Module mobile_codec 

Mobile Protocol Codec (16-byte header)

This module implements the mobile-optimized ZUS RPC protocol with a compact 16-byte header designed for mobile clients with bandwidth constraints.

Protocol Differences from Standard (40-byte)

Feature	Standard (40-byte)	Mobile (16-byte)
Header size	40 bytes	16 bytes
Magic	0xD3A7 (2 bytes)	0xDF (1 byte)
Sequence ID	u64 (8 bytes)	u16 (2 bytes)
Timeout	u64 (8 bytes)	u16 (2 bytes, seconds)
Data CRC	u32 (full CRC32)	u16 (lower 16 bits)
Trace ID	u64 (8 bytes)	Not present
Compress threshold	4096 bytes	256 bytes

Header Layout (16 bytes, Big-Endian)

Offset  Field       Type    Size    Description
------  ----------  ------  ------  -----------
0       magic       u8      1       0xDF
1       version     u8      1       Protocol version
2       cmdtype     u8      1       Message type (1=REQ, 2=RSP, 3=NOTIFY, 4=SYSRSP)
3       flag        u8      1       Flags: bit0=compressed, bit1=encrypted, bit2=fragment
4       headcrc16   u16     2       Header CRC (truncating addition)
6       datacrc     u16     2       Data CRC (lower 16 bits of CRC32)
8       seqId       u16     2       Sequence ID (0-65535, wraps around)
10      timeout     u16     2       Timeout in seconds (not milliseconds!)
12      datalen     u32     4       Body length in bytes
Total: 16 bytes

Heartbeat Packet (8 bytes)

Mobile clients send periodic heartbeat packets with magic 0xEF:

Offset  Field       Type    Size    Description
------  ----------  ------  ------  -----------
0       magic       u8      1       0xEF
1-7     padding     [u8;7]  7       Reserved/padding
Total: 8 bytes

Structs

MobileCodec

Mobile Protocol Codec

MobileHeartbeat

Mobile Heartbeat Packet (8 bytes)

MobileMessage

Mobile RPC Message

MobileProtocolHeader

Mobile Protocol Header (16 bytes)

Enums

MobilePacket

Decoded packet type from mobile protocol

Constants

HEARTBEAT_MAGIC

Mobile heartbeat magic number (1 byte)

HEARTBEAT_SIZE

Heartbeat packet size

MOBILE_COMPRESS_THRESHOLD

Default compression threshold for mobile protocol (256 bytes) Lower than standard (4KB) to optimize for mobile bandwidth

MOBILE_HEADER_SIZE

Mobile protocol header size

MOBILE_MAGIC

Mobile protocol magic number (1 byte)