Optimize C++ for a microcontroller

Hello,

I am trying to optimize C++ code for an 16 Bit Microcontroller from
renesas, does someone have any idea, how can I approach this Problem.
for any help i will be very grateful

best regards

"deel007@googlemail.com" <deel007@googlemail.com> writes:
> I am trying to optimize C++ code for an 16 Bit Microcontroller from
> renesas, does someone have any idea, how can I approach this Problem.

It would help if you gave us more information, like which Renesas
microcontroller you're using, which C++ compiler you're using, and
what kinds of optimizations you're expecting.

On 2008-03-17, deel007@googlemail.com <deel007@googlemail.com> wrote:

> I am trying to optimize C++ code for an 16 Bit Microcontroller
> from renesas, does someone have any idea, how can I approach
> this Problem. for any help i will be very grateful

 1) Measure the performance/size/whatever of various functions
    or modules.

 2) Using the results of 1), figure out which functions/modules
    are the biggest resource hogs.

 3) Fix them. 

-- 
Grant Edwards                   grante             Yow!  Here I am at the flea
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On Mar 17, 7:53 pm, Grant Edwards <gra...@visi.com> wrote:

>  1) Measure the performance/size/whatever of various functions
>  2) Using the results of 1), figure out which functions/modules
>  3) Fix them.

In summary: Lather. Rinse. Repeat.

Grant Edwards wrote:
> On 2008-03-17, deel007@googlemail.com <deel007@googlemail.com> wrote:
> 
>> I am trying to optimize C++ code for an 16 Bit Microcontroller
>> from renesas, does someone have any idea, how can I approach
>> this Problem. for any help i will be very grateful
> 
>  1) Measure the performance/size/whatever of various functions
>     or modules.
> 
>  2) Using the results of 1), figure out which functions/modules
>     are the biggest resource hogs.
> 
>  3) Fix them. 
> 
1a) compile to assembly and look at the assembly.  This will help you 
understand what the compiler is doing.  I would do this with any new 
serious* language I was learning.

2a) The C++ libraries are phenomenally capable -- and phenomenally big. 
  Avoid them unless you have phenomenal resources.  Being aware of what 
features of C++ (like 'new', and 'try') will cause you to pull in large 
swaths of library (or screw the RTOS) is a good thing, so that you can 
make intelligent decisions about what resources you _want_ pulled in.

* Don't take me to task about the chances of doing this with Java or 
Basic -- I'm being purposely chauvinistic against interpreted languages.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

deel007@googlemail.com wrote:
> Hello,
> 
> I am trying to optimize C++ code for an 16 Bit Microcontroller from
> renesas, does someone have any idea, how can I approach this Problem.

If you have to optimize the C++ code, then something is apparently 
wrong. Either the task is wrong for this microcontroller, or you are 
wrong for this task.


> for any help i will be very grateful

And how much exactly is "very grateful" ?

VLV

Op Tue, 18 Mar 2008 06:06:36 +0100 schreef Tim Wescott  
<tim@seemywebsite.com>:
> Grant Edwards wrote:
>> On 2008-03-17, deel007@googlemail.com <deel007@googlemail.com> wrote:
>>
>>> I am trying to optimize C++ code for an 16 Bit Microcontroller
>>> from renesas, does someone have any idea, how can I approach
>>> this Problem. for any help i will be very grateful
>>   1) Measure the performance/size/whatever of various functions
>>     or modules.

> 1a) compile to assembly and look at the assembly.  This will help you  
> understand what the compiler is doing.  I would do this with any new  
> serious* language I was learning.
>
> * Don't take me to task about the chances of doing this with Java or  
> Basic -- I'm being purposely chauvinistic against interpreted languages.

Java is not an interpreted language.  Granted, most JVM's choose to  
interpret a large portion of the bytecode.  But indeed looking at the  
output of either compiler (src & JIT) will most likely not be worth your  
time.



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Boudewijn Dijkstra wrote:
>
>schreef Tim Wescott:
>
>> Grant Edwards wrote:

>>>deel007@googlemail.com wrote:
>>>
>>>> I am trying to optimize C++ code for an 16 Bit Microcontroller
>>>> from renesas, does someone have any idea, how can I approach
>>>> this Problem. for any help i will be very grateful
>>>
>>>   1) Measure the performance/size/whatever of various functions
>>>     or modules.
>
>> 1a) compile to assembly and look at the assembly.  This will help you  
>> understand what the compiler is doing.  I would do this with any new  
>> serious* language I was learning.
>>
>> * Don't take me to task about the chances of doing this with Java or  
>> Basic -- I'm being purposely chauvinistic against interpreted languages.
>
>Java is not an interpreted language.  Granted, most JVM's choose to  
>interpret a large portion of the bytecode.  But indeed looking at the  
>output of either compiler (src & JIT) will most likely not be worth your  
>time.

BASIC also has both compilers and interpeters.  FreeBASIC 
uses AS/GAS (the Gnu assembler) to create executable code, 
and is on track to becoming a front end for GCC.

That being said, I have never heard of anything other than 
Assembly Language, C and Forth ( cir30 / ciforth ) being 
used with the Renesas 16-bitters.

I am not a big fan of C++ for microcontrollers, but some 
folks seem to like it.   C seems to be a better choice to
me, but this may say more about my limitations than it 
does about C or C++. :)


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Guy Macon <http://www.guymacon.com/> writes:
> That being said, I have never heard of anything other than Assembly
> Language, C and Forth ( cir30 / ciforth ) being used with the
> Renesas 16-bitters.

The Renesas m32c line uses gcc, so any of the gcc front-ends would
work.  C, C++, FORTRAN, ObjC, etc.  Assuming someone takes the time to
port the runtime bits.  I know C and C++ are there; I think someone
had FORTRAN working at one point, or at least tried.

DJ Delorie schrieb:
> Guy Macon <http://www.guymacon.com/> writes:
>> That being said, I have never heard of anything other than Assembly
>> Language, C and Forth ( cir30 / ciforth ) being used with the
>> Renesas 16-bitters.
> 
> The Renesas m32c line uses gcc, so any of the gcc front-ends would
> work.  C, C++, FORTRAN, ObjC, etc.  Assuming someone takes the time to
> port the runtime bits.  I know C and C++ are there; I think someone
> had FORTRAN working at one point, or at least tried.
The IAR compiler for the Renesas M16C is able to compile C as well as 
C++. But I did not use C++ on this platform, so I cannot judge the quality.
Greetings
  -- Dirk