cfloat.c

   1 /*
   2  * Floating point functions that are difficult or impossible to implement
   3  * in pure Haskell.
   4  *
   5  * Copyright (C) 2009-2010 Nick Bowler.
   6  *
   7  * License BSD2:  2-clause BSD license.  See LICENSE for full terms.
   8  * This is free software: you are free to change and redistribute it.
   9  * There is NO WARRANTY, to the extent permitted by law.
  10  */
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <errno.h>
  14 #include <math.h>
  15 #include <fenv.h>
  16
  17 #include "cfloat.h"
  18
  19 #pragma STDC FENV_ACCESS ON
  20
  21 int double_format(char *buf, char spec, int precision, double val)
  22 {
  23         char fmt[] = "%.*f";
  24         fmt[3] = spec;
  25
  26         if (buf == NULL)
  27                 return snprintf(NULL, 0, fmt, precision, val);
  28         return sprintf(buf, fmt, precision, val);
  29 }
  30
  31 double double_signum(double val)
  32 {
  33         if (signbit(val))
  34                 return -1;
  35         return 1;
  36 }
  37
  38 float float_signum(float val)
  39 {
  40         if (signbit(val))
  41                 return -1;
  42         return 1;
  43 }
  44
  45 int double_classify(double val)
  46 {
  47         switch (fpclassify(val)) {
  48         case FP_INFINITE:
  49                 return 0;
  50         case FP_NAN:
  51                 return 1;
  52         case FP_NORMAL:
  53                 return 2;
  54         case FP_SUBNORMAL:
  55                 return 3;
  56         case FP_ZERO:
  57                 return 4;
  58         }
  59
  60         return -1;
  61 }
  62
  63 int float_classify(float val)
  64 {
  65         switch (fpclassify(val)) {
  66         case FP_INFINITE:
  67                 return 0;
  68         case FP_NAN:
  69                 return 1;
  70         case FP_NORMAL:
  71                 return 2;
  72         case FP_SUBNORMAL:
  73                 return 3;
  74         case FP_ZERO:
  75                 return 4;
  76         }
  77
  78         return -1;
  79 }
  80
  81 int double_compare(double a, double b)
  82 {
  83         if (isless(a, b))
  84                 return 0;
  85         if (a == b)
  86                 return 1;
  87         if (isgreater(a, b))
  88                 return 2;
  89         if (isunordered(a, b))
  90                 return 3;
  91         return -1;
  92 }
  93
  94 int float_compare(float a, float b)
  95 {
  96         if (isless(a, b))
  97                 return 0;
  98         if (a == b)
  99                 return 1;
 100         if (isgreater(a, b))
 101                 return 2;
 102         if (isunordered(a, b))
 103                 return 3;
 104         return -1;
 105 }
 106
 107 int set_roundmode(int mode)
 108 {
 109         int cmode;
 110
 111         switch (mode) {
 112         case 0:
 113                 cmode = FE_TONEAREST;
 114                 break;
 115         case 1:
 116                 cmode = FE_UPWARD;
 117                 break;
 118         case 2:
 119                 cmode = FE_DOWNWARD;
 120                 break;
 121         case 3:
 122                 cmode = FE_TOWARDZERO;
 123                 break;
 124         default:
 125                 return -1;
 126         }
 127
 128         return fesetround(cmode);
 129 }
 130
 131 int get_roundmode(void)
 132 {
 133         int cmode = fegetround();
 134
 135         switch (cmode) {
 136         case FE_TONEAREST:
 137                 return 0;
 138         case FE_UPWARD:
 139                 return 1;
 140         case FE_DOWNWARD:
 141                 return 2;
 142         case FE_TOWARDZERO:
 143                 return 3;
 144         default:
 145                 return -1;
 146         }
 147 }
 148
 149 int fenv_restore(fenv_t *env, unsigned *excepts)
 150 {
 151         int raw_excepts = fetestexcept(FE_ALL_EXCEPT);
 152
 153         if (excepts) {
 154                 *excepts = 0;
 155
 156 #ifdef FE_DIVBYZERO
 157                 if (raw_excepts & FE_DIVBYZERO) *excepts |= 0x01;
 158 #endif
 159 #ifdef FE_INEXACT
 160                 if (raw_excepts & FE_INEXACT)   *excepts |= 0x02;
 161 #endif
 162 #ifdef FE_INVALID
 163                 if (raw_excepts & FE_INVALID)   *excepts |= 0x04;
 164 #endif
 165 #ifdef FE_OVERFLOW
 166                 if (raw_excepts & FE_OVERFLOW)  *excepts |= 0x08;
 167 #endif
 168 #ifdef FE_UNDERFLOW
 169                 if (raw_excepts & FE_UNDERFLOW) *excepts |= 0x10;
 170 #endif
 171         }
 172
 173         return fesetenv(env);
 174 }
 175
 176 int fenv_raise_excepts(unsigned excepts)
 177 {
 178         int raw_excepts = 0;
 179
 180 #ifdef FE_DIVBYZERO
 181         if (excepts & 0x01) raw_excepts |= FE_DIVBYZERO;
 182 #endif
 183 #ifdef FE_INEXACT
 184         if (excepts & 0x02) raw_excepts |= FE_INEXACT;
 185 #endif
 186 #ifdef FE_INVALID
 187         if (excepts & 0x04) raw_excepts |= FE_INVALID;
 188 #endif
 189 #ifdef FE_OVERFLOW
 190         if (excepts & 0x08) raw_excepts |= FE_OVERFLOW;
 191 #endif
 192 #ifdef FE_UNDERFLOW
 193         if (excepts & 0x10) raw_excepts |= FE_UNDERFLOW;
 194 #endif
 195         return feraiseexcept(raw_excepts);
 196 }