====== ATmega ======
==== PROGMEM ====
=== Strings + Array ===

<code c>
  #include <avr/pgmspace.h>
  const char ptmpUP_msg[]      PROGMEM = "Upper Temp";
  const char ptmpDN_msg[]      PROGMEM = "Lower Temp";
  const char ptmpCLG_msg[]     PROGMEM = "Chiller Temp";
  const char* const pgtmp_msg[]  PROGMEM =
  { ptmpUP_msg, ptmpDN_msg,  ptmpCLG_msg };
</code>

oder alternativ mit flash statt PROGMEM:

<code c>
  const __flash char ptmpUP_msg[]  = "Upper Temp";
  const __flash char ptmpDN_msg[]  = "Lower Temp";
  const __flash char ptmpCLG_msg[] = "Chiller Temp";
  const __flash char* const __flash pgtmp_msg[] =
  { ptmpUP_msg, ptmpDN_msg,  ptmpCLG_msg };
</code>

<code>
  pgtmp_msg is const and located in flash.  And it contains elements that are 
  pointers to const locations in flash.
</code>

=== Functionpointer===

<code>
Your functions are of prototype "void (*)(void)", not of "void (*)()".
And the return type is "void", not "__flash void"; avr-gcc throws a
diagnostic on this.
</code>
If you want to put the array in flash, then put funcArray in flash:

<code c>
void func1 (void) {}
void func2 (void) {}
void func3 (void) {}

void (* const __flash funcArray[])(void) = { func1, func2, func3 } ;

void run (unsigned char funcNo){
   funcArray[funcNo] ();
   }
</code>


====== Quadratwurzel ======
The simplest square root algorithm is to simply subtract successive odd
numbers and count the number of subtractions:\\
(9-1=8) (8-3=5) (5-5=0)\\
Three subtractions so the sq root of nine is 3.
====== Dezimalbrüche und Brüche wandeln ======
z.B.faktor=2.12345676\\
maxima: rat(2.12345676);\\
rat' replaced 2.12345676 by 172/81 = 2.123456790123457\\
Um mit Faktor zu multiplizieren: *172/81; dividieren: *81/172

====== scanf für unsigned int ======
unsigned int getint(void)
{
  unsigned int n=0;char c;
  while (((c=getchar())>='0') && (c<='9')) n=10*n+(c-'0');
  return n;
}
====== MSP430/gcc exec code im RAM ======
int machlang[15]={
        0xe3b2, 0x0031,   //xor #-1,&0x31    (emulating INV)
        0x4130            //ret
        };

        int (*machfn)() = NULL;
        machfn= (int (*)()) machlang;
        machfn();