Hi all,
I am trying to revive my AVR hobby again, this time using the avr-libc,
mainly to introduce my kids to low-level programming. I am using a
couple of Arduino boards with the ATmega328P.
I started with a simple "hello world" program that outputs a
NUL-terminated string to the UART:
static void msg(const char* PROGMEM msg)
{
char c;
while ((c = pgm_read_byte_postinc (&msg))) {
UDR0 = c;
loop_until_bit_is_set(UCSR0A, UDRE0);
}
}
For optimal AVR implementation, this would require some inline assembly:
static char pgm_read_byte_postinc (const char** PROGMEM s)
{
#ifdef __AVR_HAVE_LPMX__
char c;
asm volatile ("lpm %0, %a1+" "\n\t" : "=r" (c), "+z" (*s));
return c;
#else
return pgm_read_byte((*s)++);
#endif
}
I would like to have pre/post-increment/decrement variants of all
pgm_read_* functions in <avr/pgmspace.h> that are natively supported on
some AVR platform. I wonder what would be the practical way to achieve
this. Contribute a patch myself? I hereby contribute the above idea to
the public domain.
Best regards,
Marko
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