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https://github.com/forth-ev/VolksForth.git
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86 lines
5.4 KiB
Plaintext
86 lines
5.4 KiB
Plaintext
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0 \ ks 22 dez 87
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1 The multitasker is a simple yet powerful round robin scheme
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2 with explicit task switching. This has the major advantage
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3 that the system switches tasks only in known states.
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4 Hence the difficulties in synchronizing tasks and locking
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5 critical portions of code are greatly minimized or simply
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6 do not exist at all.
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Screen 1 not modified
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0 \ Multitasker loadscreen ks 03 apr 88
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1 Onlyforth \needs Assembler 2 loadfrom asm.scr
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2
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3 Code stop $E990 # U ) mov ' pause @ # jmp end-code
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4
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5 : singletask [ ' noop @ ] Literal ['] pause ! ;
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6 : multitask [ ' pause @ ] Literal ['] pause ! ;
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7
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8 1 3 +thru .( Multitasker geladen) cr
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Screen 2 not modified
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0 \ pass activate ks 1 jun 87
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1
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2 : pass ( n0 ... nr-1 Taddr r -- )
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3 BEGIN [ rot ]
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4 swap $E9CD over ! \ awake Task
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5 r> -rot \ Stack: IP r addr
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6 8 + >r \ s0 of Task
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7 r@ 2+ @ swap \ Stack: IP r0 r
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8 2+ 2* \ bytes on Taskstack incl. r0 & IP
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9 r@ @ over - \ new SP
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10 dup r> 2- ! \ into Ssave
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11 swap bounds ?DO I ! 2 +LOOP ; restrict
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12
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13 : activate ( Taddr -- ) 0 \ [ ' pass >body ] Literal >r ;
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14 [ -rot ] REPEAT ; restrict
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15
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Screen 3 not modified
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0 ( Building a Task ks 8 may 84 )
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1
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2 | : taskerror ( string -- ) standardi/o singletask
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3 ." Task error: " count type multitask stop ;
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4
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5 : sleep ( addr -- ) $90 swap c! ;
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6
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7 : wake ( addr -- ) $CD swap c! ;
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8
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9 : rendezvous ( semaphoraddr -- )
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10 dup unlock pause lock ;
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Screen 4 not modified
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0 \ Task ks 1 jun 87
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1
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2 : Task ( rlen slen -- ) clear
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3 0 Constant here 2- >r \ addr of task constant
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4 here -rot \ here for Task dp
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5 even allot even \ allot dictionary area
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6 here r> ! \ set task constant addr
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7 up@ here $100 cmove \ init user area
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8 here $E990 , \ JMP opcode
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9 up@ 2+ dup dup @ + here - ,
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10 2dup - 2- swap ! \ link task
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11 0 , dup 2- dup , , \ ssave and s0
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12 2dup + , \ here + rlen = r0
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13 rot , \ dp
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14 under + dp ! 0 , \ allot rstack
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15 ['] taskerror [ ' errorhandler >body c@ ] Literal rot + ! ;
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