DevHlp_Port_IO

Description

Perform IO to a specified port.

This function is used to perform input/output operations to a specified local port.

Pointer to a PORT_IO structure.

Return code.

typedef struct port_io_s{
   ulong_t port;   (Input)
   ulong_t data;   (Input/Output)
   ulong_t flags;  (Input)
} PORT_IO;

indicates which port to read to, or write from.

contains the data read from a read request, or the data to write if a write request.

indicate what operation to perform.

Read a byte from the port

Read a word from the port

Read a dword from the port

Write a byte to the port

Write a word to the port

Write a dword to the port

 ;       dh_Port_IO - Perform I/O to a specified port ;
 ;       This devhlp is called by device drivers to do
 ;       I/O to a specified local port.
 ;
 ;       ENTRY:  ES:DI = pointer to port_io structure
 ;
 ;       EXIT:   port_io.data filled in if I/O read
 ;
 ;       USES:   EAX, Flags
 ;

 port_io_s         STRUC
 port_io_port        DD   ?
 port_io_data        DD   ?
 port_io_flags       DD   ?
 port_io_s         ENDS

 IO_READ_BYTE      EQU  0000H
 IO_READ_WORD      EQU  0001H
 IO_READ_DWORD     EQU  0002H
 IO_WRITE_BYTE     EQU  0003H
 IO_WRITE_WORD     EQU  0004H
 IO_WRITE_DWORD    EQU  0005H
 IO_FLAGMASK       EQU  0007H

 MOV     PORT_IO.port_io_port,21h
 MOV     PORT_IO.port_io_data,08h
 MOV     PORT_IO.port_io_flags,IO_WRITE_BYTE

 LES     SI,PORT_IO
 MOV     DL,dh_Port_IO
 CALL    DevHlp
 JC      Error

 ;       EXIT:   port_io_struc.data filled in if I/O read

None.