Trampas Stern a écrit :
> You also need to send the rest of the code.
>
> For example it could be that rx_len is where memory overflow is happening
>
> cascade:
> * rx_len = sizeof(sak);*
> snprintf(t, 3, "%d", (*tag).level);
>
> On Thu, May 20, 2021 at 11:07 AM Trampas Stern <tst...@nc.rr.com
> <mailto:tst...@nc.rr.com>> wrote:
>
> Try changing this:
> unsigned char t[3];
>
> to this
> unsigned char t[4];
>
> Then see if your problem goes away.
I have tried to replace t[3] by t[8] before my first post, same result.
I have tried also to add a delay after each stty_print() and I obtain
the same corruption.
> So snprintf() is not well documented... is the size parameter
> including null terminator or not?
snprintf always contains null terminator.
> Even worse is when you get to
> multiple threads (ISR handlers) is snprintf() reentrant?
>
> Generally I write my own snprintf() so that I know what it does and
> make sure it is reentrant. This is not as optimized but I know what
> the results are.
>
> You also have lots of other things to consider for example the AVR
> is Harvard machine so code like this:
> stty_print("Anticol ACF\r\n");
> actually will copy string from flash to RAM and thus use more RAM.
I have found a very strange bug.
uint8_t
iso14443a_anticol(uint8_t wup, rfid_tag_t *tag)
{
...
(*tag).state = ISO14443A_STATE_ANTICOL_RUNNING;
(*tag).level = ISO14443A_LEVEL_CL1;
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
snprintf(t, 3, "%02X", (*tag).level);
vfd_print(t); vfd_print(" (0)\r\n");
//vfd_print("1"); vfd_print(" (0)\r\n");
snprintf(t, 3, "%02X", (*tag).level); stty_print(t); stty_print(" (0)\r\n");
snprintf(t, 3, "%02X", (*tag).level); stty_print(t); stty_print("
(0.0)\r\n");
cascade:
rx_len = sizeof(sak);
snprintf(t, 3, "%02X", (*tag).level); stty_print(t); stty_print("
(0.1)\r\n");
...
This code runs as expected (please note vfd_print(t); vfd_print("
(0)\r\n");).
On VFD screen, I obtain "01 (0)".
If I replace this line by vfd_print("01 (0)\r\n"); I can see my memory
corruption again.
If I deplace this line after snprintf(t, 3, "%02X", (*tag).level);
stty_print(t); stty_print(" (0.0)\r\n"); program runs as expected.
If I remove this line, memory corruption again.
My avr-gcc is an old release (5.4 given by debian). I will try a recent
gcc.
JB
