source: xtideuniversalbios/trunk/Assembly_Library/Src/Display/DisplayFormat.asm @ 134

; Project name  :   Assembly Library
; Description   :   Functions for displaying formatted strings.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; DisplayFormat_ParseCharacters
;   Parameters:
;       DS:     BDA segment (zero)
;       SS:BP:  Pointer to first format parameter (-=2 updates to next parameter)
;       CS:SI:  Pointer to string to format
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       CS:SI:  Ptr to end of format string (ptr to one past NULL)
;       DI:     Updated offset to video RAM
;   Corrupts registers:
;       AX, BX, CX, DX, BP
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
DisplayFormat_ParseCharacters:
    call    ReadCharacterAndTestForNull
    jz      SHORT ReturnFromFormat

    ePUSH_T cx, DisplayFormat_ParseCharacters   ; Return address
    xor     cx, cx                              ; Initial placeholder size
    cmp     al, '%'                             ; Format specifier?
    jne     SHORT DisplayPrint_CharacterFromAL
    ; Fall to ParseFormatSpecifier

;--------------------------------------------------------------------
; ParseFormatSpecifier
;   Parameters:
;       CX:     Placeholder size
;       DS:     BDA segment (zero)
;       SS:BP:  Pointer to first format parameter (-=2 for next parameter)
;       CS:SI:  Pointer to string to format
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       SI:     Updated to first unparsed character
;       DI:     Updated offset to video RAM
;       BP:     Updated to next format parameter
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ParseFormatSpecifier:
    call    ReadCharacterAndTestForNull
    call    Char_IsDecimalDigitInAL
    jc      SHORT ParsePlaceholderSizeDigitFromALtoCX
    call    GetFormatSpecifierParserToAX
    call    ax              ; Parser function
    dec     bp
    dec     bp              ; SS:BP now points to next parameter
    test    cx, cx
    jnz     SHORT PrependOrAppendSpaces
ReturnFromFormat:
    ret

;--------------------------------------------------------------------
; ParsePlaceholderSizeDigitFromALtoCX
;   Parameters:
;       AL:     Digit character from format string
;       CX:     Current placeholder size
;       DS:     BDA segment (zero)
;   Returns:
;       CX:     Current placeholder size
;       Jumps back to ParseFormatSpecifier
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
ParsePlaceholderSizeDigitFromALtoCX:
    mov     [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition], di
    sub     al, '0'             ; Digit '0'...'9' to integer 0...9
    mov     ah, cl              ; Previous number parameter to AH
    aad                         ; AL += (AH * 10)
    mov     cl, al              ; Updated number parameter now in CX
    jmp     SHORT ParseFormatSpecifier


;--------------------------------------------------------------------
; ReadCharacterAndTestForNull
;   Parameters:
;       CS:SI:  Pointer next character from string
;   Returns:
;       AL:     Character from string
;       SI:     Incremented to next character
;       ZF:     Set if NULL, cleared if valid character
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
ReadCharacterAndTestForNull:
    eSEG    cs
    lodsb                                   ; Load from CS:SI to AL
    test    al, al                          ; NULL to end string?
    ret


;--------------------------------------------------------------------
; GetFormatSpecifierParserToAX
;   Parameters:
;       AL:     Format specifier character
;   Returns:
;       AX:     Offset to parser function
;   Corrupts registers:
;       AX, BX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
GetFormatSpecifierParserToAX:
    mov     bx, .rgcFormatCharToLookupIndex
ALIGN JUMP_ALIGN
.CheckForNextSpecifierParser:
    cmp     al, [cs:bx]
    je      SHORT .ConvertIndexToFunctionOffset
    inc     bx
    cmp     bx, .rgcFormatCharToLookupIndexEnd
    jb      SHORT .CheckForNextSpecifierParser
    mov     ax, c_FormatCharacter
    ret
ALIGN JUMP_ALIGN
.ConvertIndexToFunctionOffset:
    sub     bx, .rgcFormatCharToLookupIndex
    shl     bx, 1               ; Shift for WORD lookup
    mov     ax, [cs:bx+.rgfnFormatSpecifierParser]
    ret

.rgcFormatCharToLookupIndex:
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    db      "aAduxsSct-+%"
%else
    db      "Auxsc-"        ; Required by XTIDE Universal BIOS
%endif
.rgcFormatCharToLookupIndexEnd:
ALIGN WORD_ALIGN
.rgfnFormatSpecifierParser:
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    dw      a_FormatAttributeForNextCharacter
%endif
    dw      A_FormatAttributeForRemainingString
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    dw      d_FormatSignedDecimalWord
%endif
    dw      u_FormatUnsignedDecimalWord
    dw      x_FormatHexadecimalWord
    dw      s_FormatStringFromSegmentCS
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    dw      S_FormatStringFromFarPointer
%endif
    dw      c_FormatCharacter
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    dw      t_FormatRepeatCharacter
%endif
    dw      PrepareToPrependParameterWithSpaces
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
    dw      PrepareToAppendSpacesAfterParameter
    dw      percent_FormatPercent
%endif


;--------------------------------------------------------------------
; PrependOrAppendSpaces
;   Parameters:
;       CX:     Minimum length for format specifier in characters
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
PrependOrAppendSpaces:
    mov     ax, di
    sub     ax, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition]
    test    cx, cx
    js      SHORT .PrependWithSpaces
    ; Fall to .AppendSpaces

;--------------------------------------------------------------------
; .AppendSpaces
;   Parameters:
;       AX:     Number of format parameter BYTEs printed
;       CX:     Minimum length for format specifier in characters
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, CX, DX
;--------------------------------------------------------------------
.AppendSpaces:
    call    DisplayContext_GetCharacterOffsetToAXfromByteOffsetInAX
    sub     cx, ax
    jle     SHORT .NothingToAppendOrPrepend
    mov     al, ' '
    jmp     DisplayPrint_RepeatCharacterFromALwithCountInCX

;--------------------------------------------------------------------
; .PrependWithSpaces
;   Parameters:
;       AX:     Number of format parameter BYTEs printed
;       CX:     Negative minimum length for format specifier in characters
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       Nothing
;   Corrupts registers:
;       AX, BX, CX, DX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.PrependWithSpaces:
    xchg    ax, cx
    neg     ax
    call    DisplayContext_GetByteOffsetToAXfromCharacterOffsetInAX
    sub     ax, cx              ; AX = BYTEs to prepend, CX = BYTEs to move
    jle     SHORT .NothingToAppendOrPrepend

    std
    push    si

    lea     si, [di-1]          ; SI = Offset to last byte formatted
    add     di, ax              ; DI = Cursor location after preceeding completed
    push    di
    dec     di                  ; DI = Offset where to move last byte formatted
    xchg    bx, ax              ; BX = BYTEs to prepend
    call    .ReverseCopyCXbytesFromESSItoESDI
    xchg    ax, bx
    call    .ReversePrintAXspacesStartingFromESDI

    pop     di
    pop     si
    cld                         ; Restore DF
.NothingToAppendOrPrepend:
    ret

;--------------------------------------------------------------------
; .ReverseCopyCXbytesFromESSItoESDI
;   Parameters:
;       CX:     Number of bytes to copy
;       DS:     BDA segment (zero)
;       ES:SI:  Ptr to old location
;       ES:DI:  Ptr to new location
;   Returns:
;       DI:     Updated to before last character copied
;   Corrupts registers:
;       AX, CX, DX, SI
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
.ReverseCopyCXbytesFromESSItoESDI:
    test    BYTE [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bFlags], FLG_CONTEXT_ATTRIBUTES
    jz      SHORT .CopyWithoutDisplayProcessing

    WAIT_RETRACE_IF_NECESSARY_THEN rep movsb
    dec     di                  ; Point to preceeding character instead of attribute
    ret
ALIGN JUMP_ALIGN
.CopyWithoutDisplayProcessing:
    eSEG_STR rep, es, movsb
    ret

;--------------------------------------------------------------------
; .ReversePrintAXspacesStartingFromESDI
;   Parameters:
;       AX:     Number of spaces to print
;       DS:     BDA segment (zero)
;       ES:DI:  Ptr to destination in video RAM
;   Returns:
;       DI:     Updated
;   Corrupts registers:
;       AX, CX, DX
ALIGN JUMP_ALIGN
.ReversePrintAXspacesStartingFromESDI:
    call    DisplayContext_GetCharacterOffsetToAXfromByteOffsetInAX
    xchg    cx, ax              ; CX = Spaces to prepend
    mov     al, ' '
    jmp     DisplayPrint_RepeatCharacterFromALwithCountInCX



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Formatting functions
;   Parameters:
;       DS:     BDA segment (zero)
;       SS:BP:  Pointer to next format parameter (-=2 updates to next parameter)
;       ES:DI:  Ptr to cursor location in video RAM
;   Returns:
;       SS:BP:  Points to last WORD parameter used
;   Corrupts registers:
;       AX, BX, DX
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
ALIGN JUMP_ALIGN
a_FormatAttributeForNextCharacter:
    mov     bl, [bp]
    xchg    bl, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute]
    push    bx
    push    cx
    push    di
    call    DisplayFormat_ParseCharacters   ; Recursive call
    pop     WORD [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.fpCursorPosition]
    pop     cx
    pop     bx
    mov     [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute], bl
    ret
%endif

ALIGN JUMP_ALIGN
A_FormatAttributeForRemainingString:
    mov     al, [bp]
    mov     [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute], al
    ret

%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
ALIGN JUMP_ALIGN
d_FormatSignedDecimalWord:
    mov     ax, [bp]
    mov     bx, 10
    jmp     DisplayPrint_SignedWordFromAXWithBaseInBX
%endif

ALIGN JUMP_ALIGN
u_FormatUnsignedDecimalWord:
    mov     ax, [bp]
    mov     bx, 10
    jmp     DisplayPrint_WordFromAXWithBaseInBX

ALIGN JUMP_ALIGN
x_FormatHexadecimalWord:
    mov     ax, [bp]
    mov     bx, 16
    call    DisplayPrint_WordFromAXWithBaseInBX
    mov     al, 'h'
    jmp     DisplayPrint_CharacterFromAL

ALIGN JUMP_ALIGN
s_FormatStringFromSegmentCS:
    xchg    si, [bp]
    call    DisplayPrint_NullTerminatedStringFromCSSI
    mov     si, [bp]
    ret

%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
ALIGN JUMP_ALIGN
S_FormatStringFromFarPointer:
    mov     bx, [bp-2]
    xchg    si, [bp]
    call    DisplayPrint_NullTerminatedStringFromBXSI
    mov     si, [bp]
    dec     bp
    dec     bp
    ret
%endif

ALIGN JUMP_ALIGN
c_FormatCharacter:
    mov     al, [bp]
    jmp     DisplayPrint_CharacterFromAL

%ifndef EXCLUDE_FROM_XTIDE_UNIVERSAL_BIOS
ALIGN JUMP_ALIGN
t_FormatRepeatCharacter:
    push    cx
    mov     cx, [bp-2]
    mov     al, [bp]
    call    DisplayPrint_RepeatCharacterFromALwithCountInCX
    pop     cx
    dec     bp
    dec     bp
    ret

ALIGN JUMP_ALIGN
percent_FormatPercent:
    mov     al, '%'
    jmp     DisplayPrint_CharacterFromAL
%endif

ALIGN JUMP_ALIGN
PrepareToPrependParameterWithSpaces:
    neg     cx
    ; Fall to PrepareToAppendSpacesAfterParameter

ALIGN JUMP_ALIGN
PrepareToAppendSpacesAfterParameter:
    add     sp, BYTE 2              ; Remove return offset
    jmp     ParseFormatSpecifier