flags

Defining struct with flags using integer mask

Current implementation support flags extraction up to 64 bits long integer

  iex> defmodule IntegerMaskFlags do
  ...>   use BinStruct
  ...>   field :value, {
  ...>    :flags,
  ...>    %{
  ...>     type: :uint32_le,
  ...>     values: [
  ...>       { 0x00000001, :info_mouse },
  ...>       { 0x00000002, :info_disablectrlaltdel }
  ...>     ]
  ...>    }
  ...>  }
  ...> end
  ...>
  ...> IntegerMaskFlags.new(value: [:info_mouse, :info_disablectrlaltdel])
  ...> |> IntegerMaskFlags.dump_binary()
  ...> |> IntegerMaskFlags.parse()
  ...> |> then(fn {:ok, struct, _rest } -> struct end)
  ...> |> IntegerMaskFlags.decode()
  %{ value: [:info_mouse, :info_disablectrlaltdel] }

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I found it's counterintuitively but preferred way to define flags using mask, not position. You can change endianness from little to big and it will be work the same, automatically reversing all positions.

Below is list of supported masks for developers to copy and paste from. Library checks its valid mask, (covering only 1 bit and never overlaps) so don't worry you will not be able to mistaken it.

  def supported_masking_values(value) do

    case value do
        0x01 -> 1
        0x02 -> 2
        0x04 -> 3
        0x08 -> 4
        0x10 -> 5
        0x20 -> 6
        0x40 -> 7
        0x80 -> 8
        0x100 -> 9
        0x200 -> 10
        0x400 -> 11
        0x800 -> 12
        0x1000 -> 13
        0x2000 -> 14
        0x4000 -> 15
        0x8000 -> 16
        0x10000 -> 17
        0x20000 -> 18
        0x40000 -> 19
        0x80000 -> 20
        0x100000 -> 21
        0x200000 -> 22
        0x400000 -> 23
        0x800000 -> 24
        0x1000000 -> 25
        0x2000000 -> 26
        0x4000000 -> 27
        0x8000000 -> 28
        0x10000000 -> 29
        0x20000000 -> 30
        0x40000000 -> 31
        0x80000000 -> 32
        0x100000000 -> 33
        0x200000000 -> 34
        0x400000000 -> 35
        0x800000000 -> 36
        0x1000000000 -> 37
        0x2000000000 -> 38
        0x4000000000 -> 39
        0x8000000000 -> 40
        0x10000000000 -> 41
        0x20000000000 -> 42
        0x40000000000 -> 43
        0x80000000000 -> 44
        0x100000000000 -> 45
        0x200000000000 -> 46
        0x400000000000 -> 47
        0x800000000000 -> 48
        0x1000000000000 -> 49
        0x2000000000000 -> 50
        0x4000000000000 -> 51
        0x8000000000000 -> 52
        0x10000000000000 -> 53
        0x20000000000000 -> 54
        0x40000000000000 -> 55
        0x80000000000000 -> 56
        0x100000000000000 -> 57
        0x200000000000000 -> 58
        0x400000000000000 -> 59
        0x800000000000000 -> 60
        0x1000000000000000 -> 61
        0x2000000000000000 -> 62
        0x4000000000000000 -> 63
        0x8000000000000000 -> 64
      end

  end
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Variable bit size

  iex> defmodule IntegerVariableBitSizeMaskFlags do
  ...>   use BinStruct
  ...>   field :value, {
  ...>    :flags,
  ...>    %{
  ...>     type: :uint_le,
  ...>     values: [
  ...>       { 0x00000001, :info_mouse },
  ...>       { 0x00000002, :info_disablectrlaltdel }
  ...>     ]
  ...>    }
  ...>  }, bits: 24
  ...> end
  ...>
  ...> IntegerVariableBitSizeMaskFlags.new(value: [:info_mouse, :info_disablectrlaltdel])
  ...> |> IntegerVariableBitSizeMaskFlags.dump_binary()
  ...> |> IntegerVariableBitSizeMaskFlags.parse()
  ...> |> then(fn {:ok, struct, _rest } -> struct end)
  ...> |> IntegerVariableBitSizeMaskFlags.decode()
  %{ value: [:info_mouse, :info_disablectrlaltdel] }
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