Commit f1b64ef1 authored by Thien-Thi Nguyen's avatar Thien-Thi Nguyen
Browse files

(Bindat Functions): Explain term "total length".

Use it in `bindat-length' and `bindat-pack' descriptions.
parent 27af5d58
2006-05-27 Thien-Thi Nguyen <ttn@gnu.org>
* processes.texi (Bindat Functions): Explain term "total length".
Use it in bindat-length and bindat-pack descriptions.
2006-05-26 Eli Zaretskii <eliz@gnu.org>
* tips.texi (Coding Conventions): Advise against using
......
......@@ -2268,10 +2268,17 @@ field @code{c} in the third element of subfield @code{b} of field
@code{a}. (This corresponds to @code{struct.a.b[2].c} in C.)
@end defun
Although packing and unpacking operations change the organization of
data (in memory), they preserve the data's @dfn{total length}, which is
the sum of all the fields' lengths, in bytes. This value is not
generally inherent in either the specification or alist alone; instead,
both pieces of information contribute to its calculation. Likewise, the
length of a string or array being unpacked may be longer than the data's
total length as described by the specification.
@defun bindat-length spec struct
@c ??? I don't understand this at all -- rms
This function returns the length in bytes of @var{struct}, according
to @var{spec}.
This function returns the total length of the data in @var{struct},
according to @var{spec}.
@end defun
@defun bindat-pack spec struct &optional raw-data pos
......@@ -2281,6 +2288,9 @@ new byte array starting at the beginning. However, if @var{raw-data}
is non-@code{nil}, it specifies a pre-allocated unibyte string or vector to
pack into. If @var{pos} is non-@code{nil}, it specifies the starting
offset for packing into @code{raw-data}.
When pre-allocating, you should make sure @code{(length @var{raw-data})}
meets or exceeds the total length to avoid an out-of-range error.
@end defun
@defun bindat-ip-to-string ip
......
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