Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mandrill!gatech!udel!rochester!pt.cs.cmu.edu!sei!sei.cmu.edu!firth From: firth@sei.cmu.edu (Robert Firth) Newsgroups: comp.arch Subject: Re: 88k trick for FP abs/neg Message-ID: <6160@aw.sei.cmu.edu> Date: 8 Jul 88 15:34:37 GMT References: <10136@tekecs.TEK.COM> <2553@obiwan.mips.COM> Sender: netnews@sei.cmu.edu Reply-To: firth@bd.sei.cmu.edu.UUCP (PUT YOUR NAME HERE) Organization: Carnegie-Mellon University, SEI, Pgh, Pa Lines: 11 In article <10136@tekecs.TEK.COM>, andrew@frip.gwd.tek.com (Andrew Klossner) writes > To clear up a question: on the 88k, floating point values are > kept in general registers, so "abs" is done by ANDing to 0 the > sign bit, "neg" is done by XORing the sign bit, and "mov" is > done with conventional register-to-register move instructions. Ho boy! The last time I saw a compiler XOR the sign bit of floating zero must have been about 1975. Old bugs never die, they just migrate to new hosts.