Byte data Parsing in flutter

Question

hi there i need to parse the byte data of a response from api the data is

[0, 2, 0, 44, 0, 6, 58, 1, 0, 1, 109, 85, 0, 0, 0, 1, 0, 1, 111, 97, 0, 115, 224, 4, 0, 0, 0, 0, 0, 0, 1, 114, 0, 1, 115, 169, 0, 1, 116, 18, 0, 1, 108, 121, 0, 1, 113, 241, 0, 44, 0, 13, 128, 1, 0, 0, 55, 200, 0, 0, 0, 10, 0, 0, 55, 227, 5, 172, 149, 3, 0, 0, 84, 154, 0, 0, 0, 0, 0, 0, 56, 79, 0, 0, 57, 28, 0, 0, 54, 226, 0, 0, 56, 89]

there are certain rules to parse the data according to api provider as below

A The first two bytes ([0 - 2] -- SHORT or int16) represent the number of packets in the message.

B The next two bytes ([2 - 4] -- SHORT or int16) represent the length (number of bytes) of the first packet.

C The next series of bytes ([4 - 4+B]) is the quote packet.

D The next two bytes ([4+B - 4+B+2] -- SHORT or int16) represent the length (number of bytes) of the second packet.

C The next series of bytes ([4+B+2 - 4+B+2+D]) is the next quote packet.

please someone help me how to parse this data according to these rules in dart. i am stuck thanks for help

Answer 1

First, you need to convert the list of integers into a list of bytes:

final byteList = Uint8List.fromList(responseList);

Then you need to create a ByteData from that byte list:

final byteData = ByteData.view(byteList.buffer);

Then you can do your parsing of various bytes, shorts, ints, or longs that you want at various byte offsets. For example:

final packetNum = byteData.getUint16(0);

final firstPacketLength = byteData.getUint16(2);
final firstPacketView = ByteData.sublistView(byteData, 4, 4 + firstPacketLength);
// Do whatever you need for that packet

final secondPacketPos = 4 + firstPacketLength;
final secondPacketLength = byteData.getUint16(secondPacketPos),
final secondPacketView = ByteData.sublistView(byteData, secondPacketPos + 2, 4 + secondPacketLength);
// Do whatever you need for the saecond packet