IRUSER Shared Memory

From 3dbrew
Jump to navigation Jump to search

This is the shared-memory for "ir:USER", which is provided by the application via InitializeIrnop or InitializeIrnopShared. The size of the shared memory is determined by parameters of the Init functions above.

Overall Structure[edit]

The shared memory consists of 2 or 5 components, depending on which Init function is called. For InitializeIrnopShared, ir service puts more information to the shared memory and applications can read it directly; for InitializeIrnop, ir service puts less information and store the rest in its local storage. All these components are adjacent to each other, without any padding, which means the data can be unaligned if the size specified in Init is unaligned.

Size Description
0x10 StatusInfo. Only presents when InitializeIrnopShared is called
0x10 ReceiveBufferInfo. Only presents when InitializeIrnopShared is called
(specified by Init paramter) ReceiveBuffer
0x10 SendBufferInfo. Only presents when InitializeIrnopShared is called
(specified by Init paramter) SendBuffer


Relative offset Size Description
0x0 0x4 Latest receive error result. Read by IRUSER:GetLatestReceiveErrorResult
0x4 0x4 Latest Send error result. Read by IRUSER:GetLatestSendErrorResult
0x8 0x1 Connection status. Read by IRUSER:GetConnectionStatus
0x9 0x1 Trying to connect status. Read by IRUSER:GetTryingToConnectStatus
0xA 0x1 Connection role. Read by IRUSER:GetConnectionRole
0xB 0x1 Machine ID. Set by IRUSER:SetOwnMachineId
0xC 0x1 Unknown. Value 1 is observed after connection
0xD 0x1 Network ID? Seems like a randomly distributed number after connection
0xE 0x1 Unknown. Value 1 is observed after initialization
0xF 0x1 Unknown


The BufferInfo sections store data validity information for the two buffers

Relative offset Size Description
0x0 0x4 Start index of valid packets
0x4 0x4 End index of valid packets
0x8 0x4 Number of valid packets
0xC 0x4 Unknown/Unused?


Relative offset Size Description
0x0 0x8 * packet_count (specified in Init parameter) PacketInfo{u32 offset_to_data_buffer, u32 data_length}
0x8 * packet_count buffer_size - 0x8 * packet_count Data buffer

The buffers are two circular buffers. A new packet is added to the end of previous packet in the data buffer, with packet info added to PacketInfo[end_index++]. Note that if an added packet exceeds the end of the buffer, the exceeding data will be wrapped around to the beginning of the data buffer.

Packet structure[edit]

A packet in the data buffer consists of a header, payload and a crc8 checksum

Relative offset Size Description
0x0 0x1 Fixed value 0xA5?
0x1 0x1 Destination network ID?
0x2 0x1 The highest bit is unknown.

When second highest bit is clear, the rest bit[0:5] of this byte is the payload length; otherwise bit[0:5] is the higher byte of the payload length

0x3 0x1 When bit[6] of previous byte is set, this byte is the lower byte of the payload length; other wise this byte doesn't present
0x3 or 0x4 payload length payload
0x3 or 0x4 +payload_length 0x1 CRC-8-CCITT over data above (header + payload)