Rockbox

  • Status Closed
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  • Task Type Patches
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  • Assigned To
    Jörg Hohensohn
  • Operating System
  • Severity Low
  • Priority Very Low
  • Reported Version
  • Due in Version Undecided
  • Due Date Undecided
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Attached to Project: Rockbox
Opened by Magnus Holmgren - 2003-08-09
Last edited by Jörg Hohensohn - 2003-10-12

FS#1604 - Faster rolo_load

This patch speeds up the rolo_load function, by
implementing the descrambling part in assembler (and in
a more efficient form). Also, the descrambling
calculates the checksum as it goes, saving a little
more time. Descrambling time is reduced from about 1.6
to 0.3 seconds (on a player, with a .mod file on
122,534 bytes).

As the patch also moves the "critical" part of
rolo_load to the internal RAM (this, including
descrambling and checksumming, needs 88 bytes), the
.topcode section is removed.

descramble.S is attached separately, because I don't
know how to make cvs diff include it in the patch… :/

   descramble.S (3.2 KiB)
   descramble.S (3.8 KiB)
   rolo.patch (5.2 KiB)
Closed by  Jörg Hohensohn
2003-10-12 16:42
Reason for closing:  Accepted
Magnus Holmgren commented on 2003-08-09 13:42

Adding descramble.S as well.

Magnus Holmgren commented on 2003-08-17 07:46

Did some more tweaking on descramble.S, so that it is ~30%
faster. :)

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