| /* @(#)s_floor.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * 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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_floor.c,v 1.8 1995/05/10 20:47:20 jtc Exp $"; |
| #endif |
| |
| /* |
| * floor(x) |
| * Return x rounded toward -inf to integral value |
| * Method: |
| * Bit twiddling. |
| * Exception: |
| * Inexact flag raised if x not equal to floor(x). |
| */ |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| #ifdef __STDC__ |
| static const double huge = 1.0e300; |
| #else |
| static double huge = 1.0e300; |
| #endif |
| |
| #ifdef __STDC__ |
| double __floor(double x) |
| #else |
| double __floor(x) |
| double x; |
| #endif |
| { |
| int32_t i0,i1,j0; |
| u_int32_t i,j; |
| EXTRACT_WORDS(i0,i1,x); |
| j0 = ((i0>>20)&0x7ff)-0x3ff; |
| if(j0<20) { |
| if(j0<0) { /* raise inexact if x != 0 */ |
| if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
| if(i0>=0) {i0=i1=0;} |
| else if(((i0&0x7fffffff)|i1)!=0) |
| { i0=0xbff00000;i1=0;} |
| } |
| } else { |
| i = (0x000fffff)>>j0; |
| if(((i0&i)|i1)==0) return x; /* x is integral */ |
| if(huge+x>0.0) { /* raise inexact flag */ |
| if(i0<0) i0 += (0x00100000)>>j0; |
| i0 &= (~i); i1=0; |
| } |
| } |
| } else if (j0>51) { |
| if(j0==0x400) return x+x; /* inf or NaN */ |
| else return x; /* x is integral */ |
| } else { |
| i = ((u_int32_t)(0xffffffff))>>(j0-20); |
| if((i1&i)==0) return x; /* x is integral */ |
| if(huge+x>0.0) { /* raise inexact flag */ |
| if(i0<0) { |
| if(j0==20) i0+=1; |
| else { |
| j = i1+(1<<(52-j0)); |
| if(j<i1) i0 +=1 ; /* got a carry */ |
| i1=j; |
| } |
| } |
| i1 &= (~i); |
| } |
| } |
| INSERT_WORDS(x,i0,i1); |
| return x; |
| } |
| weak_alias (__floor, floor) |
| #ifdef NO_LONG_DOUBLE |
| strong_alias (__floor, __floorl) |
| weak_alias (__floor, floorl) |
| #endif |
