Coverage Files¶

Coverage files are produced during simulation. They contain coverage information about noRTL engines, that can be back-annotated.

The files use the JSON Lines format. They contain a list of JSON records, separated by linebreaks. The individual records can be distinguished by their type property.

The individual records must not contain any linebreaks (\n characters). Other whitespace is ignored. This allows parsers to split the file content into a list of records.

They properties of the individual coverage records are described below.

Info Record¶

The information records contains information about the associated engine and optionally the test case.

It contains a SHA256 checksum of the engine information. The checksum is used to check if the coverage data matches the engine or if it is wrongly associated or outdated.

Only one info record must be present in each coverage file.

interface InfoRecord {
    type: "info"
    engine: EngineReference
    test: TestInfo | null
}

interface EngineReference {
    name: string
    sha256sum: string
}

interface TestInfo {
    name: string
    start_time: string
}

State Coverage¶

This record indicates coverage for a state, i.e. if this state was visited. The state is referenced by its name.

interface StateCoverageRecord {
    type: "state"
    state: string
    covered: boolean
}

Transition Coverage¶

This record indicates coverage for a transition between two states, i.e. if this transition was taken.

interface TransitionCoverageRecord {
    type: "transition"
    source: string
    target: string
    covered: boolean
}

Cover Point¶

Cover points can occur multiple times in each coverage file.

It is recommended to emit each cover point with covered=false to define it.

The combination of state, condition and point_name is used as a key, i.e. each unique combination will result in a different cover point. group_name and group_coords must be identical for all records of one cover point.

interface CoverPointRecord {
    type: "coverpoint"
    state: string
    condition: string
    point_name: string
    group_name: string | null
    group_coords: Array<number> | null
    covered: boolean
}

Cover Group¶

Only one record must be present per cover group in each coverage file.

interface CoverGroupRecord {
    type: "covergroup"
    name: string
    axis: Array<string>
    limits: Array<Array<number>> // (1)!
}

Each element in the limits array must have 2 elements, the lower and upper limits.