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path: root/src/math/s_modf.c
blob: a5528d6b12340f8be10f40b704df66e1b2ff7dab (plain)
 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 ``` ``````/* @(#)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. * ==================================================== */ /* * 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 #include "math_private.h" static const double one = 1.0; double modf(double x, double *iptr) { int32_t i0,i1,j0; uint32_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 */ uint32_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 */ uint32_t high; *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 = ((uint32_t)(0xffffffff))>>(j0-20); if((i1&i)==0) { /* x is integral */ uint32_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; } } } ``````