OpenEuphoria

1. Newbie - help with pointers

• Posted by Kenley Lim <yin95 at HOTMAIL.COM> Jul 08, 1999
• 632 views

Dear members

I just started subscribing and was wondering if anyone could help me with a
beginner's question.
I just started working with euphoria and I'm using it to interact with an
Advantech lab card.  I'm using this lab card to read in digital input.  I'm
using the dll's to link the card's functions so that I can access them in
Euphoria.  In the function DRV_DeviceOpen, a pointer for one of the input
parameters(DRIVERHANDLE) is required.
DRIVERHANDLE is a pointer to the configuration data for the lab card.
In the next function, DRV_DioReadBit, the input parameters ask for
DRIVERHANDLE again, which was assigned in DRV_DeviceOpen.

I have no idea if I am declaring the functions correctly.  I think my main
problem is with pointers.  How do I substitute C language pointers into
Euphoria if Euphoria doesn't use pointers?
I've been getting errors when I put the DRIVERHANDLE pointer variable into
DRV_DioReadBit.
I'm not sure if I explained my problem clearly enough.  If there is any more
info that you need, I'll try to supply it.  Some of the program's code is
shown below.
HELP!



--opening DLL and linking driver functions to Euphoria


global atom ad32
atom OpenBoard, Digin   --Function IDs

--link to the DLL
ad32 = linkDLL("ADAPI32.dll")

OpenBoard = define_c_func(ad32, "DRV_DeviceOpen",          --First function
being linked
--!!!!!!!!!here is where the functions requires a pointer!!!!!!!!!
                               {C_INT, C_POINTER}, C_INT)
if OpenBoard = -1 then
puts(1, "OpenBoard cannot be found!\n")
end if



Digin = define_c_func(ad32, "DRV_DioReadBit",              --Third function
being linked
!!!!!!!!here is where the function requires the pointer that was used in
DRV_OpenDevice!!!!!!!!!!!!
                           {C_POINTER, C_INT}, C_INT)

if Digin = -1 then
puts(1, "Digin cannot be found!\n")
end if

-------------------------------------------------------------------------

atom error_result, status
atom DriverHandle
DriverHandle = allocate(8)
printf(1, "This is the address of the block of memory allocated to
DriverHandle %d\n",
           {DriverHandle})

--Using the OpenBoard function


error_result= c_func(OpenBoard, {000, DriverHandle})
printf(1, "The value of error_result is %d\n", {error_result})


poke(DriverHandle, atom_to_float64(64)) -- fill the buffer
puts(1, "hello\n")


--Using the Digin function

status = c_func(Digin, {DriverHandle, 8})
printf(1, "The value of status is %d\n", {status})


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