source: buchla-68k/orig/MT/MTSWAP.S@ 7bf3856

Last change on this file since 7bf3856 was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 8 years ago

Imported original source code.
  • Property mode set to 100755
File size: 5.5 KB
Line 
1* ------------------------------------------------------------------------------
2* mtswap.s -- Multi-tasker -- swapper
3* Version 24 -- 1988-04-16 -- D.N. Lynx Crowe
4* (c) Copyright 1988 -- D.N. Lynx Crowe
5* Machine cycles are given as the first number in the comments for timing.
6* ------------------------------------------------------------------------------
7 .text
8*
9 .xdef __MT_Swp
10 .xdef __MT_Nxt
11*
12 .xdef MT_Enq
13*
14 .xref _MT_STpc
15 .xref _MT_NTpc
16 .xref _MT_LTCB
17*
18 .xref _MT_TCBs * to force loading
19 .xref _MT_CurP
20 .xref _MT_RdyQ
21*
22 .page
23*
24* TCB offsets
25* -----------
26NEXT .equ 0 * LONG - next TCB in queue
27FWD .equ NEXT+4 * LONG - next TCB in chain
28TID .equ FWD+4 * WORD - task ID
29PRI .equ TID+2 * WORD - task priority
30SLICE .equ PRI+2 * LONG - slice time limit
31REGS .equ SLICE+4 * LONG[16] - registers
32TCB_SP .equ REGS+64 * LONG - stack pointer
33TCB_PC .equ TCB_SP+4 * LONG - program counter
34TCB_SR .equ TCB_PC+4 * WORD - status register
35FLAGS .equ TCB_SR+2 * WORD - task flags
36TOS .equ FLAGS+2 * LONG - top of stack pointer
37*
38TCB_A6 .equ REGS+56 * LONG - task a6 image
39TCB_A7 .equ REGS+60 * LONG - task a7 image
40*
41MTF_RDY .equ $0001 * 'ready' bit
42NOT_RDY .equ $FFFE * 'ready' bit complement
43MTF_SWT .equ $0002 * 'wait' bit
44NOT_SWT .equ $FFFD * 'wait' bit complement
45MTF_RUN .equ $0004 * 'run' bit
46NOT_RUN .equ $FFFB * 'run' bit complement
47MTF_STP .equ $0008 * 'stop' bit
48NOT_STP .equ $FFF7 * 'stop' bit complement
49*
50IPL7 .equ $0700 * processor IPL 7 mask
51*
52RPRV .equ a1 * previous TCB pointer
53RCUR .equ a2 * current TCB pointer
54RNXT .equ a3 * next TCB pointer
55RTCP .equ a6 * general TCB pointer
56*
57RPRI .equ d0 * task priority
58RTST .equ d1 * test register
59*
60TRAP_SWP .equ 8 * swapper TRAP number 1
61TRAP_NXT .equ 9 * swapper TRAP number 2
62*
63 .page
64*
65* _MT_Swp -- swap tasks
66* ------- ----------
67__MT_Swp: ori.w #IPL7,sr * 8 disable interrupts
68 tst.l _MT_RdyQ * 20 see if anything is queued
69 beq MT_runit * 8/10 re-run current task if not
70*
71 movem.l a6-a7,-(a7) * 28 save a6,a7 on stack
72 movea.l _MT_CurP,RTCP * 20 get current TCB pointer
73 movem.l d0-d7/a0-a5,REGS(RTCP) * 152 put task d0-d7/a0-a5 in TCB
74 move.l (a7)+,TCB_A6(RTCP) * 26 put task a6 in TCB
75 move.l (a7)+,TCB_A7(RTCP) * 26 put task a7 in TCB
76 move.w (a7)+,TCB_SR(RTCP) * 17 put task sr in TCB
77 move.l (a7)+,TCB_PC(RTCP) * 26 put task pc in TCB
78 move.l a7,TCB_SP(RTCP) * 18 put task sp in TCB
79 andi.w #NOT_RUN,FLAGS(RTCP) * 21 turn off' run' bit
80 move.w PRI(RTCP),RPRI * 12 get task priority
81 lea _MT_RdyQ,RCUR * 8 point at ready queue
82 movea.l (RCUR),RNXT * 12 get highest priority TCB
83 move.l (RNXT),(RCUR) * 13 dequeue the TCB
84 andi.w #NOT_RDY,FLAGS(RNXT) * 21 turn off 'ready' bit
85*
86MT_Enq: movea.l RCUR,RPRV * 4 point at previous TCB
87 movea.l (RPRV),RCUR * 10 get pointer to next TCB
88 move.l RCUR,RTST * 4 test pointer
89 beq enq1 * 8/10 enqueue now if pointer is NIL
90*
91 cmp.w PRI(RCUR),RPRI * 12 compare priorities
92 bls MT_Enq * 8/10 jump if RPRI LE table TCB
93*
94enq1: move.l RTCP,(RPRV) * 9 set NEXT of previous TCB
95 move.l RTCP,_MT_LTCB * 22 log last TCB swapped out
96 move.l RCUR,(RTCP) * 9 set NEXT of rescheduled TCB
97 ori.w #MTF_RDY,FLAGS(RTCP) * 21 turn on 'ready' bit
98 movea.l RNXT,RTCP * 4 get new TCB pointer
99 move.l RTCP,_MT_CurP * 22 make it the current TCB
100 clr.l (RTCP) * 22 clear NEXT of current TCB
101 ori.w #MTF_RUN,FLAGS(RTCP) * 21 turn on 'run' bit
102 move.l TCB_PC(RTCP),_MT_STpc * 25 log dispatch address
103 movea.l TCB_SP(RTCP),a7 * 16 get task sp
104 move.l TCB_PC(RTCP),-(a7) * 26 put task pc on the stack
105 move.w TCB_SR(RTCP),-(a7) * 26 put task sr on the stack
106 movem.l REGS(RTCP),d0-d7/a0-a5 * 128 restore task d0-d7/a0-a5
107 movea.l TCB_A6(RTCP),a6 * 26 restore task a6
108*
109MT_runit: rte * 20 (re)start the task
110*
111 .page
112*
113* __MT_Nxt -- start the first task in the ready queue
114* -------- ---------------------------------------
115__MT_Nxt: ori.w #IPL7,sr * 8 disable interrupts
116 movem.l a6-a7,-(a7) * 28 save a6,a7 on stack
117 movea.l _MT_CurP,RTCP * 20 get current TCB pointer
118 move.l RTCP,_MT_LTCB * 22 log last TCB swapped out
119 movem.l d0-d7/a0-a5,REGS(RTCP) * 152 put task d0-d7/a0-a5 in TCB
120 move.l (a7)+,TCB_A6(RTCP) * 26 put task a6 in TCB
121 move.l (a7)+,TCB_A7(RTCP) * 26 put task a7 in TCB
122 move.w (a7)+,TCB_SR(RTCP) * 17 put task sr in TCB
123 move.l (a7)+,TCB_PC(RTCP) * 26 put task pc in TCB
124 move.l a7,TCB_SP(RTCP) * 18 put task sp in TCB
125 andi.w #NOT_RUN,FLAGS(RTCP) * 21 turn off' run' bit
126 lea _MT_RdyQ,RCUR * 8 point at ready queue
127 movea.l (RCUR),RNXT * 12 get highest priority TCB
128 move.l (RNXT),(RCUR) * 13 dequeue the TCB
129 andi.w #NOT_RDY,FLAGS(RNXT) * 21 turn off 'ready' bit
130 movea.l RNXT,RTCP * 4 get new TCB pointer
131 move.l RTCP,_MT_CurP * 22 make it the current TCB
132 clr.l (RTCP) * 22 clear NEXT of current TCB
133 ori.w #MTF_RUN,FLAGS(RTCP) * 21 turn on 'run' bit
134 move.l TCB_PC(RTCP),_MT_NTpc * 25 log dispatch address
135 movea.l TCB_SP(RTCP),a7 * 16 get task sp
136 move.l TCB_PC(RTCP),-(a7) * 26 put task pc on the stack
137 move.w TCB_SR(RTCP),-(a7) * 26 put task sr on the stack
138 movem.l REGS(RTCP),d0-d7/a0-a5 * 128 restore task d0-d7/a0-a5
139 movea.l TCB_A6(RTCP),a6 * 26 restore task a6
140 rte * 20 start the task
141*
142 .end
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