[avr-gcc-list] How to port "char flash *" used with IAR to avr-gcc?

[Günter Dannoritzer]

Hi,

I have some code that was developed under IAR. Now I want to port it to 
avr-gcc and have some trouble getting a print function to work.

This is the function, used under IAR:

        void PrintStr( char flash *str )
        {
                unsigned char count=0;

                while ((str[count] != '\0') && (count != 64)) {
                UartTransmitByte(str[count++]);
                }
        }


It prints out the given string to the serial port.

To compile it with avr-gcc I changed function parameter type to:

        void PrintStr( char * str)

leaving the remaining code in the function body the same.

It does not print out any text over the serial port.

I searched for some information of the "flash" type and in the Atmel 
application note #35 it explains that this is a pointer to a flash location.

The way I changed that now is, that I made it a pointer to a RAM location.

From the explanation in the Atmel application note it seems like that 
after reset the whole code gets copied from the flash to the RAM. So if 
I have a PrintStr("Hello World") function call, the "Hello World" string 
should get copied to the RAM as well or am I missing here something?

Reading through the libc documentation concerning reading data from the 
flash, I guess the other way to do this with avr-gcc would be to use the 
PGM_P and pgm_read_byte function to leave the string in the flash. Would 
that be the equivalent to the IAR flash pointer?

Can anybody give me a hint how to fix this?

Thanks for the help.

Guenter