[TUHS] Query on PDP-11 assembly

Warren Toomey wkt at tuhs.org
Wed Apr 30 21:56:51 AEST 2008


All, I'm trying to write a PDP-11 disassembler for a.out files. I'm having
trouble dealing with jsrs. Take, for example, the code here:
http://minnie.tuhs.org/UnixTree/1972_stuff/s1/frag19.html

I can happily deal with the   jsr pc,do   type of jsr, but the ones
involving r5 have me stumped, e.g.:

	jsr	r5,questf; < nonexistent\n\0>; .even

It appears that data is being inserted into the executable directly
after the jsr instruction. How does the rts which returns from the jsr
know how much data to skip, and what is the involvement of r5 here?

Thanks,
	Warren



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