1*1e651e1eSRoland Levillain 2*1e651e1eSRoland Levillain /* @(#)s_modf.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_modf(double x, double *iptr) 16*1e651e1eSRoland Levillain * return fraction part of x, and return x's integral part in *iptr. 17*1e651e1eSRoland Levillain * Method: 18*1e651e1eSRoland Levillain * Bit twiddling. 19*1e651e1eSRoland Levillain * 20*1e651e1eSRoland Levillain * Exception: 21*1e651e1eSRoland Levillain * No exception. 22*1e651e1eSRoland Levillain */ 23*1e651e1eSRoland Levillain 24*1e651e1eSRoland Levillain #include "fdlibm.h" 25*1e651e1eSRoland Levillain 26*1e651e1eSRoland Levillain #ifdef __STDC__ 27*1e651e1eSRoland Levillain static const double one = 1.0; 28*1e651e1eSRoland Levillain #else 29*1e651e1eSRoland Levillain static double one = 1.0; 30*1e651e1eSRoland Levillain #endif 31*1e651e1eSRoland Levillain 32*1e651e1eSRoland Levillain #ifdef __STDC__ ieee_modf(double x,double * iptr)33*1e651e1eSRoland Levillain double ieee_modf(double x, double *iptr) 34*1e651e1eSRoland Levillain #else 35*1e651e1eSRoland Levillain double ieee_modf(x, iptr) 36*1e651e1eSRoland Levillain double x,*iptr; 37*1e651e1eSRoland Levillain #endif 38*1e651e1eSRoland Levillain { 39*1e651e1eSRoland Levillain int i0,i1,j0; 40*1e651e1eSRoland Levillain unsigned i; 41*1e651e1eSRoland Levillain i0 = __HI(x); /* high x */ 42*1e651e1eSRoland Levillain i1 = __LO(x); /* low x */ 43*1e651e1eSRoland Levillain j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ 44*1e651e1eSRoland Levillain if(j0<20) { /* integer part in high x */ 45*1e651e1eSRoland Levillain if(j0<0) { /* |x|<1 */ 46*1e651e1eSRoland Levillain __HIp(iptr) = i0&0x80000000; 47*1e651e1eSRoland Levillain __LOp(iptr) = 0; /* *iptr = +-0 */ 48*1e651e1eSRoland Levillain return x; 49*1e651e1eSRoland Levillain } else { 50*1e651e1eSRoland Levillain i = (0x000fffff)>>j0; 51*1e651e1eSRoland Levillain if(((i0&i)|i1)==0) { /* x is integral */ 52*1e651e1eSRoland Levillain *iptr = x; 53*1e651e1eSRoland Levillain __HI(x) &= 0x80000000; 54*1e651e1eSRoland Levillain __LO(x) = 0; /* return +-0 */ 55*1e651e1eSRoland Levillain return x; 56*1e651e1eSRoland Levillain } else { 57*1e651e1eSRoland Levillain __HIp(iptr) = i0&(~i); 58*1e651e1eSRoland Levillain __LOp(iptr) = 0; 59*1e651e1eSRoland Levillain return x - *iptr; 60*1e651e1eSRoland Levillain } 61*1e651e1eSRoland Levillain } 62*1e651e1eSRoland Levillain } else if (j0>51) { /* no fraction part */ 63*1e651e1eSRoland Levillain *iptr = x*one; 64*1e651e1eSRoland Levillain __HI(x) &= 0x80000000; 65*1e651e1eSRoland Levillain __LO(x) = 0; /* return +-0 */ 66*1e651e1eSRoland Levillain return x; 67*1e651e1eSRoland Levillain } else { /* fraction part in low x */ 68*1e651e1eSRoland Levillain i = ((unsigned)(0xffffffff))>>(j0-20); 69*1e651e1eSRoland Levillain if((i1&i)==0) { /* x is integral */ 70*1e651e1eSRoland Levillain *iptr = x; 71*1e651e1eSRoland Levillain __HI(x) &= 0x80000000; 72*1e651e1eSRoland Levillain __LO(x) = 0; /* return +-0 */ 73*1e651e1eSRoland Levillain return x; 74*1e651e1eSRoland Levillain } else { 75*1e651e1eSRoland Levillain __HIp(iptr) = i0; 76*1e651e1eSRoland Levillain __LOp(iptr) = i1&(~i); 77*1e651e1eSRoland Levillain return x - *iptr; 78*1e651e1eSRoland Levillain } 79*1e651e1eSRoland Levillain } 80*1e651e1eSRoland Levillain } 81