Juniper Systems LandMark CE - Manual (Page 70)

70 LandMark CE User’s Manual
Programming LandMark CE
LandMark CE is designed to be used as a GPS utility for third party
applications. This chapter explains details about how LandMark CE
and third party applications work together. This chapter is intended
to give programming tips on interfacing with LandMark CE.
The Memory Exchange fi le is used to exchange information between
LandMark CE and a third party application program. There are
three methods to obtain information from Memory Exchange. These
methods are divided into two categories: data pushed by LandMark
CE (real time), or data pulled from LandMark CE by a third party
application. The following is a list and description of each category.
Using the Memory Exchange Mechanism
The memory exchange module can be accessed by third party
applications by using the lmce.dll provided with the software
package. It supports C++ projects only.
Static link the library using the fi les lmce.h and lmce.lib in the third
party application project. This is the recommended method of using
the DLL module.
The alternative method is to dynamically link to the library at run
time. If you are planning on using this method, please make sure to
use LoadLibrary at the beginning of application installation and free it
when the application closes. This methodology is needed because the
module contains state variables that should only be initialized once.
The DLL can be used by one third party application at a time.
Internal GPS — Pulled Data
The third party application calls the following function when it
needs new GPS data. The function returns with the most current GPS
data LandMark CE has copied to shared memory, or provides the
information after a three second delay.
The internal GPS function provides GPS data in WGS84 datum,
decimal degrees, and altitude/elevation in meters. This is the
recommended internal format of most GPS receivers as the most
accurate GPS data.
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