How can I define a variable in a bus as pointer ?

Hello,

I'm in some trouble with my variable definition. I have a structure that I would like to define with the Bus Editor. My structure is like :

 typedef struct
{
    uint16 a1;
    uint16 *a2;

    uint32 b1;
    uint32 b2;

} structstruct;

I don't know how to define the a2 variable who is a pointer.

Could someone help me ?

Antoine

Answer 1

[Mark McBroom]

Hi Antoine,

The idea is to use a data type that Simulink supports in place of the pointer. Since pointers are 64 bits long, use a Simulink data type that is 64 bits long. Then, in the external C code, convert the datatype used by Simulink to/form a unit16*. The best approach is to use a 64-bit integer in Simulink, since most C compilers will allow you to cast an integer to a pointer. But this requires the Fixed Point Toolbox. If you have a license for this, the set the data type of the variable to be ufix(64). If you don't have a Fixed Point license, then you can select a built-in Simulink data type that is 64 bits long, for example double or uint32[2]. C compilers won't let you cast these variables to/from a pointer, so you will need to create a temporary variable in your external code that is of type uint16* and then memcpy between the variable in the Simulink bus and the local uint16* variable.

Answer 2

[Mark McBroom]

This is not possible in Simulink. Simulink does not support pointers. So that raises the question, why do you need a pointer in the structure? This question most often comes up when people are interfacing with external C code. If this is the case, there are some tricks you can play in Simulink that usually involve defining the type to instead by a 64-bit integer using the fixed point blockset.

[Antoine Bostem]

Hi Mark,

Indeed, this is my case. I would like to include C code in an S-function. Could you explain me your tricks or give me a reference link ? Thank you

[bilal erol]

have you solved your problem which is related with using pointer in simulink?