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3259 decky 1
#
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# Copyright (c) 2008 Martin Decky
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# - Redistributions of source code must retain the above copyright
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#   notice, this list of conditions and the following disclaimer.
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# - Redistributions in binary form must reproduce the above copyright
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#   notice, this list of conditions and the following disclaimer in the
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#   documentation and/or other materials provided with the distribution.
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# - The name of the author may not be used to endorse or promote products
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#   derived from this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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"""
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Convert descriptive structure definitions to structure object
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"""
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import struct
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class Struct:
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    def size(self):
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        return struct.calcsize(self._format_)
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    def pack(self):
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        args = []
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        for variable in self._args_:
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            if (isinstance(self.__dict__[variable], list)):
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                for item in self.__dict__[variable]:
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                    args.append(item)
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            else:
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                args.append(self.__dict__[variable])
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        return struct.pack(self._format_, *args)
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def create(definition):
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    "Create structure object"
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    tokens = definition.split(None)
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    # Initial byte order tag
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    format = {
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        "little:":  lambda: "<",
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        "big:":     lambda: ">",
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        "network:": lambda: "!"
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    }[tokens[0]]()
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    inst = Struct()
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    args = []
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    # Member tags
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    comment = False
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    variable = None
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    for token in tokens[1:]:
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        if (comment):
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            if (token == "*/"):
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                comment = False
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            continue
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        if (token == "/*"):
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            comment = True
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            continue
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        if (variable != None):
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            subtokens = token.split("[")
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            if (len(subtokens) > 1):
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                format += "%d" % int(subtokens[1].split("]")[0])
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            format += variable
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            inst.__dict__[subtokens[0]] = None
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            args.append(subtokens[0])
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            variable = None
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            continue
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        if (token[0:8] == "padding["):
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            size = token[8:].split("]")[0]
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            format += "%dx" % int(size)
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            continue
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        variable = {
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            "char":     lambda: "s",
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            "uint8_t":  lambda: "B",
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            "uint16_t": lambda: "H",
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            "uint32_t": lambda: "L",
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            "uint64_t": lambda: "Q",
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            "int8_t":   lambda: "b",
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            "int16_t":  lambda: "h",
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            "int32_t":  lambda: "l",
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            "int64_t":  lambda: "q"
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        }[token]()
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    inst.__dict__['_format_'] = format
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    inst.__dict__['_args_'] = args
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    return inst