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Instances

Instances of types can be associated to a package, allowing structured constant values to be declared.

Example

The Packtype definition can either use a Python dataclass style or the Packtype custom grammar:

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import packtype
from packtype import Constant, Scalar

@packtype.package()
class MyPackage:
    pass

@MyPackage.enum()
class Month:
    JAN : Constant
    FEB : Constant
    ...
    DEC : Constant

@MyPackage.struct()
class Date:
    year  : Scalar[12]
    month : Month
    day   : Scalar[5]

MyPackage._pt_attach_instance("SUMMER_START", Month.JUN)
MyPackage._pt_attach_instance("SUMMER_END", Month.AUG)
MyPackage._pt_attach_instance("CHRISTMAS", Date(year=2025, month=Month.DEC, day=25))

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package my_package {
    enum month_e {
        JAN : constant
        FEB : constant
        ...
        DEC : constant
    }

    struct date_t {
        year  : scalar[12]
        month : month_e
        day   : scalar[5]
    }

    SUMMER_START : month_e = month_e::JUN
    SUMMER_END   : month_e = month_e::AUG
    CHRISTMAS    : date_t  = {
        year  = 2025
        month = month_e::DEC
        day   = 25
    }
}

As rendered to SystemVerilog:

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package my_package;

localparam month_e SUMMER_START = month_e'(7);

localparam month_e SUMMER_END = month_e'(9);

// CHRISTMAS
localparam date_t CHRISTMAS = '{
      day: 5'h19
    , month: month_e'(11)
    , year: 12'h7E9
};

endpackage : my_package