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