Specifications

Comedi

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5.2.2 CR_PACK_FLAGS

CR_PACK_FLAGS(chan, range, aref, flags) is similar to CR_PACK() but can be used to combine one or more ﬂag bits

(bitwise-ORed together in the flags parameter) with the other parameters.

#define CR_PACK_FLAGS(chan, range, aref, flags) \

(CR_PACK(chan, range, aref) | ((flags) & CR_FLAGS_MASK))

Depending on context, the chan parameter might not be a channel; it could be a trigger source, clock source, gate source etc.

(in which case, the range and aref parameters would probably be set to 0), and the ﬂags would modify the source in some

device-dependant way.

The following ﬂag values are deﬁned:

CR_ALT_FILTER, CR_DITHER, CR_DEGLITCH (all the same) specify that some sort of ﬁltering is to be done on the channel,

trigger source, etc.

CR_ALT_SOURCE speciﬁes that some alternate source is to be used for the channel (usually a calibration source).

CR_EDGE is usually combined with a trigger source number to specify that the trigger source is edge-triggered if the hardware

and driver supports both edge-triggering and level-triggering. If both are supported, not asserting this ﬂag speciﬁes level-

triggering.

CR_INVERT speciﬁes that the trigger source, gate source, etc. is to be inverted.

5.2.3 RANGE_LENGTH (deprecated)

Rangetype values are library-internal tokens that represent an array of range information structures. These numbers are primarily

used for communication between the kernel and library.

The RANGE_LENGTH(rangetype) macro returns the length of the array that is speciﬁed by the rangetype token.

The RANGE_LENGTH() macro is deprecated, and should not be used in new applications. It is scheduled to be removed from the

header ﬁle at version 1.0. Binary compatibility may be broken for version 1.1.

5.2.4 enum comedi_conversion_direction

enum comedi_conversion_direction

{

COMEDI_TO_PHYSICAL,

COMEDI_FROM_PHYSICAL

};

A comedi_conversion_direction is used to choose between converting data from Comedi’s integer sample values to a physical

value (COMEDI_TO_PHYSICAL), and converting from a physical value to Comedi’s integer sample values (COMEDI_FROM-

_PHYSICAL).

5.2.5 enum comedi_io_direction

enum comedi_io_direction

{

COMEDI_INPUT,

COMEDI_OUTPUT

};

A comedi_io_direction is used to select between input or output. For example, comedi_dio_config() uses the COMEDI_-

INPUT and COMEDI_OUTPUT values to specify whether a conﬁgurable digital i/o channel should be conﬁgured as an input or

output.