X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=doc%2Fudp.but;h=f7640268ee5d8a03e3c5b028d60e15c8081168b7;hb=72b659cb728b1f549c49b40d37f59b870f006fac;hp=8e425616d63e59a55d22cf90bf5840b7d6faf235;hpb=da948bc1517f1af94c774f49a831aa9ea19d18aa;p=PuTTY.git

diff --git a/doc/udp.but b/doc/udp.but
index 8e425616..f7640268 100644
--- a/doc/udp.but
+++ b/doc/udp.but
@@ -3,8 +3,6 @@
 \# PuTTY's `unwritten design principles'. It has nothing to do with
 \# the User Datagram Protocol.
 
-\define{versionidudp} \versionid $Id$
-
 \A{udp} PuTTY hacking guide
 
 This appendix lists a selection of the design principles applying to
@@ -45,7 +43,10 @@ endianness-dependent operations, and so on.
 \e{don't} care about. In particular, we expect PuTTY to be compiled
 on 32-bit architectures \e{or bigger}; so it's safe to assume that
 \c{int} is at least 32 bits wide, not just the 16 you are guaranteed
-by ANSI C.)
+by ANSI C.  Similarly, we assume that the execution character
+encoding is a superset of the printable characters of ASCII, though
+we don't assume the numeric values of control characters,
+particularly \cw{'\\n'} and \cw{'\\r'}.)
 
 \H{udp-multi-backend} Multiple backends treated equally
 
@@ -75,21 +76,23 @@ Some ports of PuTTY - notably the in-progress Mac port - are
 constrained by the operating system to run as a single process
 potentially managing multiple sessions.
 
-Therefore, the platform-independent parts of PuTTY use \e{hardly
-any} global variables. The very few that do exist, such as
-\c{flags}, are tolerated because they are not specific to a
-particular login session: instead, they define properties that are
-expected to apply equally to \e{all} the sessions run by a single
-PuTTY process. Any data that is specific to a particular network
-session is stored in dynamically allocated data structures, and
-pointers to these structures are passed around between functions.
+Therefore, the platform-independent parts of PuTTY never use global
+variables to store per-session data. The global variables that do
+exist are tolerated because they are not specific to a particular
+login session: \c{flags} defines properties that are expected to
+apply equally to \e{all} the sessions run by a single PuTTY process,
+the random number state in \cw{sshrand.c} and the timer list in
+\cw{timing.c} serve all sessions equally, and so on. But most data
+is specific to a particular network session, and is therefore stored
+in dynamically allocated data structures, and pointers to these
+structures are passed around between functions.
 
 Platform-specific code can reverse this decision if it likes. The
 Windows code, for historical reasons, stores most of its data as
 global variables. That's OK, because \e{on Windows} we know there is
 only one session per PuTTY process, so it's safe to do that. But
 changes to the platform-independent code should avoid introducing
-any more global variables than already exist.
+global variables, unless they are genuinely cross-session.
 
 \H{udp-pure-c} C, not C++