Path: utzoo!attcan!uunet!wuarchive!julius.cs.uiuc.edu!zaphod.mps.ohio-state.edu!usc!ucsd!pacbell.com!ames!vsi1!daver!bungi.com!news From: dlr@daver.bungi.com (Dave Rand) Newsgroups: comp.sys.nsc.32k Subject: Re: Running without an FPU Message-ID: Date: 18 Sep 90 20:49:49 GMT Sender: news@daver.bungi.com Lines: 34 Approved: news@daver.bungi.com [In the message entitled "Re: Running without an FPU" on Sep 18, 12:07, Amos Shapir writes:] > >2) Is there any way a user process can read the state of the F bit in > > the CFG register, given that SPRi CFG,Rn is a privileged instruction? > > Make a special system call, or have the kernel put a copy of the CFG > in a global variable. This is what we did on the Definicon 32k kernel. A system call would permit user-processes to examine the state of the CFG register (literally by extracting the bits from the config instruction). A separate program would permit the modification of the instruction prior to loading the kernel - a similar ROM-based addition to the monitor would be a good idea. > > >3) Are there any free (or nearly so) floating point emulation libraries > > for the NS32000 series? > > None that I know of, but there may be some for other processors which > are rather straightforward to convert. At one point, National was releasing the (old, slow) NSX FP emulation library in source form to its customers, with no restrictions on its use. You may want to check with your local sales-type to see if this is still the case. National does sell a FP emulation library now, but I'm not sure of the restrictions on its use. It comes with the GNX tools, as I recall. Either of these packages could be interfaced with the kernel to provide FP services. One such port was done in Japan for a large customer of NS - it offered multi-tasking enhancements to make it useable in a real-time environment. -- Dave Rand {pyramid|mips|bct|vsi1}!daver!dlr Internet: dlr@daver.bungi.com