| 1 |
|
|---|
| 2 | /* @(#)s_rint.c 5.1 93/09/24 */
|
|---|
| 3 | /*
|
|---|
| 4 | * ====================================================
|
|---|
| 5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|---|
| 6 | *
|
|---|
| 7 | * Developed at SunPro, a Sun Microsystems, Inc. business.
|
|---|
| 8 | * Permission to use, copy, modify, and distribute this
|
|---|
| 9 | * software is freely granted, provided that this notice
|
|---|
| 10 | * is preserved.
|
|---|
| 11 | * ====================================================
|
|---|
| 12 | */
|
|---|
| 13 |
|
|---|
| 14 | /*
|
|---|
| 15 | * rint(x)
|
|---|
| 16 | * Return x rounded to integral value according to the prevailing
|
|---|
| 17 | * rounding mode.
|
|---|
| 18 | * Method:
|
|---|
| 19 | * Using floating addition.
|
|---|
| 20 | * Exception:
|
|---|
| 21 | * Inexact flag raised if x not equal to rint(x).
|
|---|
| 22 | */
|
|---|
| 23 |
|
|---|
| 24 | #include "fdlibm.h"
|
|---|
| 25 |
|
|---|
| 26 | #ifndef _DOUBLE_IS_32BITS
|
|---|
| 27 |
|
|---|
| 28 | #ifdef __STDC__
|
|---|
| 29 | static const double
|
|---|
| 30 | #else
|
|---|
| 31 | static double
|
|---|
| 32 | #endif
|
|---|
| 33 | TWO52[2]={
|
|---|
| 34 | 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
|
|---|
| 35 | -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
|
|---|
| 36 | };
|
|---|
| 37 |
|
|---|
| 38 | #ifdef __STDC__
|
|---|
| 39 | double rint(double x)
|
|---|
| 40 | #else
|
|---|
| 41 | double rint(x)
|
|---|
| 42 | double x;
|
|---|
| 43 | #endif
|
|---|
| 44 | {
|
|---|
| 45 | int32_t i0,j0,sx;
|
|---|
| 46 | uint32_t i,i1;
|
|---|
| 47 | double t;
|
|---|
| 48 | volatile double w;
|
|---|
| 49 | EXTRACT_WORDS(i0,i1,x);
|
|---|
| 50 | sx = (i0>>31)&1;
|
|---|
| 51 | j0 = ((i0>>20)&0x7ff)-0x3ff;
|
|---|
| 52 | if(j0<20) {
|
|---|
| 53 | if(j0<0) {
|
|---|
| 54 | if(((i0&0x7fffffff)|i1)==0) return x;
|
|---|
| 55 | i1 |= (i0&0x0fffff);
|
|---|
| 56 | i0 &= 0xfffe0000;
|
|---|
| 57 | i0 |= ((i1|-i1)>>12)&0x80000;
|
|---|
| 58 | SET_HIGH_WORD(x,i0);
|
|---|
| 59 | w = TWO52[sx]+x;
|
|---|
| 60 | t = w-TWO52[sx];
|
|---|
| 61 | GET_HIGH_WORD(i0,t);
|
|---|
| 62 | SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
|
|---|
| 63 | return t;
|
|---|
| 64 | } else {
|
|---|
| 65 | i = (0x000fffff)>>j0;
|
|---|
| 66 | if(((i0&i)|i1)==0) return x; /* x is integral */
|
|---|
| 67 | i>>=1;
|
|---|
| 68 | if(((i0&i)|i1)!=0) {
|
|---|
| 69 | if(j0==19) i1 = 0x40000000; else
|
|---|
| 70 | i0 = (i0&(~i))|((0x20000)>>j0);
|
|---|
| 71 | }
|
|---|
| 72 | }
|
|---|
| 73 | } else if (j0>51) {
|
|---|
| 74 | if(j0==0x400) return x+x; /* inf or NaN */
|
|---|
| 75 | else return x; /* x is integral */
|
|---|
| 76 | } else {
|
|---|
| 77 | i = ((uint32_t)(0xffffffff))>>(j0-20);
|
|---|
| 78 | if((i1&i)==0) return x; /* x is integral */
|
|---|
| 79 | i>>=1;
|
|---|
| 80 | if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20));
|
|---|
| 81 | }
|
|---|
| 82 | INSERT_WORDS(x,i0,i1);
|
|---|
| 83 | w = TWO52[sx]+x;
|
|---|
| 84 | return w-TWO52[sx];
|
|---|
| 85 | }
|
|---|
| 86 |
|
|---|
| 87 | #endif /* _DOUBLE_IS_32BITS */
|
|---|
