From 572676160d5639edc0ecb663147bd291841458d1 Mon Sep 17 00:00:00 2001 From: Thomas Schwinge Date: Tue, 2 Apr 2013 13:51:02 +0200 Subject: New macro named issignaling to check for a signaling NaN (sNaN). It is based on draft TS 18661 and currently enabled as a GNU extension. --- sysdeps/ieee754/dbl-64/s_issignaling.c | 46 ++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 sysdeps/ieee754/dbl-64/s_issignaling.c (limited to 'sysdeps/ieee754/dbl-64/s_issignaling.c') diff --git a/sysdeps/ieee754/dbl-64/s_issignaling.c b/sysdeps/ieee754/dbl-64/s_issignaling.c new file mode 100644 index 0000000000..f475bc7bdf --- /dev/null +++ b/sysdeps/ieee754/dbl-64/s_issignaling.c @@ -0,0 +1,46 @@ +/* Test for signaling NaN. + Copyright (C) 2013 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include + +int +__issignaling (double x) +{ +#ifdef HIGH_ORDER_BIT_IS_SET_FOR_SNAN + u_int32_t hxi; + GET_HIGH_WORD (hxi, x); + /* We only have to care about the high-order bit of x's significand, because + having it set (sNaN) already makes the significand different from that + used to designate infinity. */ + return (hxi & 0x7ff80000) == 0x7ff80000; +#else + u_int32_t hxi, lxi; + EXTRACT_WORDS (hxi, lxi, x); + /* To keep the following comparison simple, toggle the quiet/signaling bit, + so that it is set for sNaNs. This is inverse to IEEE 754-2008 (as well as + common practice for IEEE 754-1985). */ + hxi ^= 0x00080000; + /* If lxi != 0, then set any suitable bit of the significand in hxi. */ + hxi |= (lxi | -lxi) >> 31; + /* We have to compare for greater (instead of greater or equal), because x's + significand being all-zero designates infinity not NaN. */ + return (hxi & 0x7fffffff) > 0x7ff80000; +#endif +} +libm_hidden_def (__issignaling) -- cgit 1.4.1