toolchain/gcc/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 ANSI_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 TRAD_SYNOPSIS
  24         #include <math.h>
  25         double floor(<[x]>)
  26         double <[x]>;
  27         float floorf(<[x]>)
  28         float <[x]>;
  29         double ceil(<[x]>)
  30         double <[x]>;
  31         float ceilf(<[x]>)
  32         float <[x]>;
  33
  34 DESCRIPTION
  35 <<floor>> and <<floorf>> find
  36 @tex
  37 $\lfloor x \rfloor$,
  38 @end tex
  39 the nearest integer less than or equal to <[x]>.
  40 <<ceil>> and <<ceilf>> find
  41 @tex
  42 $\lceil x\rceil$,
  43 @end tex
  44 the nearest integer greater than or equal to <[x]>.
  45
  46 RETURNS
  47 <<floor>> and <<ceil>> return the integer result as a double.
  48 <<floorf>> and <<ceilf>> return the integer result as a float.
  49
  50 PORTABILITY
  51 <<floor>> and <<ceil>> are ANSI.
  52 <<floorf>> and <<ceilf>> are extensions.
  53
  54 */
  55
  56 /*****************************************************************
  57  * floor
  58  *
  59  * Input:
  60  *   x  - floating point value
  61  *
  62  * Output:
  63  *   Smallest integer less than x.
  64  *
  65  * Description:
  66  *   This routine returns the smallest integer less than x.
  67  *
  68  *****************************************************************/
  69
  70 #include "fdlibm.h"
  71 #include "zmath.h"
  72
  73 #ifndef _DOUBLE_IS_32BITS
  74
  75 double
  76 _DEFUN (floor, (double),
  77               double x)
  78 {
  79   double f, y;
  80
  81   if (x > -1.0 && x < 1.0)
  82     return (x >= 0 ? 0 : -1.0);
  83
  84   y = modf (x, &f);
  85
  86   if (y == 0.0)
  87     return (x);
  88
  89   return (x >= 0 ? f : f - 1.0);
  90 }
  91
  92 #endif /* _DOUBLE_IS_32BITS */