez-vous pour commenter.

Connectez-vous pour répondre à cette question.

Réponse acceptée

Kaustubha Govind
Kaustubha Govind le 4 Sep 2012
Modifié(e) : Kaustubha Govind le 4 Sep 2012
I think you will find this MATLAB Coder demo useful. To be able to pass in a char buffer, I believe you also need to assert on the length:
function r = connect(a,b) %#codegen
assert(isa(a,'char'));
assert(size(a, 1) <= 1024);
assert(isa(b,'char'));
assert(size(b, 1) <= 1024);
r = [a,b];
Note that the generated prototype also expects the length of the strings to be passed in:
extern void myconnect(const char_T a_data[1024], const int32_T a_size[1], const char_T b_data[1024], const int32_T b_size[1], char_T r_data[2048], int32_T r_size[2]);
  8 commentaires
Afficher 6 commentaires plus anciens
Walter Roberson
Walter Roberson le 7 Sep 2012
Well that's a pain! No input functions at all, and the only output function is disp(). You are probably going to have to use coder.ceval()
Hank
Hank le 8 Sep 2012
Yeah, luckily disp() is sufficient for output, but it seems I will have to write some code for input conversion.

Connectez-vous pour commenter.

Plus de réponses (1)

Walter Roberson
Walter Roberson le 3 Sep 2012
That C function signature corresponds to passing a single character to "a" and a single character to "b" and (I think) passing in a pointer to an array of exactly 2 characters to write "r" into.
Note: C expects "strings" to be null terminated, and so a C string with 2 usable characters would need 3 positions, the third for the 0 that terminates it. But it is not an error to construct a character array with only exactly 2 non-zero characters, as long as you do not treat it as a string. But in that code, you do try to treat it as a string, as you want to pass the result directly to printf(). One problem with that -- the function does not return anything and instead writes into an address you pass in in the third parameter.
I do not know why the code is expecting single characters instead of character arrays -- the assert() you are using would normally be suitable for character arrays. You probably need to do something different to alert codegen that you are not working with scalars. I speculate that you will need to initialize r to an array that is the maximum size of the string you will return.
  15 commentaires
Afficher 13 commentaires plus anciens
Hank
Hank le 7 Sep 2012
Thanks again Walter. I wish I could accept two answers. Your answers helped a lot on the C side.

Connectez-vous pour commenter.

Catégories

En savoir plus sur MATLAB Coder dans Help Center et File Exchange

Tags

Produits

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by