IR:RST Shared Memory
This page describes the format of the ir:rst's shared memory. It contains the current state of New 3DS input device, ie the c-stick and the ZL/ZR shoulder buttons.
Size: 0x88 ?
|0x0||0x4||A counter that ranges from 0 to 7, presumably to indicate which entry was last updated|
|0x4||0x4||Unused ? (value 0x0)|
|0x8||0x80||Array of 8 entries, where each entry (see below) is 0x10-bytes.|
IR module first updates index0, then index1, and so on. When updating the array when the index is already 7, the index is reset to 0.
The ir:rst PAD entries are the same format as HID ones and meant to be ORd with them (they are complementary, there is no overlap in used bits).
|0x0||0x4||Current PAD state.|
|0x4||0x4||PAD state for buttons which were pressed(bitmasks which changed from value 0 to value 1) since the last HID update.|
|0x8||0x4||PAD state for buttons which were released(bitmasks which changed from value 1 to value 0) since the last HID update.|
|0xC||0x4||This stores c-stick info: the low s16 is the X coordinate, the high s16 is the Y coordinate. The c-stick center is exactly 0 for these fields. The range for these fields is approximately: -0x9C(bottom/left) - 0x9C(top/right).|