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Annotation of 43BSD/contrib/icon/src/lib/bitops.icn, revision 1.1

1.1     ! root        1: #      BITOPS(2)
        !             2: #
        !             3: #      Logical operations on strings of 0s and 1s
        !             4: #
        !             5: #      Ralph E. Griswold
        !             6: #
        !             7: #      Last modified 4/27/83
        !             8: #
        !             9: #
        !            10: 
        !            11: #  convert integer i to bit string
        !            12: #
        !            13: procedure bitstring(i)
        !            14:    local b, h
        !            15:    if i < 0 then {
        !            16:       h := 1
        !            17:       i := -(i + 1)
        !            18:       }
        !            19:    else h := 0
        !            20:    b := ""
        !            21:    while i ~= 0 do {
        !            22:       b := abs(i % 2) || b
        !            23:       i /:= 2
        !            24:       }
        !            25:    b := right(b,32,"0")
        !            26:    if h = 1 then b := neg(b)
        !            27:    return b
        !            28: end
        !            29: 
        !            30: #  logical "and" of b1 and b2
        !            31: #
        !            32: procedure and(b1,b2)
        !            33:    return map(bsum(b1,b2),"12","01")
        !            34: end
        !            35: 
        !            36: 
        !            37: #  arithmetic sum of b1 and b2 (used by other procedures)
        !            38: #
        !            39: procedure bsum(b1,b2)
        !            40:    static segment
        !            41:    initial segment := 10
        !            42:    if *b1 > *b2 then b1 :=: b2
        !            43:    b1 := right(b1,*b2,"0")
        !            44:    if *b1 <= segment then return b1 + b2
        !            45:    return b1[1+:segment] + b2[1+:segment] ||
        !            46:       bsum(b1[segment + 1:0],b2[segment + 1:0])
        !            47: end
        !            48: 
        !            49: #  convert bitstring b to integer
        !            50: #
        !            51: procedure decimal(b)
        !            52:    return integer("2r" || b)
        !            53: end
        !            54: 
        !            55: #  exclusive "or" of b1 and b2
        !            56: #
        !            57: procedure exor(b1,b2)
        !            58:    return map(bsum(b1,b2),"2","0")
        !            59: end
        !            60: 
        !            61: #  negation (complement) of b
        !            62: #
        !            63: procedure neg(b)
        !            64:    return map(b,"01","10")
        !            65: end
        !            66: 
        !            67: #  logical "or" of b1 and b2
        !            68: #
        !            69: procedure or(b1,b2)
        !            70:    return map(bsum(b1,b2),"2","1")
        !            71: end
        !            72: 
        !            73: procedure xstop(x)
        !            74:    stop("Run-time error 205 in bitstring_
        !            75:       \nvalue out of range\noffending value: ",
        !            76:       image(x))
        !            77: end

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