form_pos.h

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/* Copyright (C) 2026 Chris Piker <chris-piker@uiowa.edu>
 *
 * Author: C. Piker, via Claude Opus 5
 *
 * This file is part of das2C, the Core Das2 C Library.
 *
 * Das2C is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 2.1 as published
 * by the Free Software Foundation.
 *
 * Das2C is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
 * more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 2.1 along with das2C; if not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef _das_form_pos_h_
#define _das_form_pos_h_
 
#include <das3/form.h>
#include <das3/form_vec.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* Component systems: a position may use all six DAS_VSYS_* codes, including
   the ellipsoidal detic and graphic that a free vector refuses.  The codes and
   their lookups -- das_vsys_toStr(), das_vsys_symbol(), das_vsys_isEllipsoidal()
   and the rest -- are in form_vec.h, included above so that position code
   needs only this header. */
 
/* Exported so that its address can be compared.  Client code uses the
   DAS_FORM_POS macro below and has no reason to name this directly. */
DAS_API extern const DasForm_VTbl das_form_pos_vtbl;
 
#define DAS_FORM_POS (&das_form_pos_vtbl)
 
DAS_API DasForm* new_DasFormPos(
   const char* sBody, const char* sFrame, const char* sSurface,
   bool bFixed, ubyte uSysType, const ubyte* pDirs
);
 
DAS_API const char* DasFormPos_body(const DasForm* pThis);
 
DAS_API const char* DasFormPos_frame(const DasForm* pThis);
 
DAS_API const char* DasFormPos_surface(const DasForm* pThis);
 
DAS_API ubyte DasFormPos_sysType(const DasForm* pThis);
 
DAS_API bool DasFormPos_fixed(const DasForm* pThis);
 
DAS_API const ubyte* DasFormPos_dirs(const DasForm* pThis);
 
/* For a component's display symbol -- "λ", "φ", "h" -- use DasVar_compSym(),
   which works for every kind of composite value and not just this one. */
 
/* To read a position datum's components use das_datum_toDoubles().  It returns
   them in storage order and leaves any slot it does not fill untouched, so set
   those from das_vsys_default() in form_vec.h when a stream sends fewer
   components than its system defines. */
 
#ifdef __cplusplus
}
#endif
 
#endif /* _das_form_pos_h_ */