assembly - Converting very simple ARM instructions to binary/hex

Question

I've been trying to use this page as well as various other guides to figure out how to express very simple ARM instructions as binary and hex. It seems like it should be a straightforward process to me, but I still don't understand. Here's a few examples.

Basic NOP:

       what goes here?          what goes here?
             _↓_                  _____↓____
            |   |                |          |
mov r0, r0 ; ????00?1101?????????????????????
                         |__||__|
                          ↑    ↑
                 how do I express registers?

Same basic question for others.

Comparing two registers:

cmp r1, r0

Adding immediate to register value:

add r0, #0x1a

All of these tutorials online are excellent at describing how to use instructions like these, but none I have been able to find actually walk through how to convert an ARM instruction in to the binary/hex/machine code into which it gets assembled.

Thanks in advance for your help.

Answer 1

Here is how data processing instructions are coded:

You have condition codes table in that page of yours. Registers are coded 0000 through 1111.

All your examples fall under the same category. The picture is extracted from some document on my HDD, but I also managed to find it by google. Coding those instructions is a tedious job.

So, mov r0, r0 should go like this:

1110 00 0 0 1101 0000 0000 00000000

I put Rn to 0, because it is not actually applicable to MOV. In case of CMP, I believe, S is always 1.