fix: noconfirm auto-selects first AUR match
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@@ -0,0 +1,153 @@
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/* integer_length - find most significant bit in an 'unsigned int'.
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Copyright (C) 2011-2021 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file 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
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2011. */
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#include <config.h>
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/* Specification. */
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#include "integer_length.h"
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#include <limits.h>
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#include "float+.h"
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#if defined _MSC_VER && !(__clang_major__ >= 4)
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# include <intrin.h>
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#endif
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#define NBITS (sizeof (unsigned int) * CHAR_BIT)
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int
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integer_length (unsigned int x)
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{
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#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__clang_major__ >= 4)
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if (x == 0)
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return 0;
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else
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return NBITS - __builtin_clz (x);
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#elif defined _MSC_VER
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/* _BitScanReverse
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<https://docs.microsoft.com/en-us/cpp/intrinsics/bitscanreverse-bitscanreverse64> */
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unsigned long bit;
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if (_BitScanReverse (&bit, x))
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return bit + 1;
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else
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return 0;
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#else
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# if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
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if (NBITS <= DBL_MANT_BIT)
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{
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/* Use 'double' operations.
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Assumes an IEEE 754 'double' implementation. */
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# define DBL_EXP_MASK ((DBL_MAX_EXP - DBL_MIN_EXP) | 7)
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# define DBL_EXP_BIAS (DBL_EXP_MASK / 2 - 1)
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# define NWORDS \
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((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
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typedef union { double value; unsigned int word[NWORDS]; }
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memory_double;
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if (x == 0)
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return 0;
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else
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{
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memory_double m;
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unsigned int exponent;
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if (1)
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{
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/* Use a single integer to floating-point conversion. */
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m.value = x;
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}
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else
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{
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/* Use a single floating-point subtraction. */
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/* 2^(DBL_MANT_DIG-1). */
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static const double TWO_DBL_MANT_DIG =
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/* Assume DBL_MANT_DIG <= 5 * 31.
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Use the identity
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n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */
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(double) (1U << ((DBL_MANT_DIG - 1) / 5))
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* (double) (1U << ((DBL_MANT_DIG - 1 + 1) / 5))
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* (double) (1U << ((DBL_MANT_DIG - 1 + 2) / 5))
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* (double) (1U << ((DBL_MANT_DIG - 1 + 3) / 5))
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* (double) (1U << ((DBL_MANT_DIG - 1 + 4) / 5));
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/* Construct 2^(DBL_MANT_DIG-1) + x by hand. */
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m.word[DBL_EXPBIT0_WORD] =
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(DBL_MANT_DIG + DBL_EXP_BIAS) << DBL_EXPBIT0_BIT;
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m.word[1 - DBL_EXPBIT0_WORD] = x;
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/* Subtract 2^(DBL_MANT_DIG-1). */
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m.value = m.value - TWO_DBL_MANT_DIG;
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}
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exponent =
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(m.word[DBL_EXPBIT0_WORD] >> DBL_EXPBIT0_BIT) & DBL_EXP_MASK;
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return exponent - DBL_EXP_BIAS;
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}
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}
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else
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# endif
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if (NBITS == 32)
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{
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/* 6 comparisons. */
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if (x != 0)
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{
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int result = 1;
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if (x >= 0x10000)
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{
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x = x >> 16;
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result += 16;
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}
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if (x >= 0x100)
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{
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x = x >> 8;
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result += 8;
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}
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if (x >= 0x10)
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{
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x = x >> 4;
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result += 4;
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}
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if (x >= 0x4)
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{
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x = x >> 2;
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result += 2;
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}
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if (x >= 0x2)
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{
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x = x >> 1;
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result += 1;
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}
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return result;
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}
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else
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return 0;
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}
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else
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{
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/* Naive loop.
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Works for any value of NBITS. */
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int j;
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for (j = NBITS - 1; j >= 0; j--)
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if (x & (1U << j))
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return j + 1;
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return 0;
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}
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#endif
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}
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