You are here

Eliminating unused C and H files from a project. | Cypress Semiconductor

Eliminating unused C and H files from a project.

Summary: 1 Reply, Latest post by danaaknight on 16 Jan 2013 09:28 PM PST
Verified Answers: 0
Last post
Log in to post new comments.
Nick_Danger's picture
116 posts


I am using the PSoc 3 development kit and implementing a USBUART. What is the best way to eliminate the code it generates that will not be needed?

In the source tab I see files such as USBUART_audio.c, hid.c, midi.c etc.. It doesn't seem as though my project will be using any of that functionality and I need the code space.

Is it ok to simply delete the automatically generated C code and header files or is there something that should be done through the IDE?



user_14586677's picture
7646 posts

The IDE will regenerate these files automatically.


One quick way of seeing if compiler has optimized out the APIs in the files

would be to check list file for the f() calls present in the general module file.

If you identify a call you do not make look for it in the lst or map file. Note its

a bit complicated as that call may be used by an API you do use.


In the POC 3 Keil output there is a tech mapping section that shows removed



If you are squeezed for code space, here are some suggestions, but not they were

for a 8 bit machine, so some items will not save as the native machine size is 32







/* Style Definitions */
{mso-style-name:"Table Normal";
mso-padding-alt:0in 5.4pt 0in 5.4pt;
mso-fareast-font-family:"Times New Roman";
mso-bidi-font-family:"Times New Roman";

These helped me in a similar experience -


1 - If any float math minimize the number of lines you do divides, if possible convert

to multiplies. Convert float to integer math where possible. Pay attention to factoring

of expressions, possible operation reduction, hence code reduction may result.


2 - Lines with function calls, minimize f(g()) compound typed expressions.


3 - Make sure you only use a variable type no larger than needed.


4 - Use unsigned variables wherever possible.


5 - Watchout for structures with mixed const and ram pointers within them,

some compilers choke on this.


6 - If you are heavy on Flash, light on RAM use, convert routines to RAM based

wherever possible.


7 - Try test cases of looping structures, to see what affects code size generation.


8 - Examine .lst file for code that looks wacky in bytes used, understand what

compiler did, and consider rewrite.


9 - Use inline ASM where .lst file C generation looks excessive.


10 - Look at module reuse, sharing, dual purpose, to eliminate # modules 

needed, like counters/timers....Also look at data sheets of modules that could

serve function needed, and compare ROM/RAM requirements needed. Optimize

global HW, like clocks VC1/2/3/Sleep, to eliminate need for other timer/counters.

Use register routing control to "share" module from one task to another, one pin

to another.


11 - Extended library, functions within them are written to be perfectly general,

hence larger code size, you may be able to write one with less code needed for

your specific requirements that result in smaller code size.


12 – Look for approximations to compute transcendental functions if used.


13 - Although no longer supported by HiTech or Cypress, the HiTech Pro compiler

yielded on first try ~ 40% code reduction in my design when I first converted

to it. Then the prior comments yielded another 4 K later in design as I was up

against 32 K Flash limitation.


14 - Some compilers have a setting to optimize code size or speed, the latter

prone to larger code size. Also look at compiler vendors web site for ap notes

and suggestions on optimization, compilers from different vendors behave and

optimize  differently.


15 - const data, strings, etc.., look for ability to reuse common string mnemonics,



16 - Pointer usage can lessen code size, see url's below. Look for function calls

passing longs as value vs pointer, convert to latter. Compiler has to copy all these,

if not referenced. Do not pass longs or floats as values, keep always in mind native machine size.


17 - Most compilers will optimize when indexes, pointers, a power of 2, or divides,

divide becomes a shift.


18 - Look at how linker distributed code and data segments, sometimes you can discover

a poor decision by linker and force code/data into certain psects using pragma constructs,

thereby minimizing wasted ROM space.


19 – When you debug generally you want to turn off optimization, as compiler/linker will

remove code and make jumps that do not make “sense” but are the result of optimization.

When you are up to Flash boundary you may not be able to turn it off, otherwise

application will not load. Keep this in mind, that  your debug strategy may have to change.

I also found if using ICE Cube that debugger may no longer report “watch” variables, this

occurred at ~ 31.5K bytes. In either case you may want to comment out large code sections

to effectively debug.


20 – f() calls take overhead, if you only call a f() once you might eliminate it as a f() call and

place code inline.


21 – Look for f() opportunities, wherever you are coding and repeating similar  operations.

This is obvious, but sometimes missed.


22 – Check compiler on macros, to see if they are being optimized or just being used inline

using more code space vs a f() call solution.


23 – Examine compiler/linker parameter control. For example in HiTech there is the AUTOBANK

setting that controls where local variables are stored, in my case setting to 1 lowered code size by

~ 250 bytes. READ the MANUAL !


24 – Use inline variable declarations, vs pre declaration (compiler dependent) -


                This                        void dosomething ( void  ) {


                                                                for (  unsigned char I = 0;…..



                Not This               void dosomething ( void  ) {


                                                Unsigned char I = 0;


                                                                for (  I = 0;…..



Some help -








By using these techniques I was able to regain ~ 4K Bytes of code space in a 32K design, which

I promptly then used up again :(






Regards, Dana.

Log in to post new comments.