1*1e651e1eSRoland Levillain 2*1e651e1eSRoland Levillain /* @(#)s_floor.c 1.3 95/01/18 */ 3*1e651e1eSRoland Levillain /* 4*1e651e1eSRoland Levillain * ==================================================== 5*1e651e1eSRoland Levillain * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 6*1e651e1eSRoland Levillain * 7*1e651e1eSRoland Levillain * Developed at SunSoft, a Sun Microsystems, Inc. business. 8*1e651e1eSRoland Levillain * Permission to use, copy, modify, and distribute this 9*1e651e1eSRoland Levillain * software is freely granted, provided that this notice 10*1e651e1eSRoland Levillain * is preserved. 11*1e651e1eSRoland Levillain * ==================================================== 12*1e651e1eSRoland Levillain */ 13*1e651e1eSRoland Levillain 14*1e651e1eSRoland Levillain /* 15*1e651e1eSRoland Levillain * ieee_floor(x) 16*1e651e1eSRoland Levillain * Return x rounded toward -inf to integral value 17*1e651e1eSRoland Levillain * Method: 18*1e651e1eSRoland Levillain * Bit twiddling. 19*1e651e1eSRoland Levillain * Exception: 20*1e651e1eSRoland Levillain * Inexact flag raised if x not equal to ieee_floor(x). 21*1e651e1eSRoland Levillain */ 22*1e651e1eSRoland Levillain 23*1e651e1eSRoland Levillain #include "fdlibm.h" 24*1e651e1eSRoland Levillain 25*1e651e1eSRoland Levillain #ifdef __STDC__ 26*1e651e1eSRoland Levillain static const double huge = 1.0e300; 27*1e651e1eSRoland Levillain #else 28*1e651e1eSRoland Levillain static double huge = 1.0e300; 29*1e651e1eSRoland Levillain #endif 30*1e651e1eSRoland Levillain 31*1e651e1eSRoland Levillain #ifdef __STDC__ ieee_floor(double x)32*1e651e1eSRoland Levillain double ieee_floor(double x) 33*1e651e1eSRoland Levillain #else 34*1e651e1eSRoland Levillain double ieee_floor(x) 35*1e651e1eSRoland Levillain double x; 36*1e651e1eSRoland Levillain #endif 37*1e651e1eSRoland Levillain { 38*1e651e1eSRoland Levillain int i0,i1,j0; 39*1e651e1eSRoland Levillain unsigned i,j; 40*1e651e1eSRoland Levillain i0 = __HI(x); 41*1e651e1eSRoland Levillain i1 = __LO(x); 42*1e651e1eSRoland Levillain j0 = ((i0>>20)&0x7ff)-0x3ff; 43*1e651e1eSRoland Levillain if(j0<20) { 44*1e651e1eSRoland Levillain if(j0<0) { /* raise inexact if x != 0 */ 45*1e651e1eSRoland Levillain if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ 46*1e651e1eSRoland Levillain if(i0>=0) {i0=i1=0;} 47*1e651e1eSRoland Levillain else if(((i0&0x7fffffff)|i1)!=0) 48*1e651e1eSRoland Levillain { i0=0xbff00000;i1=0;} 49*1e651e1eSRoland Levillain } 50*1e651e1eSRoland Levillain } else { 51*1e651e1eSRoland Levillain i = (0x000fffff)>>j0; 52*1e651e1eSRoland Levillain if(((i0&i)|i1)==0) return x; /* x is integral */ 53*1e651e1eSRoland Levillain if(huge+x>0.0) { /* raise inexact flag */ 54*1e651e1eSRoland Levillain if(i0<0) i0 += (0x00100000)>>j0; 55*1e651e1eSRoland Levillain i0 &= (~i); i1=0; 56*1e651e1eSRoland Levillain } 57*1e651e1eSRoland Levillain } 58*1e651e1eSRoland Levillain } else if (j0>51) { 59*1e651e1eSRoland Levillain if(j0==0x400) return x+x; /* inf or NaN */ 60*1e651e1eSRoland Levillain else return x; /* x is integral */ 61*1e651e1eSRoland Levillain } else { 62*1e651e1eSRoland Levillain i = ((unsigned)(0xffffffff))>>(j0-20); 63*1e651e1eSRoland Levillain if((i1&i)==0) return x; /* x is integral */ 64*1e651e1eSRoland Levillain if(huge+x>0.0) { /* raise inexact flag */ 65*1e651e1eSRoland Levillain if(i0<0) { 66*1e651e1eSRoland Levillain if(j0==20) i0+=1; 67*1e651e1eSRoland Levillain else { 68*1e651e1eSRoland Levillain j = i1+(1<<(52-j0)); 69*1e651e1eSRoland Levillain if(j<i1) i0 +=1 ; /* got a carry */ 70*1e651e1eSRoland Levillain i1=j; 71*1e651e1eSRoland Levillain } 72*1e651e1eSRoland Levillain } 73*1e651e1eSRoland Levillain i1 &= (~i); 74*1e651e1eSRoland Levillain } 75*1e651e1eSRoland Levillain } 76*1e651e1eSRoland Levillain __HI(x) = i0; 77*1e651e1eSRoland Levillain __LO(x) = i1; 78*1e651e1eSRoland Levillain return x; 79*1e651e1eSRoland Levillain } 80