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86 lines
5.2 KiB
Forth
86 lines
5.2 KiB
Forth
\ *** Block No. 0 Hexblock 0
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\ ks 22 dez 87
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The multitasker is a simple yet powerful round robin scheme
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with explicit task switching. This has the major advantage
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that the system switches tasks only in known states.
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Hence the difficulties in synchronizing tasks and locking
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critical portions of code are greatly minimized or simply
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do not exist at all.
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\ *** Block No. 1 Hexblock 1
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\ Multitasker loadscreen ks 03 apr 88
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Onlyforth \needs Assembler 2 loadfrom asm.scr
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Code stop $E990 # U ) mov ' pause @ # jmp end-code
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: singletask [ ' noop @ ] Literal ['] pause ! ;
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: multitask [ ' pause @ ] Literal ['] pause ! ;
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1 3 +thru .( Multitasker geladen) cr
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\ *** Block No. 2 Hexblock 2
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\ pass activate ks 1 jun 87
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: pass ( n0 ... nr-1 Taddr r -- )
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BEGIN [ rot ]
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swap $E9CD over ! \ awake Task
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r> -rot \ Stack: IP r addr
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8 + >r \ s0 of Task
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r@ 2+ @ swap \ Stack: IP r0 r
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2+ 2* \ bytes on Taskstack incl. r0 & IP
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r@ @ over - \ new SP
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dup r> 2- ! \ into Ssave
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swap bounds ?DO I ! 2 +LOOP ; restrict
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: activate ( Taddr -- ) 0 \ [ ' pass >body ] Literal >r ;
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[ -rot ] REPEAT ; restrict
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\ *** Block No. 3 Hexblock 3
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( Building a Task ks 8 may 84 )
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| : taskerror ( string -- ) standardi/o singletask
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." Task error: " count type multitask stop ;
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: sleep ( addr -- ) $90 swap c! ;
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: wake ( addr -- ) $CD swap c! ;
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: rendezvous ( semaphoraddr -- )
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dup unlock pause lock ;
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\ *** Block No. 4 Hexblock 4
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\ Task ks 1 jun 87
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: Task ( rlen slen -- ) clear
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0 Constant here 2- >r \ addr of task constant
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here -rot \ here for Task dp
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even allot even \ allot dictionary area
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here r> ! \ set task constant addr
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up@ here $100 cmove \ init user area
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here $E990 , \ JMP opcode
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up@ 2+ dup dup @ + here - ,
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2dup - 2- swap ! \ link task
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0 , dup 2- dup , , \ ssave and s0
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2dup + , \ here + rlen = r0
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rot , \ dp
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under + dp ! 0 , \ allot rstack
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['] taskerror [ ' errorhandler >body c@ ] Literal rot + ! ;
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