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 @ postpone literal ; immediate
28: interpretation:
29: ' >body @ ;
30:
31: \ NEWTASK creates a new, sleeping task
32: : NewTask ( n -- Task ) dup 2* 2* udp @ + dup
33: allocate throw + >r
34: r@ over - udp @ - next-task over udp @ move
35: r> over user' r0 + ! dup >r
36: dup r@ user' l0 + ! over -
37: dup r@ user' f0 + ! over -
38: dup r@ user' s0 + ! over -
39: dup r@ user' normal-dp + dup >r !
40: r> r@ user' dpp + ! + $10 +
41: r@ user' >tib + !
42: r> dup 2dup 2! dup sleep ;
43:
44: : kill-task
45: next-task @ up! save-task @ sp!
46: lp! fp! rp! prev-task @ dup dup link-task user' normal-dp + @ free throw ;
47:
48: : (pass) ( x1 .. xn n task -- ) rdrop
49: [ ' kill-task >body ] ALiteral r>
50: rot >r r@ user' r0 + @ 2 cells - dup >r 2!
51: r> swap 1+
52: r@ user' f0 + @ swap 1+
53: r@ user' l0 + @ swap 1+
54: cells r@ user' s0 + @ tuck swap - dup r@ user' save-task + !
55: ?DO I ! cell +LOOP r> wake ;
56:
57: : activate ( task -- ) 0 swap (pass) ;
58: : pass ( x1 .. xn n task -- ) (pass) ;
59:
60: : single-tasking? ( -- flag )
61: next-task dup @ = ;
62:
63: : task-key BEGIN pause key? single-tasking? or UNTIL (key) ;
64: : task-emit (emit) pause ;
65: : task-type (type) pause ;
66:
67: ' task-key IS key
68: ' task-emit IS emit
69: ' task-type IS type
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