|
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.
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 |
| Addr_32_IO | Uses 32-bit address offsets for input or output string operations. If this value is not given, the 16-bit offsets are used. |
| Byte_Input | Inputs a single byte; place in AL if String_IO is not given. |
| Byte_Output | Outputs a single byte from AL if String_IO is not given. |
| Dword_Input | Inputs a doubleword; place in EAX if String_IO is not given. |
| Dword_Output | Outputs a doubleword from EAX if String_IO is not given. |
| Rep_IO | Repeats the input or output string operation the number of times specified by the Client_CX field in the Client_Reg_Struc structure. |
| Reverse_IO | Decrements string address on each input or output operation. If this value is not given, the string address is incremented on each operation. |
| String_IO | Inputs or outputs a string. The high 16-bits specifies the segment address of the buffer containing the string to output, or to receive the string input. |
| Word_Input | Inputs a word; place in AX if String_IO is not given. |
| Word_Output | Outputs a word from AX if String_IO is not given. |
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.
The EAX register contains input data if the IOType parameter specifies an input operation. IOType also specifies the size of the data in EAX.
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.
EAX, EBX, ECX, EDI, EDX, ESI, Flags