HIPC

IPC Command Structure

This is an array of u32's.

Word	Bits	Description
0	15-0	Type. 4=Request, 5=Control
0	19-16	Number of buf X descriptors (each: 2 words).
0	23-20	Number of buf A descriptors (each: 3 words).
0	27-24	Number of buf B descriptors (each: 3 words).
0	31-28	Number of type W desciptors (each: 3 words), never observed.
1	9-0	Total word count (in u32's).
1	13-10	If set to 2, enable buf C descriptor.
1	31	Enable handle descriptor.
...		Handle descriptor, if enabled.
...		Buf X descriptors, each one 2 words.
...		Buf A descriptors, each one 3 words.
...		Buf B descriptors, each one 3 words.
...		Type W descriptors, each one 3 words.
...		Padding
...		Raw data
...		Buf C descriptors, each one 2 words.

Handle descriptor

There can only be one of this descriptor type. It is enabled by bit31 of the second word.

Word	Bits	Description
0	0	Send current PID.
0	4-1	Number of handles to copy
0	8-5	Number of handles to move?
...		Handles to copy
...		Handles to move?

Buffer descriptor A/B

This packing is so unnecessarily complex.

Word	Bits	Description
0		Lower 32-bits of size.
1		Lower 32-bits of address.
2	1-0	Always set to 1 or 3. R/RW.
2	4-2	Bit 38-36 of address.
2	27-24	Bit 35-32 of size.
2	31-28	Bit 35-32 of address.

Buffer descriptor C

Word	Bits	Description
0		Lower 32-bits of address.
1	15-0	Rest of address.
1	31-16	Size

Buffer descriptor X

This one is packed even worse than A, they inserted the bit38-36 of the address on top of the counter field.

Word	Bits	Description
0	5-0	Bits 5-0 of counter.
0	8-6	Bit 38-36 of address.
0	11-9	Bits 11-9 of counter.
0	15-12	Bit 35-32 of address.
0	31-16	Size
1		Lower 32-bits of address.

Raw data portion

This is an array of u64's. It's always aligned to 16 so sometimes there is padding words before it.

Word	Description
...	Pid is written here if enabled.
+0	Magic ("SFCI" for requests, "SFCO" for responses)
+1	Cmd id
...	Rest of raw data.

Official marshalling code

The official marshalling function takes an array of (buf_ptr, size) pairs and a type-field for each such pair.

Bitmask 0x10 seems to indicate null-terminated strings, but that flag is ignored by the marshalling code.

Type Mask	Description	Direction
4 + 1	Creates an A descriptor	In
4 + 2	Creates a B descriptor	Out
8 + 1	Creates an X descriptor
8 + 2	Creates a C descriptor	Out
0x20 + 1	Creates both an A and X descriptor

Official IPC Cmd Structure

Official struct that is stored for each IPC command. It contains precalculated offsets for different portions of the command structure.

All offsets are given is in number of u32 words.

struct IpcCmdStruct {
  u8  unk0;
  u8  has_handle_descriptor;
  u8  pad0[2];
  u32 cmd0;
  u32 cmd1;
  u32 offset_handle_descriptor;
  u32 pad1;
  u32 offset_handles;          
  u32 pad2;
  u32 offset_x_descriptors;
  u32 offset_a_descriptors;
  u32 offset_b_descriptors;
  u32 offset_c_descriptors;
  u32 offset_raw_data;
  u32 unk1;
  u32 unk2;
  u32 unk3;
}