src/libm/s_floor.c
author Ozkan Sezer
Sun, 18 Nov 2018 11:50:20 +0300
changeset 12420 4a6c91d9cc33
parent 11685 1788f503254d
permissions -rw-r--r--
libm: Watcom defines huge=__huge: undefine it to fix build using Watcom.
     1 /*
     2  * ====================================================
     3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
     4  *
     5  * Developed at SunPro, a Sun Microsystems, Inc. business.
     6  * Permission to use, copy, modify, and distribute this
     7  * software is freely granted, provided that this notice
     8  * is preserved.
     9  * ====================================================
    10  */
    11 
    12 /*
    13  * floor(x)
    14  * Return x rounded toward -inf to integral value
    15  * Method:
    16  *	Bit twiddling.
    17  * Exception:
    18  *	Inexact flag raised if x not equal to floor(x).
    19  */
    20 
    21 /*#include <features.h>*/
    22 /* Prevent math.h from defining a colliding inline */
    23 #undef __USE_EXTERN_INLINES
    24 #include "math_libm.h"
    25 #include "math_private.h"
    26 
    27 #ifdef __WATCOMC__ /* Watcom defines huge=__huge */
    28 #undef huge
    29 #endif
    30 
    31 static const double huge = 1.0e300;
    32 
    33 double floor(double x)
    34 {
    35 	int32_t i0,i1,j0;
    36 	u_int32_t i,j;
    37 	EXTRACT_WORDS(i0,i1,x);
    38 	j0 = ((i0>>20)&0x7ff)-0x3ff;
    39 	if(j0<20) {
    40 	    if(j0<0) { 	/* raise inexact if x != 0 */
    41 		if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
    42 		    if(i0>=0) {i0=i1=0;}
    43 		    else if(((i0&0x7fffffff)|i1)!=0)
    44 			{ i0=0xbff00000;i1=0;}
    45 		}
    46 	    } else {
    47 		i = (0x000fffff)>>j0;
    48 		if(((i0&i)|i1)==0) return x; /* x is integral */
    49 		if(huge+x>0.0) {	/* raise inexact flag */
    50 		    if(i0<0) i0 += (0x00100000)>>j0;
    51 		    i0 &= (~i); i1=0;
    52 		}
    53 	    }
    54 	} else if (j0>51) {
    55 	    if(j0==0x400) return x+x;	/* inf or NaN */
    56 	    else return x;		/* x is integral */
    57 	} else {
    58 	    i = ((u_int32_t)(0xffffffff))>>(j0-20);
    59 	    if((i1&i)==0) return x;	/* x is integral */
    60 	    if(huge+x>0.0) { 		/* raise inexact flag */
    61 		if(i0<0) {
    62 		    if(j0==20) i0+=1;
    63 		    else {
    64 			j = i1+(1<<(52-j0));
    65 			if(j<(u_int32_t)i1) i0 +=1 ; 	/* got a carry */
    66 			i1=j;
    67 		    }
    68 		}
    69 		i1 &= (~i);
    70 	    }
    71 	}
    72 	INSERT_WORDS(x,i0,i1);
    73 	return x;
    74 }
    75 libm_hidden_def(floor)