qt/md/m88k.h

   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 QT_M88K_H
  15 #define QT_M88K_H
  16
  17 typedef unsigned long qt_word_t;
  18
  19 #define QT_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 QT_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, QT_ARGS_MD0 adds some dead
  91    space at the top of the stack. */
  92
  93 #define QT_STKBASE      (16*4 + 8*4)
  94 #define QT_VSTKBASE     (8*4 + 8*4)
  95
  96
  97 /* Index of various registers. */
  98 #define QT_1    (8+2)
  99 #define QT_14   (8+3)
 100 #define QT_15   (8+4)
 101 #define QT_16   (8+5)
 102 #define QT_17   (8+6)
 103 #define QT_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
 125 extern void qt_start(void);
 126 #define QT_ARGS_MD(sp) \
 127   (QT_SPUT (sp, QT_1, qt_start), \
 128    QT_SPUT (sp, QT_30, 0))
 129
 130
 131 /* The m88k uses a struct for `va_list', so pass a pointer to the
 132    struct. */
 133
 134 typedef void (qt_function_t)(void);
 135
 136 struct qt_t;
 137 extern 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 QT_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 QT_ONLY_INDEX   (QT_17)
 150 #define QT_USER_INDEX   (QT_16)
 151 #define QT_ARGT_INDEX   (QT_15)
 152 #define QT_ARGU_INDEX   (QT_14)
 153
 154 #define QT_VCLEANUP_INDEX       (QT_14)
 155 #define QT_VUSERF_INDEX         (QT_16)
 156 #define QT_VSTARTUP_INDEX       (QT_17)
 157 #define QT_VARGT_INDEX          (QT_15)
 158
 159 #endif /* ndef QT_M88K_H */