1 files changed, 148 insertions, 0 deletions
diff --git a/ast/erfa/cal2jd.c b/ast/erfa/cal2jd.c
new file mode 100644
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+++ b/ast/erfa/cal2jd.c
@@ -0,0 +1,148 @@
+#include "erfa.h"
+
+int eraCal2jd(int iy, int im, int id, double *djm0, double *djm)
+/*
+**  - - - - - - - - - -
+**   e r a C a l 2 j d
+**  - - - - - - - - - -
+**
+**  Gregorian Calendar to Julian Date.
+**
+**  Given:
+**     iy,im,id  int     year, month, day in Gregorian calendar (Note 1)
+**
+**  Returned:
+**     djm0      double  MJD zero-point: always 2400000.5
+**     djm       double  Modified Julian Date for 0 hrs
+**
+**  Returned (function value):
+**               int     status:
+**                           0 = OK
+**                          -1 = bad year   (Note 3: JD not computed)
+**                          -2 = bad month  (JD not computed)
+**                          -3 = bad day    (JD computed)
+**
+**  Notes:
+**
+**  1) The algorithm used is valid from -4800 March 1, but this
+**     implementation rejects dates before -4799 January 1.
+**
+**  2) The Julian Date is returned in two pieces, in the usual ERFA
+**     manner, which is designed to preserve time resolution.  The
+**     Julian Date is available as a single number by adding djm0 and
+**     djm.
+**
+**  3) In early eras the conversion is from the "Proleptic Gregorian
+**     Calendar";  no account is taken of the date(s) of adoption of
+**     the Gregorian Calendar, nor is the AD/BC numbering convention
+**     observed.
+**
+**  Reference:
+**
+**     Explanatory Supplement to the Astronomical Almanac,
+**     P. Kenneth Seidelmann (ed), University Science Books (1992),
+**     Section 12.92 (p604).
+**
+**  Copyright (C) 2013-2016, NumFOCUS Foundation.
+**  Derived, with permission, from the SOFA library.  See notes at end of file.
+*/
+{
+   int j, ly, my;
+   long iypmy;
+
+/* Earliest year allowed (4800BC) */
+   const int IYMIN = -4799;
+
+/* Month lengths in days */
+   static const int mtab[]
+                     = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+
+
+/* Preset status. */
+   j = 0;
+
+/* Validate year and month. */
+   if (iy < IYMIN) return -1;
+   if (im < 1 || im > 12) return -2;
+
+/* If February in a leap year, 1, otherwise 0. */
+   ly = ((im == 2) && !(iy%4) && (iy%100 || !(iy%400)));
+
+/* Validate day, taking into account leap years. */
+   if ( (id < 1) || (id > (mtab[im-1] + ly))) j = -3;
+
+/* Return result. */
+   my = (im - 14) / 12;
+   iypmy = (long) (iy + my);
+   *djm0 = ERFA_DJM0;
+   *djm = (double)((1461L * (iypmy + 4800L)) / 4L
+                 + (367L * (long) (im - 2 - 12 * my)) / 12L
+                 - (3L * ((iypmy + 4900L) / 100L)) / 4L
+                 + (long) id - 2432076L);
+
+/* Return status. */
+   return j;
+
+}
+/*----------------------------------------------------------------------
+**  
+**  
+**  Copyright (C) 2013-2016, NumFOCUS Foundation.
+**  All rights reserved.
+**  
+**  This library is derived, with permission, from the International
+**  Astronomical Union's "Standards of Fundamental Astronomy" library,
+**  available from http://www.iausofa.org.
+**  
+**  The ERFA version is intended to retain identical functionality to
+**  the SOFA library, but made distinct through different function and
+**  file names, as set out in the SOFA license conditions.  The SOFA
+**  original has a role as a reference standard for the IAU and IERS,
+**  and consequently redistribution is permitted only in its unaltered
+**  state.  The ERFA version is not subject to this restriction and
+**  therefore can be included in distributions which do not support the
+**  concept of "read only" software.
+**  
+**  Although the intent is to replicate the SOFA API (other than
+**  replacement of prefix names) and results (with the exception of
+**  bugs;  any that are discovered will be fixed), SOFA is not
+**  responsible for any errors found in this version of the library.
+**  
+**  If you wish to acknowledge the SOFA heritage, please acknowledge
+**  that you are using a library derived from SOFA, rather than SOFA
+**  itself.
+**  
+**  
+**  TERMS AND CONDITIONS
+**  
+**  Redistribution and use in source and binary forms, with or without
+**  modification, are permitted provided that the following conditions
+**  are met:
+**  
+**  1 Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+**  
+**  2 Redistributions in binary form must reproduce the above copyright
+**    notice, this list of conditions and the following disclaimer in
+**    the documentation and/or other materials provided with the
+**    distribution.
+**  
+**  3 Neither the name of the Standards Of Fundamental Astronomy Board,
+**    the International Astronomical Union nor the names of its
+**    contributors may be used to endorse or promote products derived
+**    from this software without specific prior written permission.
+**  
+**  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+**  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+**  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+**  FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+**  COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+**  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+**  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+**  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+**  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+**  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+**  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+**  POSSIBILITY OF SUCH DAMAGE.
+**  
+*/