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From: Grant Edwards <grante@visi.com>
To: ecos-discuss@sources.redhat.com
Subject: [ECOS]  CGY_SWAP16() seems broken to me.
Date: Sat, 22 Sep 2007 02:56:00 -0000	[thread overview]
Message-ID: <fd2091$bnn$1@sea.gmane.org> (raw)



unsigned u = CYG_SWAP16(0x1234);

What would a reasonable person (who hasn't looked at
hal_endian.h) expect u to be?

I certainly expected it to be 0x3412. 

But it's not.  It's 0x123412.  

IMO, that's just plain broken.


Here's the definition from hal_endian.h:

# define CYG_SWAP16(_x_)                                        \
    ({ cyg_uint16 _x = (_x_); ((_x << 8) | (_x >> 8)); })

Why isn't it this?

# define CYG_SWAP16(_x_)                                        \
    ({ cyg_uint16 _x = (_x_); (cyg_uint16)((_x << 8) | (_x >> 8)); })

Why would anybody expect a macro named CYG_SWAP16() to return a
"24-bit value" when passed a "16-bit value"?

-- 
Grant Edwards                   grante             Yow!  Ha ha  Ha ha Ha ha
                                  at               Ha Ha Ha Ha -- When will I
                               visi.com            EVER stop HAVING FUN?!!


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             reply	other threads:[~2007-09-22  2:56 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-22  2:56 Grant Edwards [this message]
2007-09-22 12:22 ` Sergei Gavrikov
2007-09-22 14:56   ` [ECOS] " Grant Edwards
2007-09-22 15:23     ` Grant Edwards
2007-09-22 17:17       ` Sergei Gavrikov

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