regress/lib/libc/ieeefp/subnormal/subnormal.c

   1 /* $NetBSD$ */
   2 #include <math.h>
   3 #include <float.h>
   4 #include <assert.h>
   5
   6 #ifdef USE_FLOAT
   7 #define FPTYPE float
   8 #define FPTYPE_MIN FLT_MIN
   9 #define FPTYPE_MIN_EXP FLT_MIN_EXP
  10 #define FPTYPE_MANT_DIG FLT_MANT_DIG
  11 #define LDEXP(d,e) ldexpf(d,e)
  12 #define MODF(d,ip) modff(d,ip)
  13 #define FREXP(d,e) frexpf(d,e)
  14 #else
  15 #ifdef USE_LONGDOUBLE
  16 #define FPTYPE long double
  17 #define FPTYPE_MIN LDBL_MIN
  18 #define FPTYPE_MIN_EXP LDBL_MIN_EXP
  19 #define FPTYPE_MANT_DIG LDBL_MANT_DIG
  20 #define LDEXP(d,e) ldexpl(d,e)
  21 #define MODF(d,ip) modfl(d,ip)
  22 #define FREXP(d,e) frexpl(d,e)
  23 #else
  24 #define FPTYPE double
  25 #define FPTYPE_MIN DBL_MIN
  26 #define FPTYPE_MIN_EXP DBL_MIN_EXP
  27 #define FPTYPE_MANT_DIG DBL_MANT_DIG
  28 #define LDEXP(d,e) ldexp(d,e)
  29 #define MODF(d,ip) modf(d,ip)
  30 #define FREXP(d,e) frexp(d,e)
  31 #endif
  32 #endif
  33
  34 int
  35 main()
  36 {
  37         FPTYPE d0, d1, d2, f, ip;
  38         int e, i;
  39
  40         d0 = FPTYPE_MIN;
  41         assert(fpclassify(d0) == FP_NORMAL);
  42         f = FREXP(d0, &e);
  43         assert(e == FPTYPE_MIN_EXP);
  44         assert(f == 0.5);
  45         d1 = d0;
  46
  47         /* shift a "1" bit through the mantissa (skip the implicit bit) */
  48         for (i = 1; i < FPTYPE_MANT_DIG; i++) {
  49                 d1 /= 2;
  50                 assert(fpclassify(d1) == FP_SUBNORMAL);
  51                 assert(d1 > 0 && d1 < d0);
  52
  53                 d2 = LDEXP(d0, -i);
  54                 assert(d2 == d1);
  55                 d2 = MODF(d1, &ip);
  56                 assert(d2 == d1);
  57                 assert(ip == 0);
  58
  59                 f = FREXP(d1, &e);
  60                 assert(e == FPTYPE_MIN_EXP - i);
  61                 assert(f == 0.5);
  62         }
  63
  64         d1 /= 2;
  65         assert(fpclassify(d1) == FP_ZERO);
  66         f = FREXP(d1, &e);
  67         assert(e == 0);
  68         assert(f == 0);
  69
  70         return (0);
  71 }