1 #include "erfa.h"
2
eraD2tf(int ndp,double days,char * sign,int ihmsf[4])3 void eraD2tf(int ndp, double days, char *sign, int ihmsf[4])
4 /*
5 ** - - - - - - - -
6 ** e r a D 2 t f
7 ** - - - - - - - -
8 **
9 ** Decompose days to hours, minutes, seconds, fraction.
10 **
11 ** Given:
12 ** ndp int resolution (Note 1)
13 ** days double interval in days
14 **
15 ** Returned:
16 ** sign char '+' or '-'
17 ** ihmsf int[4] hours, minutes, seconds, fraction
18 **
19 ** Notes:
20 **
21 ** 1) The argument ndp is interpreted as follows:
22 **
23 ** ndp resolution
24 ** : ...0000 00 00
25 ** -7 1000 00 00
26 ** -6 100 00 00
27 ** -5 10 00 00
28 ** -4 1 00 00
29 ** -3 0 10 00
30 ** -2 0 01 00
31 ** -1 0 00 10
32 ** 0 0 00 01
33 ** 1 0 00 00.1
34 ** 2 0 00 00.01
35 ** 3 0 00 00.001
36 ** : 0 00 00.000...
37 **
38 ** 2) The largest positive useful value for ndp is determined by the
39 ** size of days, the format of double on the target platform, and
40 ** the risk of overflowing ihmsf[3]. On a typical platform, for
41 ** days up to 1.0, the available floating-point precision might
42 ** correspond to ndp=12. However, the practical limit is typically
43 ** ndp=9, set by the capacity of a 32-bit int, or ndp=4 if int is
44 ** only 16 bits.
45 **
46 ** 3) The absolute value of days may exceed 1.0. In cases where it
47 ** does not, it is up to the caller to test for and handle the
48 ** case where days is very nearly 1.0 and rounds up to 24 hours,
49 ** by testing for ihmsf[0]=24 and setting ihmsf[0-3] to zero.
50 **
51 ** Copyright (C) 2013-2014, NumFOCUS Foundation.
52 ** Derived, with permission, from the SOFA library. See notes at end of file.
53 */
54 {
55 int nrs, n;
56 double rs, rm, rh, a, w, ah, am, as, af;
57
58
59 /* Handle sign. */
60 *sign = (char) ( ( days >= 0.0 ) ? '+' : '-' );
61
62 /* Interval in seconds. */
63 a = ERFA_DAYSEC * fabs(days);
64
65 /* Pre-round if resolution coarser than 1s (then pretend ndp=1). */
66 if (ndp < 0) {
67 nrs = 1;
68 for (n = 1; n <= -ndp; n++) {
69 nrs *= (n == 2 || n == 4) ? 6 : 10;
70 }
71 rs = (double) nrs;
72 w = a / rs;
73 a = rs * ERFA_DNINT(w);
74 }
75
76 /* Express the unit of each field in resolution units. */
77 nrs = 1;
78 for (n = 1; n <= ndp; n++) {
79 nrs *= 10;
80 }
81 rs = (double) nrs;
82 rm = rs * 60.0;
83 rh = rm * 60.0;
84
85 /* Round the interval and express in resolution units. */
86 a = ERFA_DNINT(rs * a);
87
88 /* Break into fields. */
89 ah = a / rh;
90 ah = ERFA_DINT(ah);
91 a -= ah * rh;
92 am = a / rm;
93 am = ERFA_DINT(am);
94 a -= am * rm;
95 as = a / rs;
96 as = ERFA_DINT(as);
97 af = a - as * rs;
98
99 /* Return results. */
100 ihmsf[0] = (int) ah;
101 ihmsf[1] = (int) am;
102 ihmsf[2] = (int) as;
103 ihmsf[3] = (int) af;
104
105 return;
106
107 }
108 /*----------------------------------------------------------------------
109 **
110 **
111 ** Copyright (C) 2013-2014, NumFOCUS Foundation.
112 ** All rights reserved.
113 **
114 ** This library is derived, with permission, from the International
115 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
116 ** available from http://www.iausofa.org.
117 **
118 ** The ERFA version is intended to retain identical functionality to
119 ** the SOFA library, but made distinct through different function and
120 ** file names, as set out in the SOFA license conditions. The SOFA
121 ** original has a role as a reference standard for the IAU and IERS,
122 ** and consequently redistribution is permitted only in its unaltered
123 ** state. The ERFA version is not subject to this restriction and
124 ** therefore can be included in distributions which do not support the
125 ** concept of "read only" software.
126 **
127 ** Although the intent is to replicate the SOFA API (other than
128 ** replacement of prefix names) and results (with the exception of
129 ** bugs; any that are discovered will be fixed), SOFA is not
130 ** responsible for any errors found in this version of the library.
131 **
132 ** If you wish to acknowledge the SOFA heritage, please acknowledge
133 ** that you are using a library derived from SOFA, rather than SOFA
134 ** itself.
135 **
136 **
137 ** TERMS AND CONDITIONS
138 **
139 ** Redistribution and use in source and binary forms, with or without
140 ** modification, are permitted provided that the following conditions
141 ** are met:
142 **
143 ** 1 Redistributions of source code must retain the above copyright
144 ** notice, this list of conditions and the following disclaimer.
145 **
146 ** 2 Redistributions in binary form must reproduce the above copyright
147 ** notice, this list of conditions and the following disclaimer in
148 ** the documentation and/or other materials provided with the
149 ** distribution.
150 **
151 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
152 ** the International Astronomical Union nor the names of its
153 ** contributors may be used to endorse or promote products derived
154 ** from this software without specific prior written permission.
155 **
156 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
157 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
158 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
159 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
160 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
161 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
162 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
163 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
164 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
165 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
166 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
167 ** POSSIBILITY OF SUCH DAMAGE.
168 **
169 */
170