topic Re: MQX new keyword using C++ in MQX Software Solutions

MQX new keyword using C++

KJFPE — Wed, 23 Feb 2011 17:24:21 GMT

Hi,

Hopefully some can help I am having trouble with the new keyword using C++ below is some example code I am using MQX 3.6.2 and a Kinetis K60.

When the program reaches the line "Test *T1 = new Test;" it halts and generates an MQX_UNHANDLED_INTERRUPT(0x0041)

The same is also true for something as simple as

int *p_scalar = new int(5);

Many thanks in advance

#define START_TASK 5

extern void Start_task(uint_32);

extern "C" const TASK_TEMPLATE_STRUCT MQX_template_list[] =

{

/* Task Index, Function, Stack, Priority, Name, Attributes, Param, Time Slice */

{ START_TASK, Start_task, 1500, 5, "hello", MQX_AUTO_START_TASK, 0, 0 },

{ 0 }

};

class Test

{

public:

Test(void);

~Test(){};

void Init(void);

int xx;

};

void Start_task(uint_32 initial_data)

{

printf("Start Task\n");

Test *T1 = new Test;

T1->Init();

while(T1->xx)

{

_time_delay(200);

}

_mqx_exit(0);

}

void Test::Init(void)

{

printf("Init\n");

xx=1;

}

Test::Test(void)

{

printf("Constructor\n");

xx=0;

}

Re: MQX new keyword using C++

unmannedrussery — Thu, 19 Apr 2012 01:03:48 GMT

I struggled with this same problem for a while, and was confused at why the MQX C++ example project worked, but C++ code in my own project did not work. After consulting IAR support, it turns out that the solution is to re-direct the new() and delete() operators via the Linker Options in your project settings. Under Project>Options>Linker>Extra Options, check the "Use command line options" box, and add the folloiwing into the "Command Line Options" text box:

--redirect __iar_dlmalloc=malloc
--redirect __iar_dlcalloc=calloc
--redirect __iar_dlfree=free

This causes IAR redirects new() to __iar_dlmalloc(), and this linker option then redirects __iar_dlmalloc() to malloc(), which is redirected to the MQX _mem_alloc(). This seems like a roundabout way of doing it, but this is actually how Freescale accomplishes it in their C++ example project - take a look at the project settings and you'll find this in there.

Hope this helps!