s_logb.S revision 1.6
1 1.6 thorpej /* $NetBSD: s_logb.S,v 1.6 1999/11/10 16:45:40 thorpej Exp $ */ 2 1.6 thorpej 3 1.1 jtc /*- 4 1.1 jtc * Copyright (c) 1990 The Regents of the University of California. 5 1.1 jtc * All rights reserved. 6 1.1 jtc * 7 1.1 jtc * This code is derived from software contributed to Berkeley by 8 1.1 jtc * the Systems Programming Group of the University of Utah Computer 9 1.1 jtc * Science Department. 10 1.1 jtc * 11 1.1 jtc * Redistribution and use in source and binary forms, with or without 12 1.1 jtc * modification, are permitted provided that the following conditions 13 1.1 jtc * are met: 14 1.1 jtc * 1. Redistributions of source code must retain the above copyright 15 1.1 jtc * notice, this list of conditions and the following disclaimer. 16 1.1 jtc * 2. Redistributions in binary form must reproduce the above copyright 17 1.1 jtc * notice, this list of conditions and the following disclaimer in the 18 1.1 jtc * documentation and/or other materials provided with the distribution. 19 1.1 jtc * 3. All advertising materials mentioning features or use of this software 20 1.1 jtc * must display the following acknowledgement: 21 1.1 jtc * This product includes software developed by the University of 22 1.1 jtc * California, Berkeley and its contributors. 23 1.1 jtc * 4. Neither the name of the University nor the names of its contributors 24 1.1 jtc * may be used to endorse or promote products derived from this software 25 1.1 jtc * without specific prior written permission. 26 1.1 jtc * 27 1.1 jtc * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 1.1 jtc * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 1.1 jtc * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 1.1 jtc * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 1.1 jtc * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 1.1 jtc * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 1.1 jtc * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 1.1 jtc * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 1.1 jtc * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 1.1 jtc * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 1.1 jtc * SUCH DAMAGE. 38 1.1 jtc */ 39 1.1 jtc 40 1.1 jtc #include <machine/asm.h> 41 1.1 jtc 42 1.1 jtc ;_sccsid: 43 1.1 jtc ;.asciz "from: @(#)support.s 5.2 (Berkeley) 5/17/90" 44 1.1 jtc 45 1.6 thorpej RCSID("$NetBSD: s_logb.S,v 1.6 1999/11/10 16:45:40 thorpej Exp $") 46 1.1 jtc 47 1.1 jtc | logb(x) 48 1.1 jtc | returns the unbiased exponent of x, a signed integer in double precision, 49 1.1 jtc | except that logb(0) is -INF, logb(INF) is +INF, and logb(NAN) is that NAN. 50 1.1 jtc ENTRY(logb) 51 1.6 thorpej movw %sp@(4),%d0 52 1.6 thorpej movw #0x7FF0,%d1 | exponent bits 53 1.6 thorpej andw %d1,%d0 | mask off all else 54 1.6 thorpej cmpw %d1,%d0 | max exponent? 55 1.1 jtc bne Lfinite | no, is finite 56 1.6 thorpej fmoved %sp@(4),%fp0 | yes, infinite or NaN 57 1.1 jtc fbun Ldone | NaN returns NaN 58 1.6 thorpej fabsx %fp0 | +-inf returns inf 59 1.1 jtc jra Ldone 60 1.1 jtc Lfinite: 61 1.6 thorpej fmoved %sp@(4),%fp0 | get entire number 62 1.1 jtc fbne Lnonz | zero? 63 1.6 thorpej flog2x %fp0 | yes, log(0) a convenient source of -inf 64 1.1 jtc jra Ldone 65 1.1 jtc Lnonz: 66 1.6 thorpej fgetexpx %fp0 | get exponent 67 1.2 jtc Ldone: 68 1.5 kleink #ifndef __SVR4_ABI__ 69 1.6 thorpej fmoved %fp0,%sp@- 70 1.6 thorpej movel %sp@+,%d0 71 1.6 thorpej movel %sp@+,%d1 72 1.5 kleink #endif 73 1.2 jtc rts 74
Indexes created Mon Sep 29 21:09:56 GMT 2025