newlib/libm/mathfp/s_floor.c

   1
   2 /* @(#)z_floor.c 1.0 98/08/13 */
   3
   4 /*
   5 FUNCTION
   6 <<floor>>, <<floorf>>, <<ceil>>, <<ceilf>>---floor and ceiling
   7 INDEX
   8         floor
   9 INDEX
  10         floorf
  11 INDEX
  12         ceil
  13 INDEX
  14         ceilf
  15
  16 SYNOPSIS
  17         #include <math.h>
  18         double floor(double <[x]>);
  19         float floorf(float <[x]>);
  20         double ceil(double <[x]>);
  21         float ceilf(float <[x]>);
  22
  23 DESCRIPTION
  24 <<floor>> and <<floorf>> find
  25 @tex
  26 $\lfloor x \rfloor$,
  27 @end tex
  28 the nearest integer less than or equal to <[x]>.
  29 <<ceil>> and <<ceilf>> find
  30 @tex
  31 $\lceil x\rceil$,
  32 @end tex
  33 the nearest integer greater than or equal to <[x]>.
  34
  35 RETURNS
  36 <<floor>> and <<ceil>> return the integer result as a double.
  37 <<floorf>> and <<ceilf>> return the integer result as a float.
  38
  39 PORTABILITY
  40 <<floor>> and <<ceil>> are ANSI.
  41 <<floorf>> and <<ceilf>> are extensions.
  42
  43 */
  44
  45 /*****************************************************************
  46  * floor
  47  *
  48  * Input:
  49  *   x  - floating point value
  50  *
  51  * Output:
  52  *   Smallest integer less than x.
  53  *
  54  * Description:
  55  *   This routine returns the smallest integer less than x.
  56  *
  57  *****************************************************************/
  58
  59 #include "fdlibm.h"
  60 #include "zmath.h"
  61
  62 #ifndef _DOUBLE_IS_32BITS
  63
  64 double
  65 floor (double x)
  66 {
  67   double f, y;
  68
  69   if (x > -1.0 && x < 1.0)
  70     return (x >= 0 ? 0 : -1.0);
  71
  72   y = modf (x, &f);
  73
  74   if (y == 0.0)
  75     return (x);
  76
  77   return (x >= 0 ? f : f - 1.0);
  78 }
  79
  80 #endif /* _DOUBLE_IS_32BITS */