FreeTDS Development Group

[Brian Bruns <camber AT umcc.ais.org>]

TDS is a little strange in that way considering usually networking
protocols (at least the TCP/IP ones) generally send binary data in
'network order'. The client can request either byte-order by specifying it
in the login packet and process either order.  So, in theory the Sparc
machine could be set to HW_LITTLE_ENDIAN and still work. (operative words
being 'in theory', I'm not all that convinced that the current code base 
is totally clean in this regard). This may become a necessity for TDS 7.0
or perhaps not, we'll find out more as we go I guess. IIOP (Corba) does
something similar in that is negotiates the byte order between client and
server.

I suppose the 'HW_' is a misnomer, since it really represents the wire
byte order and not the cpu endianess. 

Brian

On Mon, 30 Aug 1999, Mark Schaal wrote:

> > 
> > 
> > We've had several people running on Solaris (with some local fixes
> > apparently). Now the question may be were all the Solaris people running
> > with 4.2 and this is 5.0? I'm trying to remember but it seems the packet
> > headers were in a fixed order that did not change which would mean when
> > sending a packet it should not swap the the length.  Theoretically you
> > should be able to connect to a server with HW_LITTLE_ENDIAN set on a big
> > endian machine. There might not seem to be much value in it now, but I
> > haven't seen much in TDS 7.0 that indicates it supports multiple byte
> > orders. 
> > 
> > Brian
> 
> I finally figured it out.  These ints and smallints definitely change their
> byte order.  However, the bitflipping done by tds_small_int() accomplishes
> explicitly the same thing as calling tds_get_n(tds, &smallintval, 2) would 
> do
> implicitly.  This is why tds_get_int() works correctly even though it 
> doesn't
> try to take into account the machine byteorder.  Kind of neat, but it 
> confused
> me quite a bit.
> 
> Mark
> 
> For example:
>   [63-64] is a smallint
>   [81-82] is a smallint
>   [83-86] is an int
> 
> Solaris x86 (small endian)
> 
>           48: XXXX XXXX XXXX XXXX XXXX XXXX XXXX e30f    XXXXXXXXXXXXXX..
>           64: 0001 066d 6173 7465 7206 6d61 7374 6572    ...master.master
>           80: ab38 0045 1600 0002 0025 0043 6861 6e67    .8.E.....%.Chang
>           96: 6564 2064 6174 6162 6173 6520 636f 6e74    ed database cont
>          112: 6578 7420 746f 2027 6d61 7374 6572 272e    ext to 'master'.
>          128: 0743 4154 414c 4f47 0000 00ad 1e00 0104    .CATALOG........
>          144: 0200 0014 4d69 6372 6f73 6f66 7420 5351    ....Microsoft SQ
>          160: 4c20 5365 7276 6572 5f06 32c9 e309 0004    L Server_.2.....
>          176: 0335 3132 0335 3132 fd00 0000 0000 0000    .512.512........
>          192: 00
> 
> Solaris SPARC (big endian)
> 
>           48: XXXX XXXX XXXX XXXX XXXX XXXX XXXX e300    XXXXXXXXXXXXXX..
>           64: 0f01 066d 6173 7465 7206 6d61 7374 6572    ...master.master
>           80: ab00 3800 0016 4502 0000 2543 6861 6e67    ..8...E...%Chang
>           96: 6564 2064 6174 6162 6173 6520 636f 6e74    ed database cont
>          112: 6578 7420 746f 2027 6d61 7374 6572 272e    ext to 'master'.
>          128: 0743 4154 414c 4f47 0000 00ad 001e 0104    .CATALOG........
>          144: 0200 0014 4d69 6372 6f73 6f66 7420 5351    ....Microsoft SQ
>          160: 4c20 5365 7276 6572 5f06 32c9 e300 0904    L Server_.2.....
>          176: 0335 3132 0335 3132 fd00 0000 0000 0000    .512.512........
>          192: 00                                      .
> 
> -- 
> Mark J. Schaal                                        Phone:      (909) 
> 620-7724
> TST On Ramp                                   Fax:        (909) 620-8174
> System Administrator                          E-Mail: mark AT tstonramp.com
> 
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