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 /* 14 * modfl(long double x, long double *iptr) 15 * return fraction part of x, and return x's integral part in *iptr. 16 * Method: 17 * Bit twiddling. 18 * 19 * Exception: 20 * No exception. 21 */ 22 23 #include <openlibm_math.h> 24 25 #include "math_private.h" 26 27 static const long double one = 1.0; 28 29 long double 30 modfl(long double x, long double *iptr) 31 { 32 int64_t i0,i1,jj0; 33 u_int64_t i; 34 GET_LDOUBLE_WORDS64(i0,i1,x); 35 jj0 = ((i0>>48)&0x7fff)-0x3fff; /* exponent of x */ 36 if(jj0<48) { /* integer part in high x */ 37 if(jj0<0) { /* |x|<1 */ 38 /* *iptr = +-0 */ 39 SET_LDOUBLE_WORDS64(*iptr,i0&0x8000000000000000ULL,0); 40 return x; 41 } else { 42 i = (0x0000ffffffffffffLL)>>jj0; 43 if(((i0&i)|i1)==0) { /* x is integral */ 44 *iptr = x; 45 /* return +-0 */ 46 SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); 47 return x; 48 } else { 49 SET_LDOUBLE_WORDS64(*iptr,i0&(~i),0); 50 return x - *iptr; 51 } 52 } 53 } else if (jj0>111) { /* no fraction part */ 54 *iptr = x*one; 55 /* We must handle NaNs separately. */ 56 if (jj0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1)) 57 return x*one; 58 /* return +-0 */ 59 SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); 60 return x; 61 } else { /* fraction part in low x */ 62 i = -1ULL>>(jj0-48); 63 if((i1&i)==0) { /* x is integral */ 64 *iptr = x; 65 /* return +-0 */ 66 SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); 67 return x; 68 } else { 69 SET_LDOUBLE_WORDS64(*iptr,i0,i1&(~i)); 70 return x - *iptr; 71 } 72 } 73 } 74