1\ Multitasker                                          19aug94py
2
3\ Copyright (C) 1995,1996,1997,2001,2003,2007 Free Software Foundation, Inc.
4
5\ This file is part of Gforth.
6
7\ Gforth is free software; you can redistribute it and/or
8\ modify it under the terms of the GNU General Public License
9\ as published by the Free Software Foundation, either version 3
10\ of the License, or (at your option) any later version.
11
12\ This program is distributed in the hope that it will be useful,
13\ but WITHOUT ANY WARRANTY; without even the implied warranty of
14\ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15\ GNU General Public License for more details.
16
17\ You should have received a copy of the GNU General Public License
18\ along with this program. If not, see http://www.gnu.org/licenses/.
19
20Create sleepers  sleepers A, sleepers A, 0 ,
21
22: link-task ( task1 task2 -- )
23    \G LINK-TASK links task1 into the task chain of task2
24    over 2@  2dup cell+ ! swap !  \ unlink task1
25    2dup @ cell+ !  2dup dup @ rot 2!  ! ;
26
27: sleep ( task -- )
28    \G deactivates task
29    sleepers  link-task ;
30: wake  ( task -- )
31    \G activates task
32    next-task link-task ;
33
34: pause ( -- )
35    \G PAUSE is the task-switcher
36    rp@ fp@ lp@ sp@ save-task !
37    next-task @ up! save-task @ sp!
38    lp! fp! rp! ;
39
40: stop ( -- )
41    \G STOP sleeps a task and switches to the next
42    rp@ fp@ lp@ sp@ save-task !
43    next-task @ up! save-task @ sp!
44    lp! fp! rp! prev-task @ sleep ;
45
46:noname    ' >body @ ;
47:noname    ' >body @ postpone literal ;
48interpret/compile: user' ( 'user' -- n )
49\G USER' computes the task offset of a user variable
50
51: NewTask ( stacksize -- Task )  dup 2* 2* udp @ + dup
52    \G NEWTASK creates a new, sleeping task
53    allocate throw  + >r
54    r@ over - udp @ - next-task over udp @ move
55    r> over user' rp0 + ! dup >r
56    dup r@ user' lp0   + ! over -
57    dup r@ user' fp0   + ! over -
58    dup r@ user' sp0   + ! over -
59    dup r@ user' normal-dp + dup >r !
60    r> r@ user' dpp  + ! 2drop
61    0 r@ user' current-input + !
62    r> dup 2dup 2! dup sleep ;
63
64Create killer killer A, killer A,
65: kill ( task -- )
66    \G kills a task - deactivate and free task area
67    dup killer link-task  killer dup dup 2!
68    user' normal-dp + @ free throw ;
69
70: kill-task ( -- )
71    \G kills the current task, also on bottom of return stack of a new task
72    next-task @ up! save-task @ sp!
73    lp! fp! rp! prev-task @ kill ;
74
75: (pass) ( x1 .. xn n task -- )  rdrop
76  [ ' kill-task >body ] ALiteral r>
77  rot >r r@ user' rp0 + @ 2 cells - dup >r 2!
78  r>              swap 1+
79  r@ user' fp0 + @ swap 1+
80  r@ user' lp0 + @ swap 1+
81  cells r@ user' sp0 + @ tuck swap - dup r@ user' save-task + !
82  ?DO  I !  cell  +LOOP  r> wake ;
83
84: activate ( task -- )
85    \G activates the task.
86    \G Continues execution with the caller of ACTIVATE.
87    0 swap (pass) ;
88: pass ( x1 .. xn n task -- )
89    \G passes n parameters to the task and activates that task.
90    \G Continues execution with the caller of PASS.
91    (pass) ;
92
93: single-tasking? ( -- flag )
94    \G checks if only one task is running
95    next-task dup @ = ;
96
97: task-key   BEGIN  pause key? single-tasking? or  UNTIL  (key) ;
98: task-emit  (emit) pause ;
99: task-type  (type) pause ;
100
101' task-key  IS key
102' task-emit IS emit
103' task-type IS type
104