NAME¶
FunInfoPut - put information into a Funtools struct
SYNOPSIS¶
#include <funtools.h>
int FunInfoPut(Fun fun, int type, char *addr, ...)
DESCRIPTION¶
The
FunInfoPut() routine puts information into a
Funtools structure. The first argument is the Fun handle from which
information is to be retrieved. After this first required argument comes a
variable length list of pairs of arguments. Each pair consists of an integer
representing the type of information to store and the address of the new
information to store in the struct. The variable list is terminated by a 0.
The routine returns the number of put actions performed.
The full list of available information is described above with the
FunInfoPut() routine. Although use of this routine is expected to be
uncommon, there is one important situation in which it plays an essential
part: writing multiple extensions to a single output file.
For input, multiple extensions are handled by calling
FunOpen() for each
extension to be processed. When opening multiple inputs, it sometimes is the
case that you will want to process them and then write them (including their
header parameters) to a single output file. To accomplish this, you open
successive input extensions using
FunOpen() and then call
FunInfoPut() to set the Funtools reference handle
of the output file to that of the newly opened input extension:
/* open a new input extension */
ifun=FunOpen(tbuf, "r", NULL)) )
/* make the new extension the reference handle for the output file */
FunInfoPut(ofun, FUN_IFUN, &ifun, 0);
Resetting FUN_IFUN has same effect as when a funtools handle is passed as the
final argument to
FunOpen(). The state of the output file is reset so
that a new extension is ready to be written. Thus, the next I/O call on the
output extension will output the header, as expected.
For example, in a binary table, after resetting FUN_IFUN you can then call
FunColumnSelect() to select the columns for output. When you then call
FunImagePut() or <A
HREF="./library.html#funtablerowput">
FunTableRowPut(), a
new extension will be written that contains the header parameters from the
reference extension. Remember to call
FunFlush() to complete output of
a given extension.
A complete example of this capability is given in the evcol example code. The
central algorithm is:
- •
- open the output file without a reference handle
- •
- loop: open each input extension in turn
- •
- set the reference handle for output to the newly opened input
extension
- •
- read the input rows or image and perform processing
- •
- write new rows or image to the output file
- •
- flush the output
- •
- close input extension
- •
- close output file
Note that
FunFlush() is called after processing each input extension in
order to ensure that the proper padding is written to the output file. A call
to
FunFlush() also ensures that the extension header is written to the
output file in the case where there are no rows to output.
If you wish to output a new extension without using a Funtools reference handle,
you can call
FunInfoPut() to reset the FUN_OPS value directly. For a
binary table, you would then call
FunColumnSelect() to set up the
columns for this new extension.
/* reset the operations performed on this handle */
int ops=0;
FunInfoPut(ofun, FUN_OPS, &ops, 0);
FunColumnSelect(fun, sizeof(EvRec), NULL,
"MYCOL", "J", "w", FUN_OFFSET(Ev, mycol),
NULL);
Once the FUN_OPS variable has been reset, the next I/O call on the output
extension will output the header, as expected.
SEE ALSO¶
See
funtools(7) for a list of Funtools help pages