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134 lines
3.8 KiB
C
134 lines
3.8 KiB
C
/*
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* QuickThreads -- Threads-building toolkit.
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* Copyright (c) 1993 by David Keppel
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation for any purpose and without fee is hereby
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* granted, provided that the above copyright notice and this notice
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* appear in all copies. This software is provided as a
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* proof-of-concept and for demonstration purposes; there is no
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* representation about the suitability of this software for any
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* purpose.
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*/
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#ifndef QT_MIPS_H
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#define QT_MIPS_H
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typedef unsigned long qt_word_t;
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#define QT_GROW_DOWN
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/* Stack layout on the mips:
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Callee-save registers are: $16-$23, $30; $f20-$f30.
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Also save $31, return pc.
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Non-varargs:
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+---
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| $f30 The first clump is only saved if `qt_block'
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| $f28 is called, in which case it saves the fp regs
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| $f26 then calls `qt_blocki' to save the int regs.
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| $f24
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| $f22
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| $f20
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| $31 === return pc in `qt_block'
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+---
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| $31 === return pc; on startup == qt_start
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| $30
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| $23
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| $22
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| $21
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| $20
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| $19 on startup === only
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| $18 on startup === $a2 === userf
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| $17 on startup === $a1 === pt
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| $16 on startup === $a0 === pu
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| <a3> save area req'd by MIPS calling convention
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| <a2> save area req'd by MIPS calling convention
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| <a1> save area req'd by MIPS calling convention
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| <a0> save area req'd by MIPS calling convention <--- sp
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+---
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Conventions for varargs:
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| args ...
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+---
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| :
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| :
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| $21
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| $20
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| $19 on startup === `userf'
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| $18 on startup === `startup'
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| $17 on startup === `pt'
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| $16 on startup === `cleanup'
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| <a3>
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| <a2>
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| <a1>
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| <a0> <--- sp
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+---
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Note: if we wanted to, we could muck about and try to get the 4
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argument registers loaded in to, e.g., $22, $23, $30, and $31,
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and the return pc in, say, $20. Then, the first 4 args would
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not need to be loaded from memory, they could just use
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register-to-register copies. */
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/* Stack must be doubleword aligned. */
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#define QT_STKALIGN (8) /* Doubleword aligned. */
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/* How much space is allocated to hold all the crud for
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initialization: $16-$23, $30, $31. Just do an integer restore,
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no need to restore floating-point. Four words are needed for the
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argument save area for the helper function that will be called for
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the old thread, just before the new thread starts to run. */
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#define QT_STKBASE (14 * 4)
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#define QT_VSTKBASE QT_STKBASE
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/* Offsets of various registers. */
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#define QT_31 (9+4)
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#define QT_19 (3+4)
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#define QT_18 (2+4)
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#define QT_17 (1+4)
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#define QT_16 (0+4)
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/* When a never-before-run thread is restored, the return pc points
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to a fragment of code that starts the thread running. For
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non-vargs functions, it just calls the client's `only' function.
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For varargs functions, it calls the startup, user, and cleanup
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functions.
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The varargs startup routine always reads 4 words of arguments from
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the stack. If there are less than 4 words of arguments, then the
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startup routine can read off the top of the stack. To prevent
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errors we always allocate 4 words. If there are more than 3 words
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of arguments, the 4 preallocated words are simply wasted. */
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extern void qt_start(void);
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#define QT_ARGS_MD(sp) (QT_SPUT (sp, QT_31, qt_start))
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#define QT_VARGS_MD0(sp, vabytes) \
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((qt_t *)(((char *)(sp)) - 4*4 - QT_STKROUNDUP(vabytes)))
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extern void qt_vstart(void);
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#define QT_VARGS_MD1(sp) (QT_SPUT (sp, QT_31, qt_vstart))
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#define QT_VARGS_DEFAULT
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/* The *index* (positive offset) of where to put each value. */
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#define QT_ONLY_INDEX (QT_19)
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#define QT_USER_INDEX (QT_18)
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#define QT_ARGT_INDEX (QT_17)
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#define QT_ARGU_INDEX (QT_16)
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#define QT_VCLEANUP_INDEX (QT_16)
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#define QT_VUSERF_INDEX (QT_19)
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#define QT_VSTARTUP_INDEX (QT_18)
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#define QT_VARGT_INDEX (QT_17)
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#endif /* ndef QT_MIPS_H */
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