1: \ Multitasker 19aug94py
2:
3: Create sleepers sleepers A, sleepers A, 0 ,
4:
5: \ LINK-TASK links task1 into the task chain of task2
6: : link-task ( task1 task2 -- )
7: over 2@ 2dup cell+ ! swap ! \ unlink task1
8: 2dup @ cell+ ! 2dup dup @ rot 2! ! ;
9:
10: : sleep ( task -- ) sleepers link-task ;
11: : wake ( task -- ) next-task link-task ;
12:
13: \ PAUSE is the task-switcher
14: : pause ( -- )
15: rp@ fp@ lp@ sp@ save-task !
16: next-task @ up! save-task @ sp!
17: lp! fp! rp! ;
18:
19: \ STOP sleeps a task and switches to the next
20: : stop ( -- )
21: rp@ fp@ lp@ sp@ save-task !
22: next-task @ up! save-task @ sp!
23: lp! fp! rp! prev-task @ sleep ;
24:
25: \ USER' computes the task offset
26: : user' ( 'user' -- n )
27: ' >body @ state @ IF postpone Literal THEN ; immediate
28:
29: \ NEWTASK creates a new, sleeping task
30: : NewTask ( n -- Task ) dup 2* 2* udp @ + dup
31: allocate throw + >r
32: r@ over - udp @ - next-task over udp @ move
33: r> over user' r0 + ! dup >r
34: dup r@ user' l0 + ! over -
35: dup r@ user' f0 + ! over -
36: dup r@ user' s0 + ! over -
37: dup r@ user' normal-dp + dup >r !
38: r> r@ user' dpp + ! + $10 +
39: r@ user' >tib + !
40: r> dup 2dup 2! dup sleep ;
41:
42: : kill-task
43: next-task @ up! save-task @ sp!
44: lp! fp! rp! prev-task @ dup dup link-task user' normal-dp + @ free throw ;
45:
46: : (pass) ( x1 .. xn n task -- ) rdrop
47: [ ' kill-task >body ] ALiteral r>
48: rot >r r@ user' r0 + @ 2 cells - dup >r 2!
49: r> swap 1+
50: r@ user' f0 + @ swap 1+
51: r@ user' l0 + @ swap 1+
52: cells r@ user' s0 + @ tuck swap - dup r@ user' save-task + !
53: ?DO I ! cell +LOOP r> wake ;
54:
55: : activate ( task -- ) 0 swap (pass) ;
56: : pass ( x1 .. xn n task -- ) (pass) ;
57:
58: : task-key BEGIN pause key? UNTIL (key) ;
59: : task-emit (emit) pause ;
60: : task-type (type) pause ;
61:
62: ' task-key IS key
63: ' task-emit IS emit
64: ' task-type IS type
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