Dynamically sized IO ports in simulink

8 次查看(过去 30 天)
Hi,
I am working on a C-MEX s-function, which has 2 inputs and 1 output. All of the i/o ports are dynamically sized. The output port should always have the same size with the second input port.
Here are some fragments of my code.
/* ... */
static void mdlInitializeSizes(SimStruct *S)
{
... // Set two input and one output ports to dynamically sized
}
#if defined(MATLAB_MEX_FILE)
#define MDL_SET_INPUT_PORT_WIDTH
static void mdlSetInputPortWidth(SimStruct *S, int_T port, int_T inputPortWidth)
{
ssSetInputPortWidth(S, port, inputPortWidth);
/* This is very likely wrong */
if (1 == port) {
ssSetOutputPortWidth(S, port, inputPortWidth);
}
}
#define MDL_SET_OUTPUT_PORT_WIDTH
static void mdlSetOutputPortWidth(/* ... */)
{
/* I don't know how to set here */
}
static void mdlSetDefaultPortDimensionInfo(SimStruct *S)
{
ssSetInputPortWidth(S, 0, 10);
ssSetInputPortWidth(S, 1, 3);
ssSetOutputPortWidth(S, 0, 3);
}
#endif
/* ... */
It could be compiled with no error, but everytime I run the test simulink model with this s-function in it, MATLAB crashes.
Could someone tell me how to solve this, please?
Thanks in advance.
Ben

采纳的回答

MarkB
MarkB 2011-4-14
The code above is mostly right, but there are some minor changes that you will need to make:
  • The calls to "mdlSetOutputPortWidth" and "mdlSetInputPortWidth" can occur for any port that was originally set as dynamically typed, even if was assigned a dimension later on. As a result, you should confirm that the output port is still dynamically typed before you assign the output port dimension in "mdlSetInputPortWidth". If it's still dynamically typed, assign it. If it isn't check to see if the output port dimensions match what you would have assigned. If not, throw an error.
  • The "mdlSetOutputPortWidth" should be a mirror-image/reverse of your "mdlSetInputPortWidth" function. People often mistakenly assume that dimensions only propagate "downstream", but it is entirely possible that your block's output port dimension gets assigned first. In this case, you should assign that dimension to the second input port as well.
  • "mdlSetDefaultPortDimensionInfo" gets called if any of the ports are still dynamically typed, so it is incorrect to assume that it means that all of the ports are still unspecified. Therefore, instead of just assigning dimensions to all of the ports, you should check each one to confirm that it is still dynamically typed, and only assign dimensions in that case.
  1 个评论
Benjamin Wang
Benjamin Wang 2011-4-14
Thank you Mark. The information you posted is very helpful. I've changed my code according to your suggestion.
The reason why my code got crashed was that I accidently initialized an 'int_T' type pointer with the return value of ssGetInputPortSignal, which actually is a 'real_T' type pointer. Then I used it to index some array and got pointer overflow. Did not see this until just now...

请先登录,再进行评论。

更多回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Block and Blockset Authoring 的更多信息

Community Treasure Hunt

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

Start Hunting!

Translated by