Редактирование: Mindset (раздел)

=== DataRow Format ===
A DataRow consists of bytes in the following format:
{| class="wikitable"
|+
!([EXCODE]...) [CODE]
!([VLENGTH])
![VALUE...]
|-
|^^^^(Value Type)^^^^  
|^^(length)^^
|^^(value)^^
|}
<blockquote>Note: Bytes in parentheses are conditional, meaning that they only appear in some DataRows, and

not in others. See the following description for details.</blockquote>e DataRow may begin with zero or more [EXCODE] (Extended Code) bytes, which are bytes with

the value 0x55. e number of [EXCODE] bytes indicates the Extended Code Level. e Extended

Code Level, in turn, is used in conjuction with the [CODE] byte to determine what type of Data

Value this DataRow contains. Parsers should therefore always begin parsing a DataRow by counting

the number of [EXCODE] (0x55) bytes that appear to determine the Extended Code Level of the

DataRow's [CODE].

e [CODE] byte, in conjunction with the Extended Code Level, indicates the type of Data Value

encoded in the DataRow. For example, at Extended Code Level 0, a [CODE] of 0x04 indicates that

the DataRow contains an eSense Attention value. For a list of de􀃫ned [CODE] meanings, see the

CODE De􀃫nitions Table below. Note that the [EXCODE] byte of 0x55 will never be used as a [CODE]

(incidentally, the [SYNC] byte of 0xAA will never be used as a [CODE] either).

If the [CODE] byte is between 0x00 and 0x7F, then the the [VALUE…] is implied to be 1 byte long

(referred to as a Single-Byte Value). In this case, there is no [VLENGTH] byte, so the single [VALUE]

byte will appear immediately after the [CODE] byte.

If, however, the [CODE] is greater than 0x7F, then a [VLENGTH] ("Value Length") byte immediately

follows the [CODE] byte, and this is the number of bytes in [VALUE…] (referred to as a Multi-Byte

Value). ese higher CODEs are useful for transmitting arrays of values, or values that cannot be 􀃫t

into a single byte.

e DataRow format is de􀃫ned in this way so that any properly implemented parser will not break

in the future if new CODEs representing arbitrarily long DATA… values are added (they simply ignore

unrecognized CODEs, but do not break in parsing), the order of CODEs is rearranged in the Packet, or

if some CODEs are not always transmitted in every Packet.

A procedure for properly parsing Packets and DataRows is given below in Step-By-Step Guide to

Parsing a Packet and Step-By-Step Guide to Parsing DataRows in a Packet Payload, respectively.