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/*
* QuickThreads -- Threads-building toolkit.
* Copyright (c) 1993 by David Keppel
*
* Permission to use, copy, modify and distribute this software and
* its documentation for any purpose and without fee is hereby
* granted, provided that the above copyright notice and this notice
* appear in all copies. This software is provided as a
* proof-of-concept and for demonstration purposes; there is no
* representation about the suitability of this software for any
* purpose.
*/
#ifndef QUICKTHREADS_VAX_H
#define QUICKTHREADS_VAX_H
typedef unsigned long qt_word_t;
/* Thread's initial stack layout on the VAX:
non-varargs:
+---
| arg[2] === `userf' on startup
| arg[1] === `pt' on startup
| arg[0] === `pu' on startup
| ... === `only' on startup.
+---
| ret pc === `qt_start' on startup
| fp === 0 on startup
| ap === 0 on startup
| <mask>
| 0 (handler) <--- qt_t.sp
+---
When a non-varargs thread is started, it ``returns'' to the start
routine, which calls the client's `only' function.
The varargs case is clearly bad code. The various values should be
stored in a save area and snarfed in to callee-save registers on
startup. However, it's too painful to figure out the register
mask (right now), so do it the slow way.
+---
| arg[n-1]
| ..
| arg[0]
| nargs
+---
| === `cleanup'
| === `vuserf'
| === `startup'
| === `pt'
+---
| ret pc === `qt_start' on startup
| fp === 0 on startup
| ap === 0 on startup
| <mask>
| 0 (handler) <--- qt_t.sp
+---
When a varargs thread is started, it ``returns'' to the `qt_vstart'
startup code. The startup code pops all the extra arguments, then
calls the appropriate functions. */
/* What to do to start a thread running. */
extern void qt_start (void);
extern void qt_vstart (void);
/* Initial call frame for non-varargs and varargs cases. */
#define QUICKTHREADS_STKBASE (10 * 4)
#define QUICKTHREADS_VSTKBASE (9 * 4)
/* Stack "must be" 4-byte aligned. (Actually, no, but it's
easiest and probably fastest to do so.) */
#define QUICKTHREADS_STKALIGN (4)
/* Where to place various arguments. */
#define QUICKTHREADS_ONLY_INDEX (5)
#define QUICKTHREADS_USER_INDEX (8)
#define QUICKTHREADS_ARGT_INDEX (7)
#define QUICKTHREADS_ARGU_INDEX (6)
#define QUICKTHREADS_VSTARTUP_INDEX (6)
#define QUICKTHREADS_VUSERF_INDEX (7)
#define QUICKTHREADS_VCLEANUP_INDEX (8)
#define QUICKTHREADS_VARGT_INDEX (5)
/* Stack grows down. The top of the stack is the first thing to
pop off (predecrement, postincrement). */
#define QUICKTHREADS_GROW_DOWN
extern void qt_error (void);
#define QUICKTHREADS_VAX_GMASK_NOREGS (0)
/* Push on the error return address, null termination to call chains,
number of arguments to `only', register save mask (save no
registers). */
#define QUICKTHREADS_ARGS_MD(sto) \
(QUICKTHREADS_SPUT (sto, 0, 0), \
QUICKTHREADS_SPUT (sto, 1, QUICKTHREADS_VAX_GMASK_NOREGS), \
QUICKTHREADS_SPUT (sto, 2, 0), \
QUICKTHREADS_SPUT (sto, 3, 0), \
QUICKTHREADS_SPUT (sto, 4, qt_start))
#define QUICKTHREADS_VARGS_MD0(sto, nbytes) \
(QUICKTHREADS_SPUT (sto, (-(nbytes)/4)-1, (nbytes)/4), \
((char *)(((sto)-4) - QUICKTHREADS_STKROUNDUP(nbytes))))
#define QUICKTHREADS_VARGS_ADJUST(sp) ((char *)sp + 4)
#define QUICKTHREADS_VARGS_MD1(sto) \
(QUICKTHREADS_SPUT (sto, 0, 0), \
QUICKTHREADS_SPUT (sto, 1, QUICKTHREADS_VAX_GMASK_NOREGS), \
QUICKTHREADS_SPUT (sto, 2, 0), \
QUICKTHREADS_SPUT (sto, 3, 0), \
QUICKTHREADS_SPUT (sto, 4, qt_vstart))
#define QUICKTHREADS_VARGS_DEFAULT
#endif /* QUICKTHREADS_VAX_H */
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