@@ -4480,6 +4480,28 @@ The C<< > >> and C<< < >> modifiers can also be used on C<()> groups
4480
4480
to force a particular byte-order on all components in that group,
4481
4481
including all its subgroups.
4482
4482
4483
+ =begin comment
4484
+
4485
+ Larry recalls that the hex and bit string formats (H, h, B, b) were added to
4486
+ pack for processing data from NASA's Magellan probe. Magellan was in an
4487
+ elliptical orbit, using the antenna for the radar mapping when close to
4488
+ Venus and for communicating data back to Earth for the rest of the orbit.
4489
+ There were two transmission units, but one of these failed, and then the
4490
+ other developed a fault whereby it would randomly flip the sense of all the
4491
+ bits. It was easy to automatically detect complete records with the correct
4492
+ sense, and complete records with all the bits flipped. However, this didn't
4493
+ recover the records where the sense flipped midway. A colleague of Larry's
4494
+ was able to pretty much eyeball where the records flipped, so they wrote an
4495
+ editor named kybble (a pun on the dog food Kibbles 'n Bits) to enable him to
4496
+ manually correct the records and recover the data. For this purpose pack
4497
+ gained the hex and bit string format specifiers.
4498
+
4499
+ git shows that they were added to perl 3.0 in patch #44 (Jan 1991, commit
4500
+ 27e2fb84680b9cc1), but the patch description makes no mention of their
4501
+ addition, let alone the story behind them.
4502
+
4503
+ =end comment
4504
+
4483
4505
The following rules apply:
4484
4506
4485
4507
=over
0 commit comments