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Repeated Fields

The repeat=N attribute generates array or map types for fields that appear multiple times in a PGN.

Basic repetition​

Use repeat=N to generate a slice of N elements:

pgn 127501 "Binary Switch Bank Status" {
  instance    uint8   :8
  indicator   uint8   :2  repeat=28
}

This generates:

type BinarySwitchBankStatus struct {
    Instance  uint8
    Indicator [28]uint8
}

Each element occupies the specified bit width (:2 in this case). The 28 indicators are packed into 56 bits (7 bytes).

Map groups​

Use group="map" with repeat= to generate a map keyed by the iteration index:

indicator  uint8  :2  repeat=28  group="map"

This generates a map[int]uint8 instead of an array. Only non-null entries are included in the map, which is useful for sparse data.

Custom naming​

Use as="name" to customize the Go field name:

indicator  uint8  :2  repeat=28  as="switches"

Generates field Switches [28]uint8 instead of Indicator [28]uint8.

Bit layout​

Repeated fields are packed sequentially in the bit stream. For repeat=28 with :2 bits each:

Bit:  0-7     8-9   10-11  12-13  ...  62-63
      instance  [0]    [1]    [2]  ...  [27]

Combining with other fields​

Repeated fields can be mixed with regular fields:

pgn 127501 "Binary Switch Bank Status" {
  instance    uint8   :8           # regular field
  indicator   uint8   :2  repeat=28  # 28 x 2 bits = 56 bits
}

Total: 8 + 56 = 64 bits = 8 bytes.