.\"Copyright 2010 (c) EPFL
.TH XDF_DEFINE_ARRAYS 3 2010 "EPFL" "xdffileio library manual"
.SH NAME
xdf_define_arrays - Specify the number of input/output arrays
.SH SYNOPSIS
.LP
.B #include <xdfio.h>
.sp
.BI "int xdf_define_arrays(struct xdf* " xdf ","
.br
.BI "                      unsigned int " narrays ", const size_t *" strides ");"
.br
.SH DESCRIPTION
.LP
\fBxdf_define_arrays\fP() specifies the number of arrays and its strides for
upcoming calls to \fBxdf_write\fP(3) and \fBxdf_read\fP(3) using \fIxdf\fP.
This function is used to configure the upcoming transfer. As such, it must
be called before \fBxdf_prepare_transfer\fP(3) (calling it after will
produce an error). However the function may be called several times but
only the last call is meaningful for the transfer.
.LP
\fInarrays\fP specifies the number of arrays that will be provided in the
argument list of \fBxdf_write\fP(3) or \fBxdf_read\fP(3).
.LP
\fIstrides\fP argument should point to an array of \fInarrays\fP unsigned
int corresponding respectively to the stride of each arrays that will be
supplied to the upcoming call to \fBxdf_write\fP(3) or \fBxdf_read\fP(3).
The stride corresponds to the length in byte between two consecutive
samples of the same channel in the array.
.SH "RETURN VALUE"
.LP
\fBxdf_define_arrays\fP() returns 0 in case of success, otherwise \-1 and
\fIerrno\fP is set appropriately.
.SH ERRORS
.TP 7
.B ENOMEM
The system is unable to allocate resources.
.SH "SEE ALSO"
.BR xdf_prepare_transfer (3),
.BR xdf_read (3),
.BR xdf_write (3)