ref: 3986186c3109665b7e188e1b961a74288197f7ec
dir: /sys/src/cmd/spin/README/
the latest version of spin is always available via: http://spinroot.com/spin/whatispin.html to make the sources compile with the mkfile on Plan 9 the following changes were made: omitted memory.h from spin.h changed /lib/cpp to /bin/cpp in main.c simplified non_fatal() in main.c to remove use of yychar