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getwcstab.h
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/*============================================================================
WCSLIB 8.5 - an implementation of the FITS WCS standard.
Copyright (C) 1995-2025, Mark Calabretta
This file is part of WCSLIB.
WCSLIB is free software: you can redistribute it and/or modify it under the
terms of the GNU Lesser General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
WCSLIB 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
along with WCSLIB. If not, see http://www.gnu.org/licenses.
Author: Mark Calabretta, Australia Telescope National Facility, CSIRO.
http://www.atnf.csiro.au/people/Mark.Calabretta
$Id: getwcstab.h,v 8.5 2025/12/06 13:47:41 mcalabre Exp $
*=============================================================================
*
* WCSLIB 8.5 - C routines that implement the FITS World Coordinate System
* (WCS) standard. Refer to the README file provided with WCSLIB for an
* overview of the library.
*
* Summary of the getwcstab routines
* ---------------------------------
* fits_read_wcstab(), an implementation of a FITS table reading routine for
* 'TAB' coordinates, is provided for CFITSIO programmers. It has been
* incorporated into CFITSIO as of v3.006 with the definitions in this file,
* getwcstab.h, moved into fitsio.h.
*
* fits_read_wcstab() is not included in the WCSLIB object library but the
* source code is presented here as it may be useful for programmers using an
* older version of CFITSIO than 3.006, or as a programming template for
* non-CFITSIO programmers.
*
*
* fits_read_wcstab() - FITS 'TAB' table reading routine
* ----------------------------------------------------
* fits_read_wcstab() extracts arrays from a binary table required in
* constructing 'TAB' coordinates.
*
* Given:
* fptr fitsfile *
* Pointer to the file handle returned, for example, by
* the fits_open_file() routine in CFITSIO.
*
* nwtb int Number of arrays to be read from the binary table(s).
*
* Given and returned:
* wtb wtbarr * Address of the first element of an array of wtbarr
* typedefs. This wtbarr typedef is defined to match the
* wtbarr struct defined in WCSLIB. An array of such
* structs returned by the WCSLIB function wcstab() as
* discussed in the notes below.
*
* Returned:
* status int * CFITSIO status value.
*
* Function return value:
* int CFITSIO status value.
*
* Notes:
* 1: In order to maintain WCSLIB and CFITSIO as independent libraries it is
* not permissible for any CFITSIO library code to include WCSLIB header
* files, or vice versa. However, the CFITSIO function fits_read_wcstab()
* accepts an array of wtbarr structs defined in wcs.h within WCSLIB.
*
* The problem therefore is to define the wtbarr struct within fitsio.h
* without including wcs.h, especially noting that wcs.h will often (but
* not always) be included together with fitsio.h in an applications
* program that uses fits_read_wcstab().
*
* The solution adopted is for WCSLIB to define "struct wtbarr" while
* fitsio.h defines "typedef wtbarr" as an untagged struct with identical
* members. This allows both wcs.h and fitsio.h to define a wtbarr data
* type without conflict by virtue of the fact that structure tags and
* typedef names share different name spaces in C; Appendix A, Sect. A11.1
* (p227) of the K&R ANSI edition states that:
*
= Identifiers fall into several name spaces that do not interfere with
= one another; the same identifier may be used for different purposes,
= even in the same scope, if the uses are in different name spaces.
= These classes are: objects, functions, typedef names, and enum
= constants; labels; tags of structures, unions, and enumerations; and
= members of each structure or union individually.
*
* Therefore, declarations within WCSLIB look like
*
= struct wtbarr *w;
*
* while within CFITSIO they are simply
*
= wtbarr *w;
*
* As suggested by the commonality of the names, these are really the same
* aggregate data type. However, in passing a (struct wtbarr *) to
* fits_read_wcstab() a cast to (wtbarr *) is formally required.
*
* When using WCSLIB and CFITSIO together in C++ the situation is
* complicated by the fact that typedefs and structs share the same
* namespace; C++ Annotated Reference Manual, Sect. 7.1.3 (p105). In that
* case the wtbarr struct in wcs.h is renamed by preprocessor macro
* substitution to wtbarr_s to distinguish it from the typedef defined in
* fitsio.h. However, the scope of this macro substitution is limited to
* wcs.h itself and CFITSIO programmer code, whether in C++ or C, should
* always use the wtbarr typedef.
*
*
* wtbarr typedef
* --------------
* The wtbarr typedef is defined as a struct containing the following members:
*
* int i
* Image axis number.
*
* int m
* Array axis number for index vectors.
*
* int kind
* Character identifying the array type:
* - c: coordinate array,
* - i: index vector.
*
* char extnam[72]
* EXTNAME identifying the binary table extension.
*
* int extver
* EXTVER identifying the binary table extension.
*
* int extlev
* EXTLEV identifying the binary table extension.
*
* char ttype[72]
* TTYPEn identifying the column of the binary table that contains the
* array.
*
* long row
* Table row number.
*
* int ndim
* Expected dimensionality of the array.
*
* int *dimlen
* Address of the first element of an array of int of length ndim into
* which the array axis lengths are to be written.
*
* double **arrayp
* Pointer to an array of double which is to be allocated by the user
* and into which the array is to be written.
*
*===========================================================================*/
#ifndef WCSLIB_GETWCSTAB
#define WCSLIB_GETWCSTAB
#ifdef __cplusplus
extern "C" {
#endif
#include <fitsio.h>
typedef struct {
int i; // Image axis number.
int m; // Array axis number for index vectors.
int kind; // Array type, 'c' (coord) or 'i' (index).
char extnam[72]; // EXTNAME of binary table extension.
int extver; // EXTVER of binary table extension.
int extlev; // EXTLEV of binary table extension.
char ttype[72]; // TTYPEn of column containing the array.
long row; // Table row number.
int ndim; // Expected array dimensionality.
int *dimlen; // Where to write the array axis lengths.
double **arrayp; // Where to write the address of the array
// allocated to store the array.
} wtbarr;
int fits_read_wcstab(fitsfile *fptr, int nwtb, wtbarr *wtb, int *status);
#ifdef __cplusplus
}
#endif
#endif // WCSLIB_GETWCSTAB
fits_read_wcstab
int fits_read_wcstab(fitsfile *fptr, int nwtb, wtbarr *wtb, int *status)
FITS 'TAB' table reading routine.
wtbarr
Extraction of coordinate lookup tables from BINTABLE.
Definition getwcstab.h:167
wtbarr::extlev
int extlev
Definition getwcstab.h:173
wtbarr::m
int m
Definition getwcstab.h:169
wtbarr::extver
int extver
Definition getwcstab.h:172
wtbarr::row
long row
Definition getwcstab.h:175
wtbarr::arrayp
double ** arrayp
Definition getwcstab.h:178
wtbarr::ttype
char ttype[72]
Definition getwcstab.h:174
wtbarr::i
int i
Definition getwcstab.h:168
wtbarr::dimlen
int * dimlen
Definition getwcstab.h:177
wtbarr::extnam
char extnam[72]
Definition getwcstab.h:171
wtbarr::ndim
int ndim
Definition getwcstab.h:176
wtbarr::kind
int kind
Definition getwcstab.h:170