I'd like to move one byte from register rdx to register rbx, like this:
mov %rdx , (%rbx,%r15,1)
where rdx contains 0x33 ,r15 is index and rbx contains 0 at start.
I have tried using this method in many ways , always ending with SIGSEGV error. In the end I am going to create a rbx register which will contain an array of next rdx values
You can shift the bytes in one at a time, like this:
; Calculate first dl
...
mov %dl,%bl
; Calculate next dl
...
shlq $8,%rbx
mov %dl,%bl
; Calculate next dl
...
shlq $8,%rbx
mov %dl,%bl
etc. This assumes that you want the first byte in the msb, and the last byte in the lsb. The revesre order is a bit more complicated, but not much.