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[/] [eco32/] [trunk/] [fp/] [implementation/] [mmix/] [crypto.mms] - Rev 84
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* Cryptanalysis Problem (CLASSIFIED)
a GREG
b GREG
c GREG
t GREG
x GREG
y GREG
LOC Data_Segment
count GREG @ Base address for wyde counts
LOC @+8*(1<<16) Space for the wyde frequencies
freq GREG @ Base address for byte counts
LOC @+8*(1<<8) Space for the byte frequencies
p GREG @
BYTE "abracadabraa",0,"abc" Trivial test data
ones GREG #0101010101010101
LOC #100
2H SRU b,a,45 Isolate next wyde.
LDO c,count,b Load old count.
INCL c,1
STO c,count,b Store new count.
SLU a,a,16 Delete one wyde.
PBNZ a,2B Done with octabyte? \bracetext...
Phase1 LDOU a,p,0 Start here: Fetch the next eight bytes.
INCL p,8
BDIF t,ones,a Test if there's a zero byte.
PBZ t,2B Do main loop, unless near the end.
2H SRU b,a,45 Isolate next wyde.
LDO c,count,b Load old count.
INCL c,1
STO c,count,b Store new count.
SRU b,t,48
SLU a,a,16
BDIF t,ones,a
PBZ b,2B Continue unless done.
Phase2 SET p,8*255 1
1H SL a,p,8 255
LDA a,count,a 255 $\.a\gets{}$address of row \.p
SET b,8*255 255
LDO c,a,0 255
SET t,p 255
2H INCL t,#800 255*255
LDO x,count,t 255*255 Element of column \.p
LDO y,a,b 255*255 Element of row \.p
ADD c,c,x 255*255
ADD c,c,y 255*255
SUB b,b,8 255*255
PBP b,2B 255*255
STO c,freq,p 255
SUB p,p,8 255
PBP p,1B 255
POP
Main IS Phase1
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