From: "Jan Djärv" <jan.h.d@swipnet.se>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: 18303@debbugs.gnu.org
Subject: bug#18303: Drag and Drop fails when Emacs window/frame is above top
Date: Mon, 8 Sep 2014 07:04:54 +0200 [thread overview]
Message-ID: <A25FEC68-12A3-4830-9F8E-FCBF8D3CB4CA@swipnet.se> (raw)
In-Reply-To: <540CB70E.30206@cs.ucla.edu>
Hello.
7 sep 2014 kl. 21:50 skrev Paul Eggert <eggert@cs.ucla.edu>:
> Thanks for the patch. I noticed that '(v1 << 16) | v2' wouldn't work as desired when v2 < 0, though, as v2's sign bits will bleed into v1's encoded value. I installed an attempt at a fix as trunk bzr 117836.
Thanks, but it does not look right. We can assume v1 and v2 are 16 bit signed integers (X coordinates). In general, when data is a CONS, it must be two 16 bit numbers.
So (v1 << 16) | v2 is just a way of stuffing two signed 16 bits into 32 bits.
But when v2 is long, (v2 & 0xffff) looses the sign bit, as the code is now.
I don't know why the range X_LONG_(MIN|MAX) >> 16 is relevant here, it is way too large.
Remember, val can only be 32 bit, so X_LONG_MAX >> 16 can in it self be 48 bits.
Maybe just convert v1 and v2 to two signed 16 bit numbers (int16_t?) and shift?
Jan D.
next prev parent reply other threads:[~2014-09-08 5:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-20 12:50 bug#18303: Drag and Drop fails when Emacs window/frame is above top Paulie Pena IV
2014-09-07 17:32 ` Jan Djärv
2014-09-07 19:50 ` Paul Eggert
2014-09-08 5:04 ` Jan Djärv [this message]
2014-09-08 13:10 ` Paul Eggert
2014-09-08 15:18 ` Jan Djärv
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