don't forget to turn everything to 0 first in this example I was using:
FF C3 00 D1 SUB SP, SP, #0x30
F5 53 01 A9 STP X21, X20, [SP,#0x30+var_20]
1st I turned FF C3 00 D1 into a Dword.
2nd I turned FF C3 00 D1 F5 53 01 A9 into a Qword.
3rd I turned a Qword into 2 Dwords.
Qword = 8 bytes Dword = 4 bytes
