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http://sourceware.org/ml/libc-alpha/2013-07/msg00201.html These two functions oddly test x+1>0 when a double x is >= 0.0, and similarly when x is negative. I don't see the point of that since the test should always be true. I also don't see any need to convert x+1 to integer rather than simply using xr+1. Note that the standard allows these functions to return any value when the input is outside the range of long long, but it's not too hard to prevent xr+1 overflowing so that's what I've done. (With rounding mode FE_UPWARD, x+1 can be a lot more than what you might naively expect, but perhaps that situation was covered by the x - xrf < 1.0 test.) * sysdeps/powerpc/fpu/s_llround.c (__llround): Rewrite. * sysdeps/powerpc/fpu/s_llroundf.c (__llroundf): Rewrite.
53 lines
1.7 KiB
C
53 lines
1.7 KiB
C
/* Round double value to long long int.
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Copyright (C) 1997-2013 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_ldbl_opt.h>
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/* Round to the nearest integer, with values exactly on a 0.5 boundary
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rounded away from zero, regardless of the current rounding mode.
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If (long long)x, when x is out of range of a long long, clips at
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LLONG_MAX or LLONG_MIN, then this implementation also clips. */
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long long int
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__llround (double x)
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{
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long long xr = (long long) x;
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double xrf = (double) xr;
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if (x >= 0.0)
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{
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if (x - xrf >= 0.5)
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xr += (long long) ((unsigned long long) xr + 1) > 0;
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}
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else
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{
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if (xrf - x >= 0.5)
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xr -= (long long) ((unsigned long long) xr - 1) < 0;
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}
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return xr;
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}
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weak_alias (__llround, llround)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__llround, __llroundl)
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weak_alias (__llround, llroundl)
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#endif
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#if LONG_DOUBLE_COMPAT (libm, GLIBC_2_1)
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compat_symbol (libm, __llround, llroundl, GLIBC_2_1);
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#endif
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