Posted on May 17, 2011 at 12:55OK, sorted (with thanks to Spencer for some helpful clues).
The redirection required is _write_r(). This is my implementation
Code:
int _write_r(void *reent, int fd, char *ptr, size_t len)
{
size_t i;
for (i=0; i<len; i++)
{
uart_putc(ptr[i]);
}
return len;
}
However, newlib wasn't calling _write_r because malloc was failing. This turned out to be because the stack / heap was insufficient. Under these circumstances, newlib calls exit() which hangs up.
So I changed the relevant part of my linker script to:
Code:
_STACKSIZE = 8192;
_HEAPSIZE = 512;
and Bingo, it worked!
I also decided to leave in a verbose version of _sbrk_r to give me warning if it hangs up for the same reason in the future:
Code:
void exit(int n)
{
uart_puts(''exit()n'');
while(1);
}
register char *stack_ptr asm (''sp'');
caddr_t _sbrk_r(void *reent, size_t incr)
{
extern char end asm (''end''); // Defined by the linker
//extern char end asm (''__heap_start__''); // Defined by the linker
static char *heap_end;
char *prev_heap_end;
if( heap_end == NULL )
heap_end = &end;
prev_heap_end = heap_end;
if(( heap_end + incr ) > stack_ptr )
{
/* Some of the libstdc++-v3 tests rely upon detecting
out of memory errors, so do not abort here. */
//write( 1, ''sbrk: Heap and stack collisionn'', 32 );
//abort();
uart_puts(''HALT - heap exhaustedn'');
exit(1);
//errno = ENOMEM;
return (caddr_t) -1;
}
heap_end += incr;
return (caddr_t) prev_heap_end;
}
I hope this helps somebody else.
Chris.
