| 1 | #
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| 2 | # SPDX-FileCopyrightText: 2008 Martin Decky
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| 3 | # SPDX-FileCopyrightText: 2011 Martin Sucha
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| 4 | #
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| 5 | # SPDX-License-Identifier: BSD-3-Clause
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| 6 | #
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| 7 | """
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| 8 | Convert descriptive structure definitions to structure object
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| 9 | """
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| 10 |
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| 11 | import struct
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| 12 | import sys
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| 13 | import types
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| 14 |
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| 15 | # Handle long integer conversions nicely in both Python 2 and Python 3
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| 16 | integer_types = (int, long) if sys.version < '3' else (int,)
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| 17 |
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| 18 | # Ensure that 's' format for struct receives correct data type depending
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| 19 | # on Python version (needed due to different way to encode into bytes)
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| 20 | ensure_string = \
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| 21 | (lambda value: value if type(value) is str else bytes(value)) \
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| 22 | if sys.version < '3' else \
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| 23 | (lambda value: bytes(value, 'ascii') if type(value) is str else value)
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| 24 |
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| 25 | ranges = {
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| 26 | 'B': (integer_types, 0x00, 0xff),
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| 27 | 'H': (integer_types, 0x0000, 0xffff),
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| 28 | 'L': (integer_types, 0x00000000, 0xffffffff),
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| 29 | 'Q': (integer_types, 0x0000000000000000, 0xffffffffffffffff),
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| 30 | 'b': (integer_types, -0x80, 0x7f),
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| 31 | 'h': (integer_types, -0x8000, 0x7fff),
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| 32 | 'l': (integer_types, -0x80000000, 0x7fffffff) ,
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| 33 | 'q': (integer_types, -0x8000000000000000, 0x7fffffffffffffff),
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| 34 | }
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| 35 |
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| 36 | def check_range(varname, fmt, value):
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| 37 | if value == None:
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| 38 | raise ValueError('Variable "%s" not set' % varname)
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| 39 | if not fmt in ranges:
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| 40 | return
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| 41 | vartype, varmin, varmax = ranges[fmt]
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| 42 | if not isinstance(value, vartype):
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| 43 | raise ValueError('Variable "%s" is %s but should be %s' %
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| 44 | (varname, str(type(value)), str(vartype)))
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| 45 | if value < varmin or value > varmax:
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| 46 | raise ValueError('Variable "%s" value %s out of range %s..%s' %
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| 47 | (varname, repr(value), repr(varmin), repr(varmax)))
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| 48 |
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| 49 | class Struct:
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| 50 | def size(self):
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| 51 | return struct.calcsize(self._format_)
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| 52 |
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| 53 | def pack(self):
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| 54 | args = []
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| 55 | for variable, fmt, length in self._args_:
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| 56 | value = self.__dict__[variable]
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| 57 | if isinstance(value, list):
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| 58 | if length != None and length != len(value):
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| 59 | raise ValueError('Variable "%s" length %u does not match %u' %
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| 60 | (variable, len(value), length))
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| 61 | for index, item in enumerate(value):
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| 62 | check_range(variable + '[' + repr(index) + ']', fmt, item)
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| 63 | args.append(item)
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| 64 | else:
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| 65 | if (fmt == "s"):
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| 66 | value = ensure_string(value)
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| 67 | check_range(variable, fmt, value)
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| 68 | args.append(value)
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| 69 | return struct.pack(self._format_, *args)
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| 70 |
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| 71 | def unpack(self, data):
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| 72 | values = struct.unpack(self._format_, data)
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| 73 | i = 0
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| 74 | for variable, fmt, length in self._args_:
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| 75 | self.__dict__[variable] = values[i]
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| 76 | i += 1
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| 77 |
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| 78 | def create(definition):
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| 79 | "Create structure object"
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| 80 |
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| 81 | tokens = definition.split(None)
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| 82 |
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| 83 | # Initial byte order tag
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| 84 | format = {
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| 85 | "little:": lambda: "<",
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| 86 | "big:": lambda: ">",
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| 87 | "network:": lambda: "!"
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| 88 | }[tokens[0]]()
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| 89 | inst = Struct()
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| 90 | args = []
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| 91 |
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| 92 | # Member tags
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| 93 | comment = False
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| 94 | variable = None
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| 95 | for token in tokens[1:]:
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| 96 | if (comment):
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| 97 | if (token == "*/"):
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| 98 | comment = False
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| 99 | continue
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| 100 |
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| 101 | if (token == "/*"):
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| 102 | comment = True
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| 103 | continue
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| 104 |
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| 105 | if (variable != None):
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| 106 | subtokens = token.split("[")
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| 107 |
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| 108 | length = None
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| 109 | if (len(subtokens) > 1):
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| 110 | length = int(subtokens[1].split("]")[0])
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| 111 | format += "%d" % length
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| 112 |
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| 113 | format += variable
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| 114 |
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| 115 | inst.__dict__[subtokens[0]] = None
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| 116 | args.append((subtokens[0], variable, length))
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| 117 |
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| 118 | variable = None
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| 119 | continue
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| 120 |
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| 121 | if (token[0:8] == "padding["):
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| 122 | size = token[8:].split("]")[0]
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| 123 | format += "%dx" % int(size)
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| 124 | continue
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| 125 |
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| 126 | variable = {
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| 127 | "char": lambda: "s",
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| 128 | "uint8_t": lambda: "B",
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| 129 | "uint16_t": lambda: "H",
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| 130 | "uint32_t": lambda: "L",
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| 131 | "uint64_t": lambda: "Q",
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| 132 |
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| 133 | "int8_t": lambda: "b",
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| 134 | "int16_t": lambda: "h",
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| 135 | "int32_t": lambda: "l",
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| 136 | "int64_t": lambda: "q"
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| 137 | }[token]()
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| 138 |
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| 139 | inst.__dict__['_format_'] = format
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| 140 | inst.__dict__['_args_'] = args
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| 141 | return inst
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