1EGD_CHANNEL_INFO(3)          EEGDEV library manual         EGD_CHANNEL_INFO(3)
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NAME

6       egd_channel_info - Get various information about a particular channel
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SYNOPSIS

9       #include <eegdev.h>
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11       int egd_channel_info(const struct eegdev* dev, int stype,
12                             unsigned int index, int fieldtype, ...);
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DESCRIPTION

15       egd_channel_info()  provides  different  type  of information about the
16       channel at the index index of the  group  specified  by  stype  of  the
17       device  referenced  by  dev.  As  described for egd_acq_setup(3), stype
18       specifies the type of channel. It must one of the  values  returned  by
19       egd_sensor_type(3).
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21       The  information  returned  by  the function is defined by the variable
22       list of argument. This list is composed of successive  couple  grouping
23       one  field  type  identifier  specifying  the  feature  to be get and a
24       pointer to a value whose type depends on the previous field  type.  The
25       list must finish by EGD_END.
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27       The  field  identifers can be the following (The expected corresponding
28       pointer type is provided in parenthesis):
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30       EGD_LABEL (char*)
31              Name of the channel. The pointed array should be long enough  to
32              hold 32 characters (including the null termination character).
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34       EGD_ISINT (int*)
35              Indicates  whether  the data provided by the channel are integer
36              or floating point.  (zero  indicates  floating  point,  non-zero
37              indicates integer).
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39       EGD_MM_I (int32_t*)
40              Returns  in an array of 2 int32_t the minimal and maximal values
41              that the channel can deliver (If the  channel  deliver  floating
42              point data, these values can be underestimated due to overflow)
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44       EGD_MM_F (float*)
45              Returns  in  an  array of 2 float values the minimal and maximal
46              values that the channel can deliver (If the channel deliver dou‐
47              ble  floating point data, these values can be underestimated due
48              to overflow)
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50       EGD_MM_D (double*)
51              Returns in an array of 2 double values the minimal  and  maximal
52              values that the channel can deliver.
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54       EGD_UNIT (char*)
55              Unit  in  which the channel data is expressed. The pointed array
56              should be long enough to hold 16 characters (including the  null
57              termination character).
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59       EGD_TRANSDUCTER (char*)
60              Transducter type of the sensor. The pointed array should be long
61              enough to hold 128 characters (including  the  null  termination
62              character).
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64       EGD_PREFILTERING (char*)
65              Information  about  the  filters  already  applied  on data. The
66              pointed array should be  long  enough  to  hold  128  characters
67              (including the null termination character).
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RETURN VALUE

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

74       egd_channel_info() will fail if:
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76       EINVAL dev is NULL, stype is an invalid sensor type,  index  is  bigger
77              than the maximal number of channel in the group, any field iden‐
78              tifier is unknown or any pointer used is NULL.
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THREAD SAFETY

81       egd_channel_info() is thread-safe.
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SEE ALSO

84       egd_acq_setup(3), egd_sensor_type(3)
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90EPFL                                 2010                  EGD_CHANNEL_INFO(3)
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