1/* @(#)s_modf.c 5.1 93/09/24 */ 2/* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13#if defined(LIBM_SCCS) && !defined(lint) 14static char rcsid[] = "$NetBSD: s_modf.c,v 1.8 1995/05/10 20:47:55 jtc Exp $"; 15#endif 16 17/* 18 * modf(double x, double *iptr) 19 * return fraction part of x, and return x's integral part in *iptr. 20 * Method: 21 * Bit twiddling. 22 * 23 * Exception: 24 * No exception. 25 */ 26 27#include "math.h" 28#include "math_private.h" 29 30#ifdef __STDC__ 31static const double one = 1.0; 32#else 33static double one = 1.0; 34#endif 35 36#ifdef __STDC__ 37 double __modf(double x, double *iptr) 38#else 39 double __modf(x, iptr) 40 double x,*iptr; 41#endif 42{ 43 int32_t i0,i1,j0; 44 u_int32_t i; 45 EXTRACT_WORDS(i0,i1,x); 46 j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ 47 if(j0<20) { /* integer part in high x */ 48 if(j0<0) { /* |x|<1 */ 49 INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */ 50 return x; 51 } else { 52 i = (0x000fffff)>>j0; 53 if(((i0&i)|i1)==0) { /* x is integral */ 54 *iptr = x; 55 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */ 56 return x; 57 } else { 58 INSERT_WORDS(*iptr,i0&(~i),0); 59 return x - *iptr; 60 } 61 } 62 } else if (j0>51) { /* no fraction part */ 63 *iptr = x*one; 64 /* We must handle NaNs separately. */ 65 if (j0 == 0x400 && ((i0 & 0xfffff) | i1)) 66 return x*one; 67 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */ 68 return x; 69 } else { /* fraction part in low x */ 70 i = ((u_int32_t)(0xffffffff))>>(j0-20); 71 if((i1&i)==0) { /* x is integral */ 72 *iptr = x; 73 INSERT_WORDS(x,i0&0x80000000,0); /* return +-0 */ 74 return x; 75 } else { 76 INSERT_WORDS(*iptr,i0,i1&(~i)); 77 return x - *iptr; 78 } 79 } 80} 81weak_alias (__modf, modf) 82#ifdef NO_LONG_DOUBLE 83strong_alias (__modf, __modfl) 84weak_alias (__modf, modfl) 85#endif 86