rodman@mfci.UUCP (Paul Rodman) (07/25/89)
In article <3893@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > > I always wanted to try (I don't know why I never did) using >auto-decrement mode on r7 (i.e. the pc). I wonder what would happen? A Yes, it works... We had fun finding out that 014747 (octal) or MOV -(PC),-(PC) was a nice "seed" instr that would fill memory backwards from wherever you keyed it in until you hit the I/O and Trap vector locations, Bam! :-) pkr
rnovak@mips.COM (Robert E. Novak) (07/27/89)
I missed the start of this. I presume that someone has already posted the
infamous:
ROL -(PC)
Which turned the ROL instruction into:
MOV RO, R1
Assuming memory serves correctly. This was a favorite obfuscation that we
stuck in assembler code (I think it was A. I. Stocks that first pointed
this out to me in Urbana).
--
Robert E. Novak MIPS Computer Systems, Inc.
{ames,decwrl,pyramid}!mips!rnovak 928 E. Arques Ave. Sunnyvale, CA 94086
rnovak@abbott.mips.COM (rnovak%mips.COM@ames.arc.nasa.gov) +1 408 991-0402bmw@isgtec.UUCP (Bruce Walker) (07/27/89)
In article <958@m3.mfci.UUCP> rodman@mfci.UUCP (Paul Rodman) writes: >In article <3893@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >> >> I always wanted to try [...] auto-decrement mode on r7 (i.e. the pc). > >Yes, it works... We had fun finding out that [...] MOV -(PC),-(PC) >was a nice "seed" instr that would fill memory backwards from wherever >you keyed it in until you hit the I/O and Trap vector locations, Bam! :-) I have always known this type of addressing as: "auto-excrement mode" Just thought you should know that. -- Bruce Walker ...uunet!mnetor!lsuc!isgtec!mutant!bmw "Better Living Through Connectivity" ...utzoo!lsuc!isgtec!mutant!bmw ISG Technologies Inc. 3030 Orlando Dr. Mississauga. Ont. Can. L4V 1S8