CLiki now supports editing old versions, for greater ease of recovery from vandalism#

Thu, 03 Jun 2004 23:00:11 +0000

CLiki now supports editing old versions, for greater ease of recovering from vandalism. That is, it still saves a new version, but the text you start with when you press 'edit' is whatever version you were looking at. So, find a version that doesn't have brazilian hackers(sic) or porn spam on it, edit and save.

That's kind of an aside, but it makes a good first sentence for the rss monster. My Lisp hacking lately, what small amount of it has happened, has been about sbcl x86-64, or hammer or amd64 or whatever it's called today, with the intention of getting at least some distance further before the cmucl anon cvs repository comes back. So far since last weekend -

• The problem which had been stopping progress for, oh, months: turns out that we were calling alloc() with negative sizes, which obviously is a bad idea. alloc() was honouring our requests too, at least to the extent of decrementing the free pointer and therefore ensuring that we got the same address space again for some later request. The offending code was something to do with allocate-vector, but right now I'm on a tube train with no network and have entirely forgotten what.

• All the floating point instructions were missing REX prefixes. This is, obviously, bad when you want to index off r8 and you end up offset from rax instead.

• move-from-signed worked by shifting left twice and checking for overflow after each shift. For a target with three bits of fixnum tag, this is only doing 66% of the job.

• Thinko in movsxd

Right now we have a SIGFPE resulting from an idiv instruction. I'd say something witty about this, but am prevented by having nothing witty to say. But at last we've made to the end of MAKE-HASH-TABLE, so in the absence of humour there does at least seems to be some kind of forward progress.

Skating tomorrow!