1 /* roundf function. PowerPC64 version.
2 Copyright (C) 2004-2014 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
30 /* float [fp1] roundf (float x [fp1])
31 IEEE 1003.1 round function. IEEE specifies "round to the nearest
32 integer value, rounding halfway cases away from zero, regardless of
33 the current rounding mode." However PowerPC Architecture defines
34 "Round to Nearest" as "Choose the best approximation. In case of a
35 tie, choose the one that is even (least significant bit o).".
36 So we can't use the PowerPC "Round to Nearest" mode. Instead we set
37 "Round toward Zero" mode and round by adding +-0.5 before rounding
38 to the integer value. */
40 EALIGN (__roundf, 4, 0)
42 mffs fp11 /* Save current FPU rounding mode. */
45 fsubs fp12,fp13,fp13 /* generate 0.0 */
46 fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO23) */
47 fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
49 mtfsfi 7,1 /* Set rounding mode toward 0. */
52 fadds fp1,fp1,fp10 /* x+= 0.5; */
53 fadds fp1,fp1,fp13 /* x+= TWO23; */
54 fsubs fp1,fp1,fp13 /* x-= TWO23; */
55 fabs fp1,fp1 /* if (x == 0.0) */
57 mtfsf 0x01,fp11 /* restore previous rounding mode. */
60 fsubs fp9,fp1,fp10 /* x+= 0.5; */
61 bge- cr6,.L9 /* if (x < 0.0) */
62 fsubs fp1,fp9,fp13 /* x-= TWO23; */
63 fadds fp1,fp1,fp13 /* x+= TWO23; */
64 fnabs fp1,fp1 /* if (x == 0.0) */
67 mtfsf 0x01,fp11 /* restore previous rounding mode. */
71 weak_alias (__roundf, roundf)