60 lines
1.4 KiB
Text
60 lines
1.4 KiB
Text
.bp
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.NH
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Appendix B: Translation of a \fBPAR\fP construct to EM code using the library
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routines to simulate parallelism
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.PP
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Translation of the parallel construct:
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.DS
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.ft CW
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par
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P0
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par i = [ 1 for n ]
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P(i)
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.DE
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is
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.TS
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center;
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lf5 lf5.
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lal -20 ; Assume 20 bytes of local variables at this moment
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cal $parbegin ; Set up a process group
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asp 4 ; Assume pointersize = 4
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cal $parfork ; Split stack in two from local -20
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lfr 4 ; Assume wordsize = 4
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zne *23 ; One end jumps to second process, other continues here
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lor 0 ; Static link
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cal $P0
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asp 4
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bra *24 ; Jump to the outer parend
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23
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cal $parfork ; Fork off `par i = ...' process
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lfr 4
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zne *25 ; One end jumps to end of outer par
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lal -20 ; Place break just above i
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cal $parbegin ; Set up another process group for the P(i)
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loc 1
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stl -24 ; i:=1
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lol n ; Assume n can be addressed this simply
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stl -28 ; A nameless counter
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bra *26 ; Branch to counter test
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27
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cal $parfork ; Fork off one P(i)
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lfr 4
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zne *28 ; One jumps away to increment i, the other calls P(i)
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lol -24
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lor 0
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cal $P
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asp 8
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bra *29
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28
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inl -24 ; i:=i+1
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del -28 ; counter:=counter-1
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26
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lol -28
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zgt *27 ; while counter>0 repeat loop
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29
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cal $parend ; Wait for the P(i) to finish, then delete group
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bra *24 ; Jump to the higher up meeting place with P0
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25 ; Note that the bra will be optimized away
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24
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cal $parend ; Wait for both processes to end, then delete group
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.TE
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