cfloat.c

   1 /*
   2  * Floating point functions that are difficult or impossible to implement
   3  * in pure Haskell.
   4  *
   5  * Copyright (C) 2009 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 }