Table of Contents
Overview
This application illustrates how to hook different libraries at run time with common interface APIs, but differing in their implementation. On systems with limited RAM, this feature can be important if the application intends to load a library into memory at run-time based on some conditions.
Application Details
This is a basic application where two different library having the same interface APIs are being loaded one by one, followed by their invocation in the same order. The libraries differ in their implementations, thus giving different output when called with the same arguments.
Program Flow
- Determine a predefined function-pointer table to interface with different libraries. All libraries are expected to have the same interface.
- Identify a region in the memory for paging. The predefined function-pointer table shall be put at the beginning of this region.
- Before invoking any library function(s), the loader application loads the contents of the library from serial flash into the defined region in SRAM.
- Use the function-pointer table to access the library function(s).
The memory addresses shown in above diagram are for reference only. Developers should define the sections based on their application’s needs. The workspace for this application consists of three projects (for IAR) or three configurations (for CCS):
- app1 is the first library with four routines
- app2 is the second library also with four routines
- loader loads the above libraries from non-volatile memory to SRAM at run time and then invokes their routines
Usage
- Flash application binaries to the CC3200 serial flash.
- Start UniFlash for CC3100/CC3200. Open UCF session file at cc3200_sdk/example/dynamic_link_loader/uniflash_template.ucf
- Set SOP jumper to SOP-2 position for flashing.
- Select Program.
- Run the reference application.
- Remove the SOP jumper and reset the LaunchPad to start the application or
- Open the project in CCS/IAR. Build the application and debug to load to the device.
