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AN720

PRECISION32 OPTIMIZATIONCONSIDERATIONS FOR CODESIZE ANDSPEED

Silicon Laboratories 

AN720

5. Precision32 IDE (redlib and newlib)

This section discusses ways to optimize projects using the Precision32 IDE and both redlib and newlib libraries.

The Precision32 GCC tools used for the code size and execution speed testing discussed in this document are

ARM/embedded-4_6-branch revision 182083 (http://gcc.gnu.org/svn/gcc/branches/ARM/embedded-4_6-branch/)

with newlib v1.19 and Redlib v2 (Precision32 IDE v4.2.1 [Build 73]).

5.1. Reading the Map File

The first step in the code size optimization process is to analyze the project map file and determine what portions of

code take the most space.

The map file is an output of the linker that shows the size of each function and variable and their positions in

memory. This map file is located in the build files for a project.

In addition to the functions, the map file includes information on variables and other symbols, including unused

functions that are removed.

For a Precision32 IDE Debug build, the map file is located in the project’s Debug directory. Figure 1 shows an

excerpt of the sim3u1xx_Blinky redlib Debug example map file.

For each function in the project, the map file lists the starting address and the length. For example, the

my_rtc_alarm0_handler function starts at address 0x0000_04D4 and occupies 0x70 bytes of memory.

Figure 1. sim3u1xx_Blinky Precision32 Debug Map File Example

5.2. Determining a Project’s Code Size

Each project’s library and function usage is different. Analyzing the project’s makeup can help determine the most

effective way to reduce code space.

All Precision32 SDK projects automatically output the code and RAM size after a build. To modify this output in the

Precision32 IDE:

1. Right-click on the project_name in the Project Explorer view.

2. Select Properties.

3. In the C/C++ BuildSettingsBuild Steps tab, remove or add the following in the Post-build

stepsCommand box: arm-none-eabi-size "${BuildArtifactFileName}"

After building the si32HAL 1.0.1 sim3u1xx_Blinky example, the IDE outputs:

text data bss dec hex

13312

4 344 13660 355c

Rev. 0.1

3

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