[roondar]

I don't have exactly what you're asking for, but I did make some soft-blitting routines for the 68020 as a part of my experiment in using the CPU and Blitter concurrently.

You can find my article & video describing how it works here: http://powerprograms.nl/amiga/cpu-blit-assist.html

There's a link to the source code in the article, which contains assembly routines to do CPU based "Blitter copying" and CPU based "Blitter Cookie-Cutting".

Edit:

Originally Posted by alexh

Here is a nice article about using the blitter and software blitter side by side

http://powerprograms.nl/amiga/cpu-blit-assist.html

Including the code.

This is not concurrent blitting, but rather concurrent posting