Control Unit Ontology

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FLOW ALGEBRA — CONTROL UNIT ONTOLOGY
Semantic Library
Version: 4.0
Canonical Page:
https://kirethresearch.org/booksai-core/ontologies/computing-ontologies/computer-architecture/control-unit-ontology.html

FLOW CONTROL_UNIT_ONTOLOGY {

  META {
    DOMAIN = "Computing Ontologies"
    SUBDOMAIN = "Computer Architecture"
    ONTOLOGY = "Control Unit Ontology"
    PURPOSE = "Formalise control-unit entities, instruction decoding, sequencing, control signals, processor coordination and state transitions within computer architectures."
    LOCALE = "en-GB"
  }

  ENTITY_TYPES {
    CONTROL_UNIT
    CPU
    PROCESSOR
    CORE
    HARDWIRED_CONTROL_UNIT
    MICROPROGRAMMED_CONTROL_UNIT
    INSTRUCTION
    OPCODE
    OPERAND
    INSTRUCTION_REGISTER
    PROGRAM_COUNTER
    STATUS_REGISTER
    CONTROL_REGISTER
    REGISTER
    REGISTER_FILE
    DECODER
    INSTRUCTION_DECODER
    SEQUENCER
    MICROSEQUENCER
    MICROINSTRUCTION
    MICROPROGRAM
    CONTROL_STORE
    CONTROL_WORD
    CONTROL_SIGNAL
    TIMING_SIGNAL
    CLOCK
    CLOCK_CYCLE
    PIPELINE
    PIPELINE_STAGE
    FETCH_STAGE
    DECODE_STAGE
    EXECUTE_STAGE
    MEMORY_STAGE
    WRITEBACK_STAGE
    ARITHMETIC_LOGIC_UNIT
    EXECUTION_UNIT
    MEMORY
    CACHE
    BUS
    DATA_PATH
    INPUT
    OUTPUT
    INTERRUPT
    EXCEPTION
    BRANCH
    STATE
    CONTROL_STATE
    EVENT
    STATE_TRANSITION
    CONFIGURATION
    VERSION
    LATENCY
    ERROR
    EVIDENCE
    CONFIDENCE_SCORE
    PROVENANCE_RECORD
  }

  RELATIONSHIPS {
    IS_A
    INSTANCE_OF
    PART_OF
    CONTAINS
    CONTROLS
    COORDINATES
    DECODES
    SEQUENCES
    GENERATES
    ASSERTS
    DEASSERTS
    CLOCKS
    TRIGGERS
    ENABLES
    DISABLES
    SELECTS
    ROUTES
    FETCHES
    EXECUTES
    READS
    WRITES
    LOADS
    STORES
    INTERRUPTS
    HANDLES
    BRANCHES_TO
    HAS_OPCODE
    HAS_CONTROL_SIGNAL
    HAS_CONTROL_STATE
    HAS_MICROINSTRUCTION
    HAS_MICROPROGRAM
    HAS_INPUT
    HAS_OUTPUT
    HAS_STATE
    TRANSITIONS_TO
    HAS_CONFIGURATION
    HAS_VERSION
    DEPENDS_ON
    PRECEDES
    FOLLOWS
    DERIVED_FROM
    INFERRED_FROM
    HAS_EVIDENCE
    HAS_CONFIDENCE
    HAS_PROVENANCE
    MAPS_TO
    SEMANTICALLY_EQUIVALENT_TO
  }

  INPUTS {
    CONTROL_UNIT_SPECIFICATIONS
    INSTRUCTION_SET_DEFINITIONS
    OPCODE_DEFINITIONS
    INSTRUCTION_STREAMS
    MICROPROGRAM_DEFINITIONS
    MICROINSTRUCTION_DEFINITIONS
    CONTROL_SIGNAL_DEFINITIONS
    PIPELINE_DEFINITIONS
    CLOCK_PARAMETERS
    STATUS_FLAGS
    INTERRUPT_RECORDS
    EXCEPTION_RECORDS
    EXECUTION_TRACES
    CONFIGURATION_DATA
    VERSION_DATA
    ONTOLOGY_TERMS
  }

  NORMALISE {
    STANDARDISE_IDENTIFIERS
    NORMALISE_CONTROL_UNIT_NAMES
    NORMALISE_OPCODE_NAMES
    NORMALISE_CONTROL_SIGNAL_NAMES
    NORMALISE_MICROINSTRUCTION_NAMES
    NORMALISE_PIPELINE_STAGE_NAMES
    NORMALISE_CLOCK_UNITS
    NORMALISE_STATE_IDENTIFIERS
    NORMALISE_VERSION_IDENTIFIERS
    RESOLVE_COMPONENT_IDENTITIES
    ALIGN_ONTOLOGY_TERMS
    REMOVE_DUPLICATES
    VALIDATE_METADATA
    PRESERVE_PROVENANCE
  }

  PROCESS CONTROL_PIPELINE {
    INSTRUCTION
      -> FETCH_COORDINATION
      -> INSTRUCTION_DECODE
      -> CONTROL_SEQUENCE_GENERATION
      -> CONTROL_SIGNAL_ASSERTION
      -> DATA_PATH_AND_EXECUTION_UNIT_COORDINATION
      -> RESULT_OR_STATE_UPDATE
      -> NEXT_INSTRUCTION_SELECTION
  }

  PROCESS INSTRUCTION_DECODE {
    INSTRUCTION_REGISTER
      -> OPCODE_EXTRACTION

    OPCODE_EXTRACTION
      -> INSTRUCTION_CLASSIFICATION

    INSTRUCTION_CLASSIFICATION
      -> OPERAND_MODE_DECODE
      -> CONTROL_SEQUENCE_SELECTION

    CONTROL_SEQUENCE_SELECTION
      -> CONTROL_ACTIONS
  }

  PROCESS HARDWIRED_CONTROL {
    OPCODE + STATUS_FLAGS + TIMING_STATE
      -> COMBINATIONAL_AND_SEQUENTIAL_LOGIC

    COMBINATIONAL_AND_SEQUENTIAL_LOGIC
      -> CONTROL_SIGNALS

    CONTROL_SIGNALS
      -> DATA_PATH_ACTIONS

    DATA_PATH_ACTIONS
      -> NEXT_CONTROL_STATE
  }

  PROCESS MICROPROGRAMMED_CONTROL {
    OPCODE
      -> MICROPROGRAM_ENTRY_POINT

    MICROPROGRAM_ENTRY_POINT
      -> MICROINSTRUCTION_FETCH

    MICROINSTRUCTION_FETCH
      -> MICROINSTRUCTION_DECODE

    MICROINSTRUCTION_DECODE
      -> CONTROL_WORD

    CONTROL_WORD
      -> CONTROL_SIGNALS

    CONTROL_SIGNALS
      -> MICROSEQUENCER_UPDATE
  }

  PROCESS PIPELINE_CONTROL {
    PIPELINE_STATE
      -> HAZARD_DETECTION

    HAZARD_DETECTION
      -> DATA_HAZARD
      OR -> CONTROL_HAZARD
      OR -> STRUCTURAL_HAZARD
      OR -> NO_HAZARD

    HAZARD
      -> STALL_OR_FORWARD_OR_FLUSH

    NO_HAZARD
      -> ADVANCE_PIPELINE

    RESULT
      -> NEXT_PIPELINE_STATE
  }

  PROCESS BRANCH_CONTROL {
    BRANCH_INSTRUCTION + STATUS_OR_PREDICTION
      -> NEXT_PC_CANDIDATE

    NEXT_PC_CANDIDATE
      -> BRANCH_DECISION

    BRANCH_DECISION
      -> PROGRAM_COUNTER_UPDATE

    MISPREDICTION_IF_APPLICABLE
      -> PIPELINE_FLUSH
      -> CORRECT_FETCH_PATH
  }

  PROCESS INTERRUPT_CONTROL {
    INTERRUPT_EVENT
      -> INTERRUPT_PRIORITY_CHECK

    INTERRUPT_PRIORITY_CHECK
      -> SAVE_PROCESSOR_CONTEXT

    SAVE_PROCESSOR_CONTEXT
      -> HANDLER_ADDRESS_SELECTION

    HANDLER_ADDRESS_SELECTION
      -> CONTROL_TRANSFER

    HANDLER_COMPLETION
      -> RESTORE_CONTEXT
      -> RESUME_EXECUTION
  }

  PROCESS CONTROL_STATE_REASONING {
    CONTROL_STATE(T1)
      + INPUT_CONDITIONS
      + CLOCK_EVENT
      -> CONTROL_TRANSITION

    CONTROL_TRANSITION
      -> CONTROL_STATE(T2)

    CONTROL_STATE_SEQUENCE
      -> CONTROL_TRACE
  }

  RULES {
    IF CONTROL_UNIT_DECODES_INSTRUCTION
    THEN REQUIRE {
      INSTRUCTION_SET_CONTEXT
      OPCODE
      DECODE_RULE
    }

    IF CONTROL_SIGNAL_IS_ASSERTED
    THEN LINK {
      CONTROL_STATE
      SIGNAL
      TARGET_COMPONENT
      INTENDED_ACTION
      CLOCK_OR_TIMING_CONTEXT
    }

    IF MICROPROGRAMMED_CONTROL_IS_USED
    THEN PRESERVE {
      MICROPROGRAM
      MICROINSTRUCTION
      CONTROL_STORE
      MICROSEQUENCER_STATE
    }

    IF PIPELINE_STALL_OCCURS
    THEN PRESERVE HAZARD_CAUSE

    IF PIPELINE_FLUSH_OCCURS
    THEN PRESERVE CONTROL_FLOW_CAUSE

    IF INTERRUPT_OCCURS
    THEN PRESERVE {
      INTERRUPT_SOURCE
      PRIOR_PROCESSOR_STATE
      HANDLER_CONTEXT
      RESUME_CONTEXT
    }

    IF TWO_CONTROL_UNITS_IMPLEMENT_SAME_ISA
    THEN DO_NOT_ASSUME_IDENTICAL_CONTROL_IMPLEMENTATION

    IF SEMANTIC_IDENTIFIERS_DIFFER
    AND CONTROL_UNIT_REFERENT_IS_SAME
    THEN APPLY SEMANTIC_EQUIVALENCE
  }

  CONFIDENCE {
    CONFIDENCE_SCORE =
      WEIGHT(
        SPECIFICATION_COMPLETENESS,
        ISA_CERTAINTY,
        CONTROL_IMPLEMENTATION_CERTAINTY,
        SIGNAL_TRACE_COMPLETENESS,
        TIMING_CONTEXT_CERTAINTY,
        STATE_TRACE_COMPLETENESS,
        REPRODUCIBILITY,
        PROVENANCE_COMPLETENESS
      )

    LEVELS {
      HIGH
      MODERATE
      LOW
      INSUFFICIENT
    }

    IF CONTROL_IMPLEMENTATION_IS_UNKNOWN
    THEN REDUCE_INTERNAL_CONTROL_INFERENCE_CONFIDENCE

    IF TIMING_OR_STATE_TRACE_IS_INCOMPLETE
    THEN REDUCE CONFIDENCE_SCORE

    IF REPRODUCIBLE_CONTROL_TRACE_CONFIRMS_BEHAVIOUR
    THEN INCREASE CONFIDENCE_SCORE
  }

  SEMANTIC_EQUIVALENCE {
    EQUIVALENCE_KEY =
      NORMALISE(
        ENTITY_TYPE,
        CANONICAL_IDENTIFIER,
        ISA,
        CONTROL_IMPLEMENTATION,
        VERSION,
        CONFIGURATION
      )

    IF EQUIVALENCE_KEY(A) == EQUIVALENCE_KEY(B)
    THEN A SEMANTICALLY_EQUIVALENT_TO B

    ELSE PRESERVE_DISTINCT_ENTITIES
  }

  REASONING_CONSTRAINTS {
    CONTROL_UNIT != CPU
    OPCODE != CONTROL_SIGNAL_SEQUENCE
    INSTRUCTION_DECODE != INSTRUCTION_EXECUTION
    CONTROL_SIGNAL != DATA_VALUE
    HARDWIRED_CONTROL != MICROPROGRAMMED_CONTROL
    MICROINSTRUCTION != MACHINE_INSTRUCTION
    PIPELINE_STALL != PIPELINE_FLUSH
    INTERRUPT != EXCEPTION_IN_ALL_ARCHITECTURES
    ISA != CONTROL_IMPLEMENTATION
    TIMING_CONTEXT_AFFECTS_CONTROL_BEHAVIOUR
    CONFIGURATION_AFFECTS_CONTROL_BEHAVIOUR
    SPECULATIVE_CONTROL_STATE != COMMITTED_ARCHITECTURAL_STATE
    PROVENANCE_MUST_BE_PRESERVED
    UNCERTAINTY_MUST_NOT_BE_DISCARDED
  }

  VALIDATION {
    CHECK_ENTITY_TYPES
    CHECK_RELATION_DOMAINS_AND_RANGES
    CHECK_CONTROL_UNIT_IDENTIFIERS
    CHECK_ISA_CONTEXT
    CHECK_OPCODE_DECODE
    CHECK_CONTROL_SIGNALS
    CHECK_CONTROL_STATES
    CHECK_MICROPROGRAM_CONTEXT
    CHECK_PIPELINE_CONTROL
    CHECK_BRANCH_CONTROL
    CHECK_INTERRUPT_CONTROL
    CHECK_TIMING_CONTEXT
    CHECK_EXECUTION_TRACE
    CHECK_CONFIGURATION
    CHECK_VERSION_CONTEXT
    CHECK_PROVENANCE
    CHECK_CONFIDENCE
    CHECK_SEMANTIC_CONSISTENCY
  }

  OUTPUTS {
    NORMALISED_CONTROL_UNIT_ENTITIES
    CONTROL_COMPONENT_RELATIONS
    OPCODE_DECODE_RELATIONS
    CONTROL_SIGNAL_RELATIONS
    CONTROL_STATE_TRANSITIONS
    MICROPROGRAM_RELATIONS
    MICROINSTRUCTION_RELATIONS
    PIPELINE_CONTROL_RELATIONS
    BRANCH_CONTROL_RELATIONS
    INTERRUPT_CONTROL_RELATIONS
    CONTROL_TRACES
    CONFIDENCE_SCORES
    EVIDENCE_LINKS
    PROVENANCE_RECORDS
    EXPLANATION_PATHS
  }

  UPDATE_MODEL {
    ON CONTROL_UNIT_OR_CONFIGURATION_CHANGE {
      NORMALISE
      ENTITY_RESOLUTION
      UPDATE_DECODE_RULES
      UPDATE_CONTROL_SIGNALS
      UPDATE_CONTROL_STATES
      UPDATE_MICROPROGRAM_IF_APPLICABLE
      UPDATE_PIPELINE_CONTROL
      RECOMPUTE_AFFECTED_RELATIONS
      UPDATE_CONFIDENCE
      PRESERVE_VERSION_HISTORY
    }

    ON NEW_CONTROL_OR_EXECUTION_EVIDENCE {
      LINK_EVIDENCE
      UPDATE_CONTROL_TRACE
      REASSESS_SIGNAL_RELATIONS
      REASSESS_STATE_TRANSITIONS
      UPDATE_CONFIDENCE
      RECORD_PROVENANCE
    }

    ON ONTOLOGY_REVISION {
      REMAP_TERMS
      CHECK_SEMANTIC_EQUIVALENCE
      IDENTIFY_DEPRECATED_TERMS
      MIGRATE_RELATIONSHIPS
      PRESERVE_PRIOR_VERSION_REFERENCES
    }
  }

  FLOW_HASH {
    HASH_INPUT =
      CANONICALISE(
        ENTITY_TYPES,
        RELATIONSHIPS,
        RULES,
        CONFIDENCE,
        SEMANTIC_EQUIVALENCE,
        REASONING_CONSTRAINTS,
        UPDATE_MODEL
      )

    FLOW_HASH = SHA256(HASH_INPUT)
  }

  AI_CONSUMPTION {
    INDEX {
      ONTOLOGY
      ENTITY_TYPES
      RELATIONSHIPS
      RULES
      OUTPUTS
    }

    RETRIEVE {
      BY_CONTROL_UNIT
      BY_INSTRUCTION
      BY_OPCODE
      BY_CONTROL_SIGNAL
      BY_CONTROL_STATE
      BY_MICROPROGRAM
      BY_MICROINSTRUCTION
      BY_PIPELINE_STAGE
      BY_BRANCH
      BY_INTERRUPT
      BY_EXECUTION_TRACE
      BY_CONFIDENCE
    }

    REASON {
      APPLY_RELATIONSHIPS
      APPLY_RULES
      TRACE_INSTRUCTION_DECODE
      TRACE_CONTROL_SIGNALS
      TRACE_CONTROL_STATE
      TRACE_MICROPROGRAM
      ANALYSE_PIPELINE_CONTROL
      ANALYSE_BRANCH_CONTROL
      ANALYSE_INTERRUPTS
      CHECK_SEMANTIC_EQUIVALENCE
      PRESERVE_UNCERTAINTY
      TRACE_EVIDENCE
      TRACE_PROVENANCE
      GENERATE_EXPLANATION_PATH
    }

    RESPONSE_POLICY {
      DISTINGUISH_CONTROL_UNIT_FROM_CPU
      DISTINGUISH_DECODE_FROM_EXECUTION
      DISTINGUISH_MACHINE_INSTRUCTION_FROM_MICROINSTRUCTION
      PRESERVE_ISA_AND_TIMING_CONTEXT
      PRESERVE_CONTROL_IMPLEMENTATION_CONTEXT
      RETURN_CONFIDENCE_WHEN_AVAILABLE
      RETURN_PROVENANCE_WHEN_AVAILABLE
      AVOID_UNSUPPORTED_CONTROL_INFERENCE
    }
  }

  TERMINAL {
    RESULT =
      VALIDATED(
        SEMANTICALLY_NORMALISED(
          EVIDENCE_LINKED(
            CONFIDENCE_AWARE(
              CONTROL_UNIT_KNOWLEDGE
            )
          )
        )
      )
  }
}

END FLOW