source: xtideuniversalbios/trunk/Assembly_Library/Src/Menu/CharOutLineSplitter.asm @ 134

; Project name  :   Assembly Library
; Description   :   Functions for splitting menu lines during character output.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; CharOutLineSplitter_PrepareForPrintingTextLines
;   Parameters:
;       SS:BP:  Ptr to MENU
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, DX, DI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CharOutLineSplitter_PrepareForPrintingTextLines:
    ; Get first text line column offset to DX
    call    CharOutLineSplitter_GetFirstBorderLineColumnOffsetToAX
    add     al, MENU_TEXT_COLUMN_OFFSET<<1
    xchg    dx, ax

    ; Get last text line column offset to AX
    call    MenuLocation_GetMaxTextLineLengthToAX
    shl     ax, 1           ; Characters to BYTEs
    add     ax, dx

    xchg    ax, dx          ; AL = First text line column offset
    mov     ah, dl          ; AH = Last text line column offset
    CALL_DISPLAY_LIBRARY SetCharacterOutputParameterFromAX
    ret


;--------------------------------------------------------------------
; CharOutLineSplitter_GetFirstBorderLineColumnOffsetToAX
;   Parameters:
;       SS:BP:  Ptr to MENU
;   Returns:
;       AX:     Offset to end of text line (first border area character)
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CharOutLineSplitter_GetFirstBorderLineColumnOffsetToAX:
    call    MenuLocation_GetTitleBordersTopLeftCoordinatesToAX
    xor     ah, ah
    shl     ax, 1
    ret


;--------------------------------------------------------------------
; CharOutLineSplitter_IsCursorAtTheEndOfTextLine
;   Parameters:
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to cursor location in video memory
;   Returns:
;       CF:     Set if end of text line
;               Clear if more characters fit on current text line
;   Corrupts registers:
;       DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CharOutLineSplitter_IsCursorAtTheEndOfTextLine:
    push    ax

    mov     dl, [VIDEO_BDA.wColumns]
    shl     dl, 1           ; DX = bytes per row
    mov     ax, di
    div     dl              ; AL = row index, AH = column index
    cmp     [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.wCharOutParam+1], ah

    pop     ax
    ret


;--------------------------------------------------------------------
; CharOutLineSplitter_MovePartialWordToNewTextLine
;   Parameters:
;       AL:     Character to output
;       AH:     Attribute to output
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to end of text line in video memory
;   Returns:
;       DI:     Updated to next character for new text line
;   Corrupts registers:
;       AX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
CharOutLineSplitter_MovePartialWordToNewTextLine:
    push    si
    push    cx
    push    ax
    ; Fall to .GetOffsetToPartialWordToSIandSizeToCX

;--------------------------------------------------------------------
; .GetOffsetToPartialWordToSIandSizeToCX
;   Parameters:
;       ES:DI:  Ptr to space before border character
;   Returns:
;       CX:     Number of bytes that needs to be moved
;       ES:SI:  Ptr to beginning of partial word that needs to be moved to new line
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
.GetOffsetToPartialWordToSIandSizeToCX:
    xor     cx, cx
    mov     si, di
ALIGN JUMP_ALIGN
.ScanNextCharacter:     ; Space will always be found since one comes after border
    dec     si
    dec     si
    cmp     BYTE [es:si], ' '
    je      SHORT .PartialWordFound
    inc     cx
    jmp     SHORT .ScanNextCharacter
ALIGN JUMP_ALIGN
.PartialWordFound:
    inc     si
    inc     si          ; SI now points one past space
    shl     cx, 1       ; Characters to bytes
    ; Fall to .ChangeLine

;--------------------------------------------------------------------
; .ChangeLine
;   Parameters:
;       Nothing
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, DX
;--------------------------------------------------------------------
.ChangeLine:
    call    MenuCharOut_PrintLFCRandAdjustOffsetForStartOfLine
    jcxz    .ReturnFromMovePartialWordToNewTextLine
    ; Fall to .MovePartialWordFromPreviousLineInESSItoNewLineInESDIwithSizeInCX

;--------------------------------------------------------------------
; .MovePartialWordFromPreviousLineInESSItoNewLineInESDIwithSizeInCX
;   Parameters:
;       CX:     Number of BYTEs in partial word
;       DS:     BDA segment (zero)
;       ES:SI:  Ptr to partial word on previous line
;       ES:DI:  Ptr to new empty line
;   Returns:
;       ES:DI:  Ptr where to store next character
;   Corrupts registers:
;       AX, CX, DX, SI
;--------------------------------------------------------------------
.MovePartialWordFromPreviousLineInESSItoNewLineInESDIwithSizeInCX:
    push    si
    push    cx
    WAIT_RETRACE_IF_NECESSARY_THEN rep movsb
    pop     cx
    pop     si

    xchg    di, si
    shr     cx, 1       ; Bytes to characters
    mov     al, ' '
    call    DisplayPrint_RepeatCharacterFromALwithCountInCX
    mov     di, si

.ReturnFromMovePartialWordToNewTextLine:
    pop     ax
    pop     cx
    pop     si
    ret