Hello!
Following code is Producing an infinit loop, so main() is never reached
extern int main(void);
int main(void){
while(1);
}
#include <avr\io.h>
/*Seed aus SRAM Zellen*/
static uint16_t seedram __attribute__ ((section (".noinit")));
void __init_seed(void) __attribute__ ((naked, section (".init8")));
// Bestimme seed aus zufälligem RAM-Inhalt
// !!! FUNKTION NICHT AUFRUFEN !!!
// !!! FUNKTION WIRD AUTOMATISCH !!!
// !!! IN .init8 vor main AUSGEFÜHRT !!!
void __init_seed (void)
{
uint16_t s = 0;
uint16_t *p = (uint16_t*) (RAMEND+1);
extern uint16_t __noinit_start;
while (p >= &__noinit_start + 1)
s ^= *(--p);
seedram = s;
}
is going to
while (p >= &__noinit_start + 1)
8e: 81 e0 ldi r24, 0x01 ; 1
90: e2 30 cpi r30, 0x02 ; 2
92: f8 07 cpc r31, r24
94: c0 f7 brcc .-16 ; 0x86 <__init_seed+0x12>
s ^= *(--p);
seedram = s;
96: 30 93 01 01 sts 0x0101, r19
9a: 20 93 00 01 sts 0x0100, r18
}
9e: 20 e0 ldi r18, 0x00 ; 0
a0: 30 e0 ldi r19, 0x00 ; 0
a2: f9 cf rjmp .-14 ; 0x96 <__init_seed+0x22>
at line a2: an infinit loop starts and never leaves this function.
the Problem is only an Optimation levels O2 and O3
Orginal thread in german Forum:
http://www.mikrocontroller.net/topic/158516
compiler call:
avr-gcc -c -mmcu=atmega168 -I. -gdwarf-2 -DF_CPU=8000000UL -O2 -funsigned-char
-funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes
-Wa,-adhlns=./main.lst -std=c99 -MMD -MP -MF .dep/main.o.d main.c -o main.o
linker call:
avr-gcc -mmcu=atmega168 -I. -gdwarf-2 -DF_CPU=8000000UL -O2 -funsigned-char
-funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes
-Wa,-adhlns=main.o -std=c99 -MMD -MP -MF .dep/main.elf.d main.o --output
main.elf -Wl,-Map=main.map,--cref -lm
Compiler version:
D:\Daten\Projekte\Eclipse Workspace\test init>avr-gcc -v
Using built-in specs.
Target: avr
Configured with: ../gcc-4.3.2/configure --enable-win32-registry=WinAVR-20090313
--with-gmp=/usr/local --with-mpfr=/usr/local --prefix=/c/WinAVR --target=avr
--enable-languages=c,c++,objc --with-dwarf2 --enable-doc --disable-shared
--disable-libada --disable-libssp --disable-nls
--with-pkgversion='WinAVR20090313'
--with-bugurl='URL:http://sourceforge.net/tracker/?atid=520074&group_id=68108&func=browse'Thread
model: single
gcc version 4.3.2 (WinAVR 20090313)
Greetings Stefan
--
Summary: wrong Epilog on nacked function
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: stefan dot dreyer at yahoo dot de
GCC host triplet: Windows XP
GCC target triplet: AVR
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42240
