Hello!
I want to use LabView for DAQ. My DLL works with a PCI-E driver. Inside DLL there are many function, which return messages with a printf(" text info / some stuff here ")
Certainly, If I compile my application as an .EXE, I see those messages in Windows console. If I compile application as .DLL and use LabView as user interface.
I need to use something like Array of String to display those error messages.
The error messages are different:
printf("VIRTEX5_DMAOpen: Failed allocating memory for VIRTEX5 DMA ""struct");
and etc.
By looking at this Array of Strings structures, which is automatically generated by LabView:
typedef struct {
int32 dimSize;
LStrHandle Strings[1];
} LVStringArray;
typedef LVStringArray **LVStrArrayHdl;
we see that Strings element - is an array of elemets with type LStrHandle
Looking in LabView\cintools\extcode.h we find this type defined like this:
typedef struct {
int32 cnt; /* number of bytes that follow */
uChar str[1]; /* cnt bytes */
} LStr, *LStrPtr, **LStrHandle;
LStrHandle seems to be an array of pointers to array of structures (or something else, I might be wrong, cause It's pritty tricky code and a lot of "*" make mess in my head)
So this structures chain looks like this:
LVStrArrayHdl in_array (suppose to be an array of pointers to array of structures of type LVStringArray)
|
LVStringArray (structure)
/ \
int32 dimSize LStrHandle Strings[1] (suppose to be an array of pointers to array of structures of type LStrHandle)
(contains number / \
of Strings in our int32 cnt uChar str[1]
Array) (contains number (is array of type
of characters in unsigned char,
current string) actually it is a string
If in_array is declared in function parameter list like this: _declspec(dllexport) void WhateverFunction( LVStrArrayHdl in_array );
Then to create a pointer to string I do this:
int32 *LV_StrNum = 0 //Set a number of String
LStr *LV_array; //Set a type of pointer.
NumericArrayResize(uPtr, 1L,(UHandle*)&(in_array), (*LV_StrNum)+1 ); //Resizing array
(*in_array)->Strings[*LV_StrNum] = (LStrHandle)(DSNewHandle(sizeof(int32) + StringLen*sizeof(uChar))); //Allocating Handle for current string
LV_array = *((*in_array)->Strings[*LV_StrNum]); //Assign address to a pointer
//Now we can use simply LV_array ->
LV_array->cnt = StringLen; //Set a length of current string
sprintf(LV_array->str, LocalStr); // Write from local buffer to current String
But doing in such way - requires each time increase *LV_StrNum and after that assing pointer again:
++*LV_StrNum;
LV_array = *((*in_array)->Strings[*LV_StrNum]);
Now we are on the next line.
But the problem is - to assign LV_array pointer to Strings[...] so that we
could simply switch on the next line like:
LV_array++;
and then perform:
LV_array->cnt = StringLen;
sprintf(LV_array->str, LocalStr);
I think that I need somehow to allocate memory for *LV_array with help of malloc, but did not reach a working solution yet.
There could be another possible solutions. For example, if it is possible, - running this DLL in LabView with a console in the background, and copy messages
from console to LabView. So that way I could use just ordinary "Printf" function.
But I've spent a lot of time with those arrays and want to solve problem with this pointer.
