lib/gnu/ieee_float/frexp.c

   1 /*
   2 libc/ieee_float/frexp.c
   3
   4 Created:        Oct 14, 1993 by Philip Homburg <philip@cs.vu.nl>
   5
   6 Implementation of frexp that directly manipulates the exponent bits in an
   7 ieee float
   8 */
   9
  10 #include <sys/types.h>
  11 #include <math.h>
  12
  13 #include "ieee_float.h"
  14
  15 double frexp(value, eptr)
  16 double value;
  17 int *eptr;
  18 {
  19         struct f64 *f64p;
  20         int exp, exp_bias;
  21         double factor;
  22
  23         f64p= (struct f64 *)&value;
  24         exp_bias= 0;
  25
  26         exp= F64_GET_EXP(f64p);
  27         if (exp == F64_EXP_MAX)
  28         {       /* Either infinity or Nan */
  29                 *eptr= 0;
  30                 return value;
  31         }
  32         if (exp == 0)
  33         {
  34                 /* Either 0 or denormal */
  35                 if (F64_GET_MANT_LOW(f64p) == 0 &&
  36                         F64_GET_MANT_HIGH(f64p) == 0)
  37                 {
  38                         *eptr= 0;
  39                         return value;
  40                 }
  41
  42                 /* Multiply by 2^64 */
  43                 factor= 65536.0;        /* 2^16 */
  44                 factor *= factor;       /* 2^32 */
  45                 factor *= factor;       /* 2^64 */
  46                 value *= factor;
  47                 exp_bias= 64;
  48                 exp= F64_GET_EXP(f64p);
  49         }
  50
  51         exp= exp - F64_EXP_BIAS - exp_bias + 1;
  52         *eptr= exp;
  53         F64_SET_EXP(f64p, F64_EXP_BIAS-1);
  54
  55         return value;
  56 }
  57
  58 /*
  59  * $PchId: frexp.c,v 1.3 1996/02/22 21:01:39 philip Exp $
  60  */