glibc/sysdeps/ieee754/flt-32/s_floorf.c

/* s_floorf.c -- float version of s_floor.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
 * floorf(x)
 * Return x rounded toward -inf to integral value
 * Method:
 *	Bit twiddling.
 */

#define NO_MATH_REDIRECT
#include <math.h>
#include <math_private.h>
#include <libm-alias-float.h>
#include <math-use-builtins.h>

float
__floorf (float x)
{
#if USE_FLOORF_BUILTIN
  return __builtin_floorf (x);
#else
  /* Use generic implementation.  */
  int32_t i0, j0;
  uint32_t i;
  GET_FLOAT_WORD (i0, x);
  j0 = ((i0 >> 23) & 0xff) - 0x7f;
  if (j0 < 23)
    {
      if (j0 < 0)
	{
	  /* return 0 * sign (x) if |x| < 1  */
	  if (i0 >= 0)
	    i0 = 0;
	  else if ((i0 & 0x7fffffff) != 0)
	    i0 = 0xbf800000;
	}
      else
	{
	  i = (0x007fffff) >> j0;
	  if ((i0 & i) == 0)
	    return x;		/* x is integral  */
	  if (i0 < 0)
	    i0 += (0x00800000) >> j0;
	  i0 &= (~i);
	}
    }
  else
    {
      if (__glibc_unlikely (j0 == 0x80))
	return x + x;		/* inf or NaN  */
      else
	return x;		/* x is integral  */
    }
  SET_FLOAT_WORD (x, i0);
  return x;
#endif /* ! USE_FLOORF_BUILTIN  */
}
#ifndef __floorf
libm_alias_float (__floor, floor)
#endif