5 Replies Latest reply on Sep 25, 2012 9:58 AM by bruno.da.silva.pereira

    memory size

    bruno.da.silva.pereira

      Hi all

         

      I have a problem in my code size of the program. I'm using a CY8C29466-24PXI with 32k flash, but am finding that I do not use all that space. In reality, the configuration files are taking up too much space. Had any suggestions to better utilize the space with just the program code. sorry for bad english
      thank you

       

        • 1. Re: memory size
          user_1377889

          How long are you programming in assembly to use up 32k ? Or are you just afraid that you will run short of flash?

             

           

             

          Bob

          • 2. Re: memory size
            user_14586677

            If you are running out of code space the following suggestions might help -

               

             

               

            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,
            text.

               

            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 -

               

            [url]http://www.codeproject.com/Articles/6154/Writing-Efficient-C-and-C-Code-Optimization[/url]

               

            [url]http://www.eventhelix.com/realtimemantra/basics/optimizingcandcppcode.htm[/url]

               

            [url]http://www.azillionmonkeys.com/qed/optimize.html[/url]

               

            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.

            • 3. Re: memory size
              bruno.da.silva.pereira

              Dana thank you per aswer, but  in that program use assembly. 

                 

              Obrigado

                 

              Fique com Deus

              • 4. Re: memory size
                ki.leung

                do you mean that you ALREADY WROTE the program and you have problem because the size is over 32k?

                   

                or

                   

                You think the usage of the setup code is too hight AND that you want to reduce that part of the code, so you have more area for your program?

                • 5. Re: memory size
                  bruno.da.silva.pereira

                  thank you everybody,

                     

                  already managed to solve

                     

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