How can I repeat a command a hexadecimal number of times?

Question

The file I'm working on contains a hexdump. I pulled it directly out of memory, so it starts from an arbitrary offset, like this:

0x1234: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1244: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1254: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1264: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

I want to "rebase" this hexdump so it looks like this:

0x0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

This means I need to subtract the value 0x1234 from each of those values. My current workflow looks like this:

1. Fire up a python interpreter and convert 0x1234 to base-10 (it's 4660)
2. Position the cursor over the first 0x1234 in my file
3. Input 4660Ctrl-x
4. Repeatedly input j. until I've hit all the lines

That first step is really annoying - since I'm working with hexadecimal numbers, it feels like I ought to be able to subtract a hexadecimal value directly, rather than converting via base-10.

Is there an easier way to do this?

Answer 1

I would do:

:execute "normal! Ctrl-r=Ox1234Enter\<C-x>"

The r= use the expression register. It let you enter an expression that Vim will convert and paste.

To repeat it you can use the same technique: j. but you could also record a macro and run it 1000 times:

Record the macro in register a:

qaj.a

Run it 1000 times:

1000@a