NAME

       egd_acq_setup - specify which and how channel data should be obtained

SYNOPSIS

       #include <eegdev.h>

       int egd_acq_setup(struct eegdev* dev,
                         unsigned int narr, const size_t *strides,
                         unsigned int ngrp, const struct grpconf *grp);

DESCRIPTION

       egd_acq_setup()  configures  the  way data is provided by the device referenced by dev for
       the next calls to egd_get_data(3).

       The narr argument specifies the number of buffers that will be supplied  in  the  argument
       list  of  egd_get_data(3).  strides  should  points  to an array of narr values specifying
       respectively for each buffers its stride, i.e. the size in bytes between the data  of  two
       successive samples in this buffer.

       The  channels  data  that  must  be returns in those buffers are defined by ngrp groups of
       consecutive channels. The groups definition are passed by grp which points to an array  of
       ngrp structures, defined as follows:

           struct grpconf {
               unsigned int sensortype;    /* type of channel */
               unsigned int index;         /* index of the first channel */
               unsigned int nch;           /* number of channels */
               unsigned int iarray;        /* index of the array */
               unsigned int arr_offset;    /* offset in the array */
               unsigned int datatype;      /* type in the array */
           };

       The different fields in the structure defines the properties of the group:

        * sensortype  specifies the type of channel. it must one of the following values returned
          by egd_sensor_type(3).

        * index indicates the index of the first channel in the group. Note that channel index  i
          refers  the  i-th  channel  of  the type specified previously, i.e. the channel index i
          refers to two differents channels if sensortype differs.

        * nch specifies the number of consecutive channels that should be in the group.

        * iarray indicates which buffer the data of the channel group must be written to.

        * arr_offset defines the offset of the  memory  location  of  the  data  in  the  buffers
          relatively to the beginning of each sample.

        * datatype  specifies the type of data that must be written to the buffer. It must be one
          of the following value: EGD_INT32, EGD_FLOAT or EGD_DOUBLE

RETURN VALUE

       The function returns 0 in case of succes. Otherwise, -1  is  returned  and  errno  is  set
       accordingly.

ERRORS

       egd_acq_setup() will fail if:

       EINVAL dev is NULL.

       EPERM  The acquisition is running

THREAD SAFETY

       egd_acq_setup() is thread-safe.

EXAMPLE

       See egd_get_data(3) for a example

SEE ALSO

       egd_get_data(3), egd_start(3), egd_sensor_type(3)