unix diff side-to-side results?

How can I plot the results of a unix diff command side-to-side instead of one difference after the other? See below for an example:

    diff /tmp/test1  /tmp/test2
1,4c1,2
< asfdsadf
< asdfsad
< fsaf
< fdsadf
---
> asdfsafdsf
> saf
6,8d3
< sadf
< asdf
< sadf
10d4
< fasd
12,13c6,14
< sadfa
< fd
---
> sadf
> sadf
> sadf
> sadf
> sadf
> sadf
> sadf
> sadf
> safa

I would like to have something like:

diff /tmp/test1  /tmp/test2
1,4c1,2
< asfdsadf       > asdfsafdsf
< asdfsad        > saf       
< fsaf
< fdsadf
---
6,8d3
< sadf
< asdf
< sadf
10d4
< fasd
12,13c6,14
< sadfa               > sadf
< fd              > sadf
---               > sadf
              > sadf
              > sadf
              > sadf
              > sadf
              > sadf
              > safa

From man diff, you can use -y to do side-by-side.

-y, --side-by-side
       output in two columns

Hence, say:

diff -y /tmp/test1  /tmp/test2

Test

$ cat a                $ cat b
hello                  hello
my name                my name
is me                  is you

Let's compare them:

$ diff -y a b
hello                                                           hello
my name                                                         my name
is me                                                         | is you