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

Question asked by slaroche on Jan 8, 2014
Latest reply on Jan 17, 2014 by David E Seymour

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.

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