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include vmm.inc
 
mov     eax, Data           ; data for output operations
mov     ebx, VM             ; current VM handle
mov     ecx, IOType         ; type of I/O (as passed to I/O trap routine)
mov     edx, Port           ; I/O port number
mov     ebp, OFFSET32 crs   ; points to a Client_Reg_Struc
VMMjmp  Simulate_IO
 
mov     [Data], eax         ; data for input operation
 
The Simulate_IO service reduces complex I/O instructions to simpler I/O
operations. An I/O callback procedure typically jumps to this service
whenever the procedure receives a type of I/O that it does not directly
support.
 
Parameter  Description
────────────────────────────────────────────────────────────────────────────
 
Data       Specifies the data for an output operation. This parameter is
           used only if the IOType parameter specifies an output operation.
 
VM         Specifies a handle identifying the current virtual machine.
 
IOType     Specifies the type of I/O operation. This parameter can be a
           combination of the following values:
 
           Value         Meaning
           ─────────────────────────────────────────────────────────────────
           Byte_Input    Input a single byte; place in AL if String_IO not
                         given.
 
           Byte_Output   Output a single byte from AL if String_IO not
                         given.
 
           Word_Input    Input a word; place in AX if String_IO not given.
 
           Word_Output   Output a word from AX if String_IO not given.
 
           Dword_Input   Input a double word; place in EAX if String_IO not
                         given.
 
           Dword_Output  Output a double word from EAX if String_IO not
                         given.
 
           String_IO     Input or output a string. The high 16-bits
                         specifies segment address of buffer containing the
                         string to output or to receive the string input.
 
           Rep_IO        Repeat the input or output string operation the
                         number of times specified by the Client_CX field in
                         the Client_Reg_Struc structure.
 
           Addr_32_IO    Use 32-bit address offsets for input or output
                         string operations. If this value is not given, the
                         16-bit offsets are used.
 
           Reverse_IO    Decrement string address on each input or output
                         operation. If this value is not given, the string
                         address is incremented on each operation.
 
Port       Specifies the number of the I/O port through which to carry out
           the operation.
 
crs        Points to a Client_Reg_Struc structure containing the register
           contents for the current virtual machine.
 
Return Value
 
The EAX register contains input data if the IOType parameter specifies an
input operation. IOType also specifies the size of the data in EAX.
 
Comments
 
The parameters to this service are identical to the parameters passed to an
I/O callback procedure. A callback procedure should jump to this service
using the VMMjmp macro with all of the registers in the same state as when
the procedure was called. The procedure may modify the ESI and EDI register
before jumping, if necessary.
 
Uses
 
EAX, EBX, ECX, EDX, ESI, EDI, Flags
 
See Also
 
Dispatch_Byte_IO, Emulate_Non_Byte_IO
 
 
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