source: xtideuniversalbios/trunk/Assembly_Library/Src/Menu/Dialog/DialogFile.asm @ 593

; Project name  :   Assembly Library
; Description   :   Displays file dialog.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

CURRENTDIR_CHARACTERS   EQU     002Eh
UPDIR_CHARACTERS        EQU     2E2Eh

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; DialogFile_GetFileNameWithIoInDSSI
;   Parameters:
;       DS:SI:  Ptr to FILE_DIALOG_IO
;       SS:BP:  Ptr to parent MENU
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DialogFile_GetFileNameWithIoInDSSI:
    ; We need to store default drive because user might change drive but
    ; then cancel the file selection. In that case the original default directory
    ; must be restored.
    call    Drive_GetDefaultToAL
    push    ax

    mov     bx, FileEventHandler
    mov     BYTE [si+FILE_DIALOG_IO.bUserCancellation], TRUE
    call    Dialog_DisplayWithDialogInputInDSSIandHandlerInBX

    ; Now restore the default drive if user cancellation
    pop     dx
    cmp     BYTE [si+FILE_DIALOG_IO.bUserCancellation], TRUE
    je      Drive_SetDefaultFromDL
    ret


;--------------------------------------------------------------------
; FileEventHandler
;   Common parameters for all events:
;       BX:         Menu event (anything from MENUEVENT struct)
;       SS:BP:      Ptr to DIALOG
;   Common return values for all events:
;       CF:         Set if event processed
;                   Cleared if event not processed
;   Corrupts registers:
;       All
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
FileEventHandler:
    jmp     [cs:bx+.rgfnEventHandlers]


ALIGN JUMP_ALIGN
.ItemSelectedFromCX:
    call    LoadItemStringBufferToESDI
    call    Registers_CopyESDItoDSSI
    call    ItemLineSplitter_GetLineToDSSIandLengthToCXfromStringInDSSIwithIndexInCX
    jmp     ParseSelectionFromItemLineInDSSI


ALIGN JUMP_ALIGN
.RefreshInformation:
    call    GetInfoLinesToCXandDialogFlagsToAX
    mov     si, [cs:.rgszInfoStringLookup]
    xor     bx, bx
    xchg    dx, ax
ALIGN JUMP_ALIGN
.InfoLineLoop:
    shr     dl, 1
    jnc     SHORT .CheckNextFlag
    mov     si, [cs:bx+.rgszInfoStringLookup]
    push    bx
    CALL_DISPLAY_LIBRARY PrintNullTerminatedStringFromCSSI
    pop     bx
ALIGN JUMP_ALIGN
.CheckNextFlag:
    inc     bx
    inc     bx
    loop    .InfoLineLoop
    stc                     ; Event processed
    ret


ALIGN JUMP_ALIGN
.RefreshItemFromCX:
    call    LoadItemStringBufferToESDI
    mov     ax, FILE_STRING_LENGTH
    xchg    ax, cx
    mul     cx
    add     di, ax
    mov     si, di
    mov     bx, es
    dec     cx              ; Do not print LF at the end of file string
    CALL_DISPLAY_LIBRARY PrintCharBufferFromBXSIwithLengthInCX
    stc
    ret


ALIGN WORD_ALIGN
.rgszInfoStringLookup:
    dw      g_szChangeDrive
    dw      g_szSelectDirectory
    dw      g_szCreateNew

.rgfnEventHandlers:
istruc MENUEVENT
    at  MENUEVENT.InitializeMenuinitFromDSSI,   dw  InitializeMenuinitFromSSBP
    at  MENUEVENT.ExitMenu,                     dw  Dialog_EventExitMenu
    at  MENUEVENT.IdleProcessing,               dw  Dialog_EventNotHandled
    at  MENUEVENT.ItemHighlightedFromCX,        dw  Dialog_EventNotHandled
    at  MENUEVENT.ItemSelectedFromCX,           dw  .ItemSelectedFromCX
    at  MENUEVENT.KeyStrokeInAX,                dw  HandleFunctionKeyFromAH
    at  MENUEVENT.RefreshTitle,                 dw  Dialog_EventRefreshTitle
    at  MENUEVENT.RefreshInformation,           dw  .RefreshInformation
    at  MENUEVENT.RefreshItemFromCX,            dw  .RefreshItemFromCX
iend


;--------------------------------------------------------------------
; ReInitializeMenuinitFromSSBP
; InitializeMenuinitFromSSBP
;   Parameters:
;       SS:BP:      Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
ReInitializeMenuinitFromSSBP:
    call    DisplayLoadingMessageInInformationArea
InitializeMenuinitFromSSBP:
    call    LoadItemStringBufferToESDI
    call    CreateStringFromCurrentDirectoryContentsToESDI
    call    LoadItemStringBufferToESDI
    call    SortDirectoryContentsStringFromESDIwithCountInCX
    call    RemoveLastLFandTerminateESDIwithNull

    call    Registers_CopySSBPtoDSSI
    xor     ax, ax
    call    Dialog_EventInitializeMenuinitFromDSSIwithHighlightedItemInAX
    call    GetInfoLinesToCXandDialogFlagsToAX
    mov     [bp+MENUINIT.bInfoLines], cl
    CALL_DISPLAY_LIBRARY GetColumnsToALandRowsToAH
    mov     [bp+MENUINIT.bHeight], ah               ; Always max height
    mov     WORD [bp+MENU.wFirstVisibleItem], 0
    ret


;--------------------------------------------------------------------
; LoadItemStringBufferToESDI
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       ES:DI:  Ptr to item string buffer
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
LoadItemStringBufferToESDI:
    les     di, [bp+DIALOG.fpDialogIO]
    les     di, [es:di+FILE_DIALOG_IO.fszItemBuffer]
    ret


;--------------------------------------------------------------------
; CreateStringFromCurrentDirectoryContentsToESDI
;   Parameters:
;       ES:DI:  Buffer where to create item string
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       CX:     Number of files or directories found
;   Corrupts registers:
;       AX, BX, DX, SI, DI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CreateStringFromCurrentDirectoryContentsToESDI:
    mov     bx, di
    CALL_DISPLAY_LIBRARY PushDisplayContext
    mov     cx, -1
    CALL_DISPLAY_LIBRARY PrepareOffScreenBufferInESBXwithLengthInCX ; ES:DI now points to buffer

    lds     si, [bp+DIALOG.fpDialogIO]
    eMOVZX  cx, [si+FILE_DIALOG_IO.bFileAttributes]
    lds     si, [si+FILE_DIALOG_IO.fpFileFilterString]
    call    Directory_UpdateDTAForFirstMatchForDSSIwithAttributesInCX

    call    .ClearDLifInRootDirectory
    call    Directory_GetDiskTransferAreaAddressToDSSI
    xor     cx, cx          ; Clear file/directory count
    call    .FindMatchingFilesAndPrintThemToOffScreenBuffer

    JMP_DISPLAY_LIBRARY PopDisplayContext

;--------------------------------------------------------------------
; .ClearDLifInRootDirectory
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;       ES:DI:  Ptr to destination string buffer
;   Returns:
;       DL:     Cleared if in root directory
;               Set if in any other directory
;   Corrupts registers:
;       AX, SI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ClearDLifInRootDirectory:
    call    Registers_CopyESDItoDSSI
    call    Directory_WriteCurrentPathToDSSI
    mov     dl, [si]
    ret

;--------------------------------------------------------------------
; .FindMatchingFilesAndPrintThemToOffScreenBuffer
;   Parameters:
;       CX:     Initial directory count
;       DL:     Zero if root directory selected
;       DS:SI:  Ptr to DTA with first matching file
;   Returns:
;       CX:     Incremented by number of files/directories found
;   Corrupts registers:
;       AX, BX, DX, DI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.FindMatchingFilesAndPrintThemToOffScreenBuffer:
    call    AppendFileFromDTAinDSSItoOffScreenBuffer
    call    Directory_UpdateDTAForNextMatchUsingPreviousParameters
    jnc     SHORT .FindMatchingFilesAndPrintThemToOffScreenBuffer
    ret


;--------------------------------------------------------------------
; AppendFileFromDTAinDSSItoOffScreenBuffer
;   Parameters:
;       CX:     Files/directories found
;       DL:     Zero if root directory selected
;       DS:SI:  Ptr to DTA containing file information
;   Returns:
;       CX:     Incremented by number of files/directories found
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
AppendFileFromDTAinDSSItoOffScreenBuffer:
    cmp     WORD [si+DTA.szFile], CURRENTDIR_CHARACTERS
    je      SHORT .Return                   ; We never want "."
    test    dl, dl
    jnz     SHORT .NotInRootDirectory
    cmp     WORD [si+DTA.szFile], UPDIR_CHARACTERS
    je      SHORT .Return                   ; No ".." when in root directory
.NotInRootDirectory:
    inc     cx                              ; Nothing filtered so increment files/directories

    push    bp
    push    si
    push    dx
    push    cx
    call    .FormatFileOrDirectoryToBufferFromDTAinDSSI
    pop     cx
    pop     dx
    pop     si
    pop     bp
.Return:
    ret

;--------------------------------------------------------------------
; .FormatFileOrDirectoryToBufferFromDTAinDSSI
;   Parameters:
;       DS:SI:  Ptr to DTA containing file information
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI, BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.FormatFileOrDirectoryToBufferFromDTAinDSSI:
    mov     bp, sp
    lea     ax, [si+DTA.szFile]

    test    BYTE [si+DTA.bFileAttributes], FLG_FILEATTR_DIRECTORY
    jnz     SHORT .FormatDirectory
    ; Fall to .FormatFile

;--------------------------------------------------------------------
; .FormatFile
;   Parameters:
;       BP:     SP before pushing formatting parameters
;       DS:AX:  Far pointer to file name
;       DS:SI:  Ptr to DTA containing file information
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
.FormatFile:
    xchg    si, ax
    call    String_ConvertDSSItoLowerCase
    xchg    ax, si

    ; Push parameters for file name
    push    ax              ; Push file name offset
    push    ds              ; Push file name segment

    ; Push parameters for file size
    mov     ax, [si+DTA.dwFileSize]
    mov     dx, [si+DTA.dwFileSize+2]
    xor     bx, bx
    xor     cx, cx
    call    Size_GetSizeToAXAndCharToDLfromBXDXAXwithMagnitudeInCX
    mov     cl, 'i'
    cmp     dl, ' '
    eCMOVE  cl, dl
    push    ax
    push    dx
    push    cx

    ; Format to buffer
    mov     si, g_szFileFormat
    jmp     SHORT .FormatStringInCSSIandReturn

;--------------------------------------------------------------------
; .FormatDirectory
;   Parameters:
;       BP:     SP before pushing formatting parameters
;       DS:AX:  Far pointer to directory name
;       DS:SI:  Ptr to DTA containing file information
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.FormatDirectory:
    push    ax              ; Push directory name offset
    push    ds              ; Push directory name segment
    mov     ax, g_szSub
    cmp     WORD [si+DTA.szFile], UPDIR_CHARACTERS
    eCMOVE  ax, g_szUp
    push    ax
    mov     si, g_szDirectoryFormat
ALIGN JUMP_ALIGN
.FormatStringInCSSIandReturn:
    JMP_DISPLAY_LIBRARY FormatNullTerminatedStringFromCSSI


;--------------------------------------------------------------------
; SortDirectoryContentsStringFromESDIwithCountInCX
;   Parameters:
;       CX:     Number of files and directories
;       ES:DI:  Buffer containing directory contents string
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       ES:DI:  Ptr to end of directory contents string
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
SortDirectoryContentsStringFromESDIwithCountInCX:
    call    Registers_CopyESDItoDSSI

    ; Add directory contents string length to DI
    mov     ax, FILE_STRING_LENGTH
    push    ax
    mul     cx
    add     di, ax

    mov     dx, cx
    pop     cx
    mov     bx, .FileStringComparator
    jmp     Sort_ItemsFromDSSIwithCountInDXsizeInCXandComparatorInBX

;--------------------------------------------------------------------
; .FileStringComparator
;   Parameters:
;       CX:     Item size in bytes
;       DS:SI:  Ptr to first item to compare
;       ES:DI:  Ptr to second item to compare
;   Returns:
;       FLAGS:  Signed comparison between first and second item
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.FileStringComparator:
    push    di
    push    si
    push    cx
    push    bx

    mov     bx, FILE_STRING_LENGTH-2            ; Zero BH
    cmp     WORD [si], UPDIR_CHARACTERS
    je      SHORT .ForceValueFromDSSItoBeLess
    mov     bl, [si+bx]
    cmp     bl, [es:di+FILE_STRING_LENGTH-2]    ; 'B' for files, 'R' for directories
    jne     SHORT .ForceValueFromDSSItoBeMoreOrLess
    repe cmpsb                                  ; Two directories or two files

ALIGN JUMP_ALIGN
.ReturnFromComparison:
    pop     bx
    pop     cx
    pop     si
    pop     di
    ret
ALIGN JUMP_ALIGN
.ForceValueFromDSSItoBeMoreOrLess:
    ja      SHORT .ForceValueFromDSSItoBeLess   ; Directory in SI, file in DI
    xchg    bl, bh
    ; Fall to ForceValueFromDSSItoBeLess
ALIGN JUMP_ALIGN
.ForceValueFromDSSItoBeLess:
    cmp     bh, bl
    jmp     SHORT .ReturnFromComparison


;--------------------------------------------------------------------
; RemoveLastLFandTerminateESDIwithNull
;   Parameters:
;       ES:DI:  Ptr to end of buffer to terminate
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
RemoveLastLFandTerminateESDIwithNull:
    dec     di
    xor     ax, ax
    stosb
    ret


;--------------------------------------------------------------------
; GetInfoLinesToCXandDialogFlagsToAX
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       AX:     Dialog flags
;       CX:     Number of info lines to be displayed
;   Corrupts registers:
;       SI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
GetInfoLinesToCXandDialogFlagsToAX:
    ePUSH_T ax, Bit_GetSetCountToCXfromAX
    xor     ah, ah
    ; Fall to GetDialogFlagsToAL

;--------------------------------------------------------------------
; GetDialogFlagsToAL
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       AL:     Dialog flags
;   Corrupts registers:
;       SI, DS
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
GetDialogFlagsToAL:
    lds     si, [bp+DIALOG.fpDialogIO]
    mov     al, [si+FILE_DIALOG_IO.bDialogFlags]
    ret


;--------------------------------------------------------------------
; ParseSelectionFromItemLineInDSSI
;   Parameters:
;       DS:SI:  Ptr to char buffer containing file or directory to be selected
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
ParseSelectionFromItemLineInDSSI:
    mov     ax, [si]
    cmp     ax, UPDIR_CHARACTERS
    je      SHORT .ChangeToUpdir
    call    Char_IsUpperCaseLetterInAL
    jc      SHORT .ParseAndChangeToSubdirInDSSI
    call    Char_IsDecimalDigitInAL
    jc      SHORT .ParseAndChangeToSubdirInDSSI ; Assume subdir and check for errors
    ; Fall to .ParseAndSelectFileFromDSSI

;--------------------------------------------------------------------
; .ParseAndSelectFileFromDSSI
;   Parameters:
;       DS:SI:  NULL terminated string selected from dialog
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing (exits dialog)
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
.ParseAndSelectFileFromDSSI:
    les     di, [bp+DIALOG.fpDialogIO]
    add     di, BYTE FILE_DIALOG_IO.szFile
    mov     cx, FILENAME_BUFFER_SIZE-1
    call    Memory_CopyCXbytesFromDSSItoESDI
    xor     ax, ax
    stosb                       ; Terminate with NULL
    jmp     SHORT CloseFileDialogAfterSuccessfulSelection

;--------------------------------------------------------------------
; .ChangeToUpdir
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ChangeToUpdir:
    push    cs
    pop     ds
    mov     si, g_szUpdir
    jmp     SHORT .ChangeDirectoryToDSSI

;--------------------------------------------------------------------
; .ParseAndChangeToSubdirInDSSI
;   Parameters:
;       DS:SI:  NULL terminated string selected from dialog
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ParseAndChangeToSubdirInDSSI:
    mov     BYTE [si+12], NULL  ; Terminate with NULL (unnecessary spaces do not matter)
.ChangeDirectoryToDSSI:
    call    Directory_ChangeToPathFromDSSI
    jc      SHORT .ParseAndSelectFileFromDSSI   ; Must have been a file starting with number
    ; Fall to RefreshFilesToDisplay

;--------------------------------------------------------------------
; RefreshFilesToDisplay
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
RefreshFilesToDisplay:
    call    ReInitializeMenuinitFromSSBP
    jmp     MenuInit_RefreshMenuWindow


;--------------------------------------------------------------------
; HandleFunctionKeyFromAH
;   Parameters:
;       AH:     Scancode for function key
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, SI, DI, BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
HandleFunctionKeyFromAH:
    call    GetDialogFlagsToAL
    cmp     ah, KEY_FILEDIALOG_NEW_FILE_OR_DIR
    je      SHORT HandleFunctionKeyForCreatingNewFileOrDirectory
    cmp     ah, KEY_FILEDIALOG_SELECT_DIRECTORY
    je      SHORT HandleFunctionKeyForSelectingDirectoryInsteadOfFile
    cmp     ah, KEY_FILEDIALOG_CHANGE_DRIVE
    je      SHORT HandleFunctionKeyForDriveChange
ReturnWithoutHandlingKeystroke:
    clc     ; Event not processed
    ret


;--------------------------------------------------------------------
; HandleFunctionKeyForCreatingNewFileOrDirectory
;   Parameters:
;       AL:     File dialog flags
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Closes file dialog
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
HandleFunctionKeyForCreatingNewFileOrDirectory:
    test    al, FLG_FILEDIALOG_NEW
    jz      SHORT ReturnWithoutHandlingKeystroke

    mov     cx, STRING_DIALOG_IO_size
    call    Memory_ReserveCXbytesFromStackToDSSI

;;; InitializeStringDialogIoInDSSIforInputtingFileName
    call    InitializeNullStringsToDialogInputInDSSI
    mov     WORD [si+DIALOG_INPUT.fszTitle], g_szEnterNewFileOrDirectory
    mov     WORD [si+STRING_DIALOG_IO.fnCharFilter], NULL
    mov     WORD [si+STRING_DIALOG_IO.wBufferSize], FILENAME_BUFFER_SIZE
    les     ax, [bp+DIALOG.fpDialogIO]
    add     ax, BYTE FILE_DIALOG_IO.szFile
    mov     [si+STRING_DIALOG_IO.fpReturnBuffer], ax
    mov     [si+STRING_DIALOG_IO.fpReturnBuffer+2], es
;;;

    CALL_MENU_LIBRARY GetStringWithIoInDSSI
    mov     al, [si+STRING_DIALOG_IO.bUserCancellation]
    add     sp, BYTE STRING_DIALOG_IO_size
    test    al, al      ; User cancellation?
    jnz     SHORT ReturnWithoutHandlingKeystroke
    jmp     CloseFileDialogAfterSuccessfulSelection


;--------------------------------------------------------------------
; HandleFunctionKeyForSelectingDirectoryInsteadOfFile
;   Parameters:
;       AL:     File dialog flags
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Closes file dialog
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
HandleFunctionKeyForSelectingDirectoryInsteadOfFile:
    test    al, FLG_FILEDIALOG_DIRECTORY
    jz      SHORT ReturnWithoutHandlingKeystroke
    ; Fall to CloseFileDialogAfterSuccessfulSelection

;--------------------------------------------------------------------
; CloseFileDialogAfterSuccessfulSelection
;   Parameters:
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing (exits dialog)
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CloseFileDialogAfterSuccessfulSelection:
    lds     di, [bp+DIALOG.fpDialogIO]
    mov     BYTE [di+FILE_DIALOG_IO.bUserCancellation], FALSE
    jmp     MenuInit_CloseMenuWindow


;--------------------------------------------------------------------
; HandleFunctionKeyForDriveChange
;   Parameters:
;       AL:     File dialog flags
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
HandleFunctionKeyForDriveChange:
    test    al, FLG_FILEDIALOG_DRIVES
    jz      SHORT ReturnWithoutHandlingKeystroke

    call    DisplayLoadingMessageInInformationArea
    mov     cx, DRIVE_DIALOG_IO_size
    call    Memory_ReserveCXbytesFromStackToDSSI
    call    .DisplayDriveSelectionDialogWithIoInDSSI
    call    .ChangeDriveToUserSelectionFromIoInDSSI
    add     sp, BYTE DRIVE_DIALOG_IO_size
.UserCancelledDriveChange:
    ret

;--------------------------------------------------------------------
; .DisplayDriveSelectionDialogWithIoInDSSI
;   Parameters:
;       DS:SI:  Ptr to uninitialized DRIVE_DIALOG_IO
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       DS:SI:  Ptr to DRIVE_DIALOG_IO
;   Corrupts registers:
;       AX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.DisplayDriveSelectionDialogWithIoInDSSI:
    call    InitializeNullStringsToDialogInputInDSSI
    mov     WORD [si+DIALOG_INPUT.fszTitle], g_szSelectNewDrive
    JMP_MENU_LIBRARY GetDriveWithIoInDSSI

;--------------------------------------------------------------------
; .ChangeDriveToUserSelectionFromIoInDSSI
;   Parameters:
;       DS:SI:  Ptr to DRIVE_DIALOG_IO
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       All, except BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ChangeDriveToUserSelectionFromIoInDSSI:
    cmp     BYTE [si+DRIVE_DIALOG_IO.bUserCancellation], FALSE
    jne     SHORT .UserCancelledDriveChange

    ; Install our Custom Critical Error Handler to catch "Drive Not Ready" errors. This handler only works on DOS 3.0+ systems
    ; but that should be OK because only DOS 3.1+ will trigger it. Under older DOS versions drives are enumerated using
    ; GET_DOS_DRIVE_PARAMETER_BLOCK_FOR_SPECIFIC_DRIVE which will access the drive so we know it is available at this point.
    mov     dx, DosCritical_CustomHandler
    call    DosCritical_InstallNewHandlerFromCSDX

    ; Save the current drive on stack in case the selected drive is not ready and the user decides to cancel the change.
    call    Drive_GetDefaultToAL
    xchg    dx, ax

.RetryDrive:
    push    dx                                  ; Save the previous current drive to stack

    mov     dl, [si+DRIVE_DIALOG_IO.bReturnDriveNumber]
    call    Drive_SetDefaultFromDL

    ; Now we must try to force a media access to catch "Drive Not Ready".
    push    ds
    push    ss
    pop     ds
    ePUSH_T ax, CURRENTDIR_CHARACTERS
    mov     cx, FLG_FILEATTR_DIRECTORY
    mov     dx, sp
    mov     ax, FIND_FIRST_MATCHING_FILE<<8
    int     DOS_INTERRUPT_21h
    pop     ax
    pop     ds

    pop     dx                                  ; Restore the previous current drive from stack

    xchg    ah, [cs:bLastCriticalError]         ; Zero bLastCriticalError and fetch error code to AH
    cmp     ah, ERR_DOS_DRIVE_NOT_READY
    jne     SHORT .DriveIsReady

    mov     bx, g_szDlgDriveNotReady
    call    Dialogs_DisplayYesNoResponseDialogWithTitleStringInBX
    jz      SHORT .RetryDrive
    ; The user cancelled the drive change. Restore current drive to what it was previously.
    call    Drive_SetDefaultFromDL
    jmp     DosCritical_RestoreDosHandler

.DriveIsReady:
    call    DosCritical_RestoreDosHandler
    jmp     RefreshFilesToDisplay


;--------------------------------------------------------------------
; DisplayLoadingMessageInInformationArea
;   Parameters:
;       SS:BP:      Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX, SI, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DisplayLoadingMessageInInformationArea:
    call    MenuText_ClearInformationArea
    call    MenuText_PrepareToDrawInformationArea
    mov     si, g_szLoadingPleaseWait
    JMP_DISPLAY_LIBRARY PrintNullTerminatedStringFromCSSI


;--------------------------------------------------------------------
; InitializeNullStringsToDialogInputInDSSI
;   Parameters:
;       DS:SI:  Ptr to DIALOG_INPUT
;       SS:BP:  Ptr to DIALOG
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
InitializeNullStringsToDialogInputInDSSI:
    mov     ax, g_szNull
    mov     [si+DIALOG_INPUT.fszTitle], ax
    mov     [si+DIALOG_INPUT.fszTitle+2], cs
    mov     [si+DIALOG_INPUT.fszItems], ax
    mov     [si+DIALOG_INPUT.fszItems+2], cs
    mov     [si+DIALOG_INPUT.fszInfo], ax
    mov     [si+DIALOG_INPUT.fszInfo+2], cs
    ret