Initial revision

doc/occam/p9

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+.bp
+.NH
+Appendix B: Translation of a \fBPAR\fP construct to EM code using the library
+routines to simulate parallelism 
+.PP
+Translation of the parallel construct:
+.DS
+.ft 5
+	par
+		P0
+		par i = [ 1 for n ]
+			P(i)
+.DE
+is
+.TS
+center;
+lf5 lf5.
+ lal -20	; Assume 20 bytes of local variables at this moment
+ cal $parbegin	; Set up a process group
+ asp 4		; Assume pointersize = 4
+ cal $parfork	; Split stack in two from local -20
+ lfr 4		; Assume wordsize = 4
+ zne *23	; One end jumps to second process, other continues here
+ lor 0	; Static link
+ cal $P0
+ asp 4
+ bra *24	; Jump to the outer parend
+23
+ cal $parfork	; Fork off `par i = ...'  process
+ lfr 4
+ zne *25	; One end jumps to end of outer par
+ lal -20	; Place break just above i
+ cal $parbegin	; Set up another process group for the P(i)
+ loc 1
+ stl -24	; i:=1
+ lol n	; Assume n can be addressed this simply
+ stl -28	; A nameless counter
+ bra *26	; Branch to counter test
+27
+ cal $parfork	; Fork off one P(i)
+ lfr 4
+ zne *28	; One jumps away to increment i, the other calls P(i)
+ lol -24
+ lor 0
+ cal $P
+ asp 8
+ bra *29
+28
+ inl -24	; i:=i+1
+ del -28	; counter:=counter-1
+26
+ lol -28
+ zgt *27	; while counter>0 repeat loop
+29
+ cal $parend	; Wait for the P(i) to finish, then delete group
+ bra *24	; Jump to the higher up meeting place with P0
+25	; Note that the bra will be optimized away
+24
+ cal $parend	; Wait for both processes to end, then delete group
+.TE