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This is part of Family API which allow to create dual-os version of program runs under OS/2 and DOS

Note: This is legacy API call. It is recommended to use 32-bit equivalent

2021/09/17 04:47 · prokushev · 0 Comments
2021/08/20 03:18 · prokushev · 0 Comments

DosPortAccess

This call requests or releases access to ports for I/O privilege.

Syntax

DosPortAccess (Reserved, TypeOfAccess, FirstPort, LastPort)

Parameters

Return Code

rc (USHORT) - return:Return code descriptions are:

Remarks

Note that CLI/STI privilege is also granted automatically. There is no need to make an additional call to DosCLIAccess.

Applications that perform I/O to port(s) in IOPL segments must request port access from the operating system.

An application with no IOPL segments that accesses a device through a device driver or by an interface package such as VIO, does not need to issue this call. The device driver or interface package is responsible for obtaining the necessary I/O access.

Bindings

C

#define INCL_DOSDEVICES
 
USHORT  rc = DosPortAccess(Reserved, TypeOfAccess, FirstPort, LastPort);
 
USHORT  0;             /* 0 */
USHORT  TypeOfAccess;  /* Request or release */
USHORT  FirstPort;     /* First port number */
USHORT  LastPort;      /* Last port number */
 
USHORT  rc;            /* return code */

MASM

EXTRN  DosPortAccess:FAR
INCL_DOSDEVICES     EQU 1
 
PUSH   WORD    0             ;Reserved (must be zero)
PUSH   WORD    TypeOfAccess  ;Request or release
PUSH   WORD    FirstPort     ;First port number
PUSH   WORD    LastPort      ;Last port number
CALL   DosPortAccess
 
Returns WORD