arch/m68k-amiga/kernel/dispatch.c

   1 #include <aros/kernel.h>
   2
   3 #include <exec/alerts.h>
   4 #include <exec/execbase.h>
   5 #include <proto/exec.h>
   6
   7 #include <kernel_base.h>
   8 #include <kernel_syscall.h>
   9 #include <kernel_debug.h>
  10
  11 #if defined(DEBUG) && (DEBUG == 1)
  12 #define D(x) x
  13 #else
  14 #define D(x)
  15 #endif
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <proto/kernel.h>
  21
  22 AROS_LH0(void, KrnDispatch,
  23
  24 /*  SYNOPSIS */
  25
  26 /*  LOCATION */
  27          struct KernelBase *, KernelBase, 4, Kernel)
  28
  29 /*  FUNCTION
  30
  31     INPUTS
  32
  33     RESULT
  34
  35     NOTES
  36
  37     EXAMPLE
  38
  39     BUGS
  40
  41     SEE ALSO
  42
  43     INTERNALS
  44
  45 ******************************************************************************/
  46 {
  47     AROS_LIBFUNC_INIT
  48
  49     struct Task *next;
  50
  51     for (;;) {
  52         asm volatile ("move #0x2700, %sr\n");   // Disable CPU interrupts
  53         next = (struct Task *)RemHead(&SysBase->TaskReady);
  54         if (next != NULL)
  55                 break;
  56         SysBase->IdleCount++;
  57         SysBase->AttnFlags |= ARF_AttnSwitch;
  58         D(bug("-- IDLE HALT --\n"));
  59         asm volatile ("stop #0x2000\n"); // Wait for an interrupt
  60     }
  61
  62     D(bug(" Dispatch (%s) Task=%p, SP=%p (0x%04x, %p), TDnc=%d, IDnc=%d\n",
  63          next->tc_Node.ln_Name, next, next->tc_SPReg, *(UWORD *)(next->tc_SPReg - 6),
  64          *(ULONG *)(next->tc_SPReg - 4),
  65          next->tc_TDNestCnt,next->tc_IDNestCnt));
  66
  67     SysBase->DispCount++;
  68
  69     SysBase->IDNestCnt = next->tc_IDNestCnt;
  70     SysBase->ThisTask = next;
  71     SysBase->Elapsed = SysBase->Quantum;
  72     SysBase->SysFlags &= ~SFF_QuantumOver;
  73     next->tc_State = TS_RUN;
  74
  75     if (SysBase->IDNestCnt < 0)
  76             KrnSti();
  77     else
  78             KrnCli();
  79
  80     if (next->tc_Flags & TF_LAUNCH) {
  81             D(bug("%s:%d task->Launch called for %p\n", __func__, __LINE__, next->tc_Launch));
  82             AROS_UFC0(void, next->tc_Launch);
  83     }
  84
  85     if (next->tc_Flags & TF_EXCEPT) {
  86             D(bug("%s:%d task exception - what to do?\n"));
  87             extern int breakpoint(void); breakpoint();
  88
  89             /* Call Exec/Exception to handle the exception */
  90             Exception();
  91 #if 0
  92             /* Some MAGIC goes here, I guess, to get back to
  93              * the user process?
  94              */
  95 #endif
  96     }
  97
  98     /* Copy from the user stack to the supervisor stack,
  99      * then 'rte' to the original frame, which should
 100      * be in Switch(), which can only be called from
 101      * Supervisor mode.
 102      */
 103     asm volatile (
 104         "    move.l  %0,%%usp\n"
 105         "    btst    #0,%1\n"                   // Are we a 68010/68020?
 106         "    beq.s   0f\n"                      // Nope!
 107         "    move.w  #0x0020,%%sp@-\n"          // Yep!
 108         "0:\n"
 109         "    move.l  %0@(-(4)),%%sp@-\n"        // Return PC
 110         "    move.w  %0@(-(4+2)),%%sp@-\n"      // %sr
 111         "    movem.l %0@(-(4+2+15*4)),%%d0-%%d7/%%a0-%%a6\n" // restore everything
 112         "    rte\n"
 113         :
 114         : "a" (next->tc_SPReg),
 115           "r" ((SysBase->AttnFlags & (AFB_68010 | AFB_68020)) ? 1 : 0)
 116         : );
 117
 118     /* NOTE: We should never get here! */
 119     D(bug("[KrnDispatch] Oh noes! Unpossible code executed!\n"));
 120
 121     AROS_LIBFUNC_EXIT
 122 }