andreas@d700 comp $ avr-gcc -v                       
Reading specs from /usr/local/avr/lib/gcc-lib/avr/3.3.1/specs
Konfiguriert mit: ./configure --target=avr --prefix=/usr/local/avr --enable-languages=c,c++
Thread model: single
gcc-Version 3.3.1 20030720 (prerelease)
andreas@d700 comp $ avr-gcc -Os -g -c -Wall -mmcu=atmega8 gcd.c
andreas@d700 comp $ avr-size gcd.o
   text    data     bss     dec     hex filename
     54       0       0      54      36 gcd.o
andreas@d700 comp $ avr-objdump -d --source gcd.o
00000000 <gcd>:
unsigned int gcd (unsigned int a, unsigned int b)
{
  if( b == 0 ){
   0:   61 15           cp      r22, r1
   2:   71 05           cpc     r23, r1
   4:   31 f4           brne    .+12            ; 0x12
    if( a == 0 )
   6:   00 97           sbiw    r24, 0x00       ; 0
   8:   11 f4           brne    .+4             ; 0xe
      a = 1;
   a:   81 e0           ldi     r24, 0x01       ; 1
   c:   90 e0           ldi     r25, 0x00       ; 0
    return a;
   e:   bc 01           movw    r22, r24
  10:   10 c0           rjmp    .+32            ; 0x32
  }
  if( a != 0 ){
  12:   00 97           sbiw    r24, 0x00       ; 0
  14:   71 f0           breq    .+28            ; 0x32
    while( a != b ){
  16:   86 17           cp      r24, r22
  18:   97 07           cpc     r25, r23
  1a:   59 f0           breq    .+22            ; 0x32
      if( a < b ){
  1c:   86 17           cp      r24, r22
  1e:   97 07           cpc     r25, r23
  20:   18 f4           brcc    .+6             ; 0x28
        b -= a;
  22:   68 1b           sub     r22, r24
  24:   79 0b           sbc     r23, r25
  26:   02 c0           rjmp    .+4             ; 0x2c
      }else{
        a -= b;
  28:   86 1b           sub     r24, r22
  2a:   97 0b           sbc     r25, r23
  2c:   86 17           cp      r24, r22
  2e:   97 07           cpc     r25, r23
  30:   a9 f7           brne    .-22            ; 0x1c
      }
    }
  }
  return b;
}
  32:   cb 01           movw    r24, r22
  34:   08 95           ret