1  /*
 2   * Copyright (C) 2008-2020 Advanced Micro Devices, Inc. All rights reserved.
 3   *
 4   * Redistribution and use in source and binary forms, with or without modification,
 5   * are permitted provided that the following conditions are met:
 6   * 1. Redistributions of source code must retain the above copyright notice,
 7   *    this list of conditions and the following disclaimer.
 8   * 2. Redistributions in binary form must reproduce the above copyright notice,
 9   *    this list of conditions and the following disclaimer in the documentation
10   *    and/or other materials provided with the distribution.
11   * 3. Neither the name of the copyright holder nor the names of its contributors
12   *    may be used to endorse or promote products derived from this software without
13   *    specific prior written permission.
14   *
15   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
16   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18   * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
19   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
20   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
21   * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22   * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24   * POSSIBILITY OF SUCH DAMAGE.
25   *
26   */
27  
28  #include "libm_amd.h"
29  #include "libm_util_amd.h"
30  #include "libm_special.h"
31  
32  
33  
34  
35  double FN_PROTOTYPE_REF(nexttoward)(double x, long double y)
36  {
37  
38  
39      UT64 checkbits;
40      long double dy = (long double) y;
41      checkbits.f64=x;
42  
43  
44      /* check if the number is nan */
45      if(((checkbits.u64 & ~SIGNBIT_DP64) > EXPBITS_DP64 ))
46      {
47  #ifdef WINDOWS
48  	return  __amd_handle_error("nexttoward", __amd_nexttoward, checkbits.u64 | QNAN_MASK_64 , _DOMAIN, AMD_F_NONE, EDOM, x, 0.0, 1);
49  #else
50  	if (checkbits.u64 & QNAN_MASK_64)
51  	return  __amd_handle_error("nexttoward", __amd_nexttoward, checkbits.u64 | QNAN_MASK_64 , _DOMAIN, AMD_F_NONE, EDOM, x, 0.0, 1);
52  	else
53  	return  __amd_handle_error("nexttoward", __amd_nexttoward, checkbits.u64 | QNAN_MASK_64 , _DOMAIN, AMD_F_INVALID, EDOM, x, 0.0, 1);
54  #endif
55      }
56  
57  	   /* if x == y return y in the type of x */
58      if( x == dy )
59      {
60          return (double) dy;
61      }
62  
63      if( x == 0.0)
64      {
65          checkbits.u64 = 1;
66          if( dy > 0.0 )
67               return checkbits.f64;
68          else
69              return -checkbits.f64;
70      }
71  
72  
73      /* compute the next heigher or lower value */
74  
75      if(((x>0.0) ^ (dy>x)) == 0)
76      {
77          checkbits.u64++;
78      }
79      else
80      {
81          checkbits.u64--;
82      }
83  
84      /* check if the result is nan or inf */
85      if(((checkbits.u64 & ~SIGNBIT_DP64) >= EXPBITS_DP64 ))
86      {
87  		return  __amd_handle_error("nexttoward", __amd_nexttoward, checkbits.u64 | QNAN_MASK_64, _DOMAIN, AMD_F_NONE, EDOM, x, 0.0, 1);
88      }
89  
90      return checkbits.f64;
91  }
92