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include vmm.inc
 
VMMcall End_Crit_And_Suspend
jc      not_released            ; carry set if critical section not released
 
The End_Crit_And_Suspend service releases the critical section and
immediately suspends the current virtual machine. Virtual devices use this
service to block a virtual machine until another virtual machine can process
an event.
 
This service has no parameters.
 
Return Value
 
The carry flag is clear if this service is successful. Otherwise, the carry
flag is set to indicate an error.
 
Comments
 
This service releases the critical section only if the virtual machine has
claimed the section once. This service returns an error if the system could
not suspend the virtual machine, or could not release the critical section
because the claim count was not 1. In such cases, the service does not
decrement the claim count and the critical section is not released.
 
Example
 
The following example uses this service to display a dialog box in the
system virtual machine. The Show_Dialog_Box procedure enters a critical
section to prevent the Call_Priority_VM_Event service from switching to the
system virtual machine immediately. It then calls End_Crit_And_Suspend which
blocks the current virtual machine. The Show_Dialog_Event procedure runs in
the system virtual machine and actually displays the dialog box. When it is
finished it resumes the virtual machine that called Show_Dialog_Box by
calling the Resume_VM service.
 
Show_Dialog_Box:
    VMMcall Get_Crit_Section_Status
    jc      Cant_Do_It                  ; critical section already claimed
 
    VMMcall Begin_Critical_Section
    mov     eax, Low_Pri_Device_Boost
    VMMcall Get_System_VM_Handle
    mov     ecx, 11b
    mov     edx, OFFSET32 Dialog_Box_Data_Strucure
    mov     esi, OFFSET32 Show_Dialog_Event
    VMMcall Call_Priority_VM_Event
    VMMcall End_Crit_And_Suspend
    jc      Did_Not_Work
    ; When End_Crit_And_Suspend returns the dialog box
    ; will have been displayed
 
Show_Dialog_Event:
    ; Call Windows to display the dialog box
 
    mov     ebx, [Suspended_VM_Id]
    VMMcall Resume_VM
    jc      Error
    ret
 
Uses
 
Flags
 
See Also
 
End_Critical_Section, Resume_VM, Suspend_VM
 
 
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