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78 lines
2.5 KiB
C
78 lines
2.5 KiB
C
/* lround function. PowerPC32 version.
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Copyright (C) 2004-2025 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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<https://www.gnu.org/licenses/>. */
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#define lroundf __redirect_lroundf
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#define __lroundf __redirect___lroundf
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#include <math.h>
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#undef lroundf
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#undef __lroundf
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#include <libm-alias-float.h>
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#include <libm-alias-double.h>
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long int
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__lround (double x)
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{
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#ifdef _ARCH_PWR5X
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x = round (x);
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#else
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/* Ieee 1003.1 lround function. ieee specifies "round to the nearest
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integer value, rounding halfway cases away from zero, regardless of
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the current rounding mode." however powerpc architecture defines
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"round to nearest" as "choose the best approximation. in case of a
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tie, choose the one that is even (least significant bit o).".
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so we can't use the powerpc "round to nearest" mode. instead we set
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"round toward zero" mode and round by adding +-0.5 before rounding
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to the integer value. it is necessary to detect when x is
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(+-)0x1.fffffffffffffp-2 because adding +-0.5 in this case will
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cause an erroneous shift, carry and round. we simply return 0 if
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0.5 > x > -0.5. */
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double ax = fabs (x);
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if (ax < 0.5)
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return 0;
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if (x >= 0x7fffffff.8p0 || x <= -0x80000000.8p0)
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x = (x < 0.0) ? -0x1p+52 : 0x1p+52;
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else
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{
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/* Test whether an integer to avoid spurious "inexact". */
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double t = ax + 0x1p+52;
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t = t - 0x1p+52;
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if (ax != t)
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{
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ax = ax + 0.5;
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if (x < 0.0)
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ax = -fabs (ax);
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x = ax;
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}
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}
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#endif
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/* Force evaluation of values larger than long int, so invalid
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exceptions are raise. */
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long long int ret;
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asm ("fctiwz %0, %1" : "=d" (ret) : "d" (x));
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return ret;
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}
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#ifndef __lround
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libm_alias_double (__lround, lround)
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strong_alias (__lround, __lroundf)
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libm_alias_float (__lround, lround)
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#endif
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