Allocate 1 array of char or unsigned char with size == packet_size; Decalre constants:
const int metaFieldPos = 0;
const int sizeofMetaField = sizeof(char);
const int lengthPos = metaFieldPos + sizeofMetaField;
const int sizeofLengthField = sizeof(char) * 3;
const int dataPos = lengthPos + sizeofLengthField;
If you got the data and can recognize begining of the packet, you can use constants above to navigate by pointers.
May be these functions will help you (They use Qt, but you can easily translate them to library, that you use)
quint32 Convert::uint32_to_uint24(const quint32 value){
return value & (quint32)(0x00FFFFFFu);
}
qint32 Convert::int32_to_uint24(const qint32 value){
return value & (qint32)(0x00FFFFFF);
}
quint32 Convert::bytes_to_uint24(const char* from){
quint32 result = 0;
quint8 shift = 0;
for (int i = 0; i < bytesIn24Bits; i++) {
result |= static_cast<quint32>(*reinterpret_cast<const quint8 *>(from + i)) << shift;
shift+=bitsInByte;
}
return result;
}
void Convert::uint32_to_uint24Bytes(const quint32 value, char* from){
quint8 shift = 0;
for (int i = 0; i < bytesIn24Bits; i++) {
const quint32 buf = (value >> shift) & 0xFFu;
*(from + i) = *reinterpret_cast<const char *>(&buf);
shift+=bitsInByte;
}
}
QByteArray Convert::uint32_to_uint24QByteArray (const quint32 value){
QByteArray bytes;
bytes.resize(sizeof(value));
*reinterpret_cast<quint32 *>(bytes.data()) = value;
bytes.chop(1);
return bytes;
}