National Instruments NI-VXI - Manual (Page 28)

Chapter 2 Introduction to the NI-VXI Functions
© National Instruments Corporation 2-9 NI-VXI User Manual
Using NI-VXI
This section presents a general overview of the more commonly used
class of functions available in NI-VXI. Additional information
summarizes how you can use the functions to perform certain tasks and
further describes the general structure of NI-VXI programming.
Header Files
Although nivxi.h is the only header file you need to include in your
program for NI-VXI, the software distribution actually includes several
additional header files along with
nivxi.h . Some of these files have
type definitions and macros that can make using NI-VXI easier, and
make the code more portable across different platforms. The three main
files of interest are
datasize.h , busacc.h , and devinfo.h .
The datasize.h File
The datasize.h file defines the integer types for use in your
program. For example, INT16 is defined as a 16-bit signed integer, and
UINT32 is defined as a 32-bit unsigned integer. Using these types
benefits you by letting you apply specific type sizes across platforms.
Using undefined types can cause problems when porting your
application between platforms. For example, an int in DOS is a 16-bit
number but a 32-bit number in Solaris or LabWindows/CVI.
In addition to the integers, datasize.h defines several types for other
uses such as interrupt handlers. For example, NIVXI_HVXIINT is an
interrupt handler type. Merely defining a variable with this type is
sufficient to create the function prototype necessary for your interrupt
handler. Also, different platforms require different flags for use with
interrupt handlers. To simplify this problem,
datasize.h defines
NIVXI_HQUAL and NIVXI_HSPEC , which are used in the handler
definition and take care of the platform dependencies. See the
Interrupts and Signals section later in this chapter and your
read me
file for more information. In addition, refer to Chapter 3, Software
Overview for specific information.