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       ---
       s_floorf.c (1521B)
       ---
            1 /* s_floorf.c -- float version of s_floor.c.
            2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@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 #ifndef lint
           17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_floorf.c,v 1.7 2002/05/28 18:15:04 alfred Exp $";
           18 #endif
           19 
           20 /*
           21  * floorf(x)
           22  * Return x rounded toward -inf to integral value
           23  * Method:
           24  *        Bit twiddling.
           25  * Exception:
           26  *        Inexact flag raised if x not equal to floorf(x).
           27  */
           28 
           29 #include "math.h"
           30 #include "math_private.h"
           31 
           32 static const float huge = 1.0e30;
           33 
           34 float
           35 floorf(float x)
           36 {
           37         int32_t i0,j0;
           38         u_int32_t i;
           39         GET_FLOAT_WORD(i0,x);
           40         j0 = ((i0>>23)&0xff)-0x7f;
           41         if(j0<23) {
           42             if(j0<0) {         /* raise inexact if x != 0 */
           43                 if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
           44                     if(i0>=0) {i0=0;}
           45                     else if((i0&0x7fffffff)!=0)
           46                         { i0=0xbf800000;}
           47                 }
           48             } else {
           49                 i = (0x007fffff)>>j0;
           50                 if((i0&i)==0) return x; /* x is integral */
           51                 if(huge+x>(float)0.0) {        /* raise inexact flag */
           52                     if(i0<0) i0 += (0x00800000)>>j0;
           53                     i0 &= (~i);
           54                 }
           55             }
           56         } else {
           57             if(j0==0x80) return x+x;        /* inf or NaN */
           58             else return x;                /* x is integral */
           59         }
           60         SET_FLOAT_WORD(x,i0);
           61         return x;
           62 }