osmo-st-gsm/Messages.st

"General IE based message handling"
Object subclass: IEMessage [
    <category: 'osmo-messages'>
    | ies type |

    IEMessage class >> initWith: type [
        <category: 'creation'>
        ^ (self new)
            type: type;
            yourself
    ]

    type: aType [
        <category: 'creation'>
        type := aType.
    ]

    addIe: aIe [
        <category: 'creation'>
        self ies add: aIe.
    ]

    ies [
        <category: 'access'>
        ies isNil ifTrue: [
            ies := OrderedCollection new.
        ].

        ^ ies
    ]

    writeOn: aMsg [
        <category: 'creation'>
        aMsg putByte: type.

        self ies do: [:each | each writeOn: aMsg ]
    ]
]

Object subclass: BCD [
    <category: 'osmo-message'>
    <comment: 'Class to deal with Binary Coded Decimals'>
    BCD class >> encode: aNumber [
        <category: 'access'>
        | col num |
        col := OrderedCollection new.

        num := aNumber.
        1 to: 3 do: [:each |
            col add: num \\ 10.
            num := num // 10.
        ].

        ^ col reverse asByteArray
    ]
]