25 Apr 2014 crhodes   » (Master)

just like old times

Sometimes, it feels like old times, rolling back the years, and so on. One of the things I did while avoiding work on my PhD (on observational tests of exotic cosmologies inspired by then-fashionable high-energy physics theories, since you ask) was to assist in resurrecting old and new CMUCL backends for SBCL, and to do some additional backend hacking. I learnt a lot! (To be fair, I learnt a lot about General Relativity too). And I even wrote about some of the funny bits when porting, such as getting to a working REPL with a completely broken integer multiply on SPARC, or highly broken bignums when working on a proper 64-bit backend for alpha.

On the #sbcl IRC channel over the last few days, the ARM porting crew (not me! I've just been kibitzing) has made substantial progress, to the point that it's now possible to boot a mostly-working REPL. Some of the highlights of the non-workingness:

  (truncate (expt 2 32) 10)
21074691228794313799883120286105
6

(fib 50)
6277101738309684039858724727853387073209631205623600462197

(expt 2.0 3)
2.0

(sb-ext:run-program "uname" '() :search t :output *standard-output*)
Linux
Memory fault at 3c

Meanwhile, given that most ARM cores don't have an integer division instruction, it's a nice bit of synchronicity that one of this year's Summer of Code projects for SBCL is to improve division by constant integers; I'm very much looking forward to getting involved with that, and hopefully also bringing some of the next generation of SBCL hackers into the community. Maybe my writing a while back about a self-sustaining system wasn't totally specious.

Syndicated 2014-04-25 16:43:10 from notes

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