Posted on July 17, 2015 at 04:14
Hello.
I'm trying, for the first time in my life,to implement the printf/scanf functions on GCC.
I managed to get the UART working in interrupt mode but somehow I can not do the easiest part. That is, I can not retarget the printf.
I read that I needed to change the _write and _read function on syscalls.c so I did it. As a result, I can print only one character and then, the printf goes to HARD_FAULT.
I also tried to use the retarget.c file that I used on keil and it compiled exept from the ferror fuction. But it did nothing.
Below, I show my syscalls.c file.
I'm using System Worbench for stm32 with gcc.
thanks
/* Includes */
#include <
sys
/stat.h>
#include <
stdlib.h
>
#include <
errno.h
>
#include <
stdio.h
>
#include <
signal.h
>
#include <
time.h
>
#include <
sys
/time.h>
#include <
sys
/times.h>
#include ''serialport.h''
/* Variables */
//#undef errno
extern int errno;
extern int __io_putchar(int ch) __attribute__((weak));
extern int __io_getchar(void) __attribute__((weak));
register char * stack_ptr asm(''sp'');
char *__env[1] = { 0 };
char **environ = __env;
/* Functions */
void initialise_monitor_handles()
{
}
int _getpid(void)
{
return 1;
}
int _kill(int pid, int sig)
{
errno = EINVAL;
return -1;
}
void _exit (int status)
{
_kill(status, -1);
while (1) {} /* Make sure we hang here */
}
int _read (int file, char *ptr, int len)
{
int DataIdx;
for (DataIdx = 0; DataIdx <
len
; DataIdx++)
{
//*ptr++ = __io_getchar();
*ptr++ = GetKey();
}
return len;
}
int _write(int file, char *ptr, int len)
{
int DataIdx;
for (
DataIdx
=
0
; DataIdx < len; DataIdx++)
{
//__io_putchar(*ptr++);
SendChar((*ptr++));
}
return len;
}
caddr_t _sbrk(int incr)
{
extern char end asm(''end'');
static char *heap_end;
char *prev_heap_end;
if (heap_end == 0)
heap_end = &end;
prev_heap_end
= heap_end;
if (heap_end + incr > stack_ptr)
{
// write(1, ''Heap and stack collision\n'', 25);
// abort();
errno = ENOMEM;
return (caddr_t) -1;
}
heap_end += incr;
return (caddr_t) prev_heap_end;
}
int _close(int file)
{
return -1;
}
int _fstat(int file, struct stat *st)
{
st->st_mode = S_IFCHR;
return 0;
}
int _isatty(int file)
{
return 1;
}
int _lseek(int file, int ptr, int dir)
{
return 0;
}
int _open(char *path, int flags, ...)
{
/* Pretend like we always fail */
return -1;
}
int _wait(int *status)
{
errno = ECHILD;
return -1;
}
int _unlink(char *name)
{
errno = ENOENT;
return -1;
}
int _times(struct tms *buf)
{
return -1;
}
int _stat(char *file, struct stat *st)
{
st->st_mode = S_IFCHR;
return 0;
}
int _link(char *old, char *new)
{
errno = EMLINK;
return -1;
}
int _fork(void)
{
errno = EAGAIN;
return -1;
}
int _execve(char *name, char **argv, char **env)
{
errno = ENOMEM;
return -1;
}
