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
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
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
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
42 __math_may_uflow (uint32_t sign)
43 {
44   return xflow (sign, 0x1.8p-538);
45 }
46 #endif
47 
48 HIDDEN double
49 __math_oflow (uint32_t sign)
50 {
51   return xflow (sign, 0x1p769);
52 }
53 
54 HIDDEN double
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
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
71 __math_check_uflow (double y)
72 {
73   return y == 0.0 ? with_errno (y, ERANGE) : y;
74 }
75 
76 HIDDEN double
77 __math_check_oflow (double y)
78 {
79   return isinf (y) ? with_errno (y, ERANGE) : y;
80 }
81