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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_MIPS_H
#define QUICKTHREADS_MIPS_H
typedef unsigned long qt_word_t;
#define QUICKTHREADS_GROW_DOWN
/* Stack layout on the mips:
Callee-save registers are: $16-$23, $30; $f20-$f30.
Also save $31, return pc.
Non-varargs:
+---
| $f30 The first clump is only saved if `qt_block'
| $f28 is called, in which case it saves the fp regs
| $f26 then calls `qt_blocki' to save the int regs.
| $f24
| $f22
| $f20
| $31 === return pc in `qt_block'
+---
| $31 === return pc; on startup == qt_start
| $30
| $23
| $22
| $21
| $20
| $19 on startup === only
| $18 on startup === $a2 === userf
| $17 on startup === $a1 === pt
| $16 on startup === $a0 === pu
| <a3> save area req'd by MIPS calling convention
| <a2> save area req'd by MIPS calling convention
| <a1> save area req'd by MIPS calling convention
| <a0> save area req'd by MIPS calling convention <--- sp
+---
Conventions for varargs:
| args ...
+---
| :
| :
| $21
| $20
| $19 on startup === `userf'
| $18 on startup === `startup'
| $17 on startup === `pt'
| $16 on startup === `cleanup'
| <a3>
| <a2>
| <a1>
| <a0> <--- sp
+---
Note: if we wanted to, we could muck about and try to get the 4
argument registers loaded in to, e.g., $22, $23, $30, and $31,
and the return pc in, say, $20. Then, the first 4 args would
not need to be loaded from memory, they could just use
register-to-register copies. */
/* Stack must be doubleword aligned. */
#define QUICKTHREADS_STKALIGN (8) /* Doubleword aligned. */
/* How much space is allocated to hold all the crud for
initialization: $16-$23, $30, $31. Just do an integer restore,
no need to restore floating-point. Four words are needed for the
argument save area for the helper function that will be called for
the old thread, just before the new thread starts to run. */
#define QUICKTHREADS_STKBASE (14 * 4)
#define QUICKTHREADS_VSTKBASE QUICKTHREADS_STKBASE
/* Offsets of various registers. */
#define QUICKTHREADS_31 (9+4)
#define QUICKTHREADS_19 (3+4)
#define QUICKTHREADS_18 (2+4)
#define QUICKTHREADS_17 (1+4)
#define QUICKTHREADS_16 (0+4)
/* When a never-before-run thread is restored, the return pc points
to a fragment of code that starts the thread running. For
non-vargs functions, it just calls the client's `only' function.
For varargs functions, it calls the startup, user, and cleanup
functions.
The varargs startup routine always reads 4 words of arguments from
the stack. If there are less than 4 words of arguments, then the
startup routine can read off the top of the stack. To prevent
errors we always allocate 4 words. If there are more than 3 words
of arguments, the 4 preallocated words are simply wasted. */
extern void qt_start(void);
#define QUICKTHREADS_ARGS_MD(sp) (QUICKTHREADS_SPUT (sp, QUICKTHREADS_31, qt_start))
#define QUICKTHREADS_VARGS_MD0(sp, vabytes) \
((qt_t *)(((char *)(sp)) - 4*4 - QUICKTHREADS_STKROUNDUP(vabytes)))
extern void qt_vstart(void);
#define QUICKTHREADS_VARGS_MD1(sp) (QUICKTHREADS_SPUT (sp, QUICKTHREADS_31, qt_vstart))
#define QUICKTHREADS_VARGS_DEFAULT
/* The *index* (positive offset) of where to put each value. */
#define QUICKTHREADS_ONLY_INDEX (QUICKTHREADS_19)
#define QUICKTHREADS_USER_INDEX (QUICKTHREADS_18)
#define QUICKTHREADS_ARGT_INDEX (QUICKTHREADS_17)
#define QUICKTHREADS_ARGU_INDEX (QUICKTHREADS_16)
#define QUICKTHREADS_VCLEANUP_INDEX (QUICKTHREADS_16)
#define QUICKTHREADS_VUSERF_INDEX (QUICKTHREADS_19)
#define QUICKTHREADS_VSTARTUP_INDEX (QUICKTHREADS_18)
#define QUICKTHREADS_VARGT_INDEX (QUICKTHREADS_17)
#endif /* ndef QUICKTHREADS_MIPS_H */
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