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)

EPFL                                                  2010                                      EGD_ACQ_SETUP(3)