NAME

       egd_channel_info - Get various information about a particular channel

SYNOPSIS

       #include <eegdev.h>

       int egd_channel_info(const struct eegdev* dev, int stype,
                             unsigned int index, int fieldtype, ...);

DESCRIPTION

       egd_channel_info()  provides  different type of information about the channel at the index
       index of the group specified by stype of the device referenced by dev.  As  described  for
       egd_acq_setup(3),  stype specifies the type of channel. It must one of the values returned
       by egd_sensor_type(3).

       The information returned by the function is defined by the variable list of argument. This
       list  is  composed  of successive couple grouping one field type identifier specifying the
       feature to be get and a pointer to a value whose type depends on the previous field  type.
       The list must finish by EGD_END.

       The  field  identifers  can  be  the following (The expected corresponding pointer type is
       provided in parenthesis):

       EGD_LABEL (char*)
              Name of the channel. The pointed array should be long enough to hold 32  characters
              (including the null termination character).

       EGD_ISINT (int*)
              Indicates  whether  the data provided by the channel are integer or floating point.
              (zero indicates floating point, non-zero indicates integer).

       EGD_MM_I (int32_t*)
              Returns in an array of 2 int32_t the minimal and maximal values  that  the  channel
              can  deliver  (If  the  channel  deliver  floating  point data, these values can be
              underestimated due to overflow)

       EGD_MM_F (float*)
              Returns in an array of 2 float values the  minimal  and  maximal  values  that  the
              channel  can  deliver  (If  the  channel  deliver double floating point data, these
              values can be underestimated due to overflow)

       EGD_MM_D (double*)
              Returns in an array of 2 double values the minimal  and  maximal  values  that  the
              channel can deliver.

       EGD_UNIT (char*)
              Unit  in  which  the  channel  data  is expressed. The pointed array should be long
              enough to hold 16 characters (including the null termination character).

       EGD_TRANSDUCTER (char*)
              Transducter type of the sensor. The pointed array should be long enough to hold 128
              characters (including the null termination character).

       EGD_PREFILTERING (char*)
              Information  about the filters already applied on data. The pointed array should be
              long enough to hold 128 characters (including the null termination character).

RETURN VALUE

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

ERRORS

       egd_channel_info() will fail if:

       EINVAL dev  is  NULL,  stype  is  an invalid sensor type, index is bigger than the maximal
              number of channel in the group, any field identifier is unknown or any pointer used
              is NULL.

THREAD SAFETY

       egd_channel_info() is thread-safe.

SEE ALSO

       egd_acq_setup(3), egd_sensor_type(3)