FITS header reading/writing


Functions

qfits_header * qfits_header_read (const char *filename)
 Read a FITS header from a file to an internal structure.
qfits_header * qfits_header_read_hdr (const char *filename)
 Read a FITS header from a 'hdr' file.
qfits_header * qfits_header_read_hdr_string (const unsigned char *hdr_str, int nb_char)
 Read a FITS header from a 'hdr' string.
qfits_header * qfits_header_readext (const char *filename, int xtnum)
 Read an extension header from a FITS file.
void qfits_zeropad (const char *filename)
 Pad an existing file with zeros to a multiple of 2880.
int qfits_is_fits (const char *filename)
 Identify if a file is a FITS file.
int qfits_get_hdrinfo (const char *filename, int xtnum, int *seg_start, int *seg_size)
 Retrieve offset to start and size of a header in a FITS file.
int qfits_get_datinfo (const char *filename, int xtnum, int *seg_start, int *seg_size)
 Retrieve offset to start and size of a data section in a file.

Function Documentation

int qfits_get_datinfo const char *  filename,
int  xtnum,
int *  seg_start,
int *  seg_size
 

Retrieve offset to start and size of a data section in a file.

Parameters:
filename Name of the file to examine.
xtnum Extension number (0 for main).
seg_start Segment start in bytes (output).
seg_size Segment size in bytes (output).
Returns:
int 0 if Ok, -1 otherwise.
This function retrieves the two most important informations about a data section in a FITS file: the offset to its beginning, and the size of the section in bytes. Both values are returned in the passed pointers to ints. It is Ok to pass NULL for any pointer if you do not want to retrieve the associated value.

You must provide an extension number for the header, 0 meaning the main header in the file.

int qfits_get_hdrinfo const char *  filename,
int  xtnum,
int *  seg_start,
int *  seg_size
 

Retrieve offset to start and size of a header in a FITS file.

Parameters:
filename Name of the file to examine
xtnum Extension number (0 for main)
seg_start Segment start in bytes (output)
seg_size Segment size in bytes (output)
Returns:
int 0 if Ok, -1 otherwise.
This function retrieves the two most important informations about a header in a FITS file: the offset to its beginning, and the size of the header in bytes. Both values are returned in the passed pointers to ints. It is Ok to pass NULL for any pointer if you do not want to retrieve the associated value.

You must provide an extension number for the header, 0 meaning the main header in the file.

qfits_header* qfits_header_read const char *  filename  ) 
 

Read a FITS header from a file to an internal structure.

Parameters:
filename Name of the file to be read
Returns:
Pointer to newly allocated qfits_header or NULL in error case.
This function parses a FITS (main) header, and returns an allocated qfits_header object. The qfits_header object contains a linked-list of key "tuples". A key tuple contains:

  • A keyword
  • A value
  • A comment
  • An original FITS line (as read from the input file)

Direct access to the structure is not foreseen, use accessor functions in fits_h.h

Value, comment, and original line might be NULL pointers.

qfits_header* qfits_header_read_hdr const char *  filename  ) 
 

Read a FITS header from a 'hdr' file.

Parameters:
filename Name of the file to be read
Returns:
Pointer to newly allocated qfits_header or NULL in error case
This function parses a 'hdr' file, and returns an allocated qfits_header object. A hdr file is an ASCII format were the header is written with a carriage return after each line. The command dfits typically displays a hdr file.

qfits_header* qfits_header_read_hdr_string const unsigned char *  hdr_str,
int  nb_char
 

Read a FITS header from a 'hdr' string.

Parameters:
hdr_str String containing the hdr file
nb_char Number of characters in the string
Returns:
Pointer to newly allocated qfits_header or NULL in error case
This function parses a 'hdr' string, and returns an allocated qfits_header object.

qfits_header* qfits_header_readext const char *  filename,
int  xtnum
 

Read an extension header from a FITS file.

Parameters:
filename Name of the FITS file to read
xtnum Extension number to read, starting from 0.
Returns:
Newly allocated qfits_header structure.
Strictly similar to qfits_header_read() but reads headers from extensions instead. If the requested xtension is 0, this function returns the main header.

Returns NULL in case of error.

int qfits_is_fits const char *  filename  ) 

 

Identify if a file is a FITS file.

Parameters:
filename name of the file to check
Returns:
int 0, 1, or -1
Returns 1 if the file name looks like a valid FITS file. Returns 0 else. If the file does not exist, returns -1.
void qfits_zeropad const char *  filename  ) 
 

Pad an existing file with zeros to a multiple of 2880.

Parameters:
filename Name of the file to pad.
Returns:
void
This function simply pads an existing file on disk with enough zeros for the file size to reach a multiple of 2880, as required by FITS.