* gdb.texinfo (Overview): Clarify run-length encoding
example. Remove the restriction on "+" and "-" characters.
This commit is contained in:
parent
c162e8c9a4
commit
1d3811f649
|
@ -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.
|
||||
|
|
|
@ -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{$}, @samp{#}, @samp{+} and @samp{-} or with a numeric
|
||||
value greater than 126 should not be used.
|
||||
Response @var{data} can be run-length encoded to save space.
|
||||
Run-length encoding replaces runs of identical characters with one
|
||||
instance of the repeated character, followed by a @samp{*} and a
|
||||
repeat count. The repeat count is itself sent encoded, to avoid
|
||||
binary characters in @var{data}: a value of @var{n} is sent as
|
||||
@code{@var{n}+29}. For a repeat count greater or equal to 3, this
|
||||
produces a printable @sc{ascii} character, e.g.@: a space (@sc{ascii}
|
||||
code 32) for a repeat count of 3. (This is because run-length
|
||||
encoding starts to win for counts 3 or more.) Thus, for example,
|
||||
@samp{0* } is a run-length encoding of ``0000'': the space character
|
||||
after @samp{*} means repeat the leading @code{0} @w{@code{32 - 29 =
|
||||
3}} more times.
|
||||
|
||||
So:
|
||||
@smallexample
|
||||
"@code{0* }"
|
||||
@end smallexample
|
||||
@noindent
|
||||
means the same as "0000".
|
||||
The printable characters @samp{#} and @samp{$} 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.
|
||||
|
|
Loading…
Reference in New Issue