119 __attribute__((weak)) int _sys_close(FILEHANDLE fh)  in _sys_close()  argument
122     switch (fh)  in _sys_close()
135 __attribute__((weak)) int _sys_write(FILEHANDLE fh, const uint8_t *buf, uint32_t len, int mode)  in _sys_write()  argument
141     switch (fh)  in _sys_write()
154 __attribute__((weak)) int _sys_read(FILEHANDLE fh, uint8_t *buf, uint32_t len, int mode)  in _sys_read()  argument
160     switch (fh)  in _sys_read()
173 __attribute__((weak)) int _sys_istty(FILEHANDLE fh)  in _sys_istty()  argument
176     switch (fh)  in _sys_istty()
189 __attribute__((weak)) int _sys_seek(FILEHANDLE fh, long pos)  in _sys_seek()  argument
193     switch (fh)  in _sys_seek()
206 __attribute__((weak)) long _sys_flen(FILEHANDLE fh)  in _sys_flen()  argument
209     switch (fh)  in _sys_flen()