1 /* Double-precision math error handling.
2 Copyright (C) 2018-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <math-barriers.h>
20 #include "math_config.h"
21
22 #if WANT_ERRNO
23 #include <errno.h>
24 /* NOINLINE reduces code size and avoids making math functions non-leaf
25 when the error handling is inlined. */
26 NOINLINE static double
with_errno(double y,int e)27 with_errno (double y, int e)
28 {
29 errno = e;
30 return y;
31 }
32 #else
33 #define with_errno(x, e) (x)
34 #endif
35
36 /* NOINLINE reduces code size. */
37 NOINLINE static double
xflow(uint32_t sign,double y)38 xflow (uint32_t sign, double y)
39 {
40 y = math_opt_barrier (sign ? -y : y) * y;
41 return with_errno (y, ERANGE);
42 }
43
44 attribute_hidden double
__math_uflow(uint32_t sign)45 __math_uflow (uint32_t sign)
46 {
47 return xflow (sign, 0x1p-767);
48 }
49
50 #if WANT_ERRNO_UFLOW
51 /* Underflows to zero in some non-nearest rounding mode, setting errno
52 is valid even if the result is non-zero, but in the subnormal range. */
53 attribute_hidden double
__math_may_uflow(uint32_t sign)54 __math_may_uflow (uint32_t sign)
55 {
56 return xflow (sign, 0x1.8p-538);
57 }
58 #endif
59
60 attribute_hidden double
__math_oflow(uint32_t sign)61 __math_oflow (uint32_t sign)
62 {
63 return xflow (sign, 0x1p769);
64 }
65
66 attribute_hidden double
__math_divzero(uint32_t sign)67 __math_divzero (uint32_t sign)
68 {
69 double y = math_opt_barrier (sign ? -1.0 : 1.0) / 0.0;
70 return with_errno (y, ERANGE);
71 }
72
73 attribute_hidden double
__math_invalid(double x)74 __math_invalid (double x)
75 {
76 double y = (x - x) / (x - x);
77 return isnan (x) ? y : with_errno (y, EDOM);
78 }
79
80 /* Check result and set errno if necessary. */
81
82 attribute_hidden double
__math_check_uflow(double y)83 __math_check_uflow (double y)
84 {
85 return y == 0.0 ? with_errno (y, ERANGE) : y;
86 }
87
88 attribute_hidden double
__math_check_oflow(double y)89 __math_check_oflow (double y)
90 {
91 return isinf (y) ? with_errno (y, ERANGE) : y;
92 }
93