Hi,
I am using the ez430. I cant help noticing that precious bytes are
being lost on _exit __exit functions and startup code. Does anyone have
any lean startup and exit function they would be willing to share,
along with caveats?

With only 2kbytes to work with everything counts!

Thanks, Vincent Start a New Thread

You can write your own startup and exit in assembly. You can write the
entire program in assembly too.

--- In m..., "vincbr900" wrote:
>
> Hi,
> I am using the ez430. I cant help noticing that precious bytes are
> being lost on _exit __exit functions and startup code. Does anyone have
> any lean startup and exit function they would be willing to share,
> along with caveats?
>
> With only 2kbytes to work with everything counts!
>
> Thanks, Vincent
> Start a New Thread

Out of curiosity, how many precious bytes are being "lost?"

I would be surprised if this is your best first pass at optimizing
flash memory, but I assume that you've already exhausted the
low-hanging fruit (i.e. turned-on the optimizers, using a different
(or none) standard library, etc.)

Which compiler are you using?

Stuart

--- In m..., "vincbr900" wrote:
>
> Hi,
> I am using the ez430. I cant help noticing that precious bytes are
> being lost on _exit __exit functions and startup code. Does anyone have
> any lean startup and exit function they would be willing to share,
> along with caveats?
>
> With only 2kbytes to work with everything counts!
>
> Thanks, Vincent
> Start a New Thread

--- In m..., "Stuart_Rubin"
wrote:
> Out of curiosity, how many precious bytes are being "lost?"
>
> I would be surprised if this is your best first pass at optimizing
> flash memory, but I assume that you've already exhausted the
> low-hanging fruit (i.e. turned-on the optimizers, using a different
> (or none) standard library, etc.)
>
> Which compiler are you using?

Hi, thanks for your replies on this guys.

I am using the IAR Embedded workbench with the EZ430 which targets
F2012/3. The Compile is Version 5.11 of the 4kb kickstart from the TI
website. Optimisation is full and DLIB is used, but it was the
startup and exit code I wanted to lean off as they are not
optimisable as are hard coded assembly. I am not familiar with MSP430
assembly and the startup/exit files are confusing with a lot of
compiler directives, hence the request for help. I think they have a
lot of flexibility for features which I would not use on such a small
target, such as initialising variables, copying data constants into
RAM etc.
A module map for the 'flashing the LED' project in C is below. As you
can see, 40 bytes are used for entry/exit code, which is almost 2% of
the total available.

Thanks, Vincent

****************************************
* *
* MODULE SUMMARY *
* *
****************************************

Module CODE DATA
------ ---- ----
(Rel) (Rel) (Abs)
?__dbg_break 2
?__exit 20
?_exit 4
?cstart 12
?exit 4
?reset_vector 2
msp430x2xx_fet_1 34 4
N/A (command line) 50
------ -- -- -
Total: 78 50 4 Start a New Thread

vincbr900 wrote:
> --- In m... ,
> "Stuart_Rubin"
> wrote:
> > Out of curiosity, how many precious bytes are being "lost?"
> >
> > I would be surprised if this is your best first pass at optimizing
> > flash memory, but I assume that you've already exhausted the
> > low-hanging fruit (i.e. turned-on the optimizers, using a different
> > (or none) standard library, etc.)
> >
> > Which compiler are you using?
>
> Hi, thanks for your replies on this guys.
>
> I am using the IAR Embedded workbench with the EZ430 which targets
> F2012/3. The Compile is Version 5.11 of the 4kb kickstart from the TI
> website. Optimisation is full and DLIB is used, but it was the
> startup and exit code I wanted to lean off as they are not
> optimisable as are hard coded assembly. I am not familiar with MSP430
> assembly and the startup/exit files are confusing with a lot of
> compiler directives, hence the request for help. I think they have a
> lot of flexibility for features which I would not use on such a small
> target, such as initialising variables, copying data constants into
> RAM etc.

Have you taken a look of what actually is included in your project?

The CStartup-file is designed so that the parts of that you don't need
are excluded by the linker, for example dynamic initialization of C++
objects.

For example, an "empty main" project will only contain an initialization
of SP, a call to main, a call to "exit" and the exit functions. All on
all 26 bytes...
> A module map for the 'flashing the LED' project in C is below. As you
> can see, 40 bytes are used for entry/exit code, which is almost 2% of
> the total available.

This is partly due to the fact that you're linking your application in
debug mode (indicated by the ?__dbg_break symbol). If you rebuild it in
release mode some of the bytes will disappear.

If you still aren't satisfied you can customize the startup code any way
you want.

-- Anders Lindgren, IAR Systems
--
Disclaimer: Opinions expressed in this posting are strictly my own and
not necessarily those of my employer. Start a New Thread

One thing you can do is to declare your variables __no_init. Then
there is no need for the __low_level_init routine to be implemented by
cstartup. Of course you then have to initialize your variables (if
needed) yourself!

Another small improvement I often use is to make a local copy of
cstartup.s43 ,change it and add it to your project files, so the
changed version is compiled and linked to your project.
I use the following changes:

cstartup.s43:
...
XRSEGCSTART
PUBLIC ?cstart_call_main

EXTERN main
// EXTERN exit

?cstart_call_main:
// XCALL #main
// XCALL #exit
XBR #main
...

I don't need exit-code since I always have a endless-loop at the end
of main(). Furthermore I don't call main, instead I branch to main,
that saves me 2 bytes on the stack.

Every byte counts... ;-) Start a New Thread

Stefan Excellent, this is what I was looking for.

The module is now:-
****************************************
* *
* MODULE SUMMARY *
* *
****************************************

Module CODE DATA
------ ---- ----
(Rel) (Rel) (Abs)
?cstart 8
?reset_vector 2
msp430x2xx_fet_1 34 4
N/A (command line) 50
------ -- -- -
Total: 44 50 4

Thanks all for your help! Start a New Thread