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The C and C++ Include Header Files

/usr/include/c++/11/bits/std_abs.h


$ cat -n /usr/include/c++/11/bits/std_abs.h

     1	// -*- C++ -*- C library enhancements header.
     2	
     3	// Copyright (C) 2016-2021 Free Software Foundation, Inc.
     4	//
     5	// This file is part of the GNU ISO C++ Library.  This library is free
     6	// software; you can redistribute it and/or modify it under the
     7	// terms of the GNU General Public License as published by the
     8	// Free Software Foundation; either version 3, or (at your option)
     9	// any later version.
    10	
    11	// This library is distributed in the hope that it will be useful,
    12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
    13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14	// GNU General Public License for more details.
    15	
    16	// Under Section 7 of GPL version 3, you are granted additional
    17	// permissions described in the GCC Runtime Library Exception, version
    18	// 3.1, as published by the Free Software Foundation.
    19	
    20	// You should have received a copy of the GNU General Public License and
    21	// a copy of the GCC Runtime Library Exception along with this program;
    22	// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    23	// <http://www.gnu.org/licenses/>.
    24	
    25	/** @file include/bits/std_abs.h
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{cmath, cstdlib}
    28	 */
    29	
    30	#ifndef _GLIBCXX_BITS_STD_ABS_H
    31	#define _GLIBCXX_BITS_STD_ABS_H
    32	
    33	#pragma GCC system_header
    34	
    35	#include <bits/c++config.h>
    36	
    37	#define _GLIBCXX_INCLUDE_NEXT_C_HEADERS
    38	#include_next <stdlib.h>
    39	#ifdef __CORRECT_ISO_CPP_MATH_H_PROTO
    40	# include_next <math.h>
    41	#endif
    42	#undef _GLIBCXX_INCLUDE_NEXT_C_HEADERS
    43	
    44	#undef abs
    45	
    46	extern "C++"
    47	{
    48	namespace std _GLIBCXX_VISIBILITY(default)
    49	{
    50	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    51	
    52	  using ::abs;
    53	
    54	#ifndef __CORRECT_ISO_CPP_STDLIB_H_PROTO
    55	  inline long
    56	  abs(long __i) { return __builtin_labs(__i); }
    57	#endif
    58	
    59	#ifdef _GLIBCXX_USE_LONG_LONG
    60	  inline long long
    61	  abs(long long __x) { return __builtin_llabs (__x); }
    62	#endif
    63	
    64	// _GLIBCXX_RESOLVE_LIB_DEFECTS
    65	// 2192. Validity and return type of std::abs(0u) is unclear
    66	// 2294. <cstdlib> should declare abs(double)
    67	// 2735. std::abs(short), std::abs(signed char) and others should return int
    68	
    69	#ifndef __CORRECT_ISO_CPP_MATH_H_PROTO
    70	  inline _GLIBCXX_CONSTEXPR double
    71	  abs(double __x)
    72	  { return __builtin_fabs(__x); }
    73	
    74	  inline _GLIBCXX_CONSTEXPR float
    75	  abs(float __x)
    76	  { return __builtin_fabsf(__x); }
    77	
    78	  inline _GLIBCXX_CONSTEXPR long double
    79	  abs(long double __x)
    80	  { return __builtin_fabsl(__x); }
    81	#endif
    82	
    83	#if defined(__GLIBCXX_TYPE_INT_N_0)
    84	  inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_0
    85	  abs(__GLIBCXX_TYPE_INT_N_0 __x) { return __x >= 0 ? __x : -__x; }
    86	#endif
    87	#if defined(__GLIBCXX_TYPE_INT_N_1)
    88	  inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_1
    89	  abs(__GLIBCXX_TYPE_INT_N_1 __x) { return __x >= 0 ? __x : -__x; }
    90	#endif
    91	#if defined(__GLIBCXX_TYPE_INT_N_2)
    92	  inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_2
    93	  abs(__GLIBCXX_TYPE_INT_N_2 __x) { return __x >= 0 ? __x : -__x; }
    94	#endif
    95	#if defined(__GLIBCXX_TYPE_INT_N_3)
    96	  inline _GLIBCXX_CONSTEXPR __GLIBCXX_TYPE_INT_N_3
    97	  abs(__GLIBCXX_TYPE_INT_N_3 __x) { return __x >= 0 ? __x : -__x; }
    98	#endif
    99	
   100	#if !defined(__STRICT_ANSI__) && defined(_GLIBCXX_USE_FLOAT128) && !defined(__CUDACC__)
   101	  inline _GLIBCXX_CONSTEXPR
   102	  __float128
   103	  abs(__float128 __x)
   104	  { return __x < 0 ? -__x : __x; }
   105	#endif
   106	
   107	_GLIBCXX_END_NAMESPACE_VERSION
   108	} // namespace
   109	} // extern "C"++"
   110	
   111	#endif // _GLIBCXX_BITS_STD_ABS_H