This space is going to be 32 bytes, 8 bytes for each of the 4 registers. Because of that, accessing parameters beyond the 4th parameter is done starting with the offset of 0x20. In other words, the fourth parameter is accessed via RSP+0x20, the third RSP+0x28, etc.
You say that fourth is at 0x20 and third at 0x28, is it not fifth at 0x20 and sixth at 0x28 and so on..?
In Section 3.5,
You say that fourth is at 0x20 and third at 0x28, is it not fifth at 0x20 and sixth at 0x28 and so on..?