diff options
Diffstat (limited to 'lib/libm/arch/mc68881/s_logb.S')
| -rw-r--r-- | lib/libm/arch/mc68881/s_logb.S | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/lib/libm/arch/mc68881/s_logb.S b/lib/libm/arch/mc68881/s_logb.S new file mode 100644 index 00000000000..b912e1f39a5 --- /dev/null +++ b/lib/libm/arch/mc68881/s_logb.S @@ -0,0 +1,69 @@ +/*- + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. 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 1.4 1995/05/09 02:37:09 jtc 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: + fmoved fp0,sp@- + movel sp@+,d0 + movel sp@+,d1 + rts |