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/* round function. PowerPC64 version.
Copyright (C) 2004-2017 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
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <math_ldbl_opt.h>
#include <libm-alias-double.h>
.section ".toc","aw"
.LC0: /* 2**52 */
.tc FD_43300000_0[TC],0x4330000000000000
.LC1: /* 0.5 */
.tc FD_3fe00000_0[TC],0x3fe0000000000000
.section ".text"
/* double [fp1] round (double x [fp1])
IEEE 1003.1 round function. IEEE specifies "round to the nearest
integer value, rounding halfway cases away from zero, regardless of
the current rounding mode." However PowerPC Architecture defines
"Round to Nearest" as "Choose the best approximation. In case of a
tie, choose the one that is even (least significant bit o).".
So we can't use the PowerPC "Round to Nearest" mode. Instead we set
"Round toward Zero" mode and round by adding +-0.5 before rounding
to the integer value. */
ENTRY (__round, 4)
CALL_MCOUNT 0
lfd fp13,.LC0@toc(2)
fabs fp0,fp1
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
mffs fp11 /* Save current FPU rounding mode and
"inexact" state. */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnl- cr7,.L10
mtfsfi 7,1 /* Set rounding mode toward 0. */
lfd fp10,.LC1@toc(2)
ble- cr6,.L4
fadd fp1,fp1,fp10 /* x+= 0.5; */
fadd fp1,fp1,fp13 /* x+= TWO52; */
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) */
/* x = 0.0; */
mtfsf 0xff,fp11 /* Restore previous rounding mode and
"inexact" state. */
blr
.L4:
fsub fp9,fp1,fp10 /* x+= 0.5; */
bge- cr6,.L9 /* if (x < 0.0) */
fsub fp1,fp9,fp13 /* x-= TWO52; */
fadd fp1,fp1,fp13 /* x+= TWO52; */
fnabs fp1,fp1 /* if (x == 0.0) */
/* x = -0.0; */
.L9:
mtfsf 0xff,fp11 /* Restore previous rounding mode and
"inexact" state. */
blr
.L10:
/* Ensure sNaN input is converted to qNaN. */
fcmpu cr7,fp1,fp1
beqlr cr7
fadd fp1,fp1,fp1
blr
END (__round)
libm_alias_double (__round, round)
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