| Peter Collingbourne | 594c10d | 2014-11-27 00:12:26 +0000 | [diff] [blame] | 1 | /* go-matherr.c -- a Go version of the matherr function. |
| 2 | |
| 3 | Copyright 2012 The Go Authors. All rights reserved. |
| 4 | Use of this source code is governed by a BSD-style |
| 5 | license that can be found in the LICENSE file. */ |
| 6 | |
| 7 | /* The gccgo version of the math library calls libc functions. On |
| 8 | some systems, such as Solaris, those functions will call matherr on |
| 9 | exceptional conditions. This is a version of matherr appropriate |
| 10 | for Go, one which returns the values that the Go math library |
| 11 | expects. This is fine for pure Go programs. For mixed Go and C |
| 12 | programs this will be problematic if the C programs themselves use |
| 13 | matherr. Normally the C version of matherr will override this, and |
| 14 | the Go code will just have to cope. If this turns out to be too |
| 15 | problematic we can change to run pure Go code in the math library |
| 16 | on systems that use matherr. */ |
| 17 | |
| 18 | #include <math.h> |
| 19 | #include <stdint.h> |
| 20 | |
| 21 | #include "config.h" |
| 22 | |
| 23 | #if defined(HAVE_MATHERR) && defined(HAVE_STRUCT_EXCEPTION) |
| 24 | |
| 25 | #define PI 3.14159265358979323846264338327950288419716939937510582097494459 |
| 26 | |
| 27 | int |
| 28 | matherr (struct exception* e) |
| 29 | { |
| 30 | const char *n; |
| 31 | |
| 32 | if (e->type != DOMAIN) |
| 33 | return 0; |
| 34 | |
| 35 | n = e->name; |
| 36 | if (__builtin_strcmp (n, "acos") == 0 |
| 37 | || __builtin_strcmp (n, "asin") == 0) |
| 38 | e->retval = __builtin_nan (""); |
| 39 | else if (__builtin_strcmp (n, "atan2") == 0) |
| 40 | { |
| 41 | if (e->arg1 == 0 && e->arg2 == 0) |
| 42 | { |
| 43 | double nz; |
| 44 | |
| 45 | nz = -0.0; |
| 46 | if (__builtin_memcmp (&e->arg2, &nz, sizeof (double)) != 0) |
| 47 | e->retval = e->arg1; |
| 48 | else |
| 49 | e->retval = copysign (PI, e->arg1); |
| 50 | } |
| 51 | else |
| 52 | return 0; |
| 53 | } |
| 54 | else if (__builtin_strcmp (n, "log") == 0 |
| 55 | || __builtin_strcmp (n, "log10") == 0) |
| 56 | e->retval = __builtin_nan (""); |
| 57 | else if (__builtin_strcmp (n, "pow") == 0) |
| 58 | { |
| 59 | if (e->arg1 < 0) |
| 60 | e->retval = __builtin_nan (""); |
| 61 | else if (e->arg1 == 0 && e->arg2 == 0) |
| 62 | e->retval = 1.0; |
| 63 | else if (e->arg1 == 0 && e->arg2 < 0) |
| 64 | { |
| 65 | double i; |
| 66 | |
| 67 | if (modf (e->arg2, &i) == 0 && ((int64_t) i & 1) == 1) |
| 68 | e->retval = copysign (__builtin_inf (), e->arg1); |
| 69 | else |
| 70 | e->retval = __builtin_inf (); |
| 71 | } |
| 72 | else |
| 73 | return 0; |
| 74 | } |
| 75 | else if (__builtin_strcmp (n, "sqrt") == 0) |
| 76 | { |
| 77 | if (e->arg1 < 0) |
| 78 | e->retval = __builtin_nan (""); |
| 79 | else |
| 80 | return 0; |
| 81 | } |
| 82 | else |
| 83 | return 0; |
| 84 | |
| 85 | return 1; |
| 86 | } |
| 87 | |
| 88 | #endif |