| /* @(#)s_modf.c 5.1 93/09/24 */ |
| /* |
| * ==================================================== |
| * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| * |
| * Developed at SunPro, a Sun Microsystems, Inc. business. |
| * Permission to use, copy, modify, and distribute this |
| * software is freely granted, provided that this notice |
| * is preserved. |
| * ==================================================== |
| */ |
| |
| #ifndef lint |
| static char rcsid[] = "$FreeBSD$"; |
| #endif |
| |
| /* |
| * modf(double x, double *iptr) |
| * return fraction part of x, and return x's integral part in *iptr. |
| * Method: |
| * Bit twiddling. |
| * |
| * Exception: |
| * No exception. |
| */ |
| |
| #include "math.h" |
| #include "math_private.h" |
| |
| static const double one = 1.0; |
| |
| double |
| modf(double x, double *iptr) |
| { |
| int32_t i0,i1,j0; |
| u_int32_t i; |
| EXTRACT_WORDS(i0,i1,x); |
| j0 = ((i0>>20)&0x7ff)-0x3ff; /* exponent of x */ |
| if(j0<20) { /* integer part in high x */ |
| if(j0<0) { /* |x|<1 */ |
| INSERT_WORDS(*iptr,i0&0x80000000,0); /* *iptr = +-0 */ |
| return x; |
| } else { |
| i = (0x000fffff)>>j0; |
| if(((i0&i)|i1)==0) { /* x is integral */ |
| u_int32_t high; |
| *iptr = x; |
| GET_HIGH_WORD(high,x); |
| INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
| return x; |
| } else { |
| INSERT_WORDS(*iptr,i0&(~i),0); |
| return x - *iptr; |
| } |
| } |
| } else if (j0>51) { /* no fraction part */ |
| u_int32_t high; |
| if (j0 == 0x400) { /* inf/NaN */ |
| *iptr = x; |
| return 0.0 / x; |
| } |
| *iptr = x*one; |
| GET_HIGH_WORD(high,x); |
| INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
| return x; |
| } else { /* fraction part in low x */ |
| i = ((u_int32_t)(0xffffffff))>>(j0-20); |
| if((i1&i)==0) { /* x is integral */ |
| u_int32_t high; |
| *iptr = x; |
| GET_HIGH_WORD(high,x); |
| INSERT_WORDS(x,high&0x80000000,0); /* return +-0 */ |
| return x; |
| } else { |
| INSERT_WORDS(*iptr,i0,i1&(~i)); |
| return x - *iptr; |
| } |
| } |
| } |
