* gdb.texinfo (Overview): Clarify run-length encoding

	example.  Remove the restriction on "+" and "-" characters.

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index f1c0f359c96d4c1d975ad419c0c1d7da4348a7e2..c1150b8c1a51d851689f98b6d30394fafccc2d92 100644 (file)
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2007-12-16  Daniel Jacobowitz  <dan@codesourcery.com>
+
+       * gdb.texinfo (Overview): Clarify run-length encoding
+       example.  Remove the restriction on "+" and "-" characters.
+
 2007-12-15  Eli Zaretskii  <eliz@gnu.org>
 
        * gdb.texinfo (Host I/O Packets): Fix xref syntax.

diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 01f5db50982461b0fda9e41b4f7364f7e8440e54..36f1dc44b5992c44780d6108380506ce458b90fa 100644 (file)
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -23158,20 +23158,24 @@ must also escape @code{0x2a} (@sc{ascii} @samp{*}), so that it
 is not interpreted as the start of a run-length encoded sequence
 (described next).
 
-Response @var{data} can be run-length encoded to save space.  A @samp{*}
-means that the next character is an @sc{ascii} encoding giving a repeat count
-which stands for that many repetitions of the character preceding the
-@samp{*}.  The encoding is @code{n+29}, yielding a printable character
-where @code{n >=3} (which is where rle starts to win).  The printable
-characters @samp{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric
-value greater than 126 should not be used.
-
-So:
-@smallexample
-"@code{0* }"
-@end smallexample
-@noindent
-means the same as "0000".
+Response @var{data} can be run-length encoded to save space.
+Run-length encoding replaces runs of identical characters with one
+instance of the repeated character, followed by a @samp{*} and a
+repeat count.  The repeat count is itself sent encoded, to avoid
+binary characters in @var{data}: a value of @var{n} is sent as
+@code{@var{n}+29}.  For a repeat count greater or equal to 3, this
+produces a printable @sc{ascii} character, e.g.@: a space (@sc{ascii}
+code 32) for a repeat count of 3.  (This is because run-length
+encoding starts to win for counts 3 or more.)  Thus, for example,
+@samp{0* } is a run-length encoding of ``0000'': the space character
+after @samp{*} means repeat the leading @code{0} @w{@code{32 - 29 =
+3}} more times.
+
+The printable characters @samp{#} and @samp{$} or with a numeric value
+greater than 126 must not be used.  Runs of six repeats (@samp{#}) or
+seven repeats (@samp{$}) can be expanded using a repeat count of only
+five (@samp{"}).  For example, @samp{00000000} can be encoded as
+@samp{0*"00}.
 
 The error response returned for some packets includes a two character
 error number.  That number is not well defined.