Blocks
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ncBlock is a container class for other classes or blocks. Due to the generic nature of ncBlock it is recommended not to create derived block classes but instead always instantiate ncBlock.
The top most block in the device tree is called a root block and must always have an oId of 1 and a role of root.
Blocks have the following properties (inherited properties from ncObject are not shown here):
| Property Name | Datatype | Readonly | Description |
|---|---|---|---|
| enabled | ncBoolean | Yes | Indicates id the block is functional |
| specId | ncString | Yes | Global ID of blockspec that defines this block |
| specVersion | ncVersionCode | Yes | Version code of blockspec that defines this block |
| parentSpecId | ncString | Yes | Global ID of parent of blockspec that defines this block |
| parentSpecVersion | ncVersionCode | Yes | Version code of parent of blockspec that defines this block |
| specDescription | ncString | Yes | Description of blockSpec that defines this block |
| isDynamic | ncBoolean | Yes | Indicates if the contents of the block can change (members, ports or signal paths) |
| isModified | ncBoolean | Yes | Indicates if the contents of the block have changed since the last restart |
| members | sequence<ncOid> | Yes | Oids of this block’s members |
| ports | sequence<ncPort> | Yes | This block’s ports |
| signalPaths | sequence<ncSignalPath> | Yes | This block’s signal paths |
Where the following data types are defined:
typedef ncName ncRole;
typedef sequence(ncName) ncRolePath;
enum ncIoDirection { // Input and/or output
"undefined", // 0 Flow direction is not defined
"input", // 1 Samples flow into owning object
"output", // 2 Samples flow out of owning object
"bidirectional" // 3 For possible future use
};
interface ncPort {
attribute ncRole role; // Unique within owning object
attribute ncIoDirection direction; // Input (sink) or output (source) port
attribute ncRolePath clockPath; // Rolepath of this port's sample clock or empty if none
};
interface ncSignalPath {
attribute ncName role; // Unique within owning object
attribute ncRole source; // path origin
attribute ncRole sink; // path terminus
);
More information on ports and signal paths can be found in the architecture specification NMOS Control Architecture (NC-Architecture).
Blockspecs are defined in the NMOS Control Blockspecs (NC-Blockspecs) specification.
Tree discovery
Blocks enable device tree discovery by offering enumeration methods.
Descriptors for all the nested members can be retrieved with the getMemberDescriptors method ([element("2m1")]), which expected an ncBoolean recurse argument and returns a response of type ncMethodResultBlockMemberDescriptors.
interface ncBlockMemberDescriptor{
attribute ncRole role; // Role of member in its containing block
attribute ncOid oid; // OID of member
attribute ncBoolean constantOid // TRUE iff member's OID is hardwired into device
attribute ncClassIdentity identity; // Class ID & version of member
attribute ncLabel userLabel; // User label
attribute ncOid owner; // Containing block's OID
attribute sequence<ncPropertyConstraint> constraints // Constraints on this member or, for a block, its members.
};
interface ncMethodResultBlockMemberDescriptors : ncMethodResult { // block member descriptors result
attribute sequence<ncBlockMemberDescriptor> value;
};
Search methods
All blocks also offer some search methods for convenience:
- findMembersByRole (
[element("2m3")]) - retrieve descriptors for members filtered by the role property - findMembersByUserLabel (
[element("2m4")]) - retrieve descriptors for members filtered by the user label property - findMembersByPath (
[element("2m5")]) - retrieve descriptors for members filtered using a role path sequence of roles