On Dec 9, 2016, at 1:37 PM, Scott Deandrea <sdeand...@apple.com> wrote:
> The link-layer header format is as follows:
> struct
> {
> // Control information
> uint16_t bcdVersion; // version of this structure
What's the current version? 0, 1, or something else?
> uint8_t headerLength; // length of this structure
Presumably length in bytes.
> uint8_t requestType; // tAppleUSBHostPacketFilterRequestType
So what are the possible values for requestType? (I don't see
tAppleUSBHostPacketFilterRequestType anywhere in the public XNU source or any
header from Xcode.)
> // Transfer information
> uint32_t ioLength; // amount of data requested/transferred
Presumably length in bytes.
> uint32_t ioStatus; // IOReturn
> uint32_t ioFrameCount; // number of isoch frames following
> uint64_t ioID; // unique id for this I/O
>
> // Device information
> uint32_t deviceLocation; // locationID of the device
> uint8_t deviceSpeed; // tEndpointSpeed
Is this an enumerated value, a bits/second value, or something else?
> uint8_t deviceAddress; // tUSBHostDeviceAddress
So that's just a standard 7-bit USB device address, presumably, as per the USB
3.1 spec:
A 7-bit value representing the address of a device on the USB. The
device address is the default address (00H) when the USB device is first
powered or the device is reset. Devices are assigned a unique device address by
the USB system software.
with the 8th bit zero?
> uint8_t endpointAddress; // Address and Direction
So that's the endpoint in the lower 4 bits, and the direction somewhere in the
upper 4 bits? What are the representations for IN and OUT?
> uint8_t endpointType; // tEndpointType
So what are the values for bulk, control, interrupt, and isochronous?
> // Additional information
So the additional information's presence would be indicated by a greater
headerLength and possibly also by a different bcdVersion value?
> } __attribute__((packed, aligned(sizeof(uint32_t))));
>
> The packet payload is the raw USB data that was sent/received for I/O request.
So that would be the "data field" from section 8.3.4 "Data Field" from the USB
2.0 spec and the DWORDs following the 16-byte header from the USB 3.1 spec?
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