IRUSER Shared Memory
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
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 |
StatusInfo
| 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 |
ReceiveBufferInfo/SendBufferInfo
(Information below is poorly verified against real hardware. Please help me verify them -- Wwylele (talk))
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 |
ReceiveBuffer/SendBuffer
| 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
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 | Unknown |
| 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 | crc8 (x^8 + x^2 + x + 1) over data above (header + payload) |