[avrdude-dev] [bug #47780] Single byte read/dump results in zero byte file written

[anonymous]

URL:
  <http://savannah.nongnu.org/bugs/?47780>

                 Summary: Single byte read/dump results in zero byte file
written
                 Project: AVR Downloader/UploaDEr
            Submitted by: None
            Submitted on: Mon 25 Apr 2016 05:07:28 AM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Paul Daniels
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any

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Details:

When attempting to dump the single OSCCAL/calibration byte from a Tiny10, a
zero byte file is written.  

Apologies if this is a PEBCAK situation.


example:
   # avrdude -p attiny10 -c usbtiny -U calibration:r:cal:h
   # ls -la cal

-rw-rw-r-- 0 pld pld 9 Apr 25 14:55 cal

problem source:
  In file avr.c,  function int avr_mem_hiaddr(AVRMEM * mem),  the for() loop
terminates prematurely due to memsize being 1, meaning the initial comparison
is 0>0 which of course is false. 

   for (i=mem->size-1; i>0; i--)



***proposed fix #1,  handle the corner case directly, add the test before the
for() loop. 

  if ((mem->size == 1) && (mem->buf[0] != 0xff)) return 1;

 The problem with this is that it technically violates the word-size return
results expected from avr_mem_hiaddr().

  # cat cal
  0x70


***proposed fix #2,  change the for() loop comparison to;

   for (i=mem->size-1; i>=0; i--)

  The problem with this is that it'll return a size of '2', and write 2 bytes
to the file, for what is actually a single byte result.

  # cat cal
  0x70,0x3b


Regards,
Paul.





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