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Return real mode callback
Source position: go32.pp line 141
function get_rm_callback( |
pm_func: pointer; |
const reg: trealregs; |
var rmcb: tseginfo |
):Boolean; |
Returns a unique real mode segment:offset address, known as a "real mode callback," that will transfer control from real mode to a protected mode procedure.
Parameters:
Return values: True if successful, otherwise False.
Remark: | Callback addresses obtained with this function can be passed by a protected mode program for example to an interrupt handler, device driver, or TSR, so that the real mode program can call procedures within the protected mode program or notify the protected mode program of an event. The contents of the supplied regs structure is not valid after function call, but only at the time of the actual callback. |
Check the int31error variable.
|
Release real mode callback. |
{$ASMMODE ATT} {$MODE FPC} uses crt, go32; const mouseint = $33; var mouse_regs : trealregs; external name '___v2prt0_rmcb_regs'; mouse_seginfo : tseginfo; var mouse_numbuttons : longint; mouse_action : word; mouse_x, mouse_y : Word; mouse_b : Word; userproc_installed : Longbool; userproc_length : Longint; userproc_proc : pointer; procedure callback_handler; assembler; asm pushw %ds pushl %eax movw %es, %ax movw %ax, %ds cmpl $1, USERPROC_INSTALLED jne .LNoCallback pushal movw DOSmemSELECTOR, %ax movw %ax, %fs call *USERPROC_PROC popal .LNoCallback: popl %eax popw %ds pushl %eax movl (%esi), %eax movl %eax, %es: 42(%edi) addw $4, %es:46(%edi) popl %eax iret end; procedure mouse_dummy; begin end; procedure textuserproc; begin mouse_b := mouse_regs.bx; mouse_x := (mouse_regs.cx shr 3) + 1; mouse_y := (mouse_regs.dx shr 3) + 1; end; procedure install_mouse(userproc : pointer; userproclen : longint); var r : trealregs; begin r.eax := $0; realintr(mouseint, r); if (r.eax <> $FFFF) then begin Writeln('No Microsoft compatible mouse found'); Writeln('A Microsoft compatible mouse driver is necessary ', 'to run this example'); halt; end; if (r.bx = $ffff) then mouse_numbuttons := 2 else mouse_numbuttons := r.bx; Writeln(mouse_numbuttons, ' button Microsoft compatible mouse ', ' found.'); if (userproc <> nil) then begin userproc_proc := userproc; userproc_installed := true; userproc_length := userproclen; lock_code(userproc_proc, userproc_length); end else begin userproc_proc := nil; userproc_length := 0; userproc_installed := false; end; lock_data(mouse_x, sizeof(mouse_x)); lock_data(mouse_y, sizeof(mouse_y)); lock_data(mouse_b, sizeof(mouse_b)); lock_data(mouse_action, sizeof(mouse_action)); lock_data(userproc_installed, sizeof(userproc_installed)); lock_data(userproc_proc, sizeof(userproc_proc)); lock_data(mouse_regs, sizeof(mouse_regs)); lock_data(mouse_seginfo, sizeof(mouse_seginfo)); lock_code(@callback_handler, longint(@mouse_dummy)-longint(@callback_handler)); get_rm_callback(@callback_handler, mouse_regs, mouse_seginfo); r.eax := $0c; r.ecx := $7f; r.edx := longint(mouse_seginfo.offset); r.es := mouse_seginfo.segment; realintr(mouseint, r); r.eax := $01; realintr(mouseint, r); end; procedure remove_mouse; var r : trealregs; begin r.eax := $02; realintr(mouseint, r); r.eax := $0c; r.ecx := 0; r.edx := 0; r.es := 0; realintr(mouseint, r); free_rm_callback(mouse_seginfo); if (userproc_installed) then begin unlock_code(userproc_proc, userproc_length); userproc_proc := nil; userproc_length := 0; userproc_installed := false; end; unlock_data(mouse_x, sizeof(mouse_x)); unlock_data(mouse_y, sizeof(mouse_y)); unlock_data(mouse_b, sizeof(mouse_b)); unlock_data(mouse_action, sizeof(mouse_action)); unlock_data(userproc_proc, sizeof(userproc_proc)); unlock_data(userproc_installed, sizeof(userproc_installed)); unlock_data(mouse_regs, sizeof(mouse_regs)); unlock_data(mouse_seginfo, sizeof(mouse_seginfo)); unlock_code(@callback_handler, longint(@mouse_dummy)-longint(@callback_handler)); fillchar(mouse_seginfo, sizeof(mouse_seginfo), 0); end; begin install_mouse(@textuserproc, 400); Writeln('Press any key to exit...'); while (not keypressed) do begin gotoxy(1, wherey); write('MouseX : ', mouse_x:2, ' MouseY : ', mouse_y:2, ' Buttons : ', mouse_b:2); end; remove_mouse; end.