.\" gd_spf.3.  The gd_spf man page.
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.\" Copyright (C) 2008, 2009, 2010, 2011, 2012 D. V. Wiebe
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.TH gd_spf 3 "1 April 2012" "Version 0.8.0" "GETDATA"
.SH NAME
gd_spf \(em returns the samples per frame for a field in a
dirfile
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "unsigned int gd_spf(DIRFILE *" dirfile ", const char *" field_code );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_spf ()
function queries a dirfile(5) database specified by
.I dirfile
and returns the number of samples per frame for the field
.IR field_code .
If
.I field_code
contains a valid representation suffix, it will be ignored.

The 
.I dirfile
argument must point to a valid DIRFILE object previously created by a call to
.BR gd_open (3).

.SH RETURN VALUE
Upon successful completion,
.BR gd_spf ()
returns the number of samples per frame for the field specified.  On error, it
returns zero and sets the dirfile error
to a non-zero error value.  Possible error values are:
.TP 8
.B GD_E_ALLOC
The library was unable to allocate memory.
.TP
.B GD_E_BAD_CODE
The field specified by
.I field_code
was not found in the database.
.TP
.B GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.TP
.B GD_E_DIMENSION
A scalar field was found where a vector field was expected.
.TP
.B GD_E_INTERNAL_ERROR
An internal error occurred in the library while trying to perform the task.
This indicates a bug in the library.  Please report the incident to the
maintainer.
.TP
.B GD_E_RECURSE_LEVEL
Too many levels of recursion were encountered while trying to resolve
.IR field_code .
This usually indicates a circular dependency in field specification in the
dirfile.
.PP
The dirfile error may be retrieved by calling
.BR gd_error (3).
A descriptive error string for the last error encountered can be obtained from
a call to
.BR gd_error_string (3).
.SH SEE ALSO
.BR dirfile (5),
.BR gd_open (3),
.BR gd_error (3),
.BR gd_error_string (3)