| 1 | /* s_modfl.c -- long double version of s_modf.c. |
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| 2 | */ |
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| 3 | |
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| 4 | /* |
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| 5 | * ==================================================== |
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| 6 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 7 | * |
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| 8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 9 | * Permission to use, copy, modify, and distribute this |
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| 10 | * software is freely granted, provided that this notice |
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| 11 | * is preserved. |
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| 12 | * ==================================================== |
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| 13 | */ |
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| 14 | |
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| 15 | #if defined(LIBM_SCCS) && !defined(lint) |
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| 16 | static char rcsid[] = "$NetBSD: $" ; |
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| 17 | #endif |
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| 18 | |
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| 19 | /* |
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| 20 | * modfl(long double x, long double *iptr) |
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| 21 | * return fraction part of x, and return x's integral part in *iptr. |
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| 22 | * Method: |
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| 23 | * Bit twiddling. |
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| 24 | * |
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| 25 | * Exception: |
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| 26 | * No exception. |
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| 27 | */ |
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| 28 | |
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| 29 | #include <math.h> |
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| 30 | #include <math_private.h> |
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| 31 | #include <libm-alias-ldouble.h> |
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| 32 | |
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| 33 | static const _Float128 one = 1.0; |
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| 34 | |
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| 35 | _Float128 __modfl(_Float128 x, _Float128 *iptr) |
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| 36 | { |
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| 37 | int64_t i0,i1,j0; |
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| 38 | uint64_t i; |
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| 39 | GET_LDOUBLE_WORDS64(i0,i1,x); |
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| 40 | j0 = ((i0>>48)&0x7fff)-0x3fff; /* exponent of x */ |
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| 41 | if(j0<48) { /* integer part in high x */ |
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| 42 | if(j0<0) { /* |x|<1 */ |
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| 43 | /* *iptr = +-0 */ |
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| 44 | SET_LDOUBLE_WORDS64(*iptr,i0&0x8000000000000000ULL,0); |
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| 45 | return x; |
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| 46 | } else { |
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| 47 | i = (0x0000ffffffffffffLL)>>j0; |
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| 48 | if(((i0&i)|i1)==0) { /* x is integral */ |
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| 49 | *iptr = x; |
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| 50 | /* return +-0 */ |
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| 51 | SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); |
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| 52 | return x; |
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| 53 | } else { |
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| 54 | SET_LDOUBLE_WORDS64(*iptr,i0&(~i),0); |
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| 55 | return x - *iptr; |
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| 56 | } |
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| 57 | } |
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| 58 | } else if (j0>111) { /* no fraction part */ |
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| 59 | *iptr = x*one; |
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| 60 | /* We must handle NaNs separately. */ |
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| 61 | if (j0 == 0x4000 && ((i0 & 0x0000ffffffffffffLL) | i1)) |
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| 62 | return x*one; |
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| 63 | /* return +-0 */ |
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| 64 | SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); |
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| 65 | return x; |
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| 66 | } else { /* fraction part in low x */ |
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| 67 | i = -1ULL>>(j0-48); |
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| 68 | if((i1&i)==0) { /* x is integral */ |
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| 69 | *iptr = x; |
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| 70 | /* return +-0 */ |
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| 71 | SET_LDOUBLE_WORDS64(x,i0&0x8000000000000000ULL,0); |
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| 72 | return x; |
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| 73 | } else { |
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| 74 | SET_LDOUBLE_WORDS64(*iptr,i0,i1&(~i)); |
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| 75 | return x - *iptr; |
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| 76 | } |
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| 77 | } |
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| 78 | } |
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| 79 | libm_alias_ldouble (__modf, modf) |
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| 80 | |
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