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| -rw-r--r-- | pod/perlfunc.pod | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index 408c91572f..9358c80d32 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -4480,6 +4480,28 @@ The C<< > >> and C<< < >> modifiers can also be used on C<()> groups to force a particular byte-order on all components in that group, including all its subgroups. +=begin comment + +Larry recalls that the hex and bit string formats (H, h, B, b) were added to +pack for processing data from NASA's Magellan probe. Magellan was in an +elliptical orbit, using the antenna for the radar mapping when close to +Venus and for communicating data back to Earth for the rest of the orbit. +There were two transmission units, but one of these failed, and then the +other developed a fault whereby it would randomly flip the sense of all the +bits. It was easy to automatically detect complete records with the correct +sense, and complete records with all the bits flipped. However, this didn't +recover the records where the sense flipped midway. A colleague of Larry's +was able to pretty much eyeball where the records flipped, so they wrote an +editor named kybble (a pun on the dog food Kibbles 'n Bits) to enable him to +manually correct the records and recover the data. For this purpose pack +gained the hex and bit string format specifiers. + +git shows that they were added to perl 3.0 in patch #44 (Jan 1991, commit +27e2fb84680b9cc1), but the patch description makes no mention of their +addition, let alone the story behind them. + +=end comment + The following rules apply: =over |