![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to ioplsub.asm CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [OS/2 SDKs] / os2sdk / demos / examples / iopl|
Return to ioplsub.asm CVS log | Up to [OS/2 SDKs] / os2sdk / demos / examples / iopl |
1.1 root 1: TITLE CURSOR
2:
3: ; This file exports the function _GetCurLoc which gets the location
4: ; of the cursor on the CRT screen.
5: ;
6: ; This routine illustrates the use of the DosPortAccess() call. This
7: ; call is supposed to give the IOPL segment access to ports and CLI/STI
8: ; instructions. In fact, on the PC/AT (80286) there is no enforcement.
9: ; This call is provided for future compatibility with the 80386.
10: ; At present, the use of DosPortAccess() from an IOPL segment is not
11: ; supported (the calls are commented out here) but will be in the future.
12: ; The form and placement of these calls is indicated here as a guide
13: ; to future usage.
14: ;
15: ; One thing to beware of: if you disable interrupts (CLI) they may be
16: ; re-enabled for you by the operating system. This will occur if you
17: ; generate a fault of some sort. The easiest example is a segment not
18: ; present fault. When the segment is loaded and your code starts to
19: ; execute the interrupts will be enabled. The solution is simple: don't
20: ; load any selectors within the CLI/STI code.
21: ;
22: ; Any other fault will cause your process to be booted (i.e. GP fault).
23: ;
1.1.1.2 ! root 24: ; Created by Microsoft Corp. 1986
! 25: ;
1.1 root 26: .286p
27:
28: _TEXT2 SEGMENT BYTE PUBLIC 'CODE'
29: _TEXT2 ENDS
30: _DATA SEGMENT WORD PUBLIC 'DATA'
31: _DATA ENDS
32: CONST SEGMENT WORD PUBLIC 'CONST'
33: CONST ENDS
34: _BSS SEGMENT WORD PUBLIC 'BSS'
35: _BSS ENDS
36:
37: DGROUP GROUP CONST, _BSS, _DATA
38:
39: ; EXTRN DOSPORTACCESS:FAR
40:
41: ASSUME CS: _TEXT2, DS: DGROUP, SS: DGROUP, ES: DGROUP
42:
43: _TEXT2 SEGMENT
44:
45: PORT1 EQU 3D4h
46: PORT2 EQU 3D5h
47: CURSOR_H EQU 14 ; cursor location HIGH register
48: CURSOR_L EQU 15 ; cursor location LOW register
49: ACCESSREQ EQU 0 ; request access to port(s)
50: ACCESSREL EQU 1 ; release access to port(s)
51:
52: ;** _GetCurLoc - gets cursor location on the CRT screen
53: ;
54: ; ENTRY NONE
55: ;
56: ; EXIT (AX) = cursor location
57: ;
58: ; USES AX, BX, DX
59:
60: PUBLIC _GetCurLoc ; gets cursor location on CRT screen
61:
62: _GetCurLoc PROC FAR
63:
64: ; push 0 ; RESERVED WORD
65: ; push ACCESSREQ ; request access to port(s)
66: ; push PORT1
67: ; push PORT2
68: ; call DOSPORTACCESS ; request access to ports PORT1, PORT2
69:
70: mov ax,CURSOR_H ; address of register we want to read from
71: call ReadLoc ; gets cursor location (H) in AL
72: mov bh,al ; (BH) = cursor location (H)
73:
74: mov ax,CURSOR_L ; address of register we want to read from
75: call ReadLoc ; gets cursor location (L) in AL
76: mov ah,bh ; (AH) = cursor location (H)
77:
78: push ax ; save cursor location
79: ; push 0 ; RESERVED WORD
80: ; push ACCESSREL ; release access to port(s)
81: ; push PORT1
82: ; push PORT2
83: ; call DOSPORTACCESS ; release access to ports PORT1, PORT2
84: pop ax ; restore cursor location
85:
86: ret
87: _GetCurLoc ENDP
88:
89: ;* ReadLoc - reads cursor location on the CRT screen
90: ;
91: ; ENTRY (AX) = address of register to read from
92: ;
93: ; EXIT (AL) = cursor location read
94: ;
95: ; USES AX,DX
96:
97: ReadLoc PROC NEAR
98: cli
99: mov dx,PORT1 ; set address we want to output to
100: out dx,al
101: jmp $+2 ; PC/AT IO delay
102: mov dx,PORT2 ; set address we want to read from
103: in al,dx ; read cursor location
104: sti
105: ret
106: ReadLoc ENDP
107:
108: _TEXT2 ENDS
109:
110: END
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.