s_floor.c revision 176280
1132720Skan/* @(#)s_floor.c 5.1 93/09/24 */ 2132720Skan/* 3132720Skan * ==================================================== 4132720Skan * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5132720Skan * 6132720Skan * Developed at SunPro, a Sun Microsystems, Inc. business. 7132720Skan * Permission to use, copy, modify, and distribute this 8132720Skan * software is freely granted, provided that this notice 9132720Skan * is preserved. 10132720Skan * ==================================================== 11132720Skan */ 12132720Skan 13132720Skan#ifndef lint 14132720Skanstatic char rcsid[] = "$FreeBSD: head/lib/msun/src/s_floor.c 176280 2008-02-14 15:10:34Z bde $"; 15132720Skan#endif 16132720Skan 17132720Skan/* 18169691Skan * floor(x) 19132720Skan * Return x rounded toward -inf to integral value 20132720Skan * Method: 21132720Skan * Bit twiddling. 22132720Skan * Exception: 23132720Skan * Inexact flag raised if x not equal to floor(x). 24132720Skan */ 25132720Skan 26132720Skan#include "math.h" 27132720Skan#include "math_private.h" 28132720Skan 29132720Skanstatic const double huge = 1.0e300; 30132720Skan 31132720Skandouble 32132720Skanfloor(double x) 33132720Skan{ 34132720Skan int32_t i0,i1,j0; 35132720Skan u_int32_t i,j; 36132720Skan EXTRACT_WORDS(i0,i1,x); 37 j0 = ((i0>>20)&0x7ff)-0x3ff; 38 if(j0<20) { 39 if(j0<0) { /* raise inexact if x != 0 */ 40 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 41 if(i0>=0) {i0=i1=0;} 42 else if(((i0&0x7fffffff)|i1)!=0) 43 { i0=0xbff00000;i1=0;} 44 } 45 } else { 46 i = (0x000fffff)>>j0; 47 if(((i0&i)|i1)==0) return x; /* x is integral */ 48 if(huge+x>0.0) { /* raise inexact flag */ 49 if(i0<0) i0 += (0x00100000)>>j0; 50 i0 &= (~i); i1=0; 51 } 52 } 53 } else if (j0>51) { 54 if(j0==0x400) return x+x; /* inf or NaN */ 55 else return x; /* x is integral */ 56 } else { 57 i = ((u_int32_t)(0xffffffff))>>(j0-20); 58 if((i1&i)==0) return x; /* x is integral */ 59 if(huge+x>0.0) { /* raise inexact flag */ 60 if(i0<0) { 61 if(j0==20) i0+=1; 62 else { 63 j = i1+(1<<(52-j0)); 64 if(j<i1) i0 +=1 ; /* got a carry */ 65 i1=j; 66 } 67 } 68 i1 &= (~i); 69 } 70 } 71 INSERT_WORDS(x,i0,i1); 72 return x; 73} 74 75#if LDBL_MANT_DIG == 53 76__weak_reference(floor, floorl); 77#endif 78