Hi Michael, On Dec 20, 2010, at 06:39 , Michael Haupt wrote: > take a look at Ian's recent S3 paper, download the corresponding source code, > and have fun.
I'm glad you had fun with that code. Here's another small example that might provide some fun. http://piumarta.com/tmp/maru (On Linux, type "make". On Darwin, edit the first line of emit.l to set __MACH__ to anything other than () then type "make". MinGW has library issues and doesn't work -- sorry.) This is a metacircular evaluator for an s-expression language, plus a "level shift" from s-expressions down to IA32 machine code to escape the infinite metacircular regress. boot-eval.c contains a reader/evaluator for the s-expression language, written in C. eval.l contains the same evaluator, written in the s-expression language. emit.l contains a compiler from s-expressions to IA32 machine code, written in the s-expression language. boot.l contains some data structures and algorithms needed by emit.l, written in the s-expression language. boot-eval.c is compiled and then run on boot.l+emit.l+eval.l to create eval.s, a machine code implementation of the s-expression evaluator. eval.s is then assembled and linked to make eval, which can be run on boot.l+emit.l+eval.l to create eval.s. The C compiler is then entirely out of the loop (unless you lose a working evaluator and need to bootstrap again). The s-expression language has a few interesting characteristics. You can get a feeling for some of them by looking how messaging and multimethods are implemented. The compiler makes some attempt to be small and simple (1750 loc for all three ".l" files, including some debugging cruft that could be removed) and no attempt whatsoever to optimise. Even so, the generated code runs at 40% the speed of aggressively-optimised C on my E5430, measured by the convenient macro benchmark: dividing the run time of regenerating eval.s via eval by that of generating it initially via boot-eval. Wrap up warm against all that snow, and have a happy new year! Regards, Ian _______________________________________________ fonc mailing list fonc@vpri.org http://vpri.org/mailman/listinfo/fonc
