libgo/runtime/go-type-float.c

   1 /* go-type-float.c -- hash and equality float functions.
   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 #include <math.h>
   8 #include <stdint.h>
   9 #include "runtime.h"
  10 #include "go-type.h"
  11
  12 /* Hash function for float types.  */
  13
  14 uintptr_t
  15 __go_type_hash_float (const void *vkey, uintptr_t key_size)
  16 {
  17   if (key_size == 4)
  18     {
  19       const float *fp;
  20       float f;
  21       uint32_t si;
  22
  23       fp = (const float *) vkey;
  24       f = *fp;
  25
  26       if (isinf (f) || f == 0)
  27         return 0;
  28
  29       /* NaN != NaN, so the hash code of a NaN is irrelevant.  Make it
  30          random so that not all NaNs wind up in the same place.  */
  31       if (isnan (f))
  32         return runtime_fastrand1 ();
  33
  34       memcpy (&si, vkey, 4);
  35       return (uintptr_t) si;
  36     }
  37   else if (key_size == 8)
  38     {
  39       const double *dp;
  40       double d;
  41       uint64_t di;
  42
  43       dp = (const double *) vkey;
  44       d = *dp;
  45
  46       if (isinf (d) || d == 0)
  47         return 0;
  48
  49       if (isnan (d))
  50         return runtime_fastrand1 ();
  51
  52       memcpy (&di, vkey, 8);
  53       return (uintptr_t) di;
  54     }
  55   else
  56     runtime_throw ("__go_type_hash_float: invalid float size");
  57 }
  58
  59 /* Equality function for float types.  */
  60
  61 _Bool
  62 __go_type_equal_float (const void *vk1, const void *vk2, uintptr_t key_size)
  63 {
  64   if (key_size == 4)
  65     {
  66       const float *fp1;
  67       const float *fp2;
  68
  69       fp1 = (const float *) vk1;
  70       fp2 = (const float *) vk2;
  71
  72       return *fp1 == *fp2;
  73     }
  74   else if (key_size == 8)
  75     {
  76       const double *dp1;
  77       const double *dp2;
  78
  79       dp1 = (const double *) vk1;
  80       dp2 = (const double *) vk2;
  81
  82       return *dp1 == *dp2;
  83     }
  84   else
  85     runtime_throw ("__go_type_equal_float: invalid float size");
  86 }