Difference between revisions of "Overlay generator"

Revision as of 05:07, 15 November 2009

List of support files

• function_sizes.nm: Required by overlay_generator, generated from object files using the command line:

nm --size-sort *.o > function_sizes.nm

• region_sizes_file.dat: Used by script to describe what sizes of scratchpad memory to use, the contents are three space delimited numbers given in bytes: start_size stop_size step_size
• root_node.configure_overlay_generator: Used by script to describe the root function for the project folder
• object_filename.cfg: Needed by overlay generator to determine GCCFG of project code, one file is generated for each object file by gcc when the -fdump-tree-cfg switch is given in CFLAGS

List of files generated by overlay_generator

• common_ancestors.common: Generated by overlay_generator to record common ancestor information so that it need not be recalculated later
• included_functions.funcs: List of functions included in overlay, generated by overlay_generator
• graph_[1-8].dot and graph_[1-8].ps: dotty and postscript representations of GCCFG at various stages of construction, graphs following graph_4 each represent an overlay algorithm

Makefile settings

• Auto overlay Makefile:

MY_CFLAGS += -fdump-tree-cfg -ffunction-sections -Wl,--auto-overlay -Wl,--auto-overlay=linker.script (note that the cfg switch is not required here)

LDFLAGS += -Wl,-Map,spu.map -Wl,--auto-overlay -Wl,--gc-sections (-Map,spu.map switch is not required, -gc-sections is used to dump unused .bss .txt and .data sections in spu.map)

• Makefile with linker.script.ed

LDFLAGS= -Wl,-T,linker.script -Wl,-Map,spu.map -Wl,--gc-sections (-gc-sections is used to dump unused .bss .txt and .data sections in spu.map)

Add timing code to project

• timing.h: Add [www.esoterum.com/temp/timing.h timing.h] to main source file
• Add code to start and stop timer, i.e. at start and end of main(). STOP_TIMER will also print the elapsed time.

Start timer:

/***** add timing statements ************/

START_TIMER

/****************************************/

Stop timer:

/*MAB 10 NOV 09 : add timing statements */

STOP_TIMER

/****************************************/

Auto configuration script for auto overlay

• compile_config.sh: Auto configuration script for auto overlay, recompiles project to create automatically generated </code>linker.script</code> files based on size constraints given in the script. The size constraints ("OPTIONS" in the script) describe the size of a buffer that will be added to the code to artificially restrict the size of the local store. A smaller number means more space will be available in the local store.
• compile_config.sh requires the following declaration and assigment to be added to a global section such as the file containing "main" in the project:

Declaration: place above main()'

/*************************************************************************************/

/****************** BUFFER TO WASTE SPACE TRYING TO GET LINKER SCRIPT TO WORK ********/

int waste_of_space_index;

#define WASTE_OF_SPACE_SIZE 0

unsigned char waste_of_space[WASTE_OF_SPACE_SIZE];

/*************************************************************************************/

/*************************************************************************************/

Assignment (ensures the data section isn't dropped by --gc-sections): place within main()

/*************************************************************************************/

/****************** BUFFER TO WASTE SPACE TRYING TO GET LINKER SCRIPT TO WORK ********/

for(waste_of_space_index=0;waste_of_space_index<WASTE_OF_SPACE_SIZE;waste_of_space_index++){

waste_of_space[waste_of_space_index]=waste_of_space_index;

}

/*************************************************************************************/

/*************************************************************************************/