Utility functions¶
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check_expected_data(data, expected_data)¶ Returns True if the data and expected_data are the same.
Parameters: - data (str) – a hexadecimal string
- expected_data (str) – a hexadecimal string or a string with a list of hexadecimal string with , as separator (“9000, 6Cxx, 6xxx”)
Returns: bool : True if data matches with the expected data, False otherwize
Note
The character X or x could be set into expected data as a wildcard value
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getBytes(data, byteNumber, length=1)¶ Returns the part of data string from byte number to length bytes
Parameters: - data (str) – a hexadecimal string
- byteNumber (int) – the start offset into the string
- length (int) – The bytes length to get
Returns: str bytestr: the hexadecimal string
# get the string from byte 2 with a length of 3 astr = "3B65000 09C11 0101 03" getBytes(astr, 2, 3) # returns "650000"
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getLength(bytestr, length=1)¶ Returns a string representing the length of the string as parameter on numberOfBytes bytes
Parameters: - bytestr (str) – a hexadecimal string
- length (int) – the number of byte expected for the string
getLength("A0A40002", 2) # returns "0004" getLength("A0A40002", 1) # returns "04"
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increment(bytestr, value)¶ This function increments an hexadecimal string with the integer value. The value could be an integer or a string.
Parameters: - bytestr (str) – a hexadecimal string
- value (int) – the value to increment
aStr = '01' aInt = 0x03 newStr = increment ( aStr, aInt ) # returns "04" aInt = '03' newStr = increment ( aStr, aInt ) # returns "04"
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intToHexString(intValue, len=1)¶ Returns a hexadecimal string representing an integer
Parameters: - intValue (int) – an integer value
- len (int) – the number of byte expected for the string
Returns: str bytestr: the hexadecimal string
# get the string representation of the integer aInt = 10 intToHexString ( aInt, 2 ) #returns "000A"
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lv(bytestring)¶ Returns a byte String representing the length content preceding by its length.
Parameters: bytestring (str) – a hexadecimal string Returns: str bytestr: the hexadecimal string preceded by its length Note
for byte string up to FF bytes, the length is coded with 2 bytes.
# get the string preceded by its length astr = "3B65000 09C11 0101 03" lv(astr) # returns "093B6500009C11010103"
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ber_lv(bytestring)¶ Returns a byte String representing the BER type length content preceding by its length.
Parameters: bytestring (str) – a hexadecimal string Returns: str bytestr: the hexadecimal string preceded by its length Note
short form consist of a single byte in which bit 8 is 0. (length: range is 0 ~ 127) long form. Initial octet, bit 8 is 1, and bits 1-7 encode the number of octets that follow.
# get the string preceded by its length astr = "3B65000 09C11 0101 03" ber_lv(astr) # returns "093B6500009C11010103" # the length of astr is longer than 127. Assume that length is 0x80 astr = "3B65000 09C11 0101 03..... 00" ber_lv(astr) # returns "81803B6500009C11010103....00"
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der_lv(bytestring)¶ Returns a byte String representing the length content preceding by its length.
Parameters: bytestring (str) – a hexadecimal string Returns: str bytestr: the hexadecimal string preceded by its length Note
short form consist of a single byte (length: range is 0 ~ 127) long from consist of three octec, start with 0xFF(length: rnage is 0x0100 ~ 0xFFFF)
# get the string preceded by its length astr = "3B65000 09C11 0101 03" der_lv(astr) # returns "093B6500009C11010103" # the length of astr is longer than 255. Assume that length is 0x0100 astr = "3B65000 09C11 0101 03..... 00" der_lv(astr) # returns "FF01003B6500009C11010103....00"
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remove_space(bytestring)¶ Removes all whitespace characters of a string.
Parameters: bytestring (str) – The string to manage Returns: str bytestr: the string without whitepace characters
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toByteArray(byteString)¶ Returns a list of bytes from a byte string
Parameters: bytestring (str) – a hexadecimal string Returns: list list_byte: the list of bytes # get the list of bytes from the hexadecimal string astr = "3B65000 09C11 0101 03" toByteArray( astr ) # returns [ 0x3B, 0x65, 0x00, 0x00, 0x9C, 0x11, 0x01, 0x01, 0x03 ]
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toHexString(bytes=[])¶ Returns a hexadecimal string from a list of bytes
Parameters: bytes (list) – a list of bytes Returns: str bytestr: the hexadecimal string # get the string from the list of bytes a_list = [ 0x3B, 0x65, 0x00, 0x00, 0x9C, 0x11, 0x01, 0x01, 0x03 ] toHexString( a_list ) # returns "3B6500009C11010103"