reactos/ntoskrnl/hal/x86/irql.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            mkernel/hal/irql.c
   5  * PURPOSE:         Implements IRQLs
   6  * PROGRAMMER:      David Welch (welch@mcmail.com)
   7  */
   8
   9 /* INCLUDES *****************************************************************/
  10
  11 #include <windows.h>
  12 #include <ddk/ntddk.h>
  13 #include <internal/bitops.h>
  14 #include <internal/hal/io.h>
  15
  16 #define NDEBUG
  17 #include <internal/debug.h>
  18
  19 /* GLOBALS ******************************************************************/
  20
  21 /*
  22  * PURPOSE: Current irq level
  23  */
  24 static KIRQL CurrentIrql = HIGH_LEVEL;
  25
  26 /* FUNCTIONS ****************************************************************/
  27
  28 static unsigned int pic_get_current_mask(void)
  29 {
  30    unsigned int mask;
  31
  32    mask = inb_p(0x21);
  33    mask = mask | (inb_p(0xa1)<<8);
  34 }
  35
  36 static unsigned int pic_set_current_mask(unsigned int mask)
  37 {
  38    outb_p(0x21,mask & 0xff);
  39    outb_p(0xa1,(mask >> 8) & 0xff);
  40 }
  41
  42 static void switch_irql(void)
  43 /*
  44  * FUNCTION: Switches to the current irql
  45  * NOTE: Must be called with interrupt disabled
  46  */
  47 {
  48    unsigned int i;
  49
  50    if (CurrentIrql == HIGH_LEVEL)
  51      {
  52         pic_set_current_mask(0xffff);
  53         return;
  54      }
  55    if (CurrentIrql > DISPATCH_LEVEL)
  56      {
  57         unsigned int current_mask = 0;
  58
  59         for (i=(CurrentIrql-DISPATCH_LEVEL);i>DISPATCH_LEVEL;i--)
  60           {
  61              set_bit(NR_DEVICE_SPECIFIC_LEVELS - i,&current_mask);
  62           }
  63
  64         pic_set_current_mask(current_mask);
  65         __asm__("sti\n\t");
  66         return;
  67      }
  68
  69    if (CurrentIrql <= DISPATCH_LEVEL)
  70      {
  71         pic_set_current_mask(0);
  72         __asm__("sti\n\t");
  73         return;
  74      }
  75 }
  76
  77 VOID KeSetCurrentIrql(KIRQL newlvl)
  78 /*
  79  * PURPOSE: Sets the current irq level without taking any action
  80  */
  81 {
  82    DPRINT("KeSetCurrentIrql(newlvl %x)\n",newlvl);
  83    CurrentIrql = newlvl;
  84 }
  85
  86 KIRQL KeGetCurrentIrql()
  87 /*
  88  * PURPOSE: Returns the current irq level
  89  * RETURNS: The current irq level
  90  */
  91 {
  92    return(CurrentIrql);
  93 }
  94
  95 VOID KeLowerIrql(KIRQL NewIrql)
  96 /*
  97  * PURPOSE: Restores the irq level on the current processor
  98  * ARGUMENTS:
  99  *        NewIrql = Irql to lower to
 100  */
 101 {
 102    __asm__("cli\n\t");
 103
 104    DPRINT("NewIrql %x CurrentIrql %x\n",NewIrql,CurrentIrql);
 105    assert(NewIrql <= CurrentIrql);
 106    CurrentIrql = NewIrql;
 107    switch_irql();
 108 }
 109
 110 VOID KeRaiseIrql(KIRQL NewIrql, PKIRQL OldIrql)
 111 /*
 112  * FUNCTION: Raises the hardware priority (irql)
 113  * ARGUMENTS:
 114  *         NewIrql = Irql to raise to
 115  *         OldIrql (OUT) = Caller supplied storage for the previous irql
 116  */
 117 {
 118    /*
 119     * sanity check
 120     */
 121    DPRINT("CurrentIrql %x NewIrql %x OldIrql %x\n",CurrentIrql,NewIrql,
 122           OldIrql);
 123    if (NewIrql < CurrentIrql)
 124      {
 125         DbgPrint("%s:%d CurrentIrql %x NewIrql %x OldIrql %x\n",__FILE__,__LINE__,
 126                  CurrentIrql,NewIrql,OldIrql);
 127         for(;;);
 128      }
 129
 130    __asm__("cli\n\t");
 131    *OldIrql = CurrentIrql;
 132    CurrentIrql = NewIrql;
 133 //   *OldIrql = InterlockedExchange(&CurrentIrql,NewIrql);
 134    DPRINT("NewIrql %x OldIrql %x CurrentIrql %x\n",NewIrql,*OldIrql,
 135           CurrentIrql);
 136    switch_irql();
 137 }
 138
 139
 140