toolchain/gcc/newlib/libm/mathfp/sf_frexp.c

   1
   2 /* @(#)z_frexpf.c 1.0 98/08/13 */
   3 /******************************************************************
   4  * frexp
   5  *
   6  * Input:
   7  *   d   - floating point value
   8  *   exp - exponent value
   9  *
  10  * Output:
  11  *   A floating point value in the range [0.5, 1).
  12  *
  13  * Description:
  14  *   This routine breaks a floating point value into a number f and
  15  *   an exponent exp such that d = f * 2 ^ exp.
  16  *
  17  *****************************************************************/
  18
  19 #include "fdlibm.h"
  20 #include "zmath.h"
  21
  22 float frexpf (float d, int *exp)
  23 {
  24   float f;
  25   __int32_t wf, wd;
  26
  27   GET_FLOAT_WORD (wd, d);
  28
  29   /* Get the exponent. */
  30   *exp = ((wd & 0x7f800000) >> 23) - 126;
  31
  32   /* Get the mantissa. */
  33   wf = wd & 0x7fffff;
  34   wf |= 0x3f000000;
  35
  36   SET_FLOAT_WORD (f, wf);
  37
  38   /* Check for special values. */
  39   switch (numtestf (f))
  40     {
  41       case NAN:
  42       case INF:
  43         errno = EDOM;
  44         *exp = 0;
  45         return (f);
  46     }
  47
  48   return (f);
  49 }
  50
  51 #ifdef _DOUBLE_IS_32BITS
  52
  53 double frexp (double x, int *exp)
  54 {
  55   return (double) frexpf ((float) x, exp);
  56 }
  57
  58 #endif /* defined(_DOUBLE_IS_32BITS) */