1/*
2 * QuickThreads -- Threads-building toolkit.
3 * Copyright (c) 1993 by David Keppel
4 *
5 * Permission to use, copy, modify and distribute this software and
6 * its documentation for any purpose and without fee is hereby
7 * granted, provided that the above copyright notice and this notice
8 * appear in all copies.  This software is provided as a
9 * proof-of-concept and for demonstration purposes; there is no
10 * representation about the suitability of this software for any
11 * purpose.
12 */
13
14#ifndef QUICKTHREADS_M88K_H
15#define QUICKTHREADS_M88K_H
16
17typedef unsigned long qt_word_t;
18
19#define QUICKTHREADS_GROW_DOWN
20
21/* Stack layout on the mips:
22
23   Callee-save registers are: $16-$23, $30; $f20-$f30.
24   Also save $31, return pc.
25
26   Non-varargs:
27
28   +---
29   | r30 (fp)	on startup === 0
30   | r25
31   | r24
32   | r23
33   | r22
34   | r21
35   | r20
36   | r19
37   | r18
38   | r17	on startup === `only'
39   | r16	on startup === `userf'
40   | r15	on startup === `pt'
41   | r14	on startup === `pu'
42   | r1		on startup === `qt_start'
43   | 0
44   | 0
45   +---
46   | 0
47   | ... (8 regs worth === 32 bytes of homing area)
48   | 0						<--- sp
49   +---
50
51   Conventions for varargs:
52
53   |  :
54   | arg8
55   +---
56   | r30 (fp)	arg7
57   | r25	arg6
58   | r24	arg5
59   | r23	arg4
60   | r22	arg3
61   | r21	arg2
62   | r20	arg1
63   | r19	arg0
64   | r18
65   | r17	on startup === `startup'
66   | r16	on startup === `vuserf'
67   | r15	on startup === `pt'
68   | r14	on startup === `cleanup'
69   | r1		on startup === `qt_vstart'
70   | 0
71   | 0
72   +---
73   | 0
74   | ... (8 regs worth === 32 bytes of homing area)
75   | 0						<--- sp
76   +---
77
78   */
79
80
81/* Stack must be doubleword aligned. */
82#define QUICKTHREADS_STKALIGN	(16)	/* Doubleword aligned. */
83
84/* How much space is allocated to hold all the crud for
85   initialization: saved registers plus padding to keep the stack
86   aligned plus 8 words of padding to use as a `homing area' (for
87   r2-r9) when calling helper functions on the stack of the (not yet
88   started) thread.  The varargs save area is small because it gets
89   overlapped with the top of the parameter list.  In case the
90   parameter list is less than 8 args, QUICKTHREADS_ARGS_MD0 adds some dead
91   space at the top of the stack. */
92
93#define QUICKTHREADS_STKBASE	(16*4 + 8*4)
94#define QUICKTHREADS_VSTKBASE	(8*4 + 8*4)
95
96
97/* Index of various registers. */
98#define QUICKTHREADS_1	(8+2)
99#define QUICKTHREADS_14	(8+3)
100#define QUICKTHREADS_15	(8+4)
101#define QUICKTHREADS_16	(8+5)
102#define QUICKTHREADS_17	(8+6)
103#define QUICKTHREADS_30	(8+15)
104
105
106/* When a never-before-run thread is restored, the return pc points
107   to a fragment of code that starts the thread running.  For
108   non-vargs functions, it sets up arguments and calls the client's
109   `only' function.  For varargs functions, the startup code calls the
110   startup, user, and cleanup functions.
111
112   For non-varargs functions, we set the frame pointer to 0 to
113   null-terminate the call chain.
114
115   For varargs functions, the frame pointer register is used to hold
116   one of the arguments, so that all arguments can be laid out in
117   memory by the conventional `qt_vargs' varargs initialization
118   routine.
119
120   The varargs startup routine always reads 8 words of arguments from
121   the stack.  If there are less than 8 words of arguments, then the
122   arg list could call off the top of the stack.  To prevent fall-off,
123   always allocate 8 words. */
124
125extern void qt_start(void);
126#define QUICKTHREADS_ARGS_MD(sp) \
127  (QUICKTHREADS_SPUT (sp, QUICKTHREADS_1, qt_start), \
128   QUICKTHREADS_SPUT (sp, QUICKTHREADS_30, 0))
129
130
131/* The m88k uses a struct for `va_list', so pass a pointer to the
132   struct. */
133
134typedef void (qt_function_t)(void);
135
136struct qt_t;
137extern struct qt_t *qt_vargs (struct qt_t *sp, int nbytes,
138			      void *vargs, void *pt,
139			      qt_function_t *startup,
140			      qt_function_t *vuserf,
141			      qt_function_t *cleanup);
142
143#define QUICKTHREADS_VARGS(sp, nbytes, vargs, pt, startup, vuserf, cleanup) \
144  (qt_vargs (sp, nbytes, &(vargs), pt, (qt_function_t *)startup, \
145	     (qt_function_t *)vuserf, (qt_function_t *)cleanup))
146
147
148/* The *index* (positive offset) of where to put each value. */
149#define QUICKTHREADS_ONLY_INDEX	(QUICKTHREADS_17)
150#define QUICKTHREADS_USER_INDEX	(QUICKTHREADS_16)
151#define QUICKTHREADS_ARGT_INDEX	(QUICKTHREADS_15)
152#define QUICKTHREADS_ARGU_INDEX	(QUICKTHREADS_14)
153
154#define QUICKTHREADS_VCLEANUP_INDEX	(QUICKTHREADS_14)
155#define QUICKTHREADS_VUSERF_INDEX		(QUICKTHREADS_16)
156#define QUICKTHREADS_VSTARTUP_INDEX	(QUICKTHREADS_17)
157#define QUICKTHREADS_VARGT_INDEX		(QUICKTHREADS_15)
158
159#endif /* ndef QUICKTHREADS_M88K_H */
160