I'm currently porting a large project to Atmel Studio from ICCAVR as I need to use some of the ASF libraries for the project I'm working on.
I'm getting this error with the code example below in regards to trying to convert the following line to Atmel Studio
void debugoutf(__flash char * header, __flash char * msg);
Error pointer targeting address space '__flash' must be const in function parameter 'header'
I tried using the macro in the documentation so that it can compile in Atmel Studio.
#ifndef FLASHVAR_H_
#define FLASHVAR_H_
#include <avr/pgmspace.h>
#if defined(__ICCAVR__) // IAR C Compiler
#define FLASH_DECLARE(x) __flash x
#endif
#if defined(__GNUC__) // GNU Compiler
#define FLASH_DECLARE(x) x __attribute__((__progmem__))
#endif
IAR to AVR Conversion
void debugout(FLASH_DECLARE (char * header), char * msg);
My question is have I done the conversion correctly, as I don't think I've done it correctly as nothing is getting printed out in my UART debugging.
The problem with using __attribute__((__progmem__)) on a variable is that whenever you want to read data from such a variable, you can't just access it in the usual way that you would access a variable from RAM. Instead, you have to use special functions provided by the avr/pgmspace.h header in avr-libc, like pgm_read_byte.
That's pretty annoying, but you don't have to do it that way because why they added named address spaces like __flash to recent versions of GCC (assuming you are using C, not C++). I recommend you stop using __attribute__((__progmem__)) and use __flash instead, if your version of GCC supports it. If the compiler gives you an error or warning because it expects items stored in flash to be marked as const, you can simply add const to the declaration/definition (in the right position). If you have trouble doing that, please post a new question or edit this question so it contains a MCVE.
For the example code you gave, you should try writing:
void debugoutf(const __flash char * header, const __flash char * msg);