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      1 /* s_floorf.c -- float version of s_floor.c.
      2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian (at) cygnus.com.
      3  */
      4 
      5 /*
      6  * ====================================================
      7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
      8  *
      9  * Developed at SunPro, a Sun Microsystems, Inc. business.
     10  * Permission to use, copy, modify, and distribute this
     11  * software is freely granted, provided that this notice
     12  * is preserved.
     13  * ====================================================
     14  */
     15 
     16 #include <sys/cdefs.h>
     17 #if defined(LIBM_SCCS) && !defined(lint)
     18 __RCSID("$NetBSD: s_floorf.c,v 1.8 2008/04/25 22:21:53 christos Exp $");
     19 #endif
     20 
     21 /*
     22  * floorf(x)
     23  * Return x rounded toward -inf to integral value
     24  * Method:
     25  *	Bit twiddling.
     26  * Exception:
     27  *	Inexact flag raised if x not equal to floorf(x).
     28  */
     29 
     30 #include "math.h"
     31 #include "math_private.h"
     32 
     33 static const float huge = 1.0e30;
     34 
     35 float
     36 floorf(float x)
     37 {
     38 	int32_t i0,jj0;
     39 	u_int32_t i;
     40 	GET_FLOAT_WORD(i0,x);
     41 	jj0 = ((i0>>23)&0xff)-0x7f;
     42 	if(jj0<23) {
     43 	    if(jj0<0) { 	/* raise inexact if x != 0 */
     44 		if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
     45 		    if(i0>=0) {i0=0;}
     46 		    else if((i0&0x7fffffff)!=0)
     47 			{ i0=0xbf800000;}
     48 		}
     49 	    } else {
     50 		i = (0x007fffff)>>jj0;
     51 		if((i0&i)==0) return x; /* x is integral */
     52 		if(huge+x>(float)0.0) {	/* raise inexact flag */
     53 		    if(i0<0) i0 += (0x00800000)>>jj0;
     54 		    i0 &= (~i);
     55 		}
     56 	    }
     57 	} else {
     58 	    if(jj0==0x80) return x+x;	/* inf or NaN */
     59 	    else return x;		/* x is integral */
     60 	}
     61 	SET_FLOAT_WORD(x,i0);
     62 	return x;
     63 }
     64