Am 20.08.2012 22:53, schrieb Robert Henig:
> Apologies if this is no the right list to ask this question.  Please
> redirect me if it is.

i think this is a good place :-)

> I have an existing product that implements a bootloader compiled with
> the IAR workbench version 5.  To save space we implement the I2C
> driver once in the bootloader and then call if from the main firmware
> code based on known function addresses.  I would like to write all
> new firmware using mspgcc.

:-)

 > The firmware it upgradable but the bootloader is not.

I am not suggesting that you should do that, but you probably could 
upgrade the bootloader with an application that reflashes the boot 
loader (unless you have a F5x and use the hardware protection).

if there is no space in a regular application an dummy app only to 
reprogram the bootloader could be used. and in a second step the regular 
application is downloaded.

sure that has the risk of failure and really bricking the device on the 
users perspective (you may have JTAG or BSL access to recover).

 > Does anyone know if the calling conversion of the
> two versions is the same or what the differences are?

different.

mspgcc used to use R15 down to R12. so up to 4 parameters can be passed 
in registers. IAR used R12:R13 and R14:R15 as pairs for up to two 
parameters (i've not checked if that changed in more recent versions of 
the compilers). Further parameters go on the stack in both compilers.

You probably need to write a small wrapper function (in your firmware) 
that moves the registers forth and back. Personally i'd do these in 
assembler (or inline assembler and "naked" function attribute in 
mspgcc). To get a start on these you could use the other compiler to 
compile a sample function call using all parameters and look at the 
listing file or disassembly.

chris

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