Re: AW: [Simulavr-devel] [patch #3453] gdbserver.c gdb_extract_hex_nu m(...) bug fix (for more recent gdb versions)

[Paul Schlie]

num is an integer, not a string, hex nibbles are 4 bit's wide,
hence to build an integer out of a sequence of hex-chars->nibbles
one shifts the integer by 4.


> From: Frost_Tobias <address@hidden>
> Date: Tue, 19 Oct 2004 09:13:37 +0200
> To: <address@hidden>
> Subject: AW: [Simulavr-devel] [patch #3453] gdbserver.c gdb_extract_hex_nu
> m(...) bug fix (for more recent gdb versions)
> 
> No, the patch's correct.
> Num will be shifted by 4 every time the while is executed and then stored.
> Then the low nibble will be ored into num
> 
> Example:
> 
> *p = ABCDEF
> 
> will be: (each line is one while-execution)
> 
>     num         
> 0x0000 000A     
> 0x0000 00AB
> 0x0000 0ABC
> 0x0000 ABCD
> 0x000A BCDE
> 0x00AB CDEF 
> 
>  num = (num << (i * 4)) | hex2nib (*p);  (replaced by following line) */
> 
> without the patch you'll get:
> 
> (i=0) -> no shift         0x0000 000A
> (i=1 -> shifted with 4) ->     num = 0x0000 00A0  | 0x0B  -> num = 0x0000
> 00AB
> (i=2 -> num shifted with 8) -> num = 0x0000 AB00 | 0x0C -> num = 0x0000 AB0C
> (ERROR!)
> 
>   
>  
> 
> -----Ursprüngliche Nachricht-----
> Von: Klaus Rudolph [mailto:address@hidden
> Gesendet: Montag, 18. Oktober 2004 17:16
> An: address@hidden
> Betreff: [Simulavr-devel] [patch #3453] gdbserver.c
> gdb_extract_hex_num(...) bug fix (for more recent gdb versions)
> 
> 
> This mail is an automated notification from the patch tracker
>  of the project: Simulavr: an AVR simulator.
> 
> /**************************************************************************/
> [patch #3453] Latest Modifications:
> 
> Changes by: 
> Klaus Rudolph <address@hidden>
> 'Date: 
> Mon 18.10.2004 at 15:07 (Europe/Berlin)
> 
> ------------------ Additional Follow-up Comments
> ----------------------------
> Can you give me an idea what problem the patch should fix?
> 
> Your new line:
>  num = (num << 4) | hex2nib (*p);
> could never work I think. This will always change
> the "0000000X0" position but nothing else!?.
> If the tranmitted var is longer you have to change
> the init of max_shifts but that is not done....
> 
> maybe I am totally confused today, but please let us know
> what your problem is.
> 
> Why you have not send a patch file as patch?
> 
> 
> 
> 
> 
> 
> 
> /**************************************************************************/
> [patch #3453] Full Item Snapshot:
> 
> URL: <http://savannah.nongnu.org/patch/?func=detailitem&item_id=3453>
> Project: Simulavr: an AVR simulator
> Submitted by: Paul Schlie
> On: Mon 18.10.2004 at 12:48
> 
> Category:  bug fix
> Priority:  9 - Immediate
> Resolution:  None
> Privacy:  Public
> Assigned to:  None
> Originator Email:
> Status:  Open
> 
> 
> Summary:  gdbserver.c gdb_extract_hex_num(...) bug fix (for more recent gdb
> versions)
> 
> Original Submission:  static int
> gdb_extract_hex_num (char **pkt, char stop)
> {
>     int i = 0;
>     int num = 0;
>     char *p = *pkt;
>     int max_shifts = sizeof (int) * 2 - 1; /* max number of nibbles to shift
>                                               through */
> 
>     while ((*p != stop) && (*p != ''))
>     {
>         if (i > max_shifts)
>             avr_error ("number too large");
> 
> /* This is broken for values encoded with greater than two hex digits, which
>     is typical in gdb sessions when leading 0's are encoded for integer
> values
>         num = (num << (i * 4)) | hex2nib (*p);  (replaced by following line)
> */
>         num = (num << 4) | hex2nib (*p);
>         i++;
>         p++;
>     }
> 
>     *pkt = p;
>     return num;
> }
> 
> 
> Follow-up Comments
> ------------------
> 
> 
> -------------------------------------------------------
> Date: Mon 18.10.2004 at 15:07       By: Klaus Rudolph <zfrdh>
> Can you give me an idea what problem the patch should fix?
> 
> Your new line:
>  num = (num << 4) | hex2nib (*p);
> could never work I think. This will always change
> the "0000000X0" position but nothing else!?.
> If the tranmitted var is longer you have to change
> the init of max_shifts but that is not done....
> 
> maybe I am totally confused today, but please let us know
> what your problem is.
> 
> Why you have not send a patch file as patch?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> For detailed info, follow this link:
> <http://savannah.nongnu.org/patch/?func=detailitem&item_id=3453>
> 
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> 
> 
> 
> 
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