Returning error number as string when only Int32Ptr is accepted in Matlab

Question

Gee 2016-6-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/292002-returning-error-number-as-string-when-only-int32ptr-is-accepted-in-matlab

回答： Philip Borghesani 2016-6-24

I'm new to using dll files in Matlab and am having some trouble returning the errorNumber and the value of xMotor. The documentation for the dll is specific to C and suggests using the following to achieve what I want to:

#include “PiUsb.h”
void * pUsb1;
int ErrorNumber;
int MotorSerialNumber = 10; // Serial number from Motor
pUsb1 = piConnectMotor(&ErrorNumber,MotorSerialNum);
if (ErrorNumber == PI_DEVICE_NOT_FOUND)
AfxMessageBox( "Unable to find Motor..." );
else
AfxMessageBox( "Motor Connected." );

However, I want to be able to do this in Matlab.

I've succesffully loaded the dll into Matlab with:

fullpathToPiUSBHeader = [pwd filesep 'picardStage' filesep 'PiUsb.h']
fullpathToPiUSBDll = [pwd filesep 'picardStage' filesep 'PiUsb.dll']
fullpathToPiUSBHeader = [pwd filesep 'picardStage' filesep 'PiUsb.h']
if not(libisloaded(fullpathToPiUSBHeader))
  loadlibrary(fullpathToPiUSBDll,fullpathToPiUSBHeader)
end
libfunctions('PiUsb','-full')

And I'm returned the full list of functions, in particular this function:

[lib.pointer, int32Ptr] = piConnectMotor(int32Ptr, int32)

This is what I've got so far:

errorNumber = libpointer('int32Ptr',0);
xMotor = libpointer('voidPtr');
xMotor = calllib('PiUsb','piConnectMotor',errorNumber,xMotorSerialNumber)

I want to be able to get the errorNumber result back as well as the value for xMotor, however their values are just returned as "libpointer". Any ideas on how I can access the values/results?

Any help would be greatly appreciated!