Messages in this thread |  | | From | Rick Hohensee <> | Subject | Re: inserting a Forth-like language into the Linux kernel | Date | Thu, 10 May 2001 02:12:34 -0400 (EDT) |
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read() of a tty from the kernel does behave as per the tty settings. I now have a kernel thread with stdin, out and err, FD's 0, 1 and 2, open and reading lines of typed input. The "interpreter" adds 0x30 (ASCII 0) to the return value from read and prints it, which means it occurs at the beginning of the next line. Here's what's sitting on my tty1 screen right now... ................................................................. 1 1 1 1aaoeutasoeu aoeu oaeusntaoesutoaeut oeuoaeuo uoaeuoaeu heeee 6e 2 1 1 1 1eeeeee 7ee 3 1onetu euaoeuaoeuoa eu aoeu ao eu ao eu aoeu aoeu ao eu aoe u aoe u te e e e e ;e e e e 9e e e e 9e e e 7ee 3 ...................................................................
This should simplify hanging an interpreter off this simple little top loop. That is, userland H3sm was using cooked mode, so this is nice. This is the top loop code, which is x86 assembly and H3sm subroutines...
................................................................. abort_H3sm: call buffer
top_loop_of_H3sm: # stick a sleep in here. # Do not melt the CPU, do not slow down # the test cycle. call timespec call pdup call pplusc call pplusc call nanosleep call twopdrop call drop
HANDOFF
call zero # FD call read call literal .byte 4 .int 0x30 call plus call emit ELL( top_loop_of_H3sm) ...................................................................
emit is similar to Forth EMIT. It is a one-byte write(). buffer and timespec put addresses on the H3sm pointer stack. nanosleep and read are H3sm stack-passing wrappers for the syscalls. HANDOFF is a macro for a stack-push-wrapped schedule(). It's a macro because I suspect I'm going to have to sprinkle it judiciously around H3sm. The nanosleep keeps my load average normal.
Rick Hohensee www.clienux.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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