1 /*
2 * Double-precision math error handling.
3 *
4 * Copyright (c) 2018, Arm Limited.
5 * SPDX-License-Identifier: MIT
6 */
7
8 #include "math_config.h"
9
10 #if WANT_ERRNO
11 #include <errno.h>
12 /* NOINLINE reduces code size and avoids making math functions non-leaf
13 when the error handling is inlined. */
14 NOINLINE static double
with_errno(double y,int e)15 with_errno (double y, int e)
16 {
17 errno = e;
18 return y;
19 }
20 #else
21 #define with_errno(x, e) (x)
22 #endif
23
24 /* NOINLINE reduces code size. */
25 NOINLINE static double
xflow(uint32_t sign,double y)26 xflow (uint32_t sign, double y)
27 {
28 y = eval_as_double (opt_barrier_double (sign ? -y : y) * y);
29 return with_errno (y, ERANGE);
30 }
31
32 HIDDEN double
__math_uflow(uint32_t sign)33 __math_uflow (uint32_t sign)
34 {
35 return xflow (sign, 0x1p-767);
36 }
37
38 #if WANT_ERRNO_UFLOW
39 /* Underflows to zero in some non-nearest rounding mode, setting errno
40 is valid even if the result is non-zero, but in the subnormal range. */
41 HIDDEN double
__math_may_uflow(uint32_t sign)42 __math_may_uflow (uint32_t sign)
43 {
44 return xflow (sign, 0x1.8p-538);
45 }
46 #endif
47
48 HIDDEN double
__math_oflow(uint32_t sign)49 __math_oflow (uint32_t sign)
50 {
51 return xflow (sign, 0x1p769);
52 }
53
54 HIDDEN double
__math_divzero(uint32_t sign)55 __math_divzero (uint32_t sign)
56 {
57 double y = opt_barrier_double (sign ? -1.0 : 1.0) / 0.0;
58 return with_errno (y, ERANGE);
59 }
60
61 HIDDEN double
__math_invalid(double x)62 __math_invalid (double x)
63 {
64 double y = (x - x) / (x - x);
65 return isnan (x) ? y : with_errno (y, EDOM);
66 }
67
68 /* Check result and set errno if necessary. */
69
70 HIDDEN double
__math_check_uflow(double y)71 __math_check_uflow (double y)
72 {
73 return y == 0.0 ? with_errno (y, ERANGE) : y;
74 }
75
76 HIDDEN double
__math_check_oflow(double y)77 __math_check_oflow (double y)
78 {
79 return isinf (y) ? with_errno (y, ERANGE) : y;
80 }
81