Problem when using fopen with a hardcoded file name (data alignment problem ?)

[slaroche]

Hi,

     here is what I am using : MQX 4.0.2.2 \ CW 10.2 \ Kinetis K60

     I am trying to use the « fopen » on a SDCARD passing a hardcoded string for the filename.  For some reason, It fails when I do so :

      CfgFile = fopen ("a:\\config.txt", "r");

     If I put the name into a ram buffer, then it works :

            char FileName[16] =  "a:\\config.txt";

      CfgFile = fopen (FileName, "r");

     I traced into the fopen function and I am not exactly sure what happen, but the loop that scans for all available devices (“ttya:”, “gpio:”, …) doesn’t break at the same place.  A difference I can see between the two calls is that the one using the hardcoded string uses a pointer that is not 32 bit aligned (address is “0x1fff0569”) while the second one uses a 32 bit aligned adresss (0x1fffb47c).  I am thinking that maybe this does a difference when comparing the strings.

     Although I have a workaround for that problem (using a ram buffer), I would very like to know why it does that and how I can avoid it.

Thanks for any advice.

[DavidS]

Hello,

No idea why that wouldn't work.

I did a simple test using the web_hvac example and could do the following

log_fp = fopen("c:\\hvac_log.txt","a");          //DES worked

#define LOG_FILE "c:\\hvac_log.txt"

log_fp = fopen(LOG_FILE,"a");               //DES worked

I wonder if something funky with your flash case where the string is not NULL terminated???

As an additional test after closing the file I then re-opened it using following code and it worked fine.

  log_fp = fopen("c:\\hvac_log.txt","r");

   if (log_fp) {

   char temparray[31];

  fgets((char *)&temparray[0], (int_32)30, log_fp);

}

Lastly when you step into the fopen() can you use your Variable window to see what the "tmp_ptr" is set to?

In my picture below it is shown as "c:\\hvac_log.txt"

Regards,

David