/* $NetBSD: s_logb.S,v 1.7 2003/08/07 16:44:43 agc Exp $ */ /*- * Copyright (c) 1990 The Regents of the University of California. * All rights reserved. * * This code is derived from software contributed to Berkeley by * the Systems Programming Group of the University of Utah Computer * Science Department. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <machine/asm.h> ;_sccsid: ;.asciz "from: @(#)support.s 5.2 (Berkeley) 5/17/90" RCSID("$NetBSD: s_logb.S,v 1.7 2003/08/07 16:44:43 agc Exp $") | logb(x) | returns the unbiased exponent of x, a signed integer in double precision, | except that logb(0) is -INF, logb(INF) is +INF, and logb(NAN) is that NAN. ENTRY(logb) movw %sp@(4),%d0 movw #0x7FF0,%d1 | exponent bits andw %d1,%d0 | mask off all else cmpw %d1,%d0 | max exponent? bne Lfinite | no, is finite fmoved %sp@(4),%fp0 | yes, infinite or NaN fbun Ldone | NaN returns NaN fabsx %fp0 | +-inf returns inf jra Ldone Lfinite: fmoved %sp@(4),%fp0 | get entire number fbne Lnonz | zero? flog2x %fp0 | yes, log(0) a convenient source of -inf jra Ldone Lnonz: fgetexpx %fp0 | get exponent Ldone: #ifndef __SVR4_ABI__ fmoved %fp0,%sp@- movel %sp@+,%d0 movel %sp@+,%d1 #endif rts |