HPAVC/HPAVC CD-ROM.iso/pc/XLIBP202.ZIP/XLIB2.ASM

Assembly Source File | 1994-06-18 | 73.7 KB | 4,782 lines

; ***************************************************************************
; **                             XLibPas v2.0                              **
; **                        for Borland Pascal 7.0                         **
; **                                  by                                   **
; **                            Tristan Tarrant                            **
; ***************************************************************************
; ** Credits :                                                             **
; **   Michael Abrash    - Concepts, Algorithms                            **
; **   Themie Gouthas    - Main code and implementation                    **
; **   Matthew MacKenzie - Compiled Bitmaps, Circles, etc.                 **
; **   Tore Bastiansen   - Virtual VSync Handler                           **
; ***************************************************************************

        .MODEL TPASCAL
        .386
        LOCALS

include xlib2.inc
        .DATA

    OldHandlerSeg      dw  ?
    OldHandlerOffs     dw  ?
    OldHandlerMask     dw  ?
    OldX               dw  ?
    OldY               dw  ?
    OldScrnOffs        dw  ?

    level              dw  ?
    gencount           dw  ?
    AdjustedOffs       dw  ?
    p1xt               dw  ?
    p1yt               dw  ?
    p2xt               dw  ?
    p2yt               dw  ?
    p4xt               dw  ?
    p4yt               dw  ?
    p5xt               dw  ?
    p5yt               dw  ?
    c1xt               dw  ?
    c1yt               dw  ?
    c2xt               dw  ?
    c2yt               dw  ?
    xdiff              dw  ?
    ydiff              dw  ?
    moveline           dw  ?
    stepper            dw  ?
    bptemp             dw  ?
    Colort             dw  ?

    TicksPerSecond         dw ?
    VsyncIntTicks          label dword
    VsyncIntTicksLo        dw ?
    VsyncIntTicksHi        dw ?
    VsyncPeriod            dw ?       ;Time (in clicks) between each vsync
                                                                        ;1 click = 1.193 microseconds

    ClockRate              dw ?             ;Clock rate (in clicks) for timer 0
    ClockCounter           dw ?             ;Counts total clicks modulo 65536
    UserVsyncHandler       label dword      ;Pointer to user routine called
    UserVsyncOffs          dw ?             ;called once each vsync period.
    UserVsyncSeg           dw ?
    InUserHandler          dw ?
                db 100h dup(?)
    LocalStack             label byte       ;Local stack for user handler
    StackSeg               dw ?
    StackPtr               dw ?


    ElapsedVrts            dw ?
    VrtsToSkip             dw ?
    MouseVSyncHandler      dd ?


        .CODE

XSetMode PROC FAR Mode : Word, WidthInPixels : Word

    mov InGraphics,0
    mov ErrorValue,0
    mov DoubleScanFlag,0
    mov CurrXMode,0
    mov ScrnPhysicalByteWidth,0
    mov ScrnPhysicalPixelWidth,0
    mov ScrnPhysicalHeight,0
    mov SplitScrnOffs,0
    mov SplitScrnScanLine,0
    mov SplitScrnVisibleHeight,0
    mov SplitScrnActive,0
    mov Page0Offs,0
    mov Page1Offs,0
    mov Page2Offs,0
    mov ScrnLogicalByteWidth,0
    mov ScrnLogicalPixelWidth,0
    mov ScrnLogicalHeight,0
    mov MaxScrollX,0
    mov MaxScrollY,0
    mov DoubleBufferActive,0
    mov VisiblePageIdx,0
    mov HiddenPageOffs,0
    mov VisiblePageOffs,0
    mov NonVisualOffs,0
    mov TopClip,0
    mov BottomClip,0
    mov LeftClip,0
    mov RightClip,0
    mov PhysicalStartPixelX,0
    mov PhysicalStartByteX,0
    mov PhysicalStartY,0
IFDEF _DPMI_
    mov    ax,__AHIncr
    mov SelectorInc,ax
    mov ax, __0000H
    mov Seg0000,ax
    mov ax, __A000H
ELSE
    mov ax, 0A000h
ENDIF
    mov ScreenSeg,ax
    cld
    mov   ax,ds
    mov   es,ax
    mov   cx,mode
    cmp   cx,LastXMode
    jle   @@ValidMode
    mov   InGraphics,0
    mov   ax,-1
    jmp @@Done

@@ValidMode:
    mov   CurrXMode,cx
    mov   InGraphics,1
    xor   al,al
    cmp   cx,3
    jg    @@SetDoubleScanFlag
    mov   al,1

@@SetDoubleScanFlag:
    mov   DoubleScanFlag,al
    push  cx
    mov   ax,13h
    int   10h
    pop   cx
    mov   dx,ScIndex
    mov   ax,0604h
    out   dx,ax
    mov   ax,0100h
    out   dx,ax
    mov   bx,offset ModeTable
    shl   cx,1
    add   bx,cx
    mov   si, word ptr [bx]
    lodsb
    or    al,al
    jz    @@DontSetDot
    mov   dx,MISCOUTPUT
    out   dx,al

@@DontSetDot:
    mov   dx,ScIndex
    mov   ax,0300h
    out   dx,ax
    mov   dx,CrtcIndex
    mov   al,11h
    out   dx,al
    inc   dx
    in    al,dx
    and   al,07fh
    out   dx,al
    dec   dx
    cld
    xor   cx,cx
    lodsb
    mov   cl,al

@@SetCRTParmsLoop:
    lodsw

    out   dx,ax
    loop  @@SetCRTParmsLoop
    mov   dx,ScIndex
    mov   ax,0f02h
    out   dx,ax
    mov   ax,ScreenSeg
    mov   es,ax
    sub   di,di
    sub   ax,ax
    mov   cx,8000h
    rep   stosw
    lodsw
    mov   ScrnPhysicalPixelWidth,ax
    mov   SplitScrnScanLine,ax
    mov   bx,ax
    shr   ax,2
    mov   ScrnPhysicalByteWidth,ax
    lodsw
    mov   ScrnPhysicalHeight,ax
    mov   cx,widthinpixels
    mov   dx,CrtcIndex
    mov   al,CRTCOFFSET
    out   dx,al
    inc   dx
    mov   ax,cx
    cmp   ax,ScrnPhysicalPixelWidth
    jge   @@ValidLogicalWidth
    mov   ax,bx

@@ValidLogicalWidth:
    shr   ax,3
    out   dx,al
    shl   ax,1
    mov   bx,ax
    mov   ScrnLogicalByteWidth,ax
    mov   RightClip,ax
    sub   ax,ScrnPhysicalByteWidth
    shl   ax,2
    mov   MaxScrollX,ax
    mov   ax,bx
    shl   ax,2
    mov   ScrnLogicalPixelWidth,ax
    mov   cx,ax
    mov   ax,0ffffh
    sub   dx,dx
    div   bx
    mov   ScrnLogicalHeight,ax
    mov   BottomClip,ax
    sub   ax,ScrnPhysicalHeight
    mov   MaxScrollY,ax
    mov   ax,cx
    mov   ax,ScrnLogicalByteWidth
    mul   ScrnPhysicalHeight
    mov   NonVisualOffs,ax

@@Done:
    mov   ax, 0CB00h
    int   10h
    ret

XSetMode ENDP

XSelectDefaultPlane PROC FAR Plane : Byte

    mov  cl,Plane
    and  cl,011b
    mov  ax,0100h + MapMask
    shl  ah,cl
    mov  dx,ScIndex
    out  dx,ax
    mov  ah,cl
    mov  al,ReadMap
    mov  dx,GcIndex
    out  dx,ax
    ret

XSelectDefaultPlane ENDP

XSetSplitscreen PROC FAR Line : Word

    xor  si,si
    cmp  DoubleBufferActive,0
    jne  @@error
    cmp  SplitScrnActive,0
    je   @@NotPreviouslyCalled

@@error:
    mov  ErrorValue,ERROR
    ret

@@NotPreviouslyCalled:
    mov  dx,InputStatus0
    in   al,dx
    mov  al,ACMODECONTROL+20h
    mov  dx,ACINDEX
    out  dx,al
    inc  dx
    in   al,dx
    or   al,20h
    dec  dx
    out  dx,al
    mov  PhysicalStartByteX,ax
    mov  PhysicalStartPixelX,ax
    mov  PhysicalStartY,ax
    mov  SplitScrnActive,1
    mov  ax,Line
    jns  @@NotNeg
    mov  ax,0

@@NotNeg:
    mov  SplitScrnScanLine,ax
    or   DoubleScanFlag,0
    jz   @@NotDoubleScanned
    shl  ax,1
    dec  ax

@@NotDoubleScanned:
    mov  bx,ax
    mov  dx,InputStatus0

@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync

@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    cli
    mov  dx,CrtcIndex
    mov  ah,bl
    mov  al,LINECOMPARE
    out  dx,ax
    mov  ah,bh
    and  ah,1
    shl  ah,4
    mov  al,Overflow
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 10h
    or   al,ah
    out  dx,al
    dec  dx
    mov  ah,bh
    and  ah,2
    ror  ah,3
    mov  al,MAXSCANLINE
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 40h
    or   al,ah
    out  dx,al
    sti
    mov  ax,ScrnPhysicalHeight
    sub  ax,SplitScrnScanLine
    mov  SplitScrnVisibleHeight,ax
    mov  bx,ScrnLogicalByteWidth
    mul  bx
    mov  Page0Offs,ax
    mov  Page1Offs,ax
    mov  Page2Offs,ax
    mov  cx,0ffffh
    sub  cx,ax
    xchg cx,ax
    sub  dx,dx
    div  bx
    mov  ScrnLogicalHeight,ax
    cmp  ax,BottomClip
    jle  @@BottomClipOK
    mov  BottomClip,ax

@@BottomClipOK:
    sub  ax,SplitScrnScanLine
    mov  MaxScrollY,ax
    xchg cx,ax
    mov  bh,al
    mov  ch,ah
    mov  bl,ADDRLOW
    mov  cl,ADDRHIGH
    and  si,0003h
    mov  ah,byte ptr PelPanMask[si]
    mov  al,PELPANNING+20h
    mov  si,ax

; VSync Handler stuff

    cmp  VSyncHandlerActive, TRUE
    jne   @@NoVsyncHandler

@@WaitLast:
    cmp   StartAddressFlag,0
    jne   @@WaitLast
    cli
    mov  WaitingStartLow,bx
    mov  WaitingStartHigh,cx
    mov  WaitingPelPan,si
    mov  StartAddressFlag,1
    sti
    jmp  short @@Return

; End VSync Handler stuff

@@NoVsyncHandler:
    mov  dx,InputStatus0

@@WaitDE:
    in   al,dx
    test al,01h
    jnz  @@WaitDE
    mov  dx,CrtcIndex
    mov  ax,bx
    cli
    out  dx,ax
    mov  ax,cx
    out  dx,ax
    sti
    mov  dx,InputStatus0

@@WaitVS:
    in   al,dx
    test al,08h
    jz @@WaitVS

    mov  dx,ACINDEX
    mov  ax,si
    cli
    out  dx,al
    mov  al,ah
    out  dx,al
    sti

@@Return:
    mov  ErrorValue,OK
    ret

XSetSplitScreen ENDP

XSetStartAddr PROC FAR X : Word, Y : Word

    mov  si,x
    mov  ax,ScrnLogicalByteWidth
    mov  cx,y
    mul  cx
    cmp  DoubleBufferActive,1
    je   @@PageResolution
    cmp  TripleBufferActive,1
    je   @@PageResolution

@@PageFlipEntry1:
    add  ax,Page0Offs
    jmp  @@AddColumn

@@PageFlipEntry2:
    mov  PhysicalStartPixelX,si
    mov  PhysicalStartY,cx

@@PageResolution:
    add  ax,VisiblePageOffs

@@AddColumn:
    mov  cx,si
    shr  cx,2
    mov  PhysicalStartByteX,cx
    add  ax,cx
    mov  bh,al
    mov  ch,ah

@@StartAddrEntry:
    mov  bl,ADDRLOW
    mov  cl,ADDRHIGH
    and  si,0003h
    mov  ah,byte ptr PelPanMask[si]
    mov  al,PELPANNING+20h
    mov  si,ax

; VSync Handler stuff

    cmp  VSyncHandlerActive, TRUE
    jne   @@NoVsyncHandler

@@WaitLast:
    cmp   StartAddressFlag,0
    jne   @@WaitLast
    cli
    mov  WaitingStartLow,bx
    mov  WaitingStartHigh,cx
    mov  WaitingPelPan,si
    mov  StartAddressFlag,1
    sti
    jmp  short @@Return

; End VSync Handler stuff

@@NoVsyncHandler:
    mov  dx,InputStatus0

@@WaitDE:
    in   al,dx
    test al,01h
    jnz  @@WaitDE
    mov  dx,CrtcIndex
    mov  ax,bx
    cli
    out  dx,ax
    mov  ax,cx
    out  dx,ax
    sti
    mov  dx,InputStatus0

@@WaitVS:
    in   al,dx
    test al,08h
    jz @@WaitVS

    mov  dx,ACINDEX
    mov  ax,si
    cli
    out  dx,al
    mov  al,ah
    out  dx,al
    sti

@@Return:
    mov  ErrorValue,OK
    ret

XSetStartAddr ENDP

XHideSplitscreen PROC FAR

    cmp  SplitScrnActive,1
    je   @@SplitScreenEnabled

@@error:
    mov  ErrorValue,ERROR
    jmp  @@Done

@@SplitScreenEnabled:
    cmp  CurrXMode,4
    jg   @@error
    mov  bx,ScrnPhysicalHeight
    mov  ax,ScrnLogicalHeight
    sub  ax,bx
    mov  MaxScrollY,ax
    xor  ax,ax
    mov  SplitScrnVisibleHeight,ax
    or   DoubleScanFlag,0
    jz   @@NotDoubleScanned
    shl  bx,1
    dec  bx

@@NotDoubleScanned:
    cmp  VSyncHandlerActive,1
    je   @@VSyncHandling
    mov  dx,InputStatus0

@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync

@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    jmp  short @@SetRegs
@@VSyncHandling:
    cmp  StartAddressFlag,0
    jne  @@VSyncHandling
    mov  StartAddressFlag,1
@@SetRegs:
    cli
    mov  dx,CrtcIndex
    mov  ah,bl
    mov  al,LINECOMPARE
    out  dx,ax
    mov  ah,bh
    and  ah,1
    shl  ah,4
    mov  al,Overflow
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 10h
    or   al,ah
    out  dx,al
    dec  dx
    mov  ah,bh
    and  ah,2
    ror  ah,3
    mov  al,MAXSCANLINE
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 40h
    or   al,ah
    out  dx,al
    sti

@@done:
    mov  ErrorValue,OK
    ret

XHideSplitScreen ENDP

XShowSplitscreen PROC FAR

    cmp  SplitScrnActive,1
    je   @@SplitScreenEnabled

@@error:
    mov  ErrorValue,ERROR
    jmp  @@Done

@@SplitScreenEnabled:
    cmp  CurrXMode,4
    jg   @@error
    mov  bx,SplitScrnScanLine
    mov  ax,ScrnLogicalHeight
    sub  ax,bx
    mov  MaxScrollY,ax
    mov  ax,ScrnPhysicalHeight
    sub  ax,bx
    mov  SplitScrnVisibleHeight,ax
    or   DoubleScanFlag,0
    jz   @@NotDoubleScanned
    shl  bx,1
    dec  bx

@@NotDoubleScanned:
    cmp  VsyncHandlerActive,1
    je   @@VSyncHandling
    mov  dx,InputStatus0

@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync

@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    jmp short @@SetRegs
@@VSyncHandling:
    cmp  StartAddressFlag,0
    jne  @@VSyncHandling
    mov  StartAddressFlag,1
@@SetRegs:
    cli
    mov  dx,CrtcIndex
    mov  ah,bl
    mov  al,LINECOMPARE
    out  dx,ax
    mov  ah,bh
    and  ah,1
    shl  ah,4
    mov  al,Overflow
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 10h
    or   al,ah
    out  dx,al
    dec  dx
    mov  ah,bh
    and  ah,2
    ror  ah,3
    mov  al,MAXSCANLINE
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 40h
    or   al,ah
    out  dx,al
    sti

@@Done:
    mov  ErrorValue,0
    ret

XShowSplitScreen ENDP

XAdjustSplitScreen PROC FAR Line : Word

    cmp  SplitScrnActive,1
    je   @@SplitScreenEnabled

@@error:
    mov  ErrorValue,ERROR
    jmp  @@Done

@@SplitScreenEnabled:
    cmp  CurrXMode,4
    jg   @@error
    mov  bx,Line
    cmp  bx,SplitScrnScanLine
    js   @@Done

@@ValidScanLine:
    mov  ax,ScrnLogicalHeight
    sub  ax,bx
    mov  MaxScrollY,ax
    mov  ax,ScrnPhysicalHeight
    sub  ax,bx
    mov  SplitScrnVisibleHeight,ax
    or   DoubleScanFlag,0
    jz   @@NotDoubleScanned
    shl  bx,1
    dec  bx

@@NotDoubleScanned:
    cmp  VsyncHandlerActive,1
    je   @@VsyncHandling

    mov  dx,InputStatus0

@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync

@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    jmp  short @@SetRegs

@@VsyncHandling:
    cmp  StartAddressFlag,0
    jne  @@VSyncHandling
    mov  StartAddressFlag,2
@@SetRegs:
    cli
    mov  dx,CrtcIndex
    mov  ah,bl
    mov  al,LINECOMPARE
    out  dx,ax
    mov  ah,bh
    and  ah,1
    shl  ah,4
    mov  al,Overflow
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 10h
    or   al,ah
    out  dx,al
    dec  dx
    mov  ah,bh
    and  ah,2
    ror  ah,3
    mov  al,MAXSCANLINE
    out  dx,al
    inc  dx
    in   al,dx
    and  al, not 40h
    or   al,ah
    out  dx,al
    sti

@@Done:
    mov  ErrorValue,OK
    ret

XAdjustSplitScreen ENDP

XSetDoubleBuffer PROC FAR PageHeight : Word

    cmp   DoubleBufferActive,0
    je    @@OkToContinue
@error:
    mov   ErrorValue,ERROR
    ret

@@OkToContinue:
    mov  VisiblePageIdx,0
    mov  ax,ScrnLogicalHeight
    shr  ax,1
    mov  bx,PageHeight
    cmp  ax,bx
    js   @@InvalidHeight
    mov  ax,bx

@@InvalidHeight:
    mov   ScrnLogicalHeight,ax
    cmp   ax,BottomClip
    jle   @@BottomClipOK
    mov   BottomClip,ax
@@BottomClipOK:
    mov   dx,ax
    mul   ScrnLogicalByteWidth
    mov   cx,ax
    mov   bx,Page0Offs
    mov   VisiblePageOffs,bx
    add   ax,bx
    mov   Page1Offs,ax
    mov   HiddenPageOffs,ax
    add   ax,cx
    mov   NonVisualOffs,ax
    mov   DoubleBufferActive,1
    mov   ax,dx
    sub   ax,ScrnPhysicalHeight
    add   ax,SplitScrnVisibleHeight
    mov   MaxScrollY,ax
    mov   ax,dx
    mov   ErrorValue,OK
    ret

XSetDoubleBuffer ENDP

XSetTripleBuffer PROC FAR PageHeight : word

    cmp   DoubleBufferActive,0
    jne   @@Error
    cmp   TripleBufferActive,0
    je    @@OkToContinue

@@Error:
    mov   ErrorValue,ERROR
    jmp @@Done

@@OkToContinue:
    mov   VisiblePageIdx,0
    mov   ax,ScrnLogicalHeight
    mov   bx,3
    xor   dx,dx
    idiv  bx
    mov   bx,PageHeight
    cmp   ax,bx
    js    @@InvalidHeight
    mov   ax,bx

@@InvalidHeight:
    mov   ScrnLogicalHeight,ax
    cmp   ax,BottomClip
    jle   @@BottomClipOK
    mov   BottomClip,ax

@@BottomClipOK:
    push  ax
    mul   ScrnLogicalByteWidth
    mov   cx,ax
    mov   bx,Page0Offs
    mov   VisiblePageOffs,bx
    add   ax,bx
    mov   Page1Offs,ax
    mov   HiddenPageOffs,ax
    add   ax,cx
    mov   Page2Offs,ax
    mov   WaitingPageOffs,ax
    add   ax,cx
    mov   NonVisualOffs,ax
    mov   TripleBufferActive,1
    pop   ax
    sub   ax,ScrnPhysicalHeight
    add   ax,SplitScrnVisibleHeight
    mov   MaxScrollY,ax
    mov   ax,dx
    mov   ErrorValue,OK

@@Done:
    ret

XSetTripleBuffer ENDP

XPageFlip PROC FAR X : Word, Y : Word

    mov  si,x
    mov  ax,ScrnLogicalByteWidth
    mov  cx,y
    mul  cx
    cmp  DoubleBufferActive,1
    je   @@DoubleBuffer
    cmp  TripleBufferActive,1
    jne  @@PageFlipEntry1
    mov  bx,HiddenPageOffs
    xchg bx,VisiblePageOffs
    xchg bx,WaitingPageOffs
    mov  HiddenPageOffs,bx
    mov  bx, VisiblePageIdx
    inc  bx
    cmp  bx,3
    jne  @@IdxOk
    xor  bx,bx
@@IdxOk:
    mov  VisiblePageIdx,bx
    jmp  @@PageFlipEntry2

@@DoubleBuffer:
    mov  bx,HiddenPageOffs
    xchg bx,VisiblePageOffs
    xchg HiddenPageOffs,bx
    xor  VisiblePageIdx,01h
    jmp  @@PageFlipEntry2

@@PageFlipEntry1:
    add  ax,Page0Offs
    jmp  @@AddColumn

@@PageFlipEntry2:
    mov  PhysicalStartPixelX,si
    mov  PhysicalStartY,cx

@@PageResolution:
    add  ax,VisiblePageOffs

@@AddColumn:
    mov  cx,si
    shr  cx,2
    mov  PhysicalStartByteX,cx
    add  ax,cx
    mov  bh,al
    mov  ch,ah

@@StartAddrEntry:
    mov  bl,ADDRLOW
    mov  cl,ADDRHIGH
    and  si,0003h
    mov  ah,byte ptr PelPanMask[si]
    mov  al,PELPANNING+20h
    mov  si,ax
; VSync Handler stuff

    cmp  VSyncHandlerActive, TRUE
    jne   @@NoVsyncHandler

@@WaitLast:
    cmp   StartAddressFlag,0
    jne   @@WaitLast
    cli
    mov  WaitingStartLow,bx
    mov  WaitingStartHigh,cx
    mov  WaitingPelPan,si
    mov  StartAddressFlag,1
    sti
    jmp  short @@Return

; End VSync Handler stuff

@@NoVsyncHandler:
    mov  dx,InputStatus0

@@WaitDE:
    in   al,dx
    test al,01h
    jnz  @@WaitDE
    mov  dx,CrtcIndex
    mov  ax,bx
    cli
    out  dx,ax
    mov  ax,cx
    out  dx,ax
    sti
    mov  dx,InputStatus0

@@WaitVS:
    in   al,dx
    test al,08h
    jz @@WaitVS

    mov  dx,ACINDEX
    mov  ax,si
    cli
    out  dx,al
    mov  al,ah
    out  dx,al
    sti

@@Return:
    mov  ErrorValue,OK
    ret

XPageFlip ENDP

XSetClipRect PROC FAR Left : Word, Top : Word, Right : Word, Bottom : Word

    mov   ax,left
    mov   bx,right
    cmp   bx,ax
    jns   @@CorrectXOrder
    xchg  bx,ax
@@CorrectXOrder:
    mov   LeftClip,ax
    mov   RightClip,bx
    mov   ax,top
    mov   bx,bottom
    cmp   bx,ax
    jns   @@CorrectYOrder
    xchg  bx,ax
@@CorrectYOrder:
    mov   TopClip,ax
    mov   BottomClip,bx
    ret

XSetClipRect ENDP

XTextMode PROC FAR

    mov   ax,03h
    int   10h
    ret

XTextMode ENDP

XWaitVSync PROC FAR

    mov   dx,InputStatus0
@@WaitNotVsync:
    in    al,dx
    test  al,08h
    jnz   @@WaitNotVsync

@@WaitVsync:
    in    al,dx
    test  al,08h
    jz    @@WaitVsync
    ret

XWaitVSync ENDP

XLine PROC FAR x1 : Word, y1 : Word, x2 : Word, y2 : Word, Color : Word,\
                             PgOffs : Word
LOCAL vertincr : Word, incr1 : Word, incr2 : Word, routine : Word

    mov ax,ScreenSeg
    mov es,ax

    mov dx,ScIndex
    mov si,ScrnLogicalByteWidth
    mov cx,x2
    sub cx,x1
    jz  @@VertLine
    jns @@L01

    neg cx

    mov bx,x2
    xchg  bx,x1
    mov x2,bx

    mov bx,y2
    xchg  bx,y1
    mov y2,bx

@@L01:
    mov bx,y2
    sub bx,y1
    jnz @@skip
    jmp @@HorizLine

@@skip:
    jns @@L03
    neg bx
    neg si

@@L03:
    mov vertincr,si
    mov routine,offset @@LoSlopeLine
    cmp bx,cx
    jle @@L04
    mov routine,offset @@HiSlopeLine
    xchg  bx,cx


@@L04:
    shl bx,1
    mov incr1,bx
    sub bx,cx
    mov si,bx
    sub bx,cx
    mov incr2,bx

    push  cx
    mov ax,y1
    mov bx,x1
    mov cl,bl
    push dx
    mov dx,ScrnLogicalByteWidth
    mul dx
    pop dx
    shr bx,2
    add bx,ax
    add bx,PgOffs
    and cl,3
    mov di,bx
    mov al,1
    shl al,cl
    mov ah,al
    shl al,4
    add ah,al
    mov bl,ah
    pop cx
    inc cx
    jmp routine

@@VertLine:
    mov ax,y1
    mov bx,y2
    mov cx,bx
    sub cx,ax
    jge @@L31
    neg cx
    mov ax,bx

@@L31:
    inc cx
    mov bx,x1
    push  cx
    mov cl,bl
    push dx
    mov dx,ScrnLogicalByteWidth
    mul dx
    pop dx
    shr bx,2
    add bx,ax
    add bx,PgOffs
    and cl,3

    mov ah,1
    shl ah,cl
    mov al,MapMask
    out dx,ax
    pop cx
    mov ax, word ptr [Color]

@@L32:
    mov es:[bx],al
    add bx,si
    loop  @@L32
    jmp @@Lexit

@@HorizLine:
    push  ds

    mov ax,y1
    mov bx,x1
    mov cl,bl
    push dx
    mov dx,ScrnLogicalByteWidth
    mul dx
    pop dx
    shr bx,2
    add bx,ax
    add bx,PgOffs
    and cl,3

    mov di,bx
    mov dl,00fh
    shl dl,cl

    mov cx,x2
    and cl,3
    mov dh,00eh
    shl dh,cl
    not dh

    mov ax,x2
    mov bx,x1

    shr ax,2
    shr bx,2
    mov cx,ax
    sub cx,bx

    mov ax,dx
    mov dx,SCINDEX
    mov bx, [Color]
    or  cx,cx
    jnz @@L42
    and ah,al
    jmp @@L44

@@L42:
    push ax
    mov ah,al
    mov al,MAPMASK
    out dx,ax
    mov al,bl
    stosb
    dec cx

@@L43:
    mov ah,0Fh
    mov al,MAPMASK
    out dx,ax
    mov al,bl
    rep stosb
    pop     ax

@@L44:
    mov al,MAPMASK
    out dx, ax
    mov     byte ptr es:[di],bl
    pop ds
    jmp @@Lexit


@@LoSlopeLine:
    mov al,MAPMASK
    mov bh,byte ptr [Color]
@@L10:
    mov ah,bl

@@L11:
    or  ah,bl
    rol bl,1
    jc  @@L14

    or  si,si
    jns @@L12
    add si,incr1
    loop  @@L11

    out dx,ax
    mov es:[di],bh
    jmp @@Lexit

@@L12:
    add si,incr2
    out dx,ax
    mov es:[di],bh
    add di,vertincr
    loop  @@L10
    jmp @@Lexit

@@L14:
    out dx,ax
    mov es:[di],bh
    inc di
    or  si,si
    jns @@L15
    add si,incr1
    loop  @@L10
    jmp @@Lexit

@@L15:
    add si,incr2
    add di,vertincr
    loop  @@L10
    jmp @@Lexit

@@HiSlopeLine:
    mov bx,vertincr
    mov al,MAPMASK
@@L21:
    out dx,ax
    push  ax
    mov ax,Color
    mov es:[di],al
    pop ax
    add di,bx

@@L22:
    or  si,si
    jns @@L23

    add si,incr1
    loop  @@L21
    jmp @@Lexit

@@L23:
    add si,incr2
    rol ah,1
    adc di,0
@@lx21: loop  @@L21


@@Lexit:
    ret

XLine ENDP

XPutPix PROC FAR X : Word, Y : Word, PgOfs : Word, Color : Word

    mov  ax,ScrnLogicalByteWidth
    mul  Y
    mov  bx,X
    shr  bx,2
    add  bx,ax
    add  bx,PgOfs
    mov  ax,SCREENSEG
    mov  es,ax

    mov  cl,byte ptr X
    and  cl,011b
    mov  ax,0100h + MAPMASK
    shl  ah,cl
    mov  dx,SCINDEX
    out  dx,ax
    mov  al,byte ptr Color
    mov  es:[bx],al
    ret

XPutPix ENDP

XGetPix PROC FAR x : Word, y : Word, PageBase : Word

    mov  ax,ScrnLogicalByteWidth
    mul  Y
    mov  bx,X
    shr  bx,1
    shr  bx,1
    add  bx,ax
    add  bx,PageBase
    mov  ax,SCREENSEG
    mov  es,ax
    mov  ah,byte ptr X
    and  ah,011b
    mov  al,READMAP
    mov  dx,GCINDEX
    out  dx,ax
    mov  al,es:[bx]
    sub  ah,ah
    ret

XGetPix ENDP

XRectFill PROC FAR StartX : Word, StartY : Word, EndX : Word, EndY : Word,\
                        PageBase : Word, Color : Word

    push bp
    cld
    mov  ax,ScrnLogicalByteWidth
    mul  StartY
    mov  di,StartX
    shr  di,1
    shr  di,1
    add  di,ax
    add  di,PageBase
    mov  ax,SCREENSEG
    mov  es,ax
    mov  dx,SCINDEX
    mov  al,MAPMASK
    out  dx,al
    inc  dx
    mov  si,StartX
    and  si,0003h
    mov  bh,byte ptr LeftClipPlaneMask[si]
    mov  si,EndX
    and  si,0003h
    mov  bl,byte ptr RightClipPlaneMask[si]
    mov  cx,EndX
    mov  si,StartX
    cmp  cx,si
    jle  @@FillDone
    dec  cx
    and  si,not 011b
    sub  cx,si
    shr  cx,1
    shr  cx,1
    jnz  @@MasksSet
    and  bh,bl

@@MasksSet:
    mov  si,EndY
    sub  si,StartY
    jle  @@FillDone
    mov  ah,byte ptr Color
    mov  bp,ScrnLogicalByteWidth
    sub  bp,cx
    dec  bp
@@FillRowsLoop:
    push cx
    mov  al,bh
    out  dx,al
    mov  al,ah
    stosb
    dec  cx
    js   @@FillLoopBottom
    jz   @@DoRightEdge
    mov  al,00fh
    out  dx,al
    mov  al,ah
    rep  stosb
@@DoRightEdge:
    mov  al,bl
    out  dx,al
    mov  al,ah
    stosb
@@FillLoopBottom:
    add  di,bp
    pop  cx
    dec  si
    jnz  @@FillRowsLoop
@@FillDone:
    pop bp
    ret

XRectFill ENDP



XRectPattern PROC FAR StartX : Word, StartY : Word, EndX : Word, EndY : Word,\
                                            PageBase : Word, Pattern : DWord
LOCAL NextScanOffset : Word, RectAddrWidth : Word, Height : word

    push ds
    cld
    mov  ax,SCREENSEG
    mov  es,ax
    lds  si,Pattern
    mov  di,PATTERNBUFFER
    mov  dx,SCINDEX
    mov  al,MAPMASK
    out  dx,al
    inc  dx
    mov  cx,4
@@DownloadPatternLoop:
    mov  al,1
    out  dx,al
    movsb
    dec  di
    mov  al,2
    out  dx,al
    movsb
    dec  di
    mov  al,4
    out  dx,al
    movsb
    dec  di
    mov  al,8
    out  dx,al
    movsb
    loop @@DownloadPatternLoop
    pop  ds

    mov  dx,GCINDEX
    mov  ax,00000h+BITMASK
    out  dx,ax

    mov  ax,StartY
    mov  si,ax
    and  si,011b
    add  si,PATTERNBUFFER

    mov  dx,ScrnLogicalByteWidth
    mul  dx
    mov  di,StartX
    mov  bx,di
    shr  di,1
    shr  di,1
    add  di,ax
    add  di,PageBase

    and  bx,0003h
    mov  ah,byte ptr LeftClipPlaneMask[bx]
    mov  bx,EndX
    and  bx,0003h
    mov  al,byte ptr RightClipPlaneMask[bx]
    mov  bx,ax

    mov  cx,EndX
    mov  ax,StartX
    cmp  cx,ax
    jle  @@FillDone
    dec  cx
    and  ax,not 011b
    sub  cx,ax
    shr  cx,1
    shr  cx,1
    jnz  @@MasksSet
    and  bh,bl

@@MasksSet:
    mov  ax,EndY
    sub  ax,StartY
    jle  @@FillDone
    mov  Height,ax
    mov  ax,ScrnLogicalByteWidth
    sub  ax,cx
    dec  ax
    mov  NextScanOffset,ax
    mov  RectAddrWidth,cx
    mov  dx,SCINDEX+1

@@FillRowsLoop:
    mov  cx,RectAddrWidth
    mov  al,es:[si]
    inc  si
    jnz  @@NoWrap
    sub  si,4
@@NoWrap:
    mov  al,bh
    out  dx,al
    stosb

    dec  cx
    js   @@FillLoopBottom
    jz   @@DoRightEdge
    mov  al,00fh
    out  dx,al
    rep  stosb

@@DoRightEdge:
    mov  al,bl
    out  dx,al
    stosb

@@FillLoopBottom:
    add  di,NextScanOffset
    dec  word ptr Height
    jnz  @@FillRowsLoop
@@FillDone:
    mov  dx,GCINDEX+1
    mov  al,0ffh
    out  dx,al
    ret

XRectPattern ENDP

XCpVidPage PROC FAR SourceOffs : Word, DestOffs : Word

LOCAL ScreenSize : Word

    push    ds
    cld
    mov     ax, ScrnLogicalByteWidth
    mov     bx, ScrnLogicalHeight
    mul     bx
    mov     ScreenSize, ax
    mov     ax, SCREENSEG
    mov     ds, ax
    mov     es, ax

@@PlaneLoop:

    mov     si, SourceOffs
    mov     di, DestOffs

    mov     ax,BITMASK
    mov     dx,GCINDEX
    out     dx,ax
    mov     dx,SCINDEX+1
    mov     al, 00fh
    out     dx, al

    mov     cx,ScreenSize

    rep     movsb

    mov     dx,GCINDEX+1
    mov     al,0ffh
    out     dx,al
    pop     ds
    ret

XCpVidPage ENDP

XCpVidRect PROC FAR SrcStartX : Word, SrcStartY : Word, SrcEndX : Word,\
                                        SrcEndY : Word, DestStartX : Word, DestStartY : Word,\
                                        SrcPageBase : Word, DestPageBase : Word,\
                                        SrcBitmapW : Word, DestBitmapW : Word
LOCAL SrcNextOffs : Word, DestNextOffs : Word, RectAddrW : Word, Height : Word

    push    ds
    cld
    mov     dx,GCINDEX
    mov     ax,BITMASK
    out     dx,ax
    mov     ax,SCREENSEG
    mov     es,ax
    mov     ax,DestBitmapW
    shr     ax,2
    mul     DestStartY
    mov     di,DestStartX
    shr     di,2
    add     di,ax
    add     di,DestPageBase
    mov     ax,SrcBitmapW
    shr     ax,2
    mul     SrcStartY
    mov     si,SrcStartX
    mov     bx,si
    shr     si,2
    add     si,ax
    add     si,SrcPageBase
    and     bx,0003h
    mov     ah,byte ptr LeftClipPlaneMask[bx]
    mov     bx,SrcEndX
    and     bx,0003h
    mov     al,byte ptr RightClipPlaneMask[bx]
    mov     bx,ax
    mov     cx,SrcEndX
    mov     ax,SrcStartX
    cmp     cx,ax
    jle     @@CopyDone
    dec     cx
    and     ax,not 011b
    sub     cx,ax
    shr     cx,2
    jnz     @@MasksSet
    and     bh,bl
@@MasksSet:
    mov     ax,SrcEndY
    sub     ax,SrcStartY
    jle     @@CopyDone
    mov     Height,ax
    mov     ax,DestBitmapW
    shr     ax,2
    sub     ax,cx
    dec     ax
    mov     DestNextOffs,ax
    mov     ax,SrcBitmapW
    shr     ax,2
    sub     ax,cx
    dec     ax
    mov     SrcNextOffs,ax
    mov     RectAddrW,cx
    mov     dx,SCINDEX+1
    mov     ax,es
    mov     ds,ax
@@CopyRowsLoop:
    mov     cx,RectAddrW
    mov     al,bh
    out     dx,al
    movsb
    dec     cx
    js      @@CopyLoopBottom
    jz      @@DoRightEdge
    mov     al,00fh
    out     dx,al
    rep     movsb
@@DoRightEdge:
    mov     al,bl
    out     dx,al
    movsb
@@CopyLoopBottom:
    add     si,SrcNextOffs
    add     di,DestNextOffs
    dec     word ptr Height
    jnz     @@CopyRowsLoop
@@CopyDone:
    mov     dx,GCINDEX+1
    mov     al,0ffh
    out     dx,al
    pop     ds
    ret

XCpVidRect ENDP

XShiftRect PROC FAR SrcLeft : Word, SrcTop : Word, SrcRight : Word,\
                                        SrcBottom : Word, DestLeft : Word, DestTop : Word,\
                                        ScreenOffs : Word
LOCAL widthtemp : Word

    push ds
    mov si, SrcLeft
    shr si, 2

    mov di, DestLeft
    shr di, 2

    mov bx, SrcRight
    add bx, 3
    shr bx, 2
    sub bx, si
    mov ax, bx
    inc bx
    mov widthtemp, bx

    cld

    cmp si, di
    jge @@MovingLeft

    add si, ax
    add di, ax
    neg bx
    std

@@MovingLeft:

    mov cx, ScrnLogicalByteWidth
    mov ax, SrcTop
    mov dx, DestTop
    cmp ax, dx
    jge @@MovingUp

    mov ax, SrcBottom
    add dx, ax
    sub dx, SrcTop
    neg cx

@@MovingUp:
    push dx
    mul ScrnLogicalByteWidth
    add si, ax
    pop ax
    mul ScrnLogicalByteWidth
    add di, ax

    sub cx, bx

    add si, ScreenOffs
    add di, ScreenOffs

    mov dx, SCINDEX
    mov ax, 00f02h
    out dx, ax

    mov dx, GCINDEX
    mov ax, BITMASK
    out dx, ax

    mov ax, SCREENSEG
    mov es, ax
    mov ds, ax

    mov ah, byte ptr widthtemp

    mov bx, SrcBottom
    sub bx, SrcTop

    mov dx, cx

    xor ch, ch

@@LineLoop:
    mov cl, ah
    rep movsb

    add si, dx
    add di, dx

    dec bx
    jge @@LineLoop

    mov dx, GCINDEX + 1
    mov al, 0ffh
    out dx, al
    pop ds
    ret

XShiftRect ENDP

XCircle PROC FAR Left : Word, Top : Word, Diameter : Word, Color : Word,\
                                 ScreenOffs : Word
LOCAL offset0 : Word, offset1 : Word, offset2 : Word, offset3 : Word,\
            offset4 : Word, offset5 : Word, offset6 : Word, offset7 : Word,\
            mask0n1 : Word, mask2n3 : Word, mask4n5 : Word, mask6n7 : Word,\
            shrunkradius : Word, diametereven : Word, Aerror : Word

    push ds
    mov di, ScrnLogicalByteWidth
    xor dx, dx
    mov ax, Diameter
    dec ax
    shr ax, 1
    adc dx, 0
    mov shrunkradius, ax
    mov diametereven, dx
    add ax, Top
    mul di
    add ax, ScreenOffs

    mov bx, Left
    mov cx, bx
    mov si, bx
    shr si, 2
    add si, ax
    mov offset6, si
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask6n7, bx

    add cx, Diameter
    dec cx
    mov bx, cx
    shr cx, 2
    add cx, ax
    mov offset2, cx
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask2n3, bx

    cmp diametereven, 1
    jne @@MiddlePlotsOverlap
    add si, di
    add cx, di
@@MiddlePlotsOverlap:
    mov offset7, si
    mov offset3, cx

    mov bx, Left
    add bx, shrunkradius

    mov ax, Top
    mul di
    add ax, ScreenOffs
    mov si, ax

    mov ax, Diameter
    dec ax
    mul di
    add ax, si

    mov di, bx
    shr di, 2
    add si, di
    mov offset4, si
    add di, ax
    mov offset5, di
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask4n5, bx

    cmp diametereven, 1
    jne @@TopAndBottomPlotsOverlap
    rol bl, 1
    jnc @@TopAndBottomPlotsOverlap
    inc si
    inc di
@@TopAndBottomPlotsOverlap:
    mov offset0, si
    mov offset1, di
    mov mask0n1, bx
    mov bx, ScrnLogicalByteWidth

    mov dx, SCREENSEG
    mov ds, dx

    mov dx, SCINDEX
    mov al, MAPMASK
    out dx, al
    inc dx

    mov si, Diameter
    inc si

    mov cx, si
    neg cx
    add cx, 2
    mov Aerror, cx

    xor cx, cx
    mov ah, byte ptr Color
    jmp @@CircleCalc

@@NoAdvance:
    mov al, byte ptr mask0n1
    out dx, al
    mov di, offset0
    mov [di], ah
    rol al, 1
    mov byte ptr mask0n1, al
    adc di, 0
    mov offset0, di
    mov di, offset1
    mov [di], ah
    ror al, 1
    adc di, 0
    mov offset1, di

    mov al, byte ptr mask2n3
    out dx, al
    mov di, offset2
    mov [di], ah
    sub di, bx
    mov offset2, di
    mov di, offset3
    mov [di], ah
    add di, bx
    mov offset3, di

    mov al, byte ptr mask4n5
    out dx, al
    mov di, offset4
    mov [di], ah
    ror al, 1
    mov byte ptr mask4n5, al
    sbb di, 0
    mov offset4, di
    mov di, offset5
    mov [di], ah
    rol al, 1
    sbb di, 0
    mov offset5, di

    mov al, byte ptr mask6n7
    out dx, al
    mov di, offset6
    mov [di], ah
    sub di, bx
    mov offset6, di
    mov di, offset7
    mov [di], ah
    add di, bx
    mov offset7, di

    jmp @@CircleCalc

@@Advance:
    mov al, byte ptr mask0n1
    out dx, al
    mov di, offset0
    mov [di], ah
    rol al, 1
    mov byte ptr mask0n1, al
    adc di, bx
    mov offset0, di
    mov di, offset1
    mov [di], ah
    ror al, 1
    adc di, 0
    sub di, bx
    mov offset1, di

    mov al, byte ptr mask2n3
    out dx, al
    mov di, offset2
    mov [di], ah
    ror al, 1
    mov byte ptr mask2n3, al
    sbb di, bx
    mov offset2, di
    mov di, offset3
    mov [di], ah
    rol al, 1
    sbb di, 0
    add di, bx
    mov offset3, di

    mov al, byte ptr mask4n5
    out dx, al
    mov di, offset4
    mov [di], ah
    ror al, 1
    mov byte ptr mask4n5, al
    sbb di, 0
    add di, bx
    mov offset4, di
    mov di, offset5
    mov [di], ah
    rol al, 1
    sbb di, bx
    mov offset5, di

    mov al, byte ptr mask6n7
    out dx, al
    mov di, offset6
    mov [di], ah
    rol al, 1
    mov byte ptr mask6n7, al
    adc di, 0
    sub di, bx
    mov offset6, di
    mov di, offset7
    mov [di], ah
    ror al, 1
    adc di, bx
    mov offset7, di

@@CircleCalc:
    add cx, 2
    mov di, Aerror
    add di, cx
    inc di
    jl @@CircleNoError
    cmp cx, si
    ja @@FleeFlyFlowFum
    sub si, 2
    sub di, si
    mov Aerror, di
    jmp @@Advance
@@CircleNoError:
    mov Aerror, di
    jmp @@NoAdvance

@@FleeFlyFlowFum:
    pop ds
    ret

XCircle ENDP

XFilledCircle PROC FAR Left : Word, Top : Word, Diameter : Word,\
                                             Color : Word, ScreenOffs : Word
LOCAL offset0 : Word, offset1 : Word, offset2 : Word, offset3 : Word,\
            offset4 : Word, offset5 : Word, offset6 : Word, offset7 : Word,\
            mask0n1 : Word, mask2n3 : Word, mask4n5 : Word, mask6n7 : Word,\
            shrunkradius : Word, diametereven : Word, Aerror : Word,\
            jumpvector : Word

    cld
    mov di, ScrnLogicalByteWidth
    xor dx, dx
    mov ax, Diameter
    dec ax
    shr ax, 1
    adc dx, 0
    mov shrunkradius, ax
    mov diametereven, dx
    add ax, Top
    mul di
    add ax, ScreenOffs

    mov bx, Left
    mov cx, bx
    mov si, bx
    shr si, 2
    add si, ax
    mov offset6, si
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask6n7, bx

    add cx, Diameter
    dec cx
    mov bx, cx
    shr cx, 2
    add cx, ax
    mov offset2, cx
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask2n3, bx

    cmp diametereven, 1
    jne @@MiddlePlotsOverlap
    add si, di
    add cx, di
@@MiddlePlotsOverlap:
    mov offset7, si
    mov offset3, cx

    mov bx, Left
    add bx, shrunkradius

    mov ax, Top
    mul di
    add ax, ScreenOffs
    mov si, ax

    mov ax, Diameter
    dec ax
    mul di
    add ax, si

    mov di, bx
    shr di, 2
    add si, di
    mov offset4, si
    add di, ax
    mov offset5, di
    and bx, 3
    mov bl, byte ptr ColumnMask[bx]
    mov mask4n5, bx

    cmp diametereven, 1
    jne @@TopAndBottomPlotsOverlap
    rol bl, 1
    jnc @@TopAndBottomPlotsOverlap
    inc si
    inc di
@@TopAndBottomPlotsOverlap:
    mov offset0, si
    mov offset1, di
    mov mask0n1, bx

    mov bx, ScrnLogicalByteWidth

    mov dx, SCREENSEG
    mov es, dx

    mov dx, SCINDEX
    mov al, MAPMASK
    out dx, al
    inc dx
    mov si, Diameter
    inc si

    mov cx, si
    neg cx
    add cx, 2
    mov Aerror, cx
    xor cx, cx
    mov ah, byte ptr Color
    jmp @@FilledCircleCalc
@@PlotLines:
    push cx

    mov di, mask0n1
    and di, 0000fh
    mov al, byte ptr RightMaskTable[di]
    mov di, offset0
    cmp di, offset4
    jne @@PlotXMajorNontrivial
    mov di, mask4n5
    and di, 0000fh
    and al, byte ptr LeftMaskTable[di]
    out dx, al
    mov di, offset4
    mov es:[di], ah
    mov di, offset5
    mov es:[di], ah
    jmp @@PlotYMajor
@@PlotXMajorNontrivial:
    out dx, al
    mov es:[di], ah
    mov di, offset1
    mov es:[di], ah

    mov di, mask4n5
    and di, 0000fh
    mov al, byte ptr LeftMaskTable[di]
    out dx, al
    mov di, offset4
    mov es:[di], ah
    mov di, offset5
    mov es:[di], ah

    mov al, 0ffh
    out dx, al
    mov al, ah
    inc di
    mov cx, offset1
    sub cx, di
    push cx
    shr cx, 1
    rep stosw
    adc cx, 0
    rep stosb

    mov di, offset4
    inc di
    pop cx
    shr cx, 1
    rep stosw
    adc cx, 0
    rep stosb

@@PlotYMajor:
    mov di, mask2n3
    and di, 0000fh
    mov al, byte ptr RightMaskTable[di]
    mov di, offset2
    cmp di, offset6
    jne @@PlotYMajorNontrivial
    mov di, mask6n7
    and di, 0000fh
    and al, byte ptr LeftMaskTable[di]
    out dx, al
    mov di, offset6
    mov es:[di], ah
    mov di, offset7
    mov es:[di], ah
    jmp @@ClimaxOfPlot
@@PlotYMajorNontrivial:
    out dx, al
    mov es:[di], ah
    mov di, offset3
    mov es:[di], ah

    mov di, mask6n7
    and di, 0000fh
    mov al, byte ptr LeftMaskTable[di]
    out dx, al
    mov di, offset6
    mov es:[di], ah
    mov di, offset7
    mov es:[di], ah

    mov al, 0ffh
    out dx, al
    mov al, ah

    inc di
    mov cx, offset3
    sub cx, di
    push cx
    shr cx, 1
    rep stosw
    adc cx, 0
    rep stosb

    mov di, offset6
    inc di
    pop cx
    shr cx, 1
    rep stosw
    adc cx, 0
    rep stosb

@@ClimaxOfPlot:
    pop cx
    jmp [jumpvector]


@@NoAdvance:
    mov al, byte ptr mask0n1
    mov di, offset0
    rol al, 1
    mov byte ptr mask0n1, al
    adc di, 0
    mov offset0, di
    mov di, offset1
    ror al, 1
    adc di, 0
    mov offset1, di

    mov al, byte ptr mask4n5
    mov di, offset4
    ror al, 1
    mov byte ptr mask4n5, al
    sbb di, 0
    mov offset4, di
    mov di, offset5
    rol al, 1
    sbb di, 0
    mov offset5, di

    mov al, byte ptr mask2n3
    mov di, offset2
    sub di, bx
    mov offset2, di
    mov di, offset3
    add di, bx
    mov offset3, di

    mov al, byte ptr mask6n7
    mov di, offset6
    sub di, bx
    mov offset6, di
    mov di, offset7
    add di, bx
    mov offset7, di

    jmp @@FilledCircleCalc

@@Advance:
    mov al, byte ptr mask0n1
    mov di, offset0
    rol al, 1
    mov byte ptr mask0n1, al
    adc di, bx
    mov offset0, di
    mov di, offset1
    ror al, 1
    adc di, 0
    sub di, bx
    mov offset1, di

    mov al, byte ptr mask2n3
    mov di, offset2
    ror al, 1
    mov byte ptr mask2n3, al
    sbb di, bx
    mov offset2, di
    mov di, offset3
    rol al, 1
    sbb di, 0
    add di, bx
    mov offset3, di

    mov al, byte ptr mask4n5
    mov di, offset4
    ror al, 1
    mov byte ptr mask4n5, al
    sbb di, 0
    add di, bx
    mov offset4, di
    mov di, offset5
    rol al, 1
    sbb di, bx
    mov offset5, di

    mov al, byte ptr mask6n7
    mov di, offset6
    rol al, 1
    mov byte ptr mask6n7, al
    adc di, 0
    sub di, bx
    mov offset6, di
    mov di, offset7
    ror al, 1
    adc di, bx
    mov offset7, di

@@FilledCircleCalc:
    add cx, 2
    mov di, Aerror
    add di, cx
    inc di
    jl @@FilledCircleNoError
    cmp cx, si
    ja @@FleeFlyFlowFum
    sub si, 2
    sub di, si
    mov Aerror, di
    mov jumpvector, offset @@Advance
    jmp @@PlotLines
@@FilledCircleNoError:
    mov Aerror, di
    mov jumpvector, offset @@NoAdvance
    jmp @@PlotLines

@@FleeFlyFlowFum:
    ret

XFilledCircle ENDP

XGetPalStruc PROC FAR PalBuff : DWord, NumColors : Word, StartColor : Word

    cld
    les  di,PalBuff
    mov  si,StartColor
    mov  ax,si
    stosb
    mov  dx,NumColors
    mov  al,dl
    stosb
    mov  cx,dx
    cld
    cmp  VSyncHandlerActive,1
    je   @@HandleVVH
    mov  dx,INPUTSTATUS0
@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync
@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    jmp  short @@SkipVSync
@@HandleVVH:
    cmp  StartAddressFlag,0
    jne  @@HandleVVH
@@SkipVSync:
    mov  ax, si
    mov  dx, DACREADINDEX
    cli
    out  dx, al
    mov  dx, DACDATA
    mov  bx, cx
    shl  bx, 1
    add  cx, bx
    rep  insb
    sti
    ret

XGetPalStruc ENDP

XGetPalRaw PROC FAR PalBuff : DWord, NumColors : Word, StartColor : Word

    les  di,PalBuff
    mov  si,StartColor
    mov  cx,NumColors
@@ReadPalEntry:
    cld
    cmp  VSyncHandlerActive,1
    je   @@HandleVVH
    mov  dx,INPUTSTATUS0
@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync
@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    jmp  short @@SkipVSync
@@HandleVVH:
    cmp  StartAddressFlag,0
    jne  @@HandleVVH
@@SkipVSync:

    mov  ax,si
    mov  dx,DACREADINDEX
    cli
    out  dx,al
    mov  dx,DACDATA
    mov  bx,cx
    shl  bx,1
    add  cx,bx
    rep  insb
    sti
    ret

XGetPalRaw ENDP


XPutPalStruc PROC FAR CompPalBuff : DWord

    push ds
    cld
    lds  si,CompPalBuff
    lodsb
    mov  ah,0
    mov  bx,ax
    lodsb
    mov  ah,0
    mov  cx,ax

    mov  ax, @data
    mov  es, ax
    cmp  es:[VSyncHandlerActive], TRUE
    jne  @@NoVSyncHandler

@@WaitForLast:
    cmp  es:[VsyncPaletteCount],0
    jne  @@WaitForLast
    push cx
    push es
    mov  di, offset VsyncPaletteBuffer
    mov  ax,3
    mul  cx
    mov  cx,ax
    rep  movsb
    pop  ds
    pop  cx
    mov  VsyncPaletteStart,bx
    mov  VsyncPaletteCount,cx
    jmp  short @@Done

@@NoVsyncHandler:
    or   cx,cx
    jz   @@Done
    ;cli
    cld
    mov  dx,INPUTSTATUS0
@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync
@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync

    ;new stuff
    mov  ax,3
    mul  cx
    mov  cx,ax
    ;end new stuff

    mov  ax,bx
    mov  bx,60
@@SetLoop:
    mov  dx,DACWRITEINDEX
    out  dx,al
    mov  dx,DACDATA

    rep outsb

;    outsb
;    outsb
;    outsb
;    inc  al
;    dec  bx
;    js   @@testvsync
;    loop @@SetLoop
    jmp  @@Done
@@testvsync:
    mov     dx,INPUTSTATUS0
    push    ax
@@Wait:
    in      al,dx
    test    al,08h
    jz      @@Wait
    pop     ax
    mov     bx,60
    loop @@SetLoop
@@Done:
    sti
    pop  ds
    ret

XPutPalStruc ENDP

XTransposePalStruc PROC FAR CompPalBuff : DWord, StartColor : Word

    push ds
    cld
    lds  si,CompPalBuff
    mov  bx,StartColor
    mov  [si],bl
    inc  si
    lodsb
    mov  ah,0
    mov cx,ax

    mov  ax, @data
    mov  es, ax
    cmp  es:[VSyncHandlerActive], TRUE
    jne  @@NoVSyncHandler

@@WaitForLast:
    cmp  es:[VsyncPaletteCount],0
    jne  @@WaitForLast
    push cx
    push es
    mov  di, offset VsyncPaletteBuffer
    mov  ax,3
    mul  cx
    mov  cx,ax
    rep  movsb
    pop  ds
    pop  cx
    mov  VsyncPaletteStart,bx
    mov  VsyncPaletteCount,cx
    jmp  short @@Done

@@NoVsyncHandler:
    or   cx,cx
    jz   @@Done
    ;cli
    cld
    mov  dx,INPUTSTATUS0
@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync
@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync
    mov  ax,bx
    mov  bx,60
@@SetLoop:
    mov  dx,DACWRITEINDEX
    out  dx,al
    mov  dx,DACDATA
    outsb
    outsb
    outsb
    inc  al
;    dec  bx
;    js   @@testvsync
    loop @@SetLoop
    jmp  @@Done
@@testvsync:
    mov     dx,INPUTSTATUS0
    push    ax
@@Wait:
    in      al,dx
    test    al,08h
    jz      @@Wait
    pop     ax
    mov     bx,60
    loop @@SetLoop
@@Done:
    sti
    pop  ds
    ret

XTransposePalStruc ENDP


XPutPalRaw PROC FAR PalBuff : DWord, NumColors : Word, StartColor : Word

    push ds
    mov  cx,NumColors
    mov  bx,StartColor
    lds  si,PalBuff

@@WritePalEntry:
    mov  ax, @data
    mov  es, ax
    cmp  es:[VSyncHandlerActive], TRUE
    jne  @@NoVSyncHandler

@@WaitForLast:
    cmp  es:[VsyncPaletteCount],0
    jne  @@WaitForLast
    push cx
    push es
    mov  di, offset VsyncPaletteBuffer
    mov  ax,3
    mul  cx
    mov  cx,ax
    rep  movsb
    pop  ds
    pop  cx
    mov  VsyncPaletteStart,bx
    mov  VsyncPaletteCount,cx
    jmp  short @@Done

@@NoVsyncHandler:
    or   cx,cx
    jz   @@Done
    cld
    mov  dx,INPUTSTATUS0
@@WaitNotVsync:
    in   al,dx
    test al,08h
    jnz  @@WaitNotVsync
@@WaitVsync:
    in   al,dx
    test al,08h
    jz   @@WaitVsync

    ;new stuff
    mov  ax,3
    mul  cx
    mov  cx,ax
    ;end new stuff

    mov  ax,bx
    mov  bx,60
@@SetLoop:
    mov  dx,DACWRITEINDEX
    out  dx,al
    mov  dx,DACDATA

    rep outsb

;    outsb
;    outsb
;    outsb
;    inc  al
;    dec  bx
;    js   @@testvsync
;    loop @@SetLoop
    jmp  @@Done
@@testvsync:
    mov     dx,INPUTSTATUS0
    push    ax
@@Wait:
    in      al,dx
    test    al,08h
    jz      @@Wait
    pop     ax
    mov     bx,60
    loop @@SetLoop
@@Done:
    pop  ds
    ret

XPutPalRaw ENDP


XSetRGB PROC FAR ColorIndex : Byte, R : Byte, G : Byte, B : Byte

    mov  al,ColorIndex
    mov  dx,DACWRITEINDEX
    out  dx,al
    mov  dx,DACDATA
    mov  al,R
    out  dx,al
    mov  al,G
    out  dx,al
    mov  al,B
    out  dx,al
    ret

XSetRGB ENDP

XRotPalStruc PROC FAR PalBuff : DWord, Direction : Word

    push ds
    cld
    lds  si,PalBuff
    lodsw
    xor  ch,ch
    mov  cl,ah
    mov  ax,ds
    mov  es,ax
    dec  cx
    mov  bx,cx
    shl  bx,1
    add  cx,bx
    cmp  Direction,0
    jne  @@forward
    std
    add  si,cx
    add  si,2
@@forward:
    mov  ax,si
    mov  di,ax
    lodsb
    mov  dl,al
    lodsb
    mov  dh,al
    lodsb
    mov  bl,al
    rep  movsb
    mov  al,dl
    stosb
    mov  al,dh
    stosb
    mov  al,bl
    stosb
    pop  ds
    ret

XRotPalStruc ENDP

XRotPalRaw PROC FAR PalBuff : DWord, Direction : Word, NumColors : Word

    push ds
    cld
    mov  cx,NumColors
    lds  si,PalBuff
@@RotatePalEntry:
    mov  ax,ds
    mov  es,ax
    dec  cx
    mov  bx,cx
    shl  bx,1
    add  cx,bx
    cmp  Direction,0
    jne  @@forward
    std
    add  si,cx
    add  si,2
@@forward:
    mov  ax,si
    mov  di,ax
    lodsb
    mov  dl,al
    lodsb
    mov  dh,al
    lodsb
    mov  bl,al
    rep  movsb
    mov  al,dl
    stosb
    mov  al,dh
    stosb
    mov  al,bl
    stosb
    pop  ds
    ret

XRotPalRaw ENDP

XCpContrastPalStruc PROC FAR PalSrcBuff : DWord, PalDestBuff : DWord,\
                                                         Intensity : Byte

    push ds
    cld
    mov  bh,0ffh
    sub  bh,Intensity
    and  bh,07fh
    lds  si,PalSrcBuff
    les  di,PalDestBuff
    lodsw
    stosw
    xor  ch,ch
    mov  cl,ah
    mov  dx,0
@@MainLoop:
    lodsw
    sub  al,bh
    jns  @@DecrementOKR
    xor  al,al
@@DecrementOKR:
    sub  ah,bh
    jns  @@DecrementOKG
    xor  ah,ah
@@DecrementOKG:
    or   dx,ax
    or   dl,ah
    stosw
    lodsb
    sub  al,bh
    jns  @@DecrementOKB
    xor  al,al
@@DecrementOKB:
    or   dl,al
    stosb
    loop @@MainLoop
    mov  ax,dx
    pop  ds
    ret

XCpContrastPalStruc ENDP


XPutContrastPalStruc PROC FAR CompPalBuff : DWord, Intensity : Byte

    push    ds
    cld
    mov     bh,0ffh
    sub     bh,Intensity
    and     bh,07fh
    mov     di,40
    lds     si,CompPalBuff
    lodsb
    mov     bl,al
    lodsb
    mov     ah,0
    mov     cx,ax
    or      cx,cx
    jz      @@Done

    mov     dx,INPUTSTATUS0
@@WaitNotVsync:
    in      al,dx
    test    al,08h
    jnz     @@WaitNotVsync
@@WaitVsync:
    in      al,dx
    test    al,08h
    jz      @@WaitVsync

@@MainLoop:
    mov  al,bl
    mov  dx,DACWRITEINDEX
    out  dx,al
    inc  dx
    lodsb
    sub  al,bh
    jns  @@DecrementOKR
    xor  al,al
@@DecrementOKR:
    out  dx,al

    lodsb
    sub  al,bh
    jns  @@DecrementOKG
    xor  al,al
@@DecrementOKG:
    out  dx,al

    lodsb
    sub  al,bh
    jns  @@DecrementOKB
    xor  al,al
@@DecrementOKB:
    out  dx,al

    inc  bl
    dec  di
    js   @@testvsync
    loop @@MainLoop
    jmp  @@Done


@@testvsync:
    mov     dx,INPUTSTATUS0
    push    ax
@@Wait:
    in      al,dx
    test    al,08h
    jz      @@Wait
    pop     ax
    mov     di,40
    loop    @@MainLoop
@@Done:
    ;sti
    pop  ds
    ret

XPutContrastPalStruc ENDP

XTextInit PROC FAR

    push bp
    mov  FontDriverActive,1
    mov  ax,1130h
    push ax
    mov  bh,3
    int  10h
    mov  word ptr F8x8Ptr,bp
IFDEF _DPMI_
    mov  ax, __C000H
    mov  es, ax
ENDIF
    mov  word ptr F8x8Ptr+2,es

    mov  word ptr FontPtr,bp
    mov  word ptr FontPtr+2,es

    pop  ax
    mov  bh,2
    int  10h
    mov  word ptr F8x14Ptr,bp
IFDEF _DPMI_
    mov  ax, __C000H
    mov  es, ax
ENDIF
    mov  word ptr F8x14Ptr+2,es


    mov  al,8
    mov  CharHeight,al
    mov  CharWidth ,al

    mov  dx,offset MirrorTable
    mov  MirrorTableOffs,dx
    pop  bp
    ret

XTextInit ENDP


XSetFont PROC FAR FontID : Word

    xor  dx,dx
    mov  cx,FontID
    cmp  cx,2

    jne  @@notuserfont
    mov  ax,word ptr UserFontPtr
    mov  word ptr FontPtr,ax

    mov  ax,word ptr UserFontPtr+2
    mov  word ptr FontPtr+2,ax

    mov  al,UserChHeight
    mov  CharHeight,al

    mov  al,UserChWidth
    mov  CharWidth,al

    mov  al,UserFirstCh
    mov  FirstChar,al
    jmp  @@done

@@notuserfont:

    mov  dx,offset MirrorTable
    mov  CharWidth,8
    mov  FirstChar,0
    cmp  cx,1
    jne  @@not8x14font

    mov  ax,word ptr F8x14Ptr
    mov  word ptr FontPtr,ax

    mov  ax,word ptr F8x14Ptr+2
    mov  word ptr FontPtr+2,ax

    mov  CharHeight,14
    jmp  @@done

@@not8x14font:
    mov  ax,word ptr F8x8Ptr
    mov  word ptr FontPtr,ax

    mov  ax,word ptr F8x8Ptr+2
    mov  word ptr FontPtr+2,ax

    mov  CharHeight,8

@@done:
    mov  MirrorTableOffs,dx
    ret

XSetFont ENDP

XRegisterUserFont PROC FAR FontToRegister : DWord

    mov  ax,word ptr FontToRegister
    mov  bx,word ptr FontToRegister+2
    add  ax,4
    mov  word ptr UserFontPtr,ax
    mov  word ptr UserFontPtr+2,bx

    push ds
    lds  si,FontToRegister
    lodsw
    mov  bx,ax
    lodsw
    pop  ds
    mov  UserChHeight,al
    mov  UserChWidth,ah
    mov  UserFirstCh,bl
    ret

XRegisterUserFont ENDP

XGetCharWidth PROC FAR ACh : Byte

    xor  ah,ah
    mov  al,CharWidth
    or   al,al
    jz   @@NotFixed
    jmp  @@Done

@@NotFixed:
    push si
    mov  al,CharHeight
    mov  bx,ax
    inc  al
    mov  dl, ACh
    sub  dl,FirstChar
    mul  dl
    add  ax,bx
    les  si,dword ptr FontPtr
    add  si,ax
    xor  ah,ah
    mov  al,byte ptr es:[si]
@@Done:
    ret

XGetCharWidth ENDP

XCharPut PROC FAR Chr : Byte, X : Word, Y : Word, ScrnOffs : Word, Color : Word
LOCAL ScreenInc : Word, Hold : Word

    push ds
    cld
    mov  ax,ScrnLogicalByteWidth
    mov  bx,ax
    sub  bx,3
    mov  ScreenInc,bx
    mul  Y
    mov  di,X
    mov  cx,di
    shr  di,2
    add  di,ax
    add  di,ScrnOffs

    mov  ax,SCREENSEG
    mov  es,ax

    and  cx,3

    mov  bx,MirrorTableOffs
    mov  al,CharHeight
    xor  ah,ah
    mov  ch,al

    cmp  CharWidth,0
    jne  @@NoWidthByte
    inc  al

@@NoWidthByte:
    mov  dl,Chr
    sub  dl,FirstChar
    mul  dl
    lds  si,dword ptr FontPtr
    add  si,ax

    mov  dx,SCINDEX

@@MainLoop:

    lodsb
    or   al,al
    jz   @@NoCharPixels

    or   bx,bx
    jz   @@DontMirror
    push ds
    mov  dx,seg @data
    mov  ds,dx
    xlat
    pop  ds
    mov  dx,SCINDEX

@@DontMirror:
    xor  ah,ah
    shl  ax,cl
    mov  Hold,ax

    mov  ah,al
    and  ah,0fh
    jnz  @@p1
    inc  di
    jmp  @@SecondNibble

@@p1:
    mov  al,MAPMASK
    out  dx,ax
    mov  al,byte ptr Color
    stosb

@@SecondNibble:
    mov  ax,Hold
    shl  ax,4
    and  ah,0fh
    jnz  @@p2
    inc  di
    jmp  @@ThirdNibble

@@p2:
    mov  al,MAPMASK
    out  dx,ax
    mov  al,byte ptr Color
    stosb

@@ThirdNibble:
    mov  ax,Hold
    and  ah,0fh
    jnz  @@p3
    inc  di
    jmp  @@NextCharRow

@@p3:
    mov  al,MAPMASK
    out  dx,ax
    mov  al,byte ptr Color
    stosb

@@NextCharRow:
    add  di,ScreenInc
    dec  ch
    jnz  @@MainLoop

@@done:
    pop  es
    mov  ah,0
    mov  al,es:CharWidth
    or   al,al
    jnz  @@FixedSpacing
    lodsb
@@FixedSpacing:

    mov  bx,es
    mov  ds,bx
    jmp @@TheEnd


@@NoCharPixels:
    add  di,3
    add  di,ScreenInc
    dec  ch
    jnz  @@MainLoop
    jmp  @@done

@@TheEnd:
    ret
XCharPut ENDP

HLineClipR PROC NEAR

    push    di
    cmp     dx,ax
    jl      @@Invisible

    cmp     cx,TopClip
    jl      @@Invisible

    cmp     cx,BottomClip
    jg      @@Invisible

    mov     di,RightClip
    sal     di,2
    cmp     ax,di
    jg      @@Invisible
    cmp     dx,di
    jle     @@ClipLeft
    mov     dx,di

@@ClipLeft:
    mov     di,LeftClip
    sal     di,2
    cmp     dx,di
    jl      @@Invisible
    cmp     ax,di
    jge     @@DoLine
    mov     ax,di
    jmp     @@DoLine

@@Invisible:
    pop     di
    ret

@@DoLine:
    pop     di
    xchg    cx,ax
    mov     si,dx
    mul     ScrnLogicalByteWidth
    mov     dx,si
    add     ax,di
    mov     di,cx
    sar     di,2
    add     di,ax
    and     si,03h
    mov     ah,byte ptr RightClipPlaneMask[si]
    mov     si,cx
    and     si,03h
    mov     al,byte ptr LeftClipPlaneMask[si]
    cmp     dx,cx
    jle     @@Invisible2
    xchg    cx,dx
    dec     cx
    and     dx,not 03h
    sub     cx,dx
    js      @@Invisible2
    shr     cx,2
    jnz     @@MasksSet
    and     al,ah
@@MasksSet:
    mov     dl,bl
    mov     bx,ax
    mov     ah,dl
    mov     dx,SCINDEX+1
    mov     al,bl
    out     dx,al
    mov     al,ah
    stosb
    dec     cx
    js      @@Invisible2
    jz      @@RightEnd
    mov     al,0fh
    out     dx,al
    mov     al,ah
    shr     cx,1
    rep     stosw
    adc     cx,cx
    rep     stosb

@@RightEnd:
    mov     al,bh
    out     dx,al
    mov     al,ah
    stosb
@@Invisible2:
    ret

HLineClipR ENDP

XTriangle PROC FAR X0, Y0, X1, Y1, X2, Y2, Color, PageOffset : Word
LOCAL DX01, DY01, DX02, DY02, DX12, DY12, DP01, DP02, DP12, XA01, XA02, XA12 : Word

    push    di
    push    es
    push    ds
    mov     ax,X0
    mov     bx,Y0
    mov     cx,X1
    mov     dx,Y1
    cmp     bx,dx
    jl      @@triY0lY1
    je      @@triY0eY1
    xchg    ax,cx
    xchg    bx,dx

@@triY0lY1:
    cmp     dx,Y2
    jg      @@tria
    jmp     @@trisorted
@@tria:
    xchg    cx,X2
    xchg    dx,Y2
    cmp     bx,dx
    jge     @@trib
    jmp     @@trisorted
@@trib:
    je      @@tribot
    xchg    ax,cx
    xchg    bx,dx
    jmp     @@trisorted
@@triY0eY1:
    cmp     bx,Y2
    jl      @@tribot
    jg      @@tric
    jmp     @@tridone
@@tric:
    xchg    ax,X2
    xchg    bx,Y2
    jmp     @@trisorted

@@tribot:
    cmp     ax,cx
    jl      @@tribotsorted
    jg      @@tribota
    jmp     @@tridone
@@tribota:
    xchg    ax,cx
@@tribotsorted:
    cmp     bx,BottomClip
    jle     @@triboty0ok
    jmp     @@tridone
@@triboty0ok:
    mov     si,Y2
    cmp     si,TopClip
    jge     @@triboty2ok
    jmp     @@tridone
@@triboty2ok:
    mov     X0,ax
    mov     Y0,bx
    mov     X1,cx
    mov     Y1,dx

    mov     bx,Y2
    sub     bx,Y0
    mov     DY02,bx
    mov     ax,X2
    sub     ax,X0
    mov     DX02,ax
    mov     cx,ax
    cwd
    idiv    bx
    cmp     cx,0
    jge     @@tribot02
    dec     ax
@@tribot02:
    mov     XA02,ax
    imul    bx
    sub     cx,ax
    mov     DP02,cx

    mov     bx,Y2
    sub     bx,Y1
    mov     DY12,bx
    mov     ax,X2
    sub     ax,X1
    mov     DX12,ax
    mov     cx,ax
    cwd
    idiv    bx
    cmp     cx,0
    jge     @@tribot12
    dec     ax
@@tribot12:
    mov     XA12,ax
    imul    bx
    sub     cx,ax
    mov     DP12,cx

    mov     ax,0
    mov     bx,0
    mov     cx,Y0
    mov     si,X0
    mov     di,X1
    dec     di
@@tribotloop:
    inc     cx

    add     ax,DP02
    jle     @@tribotshortl
    sub     ax,DY02
    inc     si
@@tribotshortl:
    add     si,XA02

    add     bx,DP12
    jle     @@tribotshortr
    sub     bx,DY12
    inc     di
@@tribotshortr:
    add     di,XA12

    push    di
    push    si
    cmp     cx,Y2
    jl      @@tribotloop

    jmp     @@tridrawlines


@@trisorted:
    cmp     bx,BottomClip
    jle     @@triy0ok
    jmp     @@tridone
@@triy0ok:
    mov     si,Y2
    cmp     si,TopClip
    jge     @@triy2ok
    jmp     @@tridone
@@triy2ok:
    mov     X0,ax
    mov     Y0,bx
    mov     X1,cx
    mov     Y1,dx

    mov     bx,dx
    sub     bx,Y0
    mov     DY01,bx
    mov     ax,X1
    sub     ax,X0
    mov     DX01,ax
    mov     cx,ax
    cwd
    idiv    bx
    cmp     cx,0
    jge     @@tripsl01
    dec     ax
@@tripsl01:
    mov     XA01,ax
    imul    bx
    sub     cx,ax
    mov     DP01,cx

    mov     bx,Y2
    sub     bx,Y0
    mov     DY02,bx
    mov     ax,X2
    sub     ax,X0
    mov     DX02,ax
    mov     cx,ax
    cwd
    idiv    bx
    cmp     cx,0
    jge     @@tripsl02
    dec     ax
@@tripsl02:
    mov     XA02,ax
    imul    bx
    sub     cx,ax
    mov     DP02,cx

    mov     bx,Y2
    sub     bx,Y1
    jle     @@triconstcomputed
    mov     DY12,bx
    mov     ax,X2
    sub     ax,X1
    mov     DX12,ax
    mov     cx,ax
    cwd
    idiv    bx
    cmp     cx,0
    jge     @@tripsl12
    dec     ax
@@tripsl12:
    mov     XA12,ax
    imul    bx
    sub     cx,ax
    mov     DP12,cx

@@triconstcomputed:
    mov     ax,DX01
    imul    word ptr DY02
    mov     bx,ax
    mov     cx,dx

    mov     ax,DX02
    imul    word ptr DY01
    cmp     cx,dx
    jg      @@tript1rt
    jl      @@tript1lt
    cmp     bx,ax
    ja      @@tript1rt
    jb      @@tript1lt
    jmp     @@tridone

@@tript1lt:
    mov     ax,0
    mov     bx,0
    mov     cx,Y0
    mov     si,X0
    mov     di,si
    dec     si
@@triltloop:
    inc     cx

    add     ax,DP02
    jle     @@triltshortl
    sub     ax,DY02
    inc     si
@@triltshortl:
    add     si,XA02
    add     bx,DP01
    jle     @@triltshortr
    sub     bx,DY01
    inc     di
@@triltshortr:
    add     di,XA01
    push    si
    push    di
    cmp     cx,Y1
    jl      @@triltloop
    jmp     @@trilbstart
@@trilbloop:
    inc     cx
    add     ax,DP02
    jle     @@trilbshortl
    sub     ax,DY02
    inc     si
@@trilbshortl:
    add     si,XA02

    add     bx,DP12
    jle     @@trilbshortr
    sub     bx,DY12
    inc     di
@@trilbshortr:
    add     di,XA12

    push    si
    push    di
@@trilbstart:
    cmp     cx,Y2
    jl      @@trilbloop
    jmp     @@tridrawlines

@@tript1rt:
    mov     ax,0
    mov     bx,0
    mov     cx,Y0
    mov     si,X0
    mov     di,si
    dec     di
@@trirtloop:
    inc     cx

    add     ax,DP02
    jle     @@trirtshortl
    sub     ax,DY02
    inc     si
@@trirtshortl:
    add     si,XA02

    add     bx,DP01
    jle     @@trirtshortr
    sub     bx,DY01
    inc     di
@@trirtshortr:
    add     di,XA01

    push    di
    push    si
    cmp     cx,Y1
    jl      @@trirtloop
    jmp     @@trirbstart

@@trirbloop:
    inc     cx
    add     ax,DP02
    jle     @@trirbshortl
    sub     ax,DY02
    inc     si
@@trirbshortl:
    add     si,XA02

    add     bx,DP12
    jle     @@trirbshorts
    sub     bx,DY12
    inc     di
@@trirbshorts:
    add     di,XA12

    push    di
    push    si
@@trirbstart:
    cmp     cx,Y2
    jl      @@trirbloop

@@tridrawlines:
    mov     cx,SCREENSEG
    mov     es,cx
    mov     dx,SCINDEX
    mov     al,MAPMASK
    out     dx,al

@@lineloop:
    pop     ax
    pop     dx
    cmp     ax,dx
    jg      @@tridrawnext
    mov     bx,Color
    mov     cx,Y2
    add     dx,2
    mov     di,PageOffset
    call    HLineClipR
@@tridrawnext:
    dec     word ptr Y2
    dec     word ptr DY02
    jnz     @@lineloop

@@tridone:
    pop     ds
    pop     es
    pop     di
    ret

XTriangle ENDP

XPolygon PROC FAR vertices : DWord, numvertices : Word, Color : Word,\
                                    PageOffset : Word
LOCAL x0 : Word, y0 : Word, tricount : Word

    mov   cx,numvertices
    cmp   cx,3
    jl    @@Done
    sub   cx,3
    mov   tricount,cx
    les   di,vertices
    mov   ax,es:[di]
    mov   x0,ax
    mov   ax,es:[di+2]
    mov   y0,ax

@@NextTriangle:
    add   di, 4
    mov   ax, x0
    push  ax
    mov   ax, y0
    push  ax
    mov   ax, es:[di+4]
    push  ax
    mov   ax, es:[di+6]
    push  ax
    mov   ax,es:[di]
    push  ax
    mov   ax,es:[di+2]
    push  ax
    mov   ax, color
    push  ax
    mov   ax, pageoffset
    push  ax
    call  xtriangle
    dec   tricount
    jns   @@NextTriangle
@@Done:
    ret

XPolygon ENDP

XPutCursor PROC FAR X : Word, Y : Word, ATopClip : Word, ABottomClip : Word,\
                                        ScrnOffs : Word
LOCAL Height : Word, TopRow : Word, NextLineIncr : Word

    push  si
    push  di
    push  ds
    mov   ax,seg @data
    mov   ds,ax
    cld
    mov   ax,14
    mov   bx,Y
    mov   dx,ATopClip
    sub   dx,bx
    jle   @@NotTopClip
    cmp   dx,ax
    jnl   @@NotVisible
    mov   cx,dx
    sub   ax,dx
    add   bx,dx
    jmp   @@VertClipDone

@@NotVisible:
    pop   ds
    pop   di
    pop   si
    jmp   @@Done

@@NotTopClip:
    mov   dx,ABottomClip
    sub   dx,bx
    js    @@NotVisible
    mov   cx,0
    cmp   dx,ax
    jg    @@VertClipDone
    inc   dx
    mov   ax,dx

@@VertClipDone:
    mov   Height,ax
    mov   TopRow,cx
    mov   ax,SCREENSEG
    mov   es,ax
    mov   ax,bx
    mov   cx,ScrnLogicalByteWidth
    mul   cx
    mov   di,ax
    sub   cx,3
    mov   NextLineIncr,cx
    mov   cx,X
    mov   bx,cx
    shr   cx,2
    add   di,cx
    and   bx,3
    add   di,ScrnOffs
    mov   ax,42
    mul   bx
    mov   si,offset MouseMask
    add   si,ax
    mov   ax,3
    mul   TopRow
    add   si,ax
    mov   dx,SCINDEX
    mov   al,MAPMASK
    out   dx,al
    inc   dx
    mov   ah,byte ptr Height
    mov   bl,MouseColor

@@RowLoop:
    mov   cx,3

@@ColLoop:
    lodsb
    out   dx,al
    mov   es:[di],bl
    inc   di
    loop  @@ColLoop

    add   di,NextLineIncr
    dec   ah
    jnz   @@RowLoop

    pop   ds
    pop   di
    pop   si

@@Done:
    ret

ENDP

GetBG PROC NEAR

    push  ds
    cld
    mov   cx,ScrnLogicalByteWidth
    mul   cx
    add   si,ax
    sub   cx,3
    shr   bx,2
    add   si,bx
    mov   bx,cx
    mov   di,BGSaveOffs
    mov   ax,SCREENSEG
    mov   es,ax
    mov   ds,ax
    mov   dx,GCINDEX
    mov   ax,BITMASK
    out   dx,ax
    mov   dx,SCINDEX
    mov   al,MAPMASK
    out   dx,al
    inc   dx
    mov   al,0fh
    out   dx,al
    mov   cx,14
@@Loop:
    movsb
    movsb
    movsb
    add si,bx
    loop @@Loop
    mov  dx,GCINDEX+1
    mov  al,0ffh
    out  dx,al
    pop  ds
    ret

GetBg ENDP

RestoreBG PROC NEAR

    push  ds
    cld
    mov   cx,ScrnLogicalByteWidth
    mul   cx
    add   di,ax
    sub   cx,3
    shr   bx,2
    add   di,bx
    mov   si,BGSaveOffs
    mov   ax,SCREENSEG
    mov   es,ax
    mov   ds,ax
    mov   dx,GCINDEX
    mov   ax,BITMASK
    out   dx,ax
    mov   dx,SCINDEX
    mov   al,MAPMASK
    out   dx,al
    inc   dx
    mov   al,0fh
    out   dx,al
    mov   bx,cx
    mov   cx,14
@@Loop:
    movsb
    movsb
    movsb
    add di,bx
    loop @@Loop
    mov  dx,GCINDEX+1
    mov  al,0ffh
    out  dx,al
    pop   ds
    ret

RestoreBg ENDP

UpdateCursor PROC FAR
    cmp VSyncHandlerActive,1
    je  @@SkipVS
    mov dx,InputStatus0
@@WaitNotVsync:
    in  al,dx
    test al,08h
    jnz @@WaitNotVSync
@@WaitVSync:
    in  al,dx
    test al,08h
    jz  @@WaitVSync
@@SkipVS:
    mov di,OldScrnOffs
    mov ax,OldY
    mov bx,OldX
    call restorebg
    mov si,VisiblePageOffs
    mov ax,MouseY
    mov bx,MouseX
    mov OldScrnOffs,si
    mov OldY,ax
    mov OldX,bx
    call getbg
    push OldX
    push OldY
    mov  ax,0
    push ax
    mov  ax,ScrnPhysicalHeight
    push ax
    push VisiblePageOffs
    call xputcursor
    ret

UpdateCursor ENDP

MouseHandler PROC FAR

    push  ds
    mov   di,seg @data
    mov   ds,di
    cmp   inhandler,1
    jne   @@NotActive
    jmp   @@Done2
@@NotActive:
    mov   inhandler,1
    mov   MouseButtonStatus,bx
    test  ax,1
    jz    @@Done
    shr   cx,1
    mov   MouseX,cx
    mov   MouseY,dx
    cmp   MouseHidden,1
    je    @@Done
    cmp   MouseFrozen,1
    je    @@Done
    cmp   VSyncHandlerActive,1
    je    @@VSyncHandle
    call  updatecursor
    jmp   short @@Done
@@VSyncHandle:
    mov   MouseRefreshFlag,1
@@Done:
    mov   inhandler,0
@@Done2:
    pop  ds
    ret

MouseHandler ENDP

XDefineMouseCursor PROC FAR MouseDef : DWord, MouseColour : Byte

    cmp   MouseInstalled,0
    je    @@Done
    mov   al,MouseColour
    mov   MouseColor,al
    push  si
    push  di
    push  ds
    mov   ax,ds
    mov   es,ax
    mov   di,offset MouseMask
    lds   si,MouseDef
    xor   cl,cl
@@AlignmentLoop:
    push  si
    mov   dh,14
@@RowLoop:
    lodsb
    xor   ah,ah
    shl   ax,cl
    mov   bl,al
    and   bl,0fh
    mov   es:[di],bl
    inc   di
    shr   al,4
    stosw
    dec   dh
    jnz   @@RowLoop
    pop   si
    inc   cl
    cmp   cl,4
    jne   @@AlignmentLoop
    pop   ds
    pop   di
    pop   si
@@Done:
    ret

XDefineMouseCursor ENDP


XMouseInit PROC FAR

    mov   InHandler,0
    mov   mousehidden,0
    mov   BGSaveOffs,0
    mov   MouseX,0
    mov   MOuseY,0
    mov   MouseButtonStatus,0
    mov   MouseFrozen,0
    mov   MouseColor,0
    mov   MouseInstalled,0
    cmp   MouseButtonCount,0
    jne   @@DontInitialize
    xor   ax,ax
    int   33h
    or    ax,ax
    jz    @@Done
    mov   MouseButtonCount,bx

@@DontInitialize:
    mov   MouseInstalled,ax
    or    ax,ax
    jz    @@Done
    mov   ax,NonVisualOffs
    mov   BGSaveOffs,ax
    add   ax,42
    mov   NonVisualOffs,ax
    mov   ax,02
    int   33h
    mov   MouseInstalled,1
    mov   ax,07h
    mov   cx,0
    mov   dx,ScrnPhysicalPixelWidth
    shl   dx,1
    int   33h
    mov   ax,08h
    mov   cx,0
    mov   dx,ScrnPhysicalHeight
    int   33h
    mov   ax,0fh
    mov   cx,4
    mov   dx,8
    int   33h
    mov   ax,3
    int   33h
    mov   MouseY,dx
    shr   cx,1
    mov   MouseX,cx
    mov   ax,12
    mov   bx,seg mousehandler
    mov   es,bx
    mov   dx,offset mousehandler
    mov   cx,1fh
    int   33h
    mov   MouseHidden,1
    push  ds
    mov   ax,offset InitMouseDef
    push  ax
    mov   al, MouseColor
    push  ax
    call  xdefinemousecursor
    cmp   VSyncHandlerActive,1
    jne   @@AllIsWell
    mov   ax, offset updatecursor
    mov   dx, seg updatecursor
    cli
    mov   word ptr [MouseVSyncHandler],ax
    mov   word ptr [MouseVsyncHandler+2],dx
    mov   MouseRefreshFlag,0
    sti
@@AllIsWell:
    mov   ax,MouseInstalled
@@Done:
    ret

XMouseInit ENDP

XMouseWindow PROC FAR x0 : Word, y0 : Word, x1 : Word, y1 : Word

    mov   ax,7
    mov   cx,x0
    shl   cx,1
    mov   dx,x1
    shl   dx,1
    int   33h
    mov   ax,8
    mov   cx,y0
    mov   dx,y1
    int   33h
    ret

XMouseWindow ENDP


XShowMouse PROC FAR

    cmp   MouseInstalled,0
    je    @@Done
    cmp   MouseHidden,0
    je    @@Done
    push  si
    push  di

@@WaitEndOfHandler:
    mov   cl,inhandler
    or    cl,cl
    jnz   @@WaitEndOfHandler
    mov   si,VisiblePageOffs
    mov   ax,MouseY
    mov   bx,MouseX
    mov   OldScrnOffs,si
    mov   OldY,ax
    mov   OldX,bx
    call  getbg
    push  OldX
    push  OldY
    xor   ax,ax
    push  ax
    push  ScrnLogicalHeight
    push  VisiblePageOffs
    call  xputcursor
    mov   MouseHidden,0
    pop   di
    pop   si
@@Done:
    ret

XShowMouse ENDP

XHideMouse PROC FAR

    cmp   MouseInstalled,0
    je    @@Done
    cmp   MouseHidden,0
    jne   @@Done
    push  si
    push  di
@@WaitEndOfHandler:
    mov   cl,inhandler
    or    cl,cl
    jnz   @@WaitEndOfHandler
    mov   MouseHidden,TRUE
    mov   di,OldScrnOffs
    mov   ax,OldY
    mov   bx,OldX
    call  restorebg
    pop   di
    pop   si
@@Done:
    ret

XHideMouse ENDP

XMouseRemove PROC FAR

    cmp   MouseInstalled,0
    je    @@Done
    call  xhidemouse
    mov   ax,12
    xor   cx,cx
    int   33h
    mov   MouseRefreshFlag,0
    mov   MouseInstalled,0
@@Done:
    ret

XMouseRemove ENDP

XPositionMouse PROC FAR X : Word, Y : Word

@@WaitEndOfHandler:
    mov   bl,inhandler
    or    bl,bl
    jnz   @@WaitEndOfHandler
    mov   ax,4
    mov   cx,X
    mov   dx,Y
    mov   MouseX,cx
    mov   MouseY,dx
    shl   cx,1
    mov   inhandler,1
    int   33h
    cmp   MouseHidden,FALSE
    jne   @@NotVisible
    push  di
    push  si
    call  updatecursor
    pop   si
    pop   di
@@NotVisible:
    mov   inhandler,0
    ret

XPositionMouse ENDP

XUpdateMouse PROC FAR

    cmp   MouseInstalled,0
    je    @@Done
    cmp   MouseHidden,0
    jne   @@Done
    mov   ax,03h
    int   33h
    shr   cx,1
    mov   MouseX,cx
    mov   MouseY,dx
    mov   MouseButtonStatus,bx
    cmp   VSyncHandlerActive,1
    je    @@HandleVSync
    call  updatecursor
    jmp   short @@Done
@@HandleVSync:
    mov   MouseRefreshFlag,1
@@Done:
    ret

XUpdateMouse ENDP


XFloodFill PROC FAR X : Word, Y : Word, PgOfs : Word, Color : Word
LOCAL len : Word, y1 : Word, y2 : Word, deltax : Word, floodval : Word,\
            Astackptr : Word, FillCount : Word

    mov  FillCount,0
    mov  si,Y
    mov  ax,ScrnLogicalByteWidth
    mul  si
    mov  di,X
    mov  bx,di
    shr  di,2
    add  di,ax
    add  di,PgOfs
    mov  ax,SCREENSEG
    mov  es,ax
    mov  ah,bl
    and  ah,011b
    mov  al,READMAP
    mov  dx,GCINDEX
    out  dx,ax

    mov  al,es:[di]
    cmp  al,byte ptr Color
    je   @@Done

    mov  cx,LeftClip
    sal  cx,2
    cmp  bx,cx
    jl   @@Done

    mov  cx,RightClip
    sal  cx,2
    cmp  bx,cx
    jg   @@Done

    mov  floodval,ax

    push bx
    push si
    push si
    mov  cx,1
    push cx
    mov  Astackptr,1

    mov  deltax,-1
    mov  y1,si
    mov  y2,si
    jmp  @@entry

@@Done2:
    jmp @@Done

@@NextScanCol:
    dec  Astackptr
    js   @@Done2

@@WhileLoop:
    pop  cx
    mov  deltax,cx
    pop  ax
    mov  y2,ax
    pop  si
    mov  y1,si
    pop  bx

    sub  ax,si
    jns  @@PositiveY
    neg  ax
@@PositiveY:
    add  FillCount,ax
    add  bx,cx
    mov  ax,bx
    sar  ax,2
    cmp  ax,LeftClip
    jl   @@NextScanCol
    cmp  ax,RightClip
    jg   @@NextScanCol

    mov  ah,bl
    and  ah,011b
    mov  al,READMAP
    mov  dx,GCINDEX
    out  dx,ax

@@entry:
    mov  cl,bl
    and  cl,011b
    mov  ax,0100h + MAPMASK
    shl  ah,cl
    mov  dx,SCINDEX
    out  dx,ax
    mov  ax,ScrnLogicalByteWidth
    mov  cx,ax
    mul  si
    mov  di,bx
    shr  di,2
    add  di,ax
    add  di,PgOfs
    mov  dx,di

    mov  al,byte ptr Color
    mov  ah,byte ptr floodval

@@FillColUpward:
    cmp  si,TopClip
    jl   @@UpwardFillDone

    cmp  es:[di],ah
    jne  @@UpwardFillDone

    mov  es:[di],al
    sub  di,cx
    dec  si
    jmp  @@FillColUpward

@@UpwardFillDone:
    cmp  si,y1
    jge  @@Skip

    inc  si
    mov  len,si

    cmp  si,y1
    jge  @@AtColumnTop

    push bx
    push si
    mov  ax,y1
    dec  ax
    push ax
    mov  ax,deltax
    neg  ax
    push ax
    inc  Astackptr

@@AtColumnTop:
    mov  si,y1
    mov  di,dx
    add  di,cx
    inc  si


@@ColumnLoop:
    mov  ah,byte ptr floodval
    mov  al,byte ptr Color

@@DownwardFill:
    cmp  si,BottomClip
    jg   @@DownwardFillDone
    cmp  es:[di],ah
    jne  @@DownwardFillDone
    mov  es:[di],al
    add  di,cx
    inc  si
    jmp  @@DownwardFill

@@DownwardFillDone:

    push bx
    mov  ax,len
    push ax
    mov  ax,si
    dec  ax
    push ax
    mov  ax,deltax
    push ax
    inc  Astackptr

    mov  ax,y2
    inc  ax
    cmp  si,ax
    jle  @@Skip

    push bx
    push ax
    mov  ax,si
    dec  ax
    push ax
    mov  ax,deltax
    neg  ax
    push ax
    inc  Astackptr

@@Skip:
    mov  ah,byte ptr floodval
    mov  dx,y2

@@Backtrack:
    add  di,cx
    inc  si
    cmp  si,dx
    jg   @@BacktrackDone

    cmp  byte ptr es:[di],ah
    jne  @@Backtrack

@@BacktrackDone:
    mov  len,si
    cmp  si,dx
    jle  @@ColumnLoop

    dec  Astackptr
    js   @@Done
    jmp  @@WhileLoop
@@Done:
    mov  ax,FillCount
    ret

XFloodFill ENDP


XBoundaryFill PROC FAR X : Word, Y : Word, PgOfs : Word, BoundaryColor : Word,\
                                             Color : Word
LOCAL len : Word, y1 : Word, y2 : Word, deltax : Word, y1offs : Word,\
            Astackptr : Word, FillCount : Word

    mov  FillCount,0
    mov  si,Y
    mov  ax,ScrnLogicalByteWidth
    mul  si
    mov  di,X
    mov  bx,di
    shr  di,2
    add  di,ax
    add  di,PgOfs
    mov  ax,SCREENSEG
    mov  es,ax
    mov  ah,bl
    and  ah,011b
    mov  al,READMAP
    mov  dx,GCINDEX
    out  dx,ax
    mov  al,es:[di]
    cmp  al,byte ptr Color
    je   @@Done
    cmp  al,byte ptr BoundaryColor
    je   @@Done


    mov  cx,LeftClip
    sal  cx,2
    cmp  bx,cx
    jl   @@Done

    mov  cx,RightClip
    sal  cx,2
    cmp  bx,cx
    jg   @@Done

    push bx
    push si
    push si
    mov  cx,1
    push cx
    mov  Astackptr,1
    mov  al,byte ptr BoundaryColor
    mov  byte ptr [Color+1],al

    mov  deltax,-1
    mov  y1,si
    mov  y2,si
    jmp  @@entry

@@NextScanCol:
    dec  Astackptr
    js   @@Done

@@WhileLoop:
    pop  cx
    mov  deltax,cx
    pop  ax
    mov  y2,ax
    pop  si
    mov  y1,si
    pop  bx
    add  bx,cx

    sub  ax,si
    jns  @@PositiveY
    neg  ax
@@PositiveY:
    add  FillCount,ax
    mov  ax,bx
    sar  ax,2
    cmp  ax,LeftClip
    jl   @@NextScanCol
    cmp  ax,RightClip
    jg   @@NextScanCol
    mov  ah,bl
    and  ah,011b
    mov  al,READMAP
    mov  dx,GCINDEX
    out  dx,ax

@@entry:
    mov  cl,bl
    and  cl,011b
    mov  ax,0100h + MAPMASK
    shl  ah,cl
    mov  dx,SCINDEX
    out  dx,ax
    mov  ax,ScrnLogicalByteWidth
    mov  cx,ax
    mul  si
    mov  di,bx
    shr  di,2
    add  di,ax
    add  di,PgOfs
    mov  y1offs,di
    mov   ax,Color

@@FillColUpward:
    cmp  si,TopClip
    jl   @@UpwardFillDone

    mov  dl,es:[di]
    cmp  dl,ah
    je   @@UpwardFillDone

    cmp  dl,al
    je   @@UpwardFillDone

    mov  es:[di],al
    sub  di,cx
    dec  si
    jmp  @@FillColUpward

@@UpwardFillDone:
    cmp  si,y1
    jge  @@Skip

    inc  si
    mov  len,si

    cmp  si,y1
    jge  @@AtColumnTop

    push bx
    push si
    mov  ax,y1
    dec  ax
    push ax
    mov  ax,deltax
    neg  ax
    push ax
    inc  Astackptr

@@AtColumnTop:
    mov  si,y1
    mov  di,y1offs
    add  di,cx
    inc  si


@@ColumnLoop:
    mov   ax,Color

@@DownwardFill:
    cmp  si,BottomClip
    jg   @@DownwardFillDone

    cmp  es:[di],ah
    je   @@DownwardFillDone

    cmp  es:[di],al
    je   @@DownwardFillDone

    mov  es:[di],al
    add  di,cx
    inc  si
    jmp  @@DownwardFill

@@DownwardFillDone:

    push bx
    mov  ax,len
    push ax
    mov  ax,si
    dec  ax
    push ax
    mov  ax,deltax
    push ax
    inc  Astackptr

    mov  ax,y2
    inc  ax
    cmp  si,ax
    jle  @@Skip

    push bx
    push ax
    mov  ax,si
    dec  ax
    push ax
    mov  ax,deltax
    neg  ax
    push ax
    inc  Astackptr

@@Skip:
    mov  ax,Color

@@Backtrack:
    add  di,cx
    inc  si
    cmp  si,y2
    jg   @@BacktrackDone

    mov  dl,byte ptr es:[di]
    cmp  dl,al
    je   @@Backtrack

    cmp  dl,ah
    je   @@Backtrack

@@BacktrackDone:
    mov  len,si
    cmp  si,y2
    jle  @@ColumnLoop

    dec  Astackptr
    js   @@Done
    jmp  @@WhileLoop
@@Done:
    mov  ax,FillCount
    ret

XBoundaryFill ENDP

getvsyncperiod proc near
    mov    al,TIMERMODE            ;Start timer
    out    TIMERCONTROL,al
    mov    al,0
    out    TIMER0,al
    out    TIMER0,al

    WaitVsyncStart

    mov    al,LATCHCOUNT
    out    TIMERCONTROL,al
    in     al,TIMER0
    mov    cl,al
    in     al,TIMER0
    mov    ch,al                    ;cx=65536-clicks

    WaitVsyncStart

    mov    al,LATCHCOUNT
    out    TIMERCONTROL,al
    in     al,TIMER0
    mov    dl,al
    in     al,TIMER0
    mov    dh,al

    sub    cx,dx
    mov    ax,cx
    ret
getvsyncperiod endp

vsyncint proc far

    pusha
    push   ds
    push   es

    mov    ax,@data
    mov    ds,ax
    add    VsyncIntTicksLo,1
    adc    VsyncIntTicksHi,0

    inc    ElapsedVrts
    mov    cx,ElapsedVrts
    cmp    cx,VrtsToSkip
    jl     @@StopClock

    cmp    StartAddressFlag,1
    jne    @@StopClock

    mov    dx,CRTCINDEX
    mov    ax,WaitingStartLow
    mov    bx,WaitingStartHigh
    out    dx,ax
    mov    ax,bx
    out    dx,ax

@@StopClock:
    cli
    mov    al,TIMERMODE
    out    TIMERCONTROL,al
    mov    al,255
    out    TIMER0,al
    out    TIMER0,al
    sti

    cli
    mov    dx,INPUTSTATUS0
@@WaitVS:
    in     al,dx
    test   al,08h
    jz     @@WaitVS

    mov    al,TIMERMODE
    out    TIMERCONTROL,al
    mov    ax,ClockRate
    out    TIMER0,al
    mov    al,ah
    out    TIMER0,al

    cmp    cx,VrtsToSkip
    jl     @@PaletteInt

    cmp    StartAddressFlag,1
    jne    @@PaletteInt

    xor    cx,cx
    mov    ElapsedVrts,cx

    mov    ax,WaitingPelPan
    mov    dx,ACINDEX
    out    dx,al
    mov    al,ah
    out    dx,al

@@PaletteInt:
    mov    StartAddressFlag,0
    cmp    VsyncPaletteCount,0
    je     @@MouseInt
    mov    si, offset VsyncPaletteBuffer
    mov    cx, VsyncPaletteCount
    mov    ax, cx
    shl    cx, 1
    add    cx, ax
    mov    ax, VsyncPaletteStart
    mov    dx, DACWRITEINDEX
    out    dx, al
    mov    dx, DACDATA

    rep    outsb
    mov    VsyncPaletteCount,0

@@MouseInt:
    cmp    MouseRefreshFlag,1
    jne    @@UserInt
    call   dword ptr [MouseVsyncHandler]
    mov    MouseRefreshFlag,0

@@UserInt:
    cmp    UserVsyncSeg, 0
    je     short @@Sim182
    cmp    InUserHandler,0
    jne    short @@Sim182
    mov    InUserHandler,1
    mov    StackSeg,ss
    mov    StackPtr,sp
    push   ds
    pop    ss
    mov    sp, offset LocalStack
    sti
    call   dword ptr [UserVsyncHandler]
    cli
    mov    sp, StackPtr
    mov    ss, StackSeg
    mov    InUserHandler,0

@@Sim182:
    mov    ax,[VsyncPeriod]
    add    [ClockCounter],ax
    jnc    short @@DontChainOld
    pop    es
    pop    ds
    popa
    sti
    pushf
    db     09ah            ; call far
OldTimerInt dd 0         ; Self modifying code
    iret

@@DontChainOld:
    mov    al,NONSPECEOI
    out    PICCMD,al
    pop    es
    pop    ds
    popa
    sti
    iret

vsyncint endp


xinstallvsynchandler proc far VrtSkipCount:word

    mov     ax,[VrtSkipCount]
    or      ax,ax
    jnz     @@NonZeroCount
    mov     ax,1
@@NonZeroCount:
    mov     [VrtsToSkip],ax
    mov     [ElapsedVrts],0
    cmp     [VsyncHandlerActive],TRUE      ;Is it already active
    je      short @@Return
    call    getvsyncperiod                ;no, get the vsync period

    mov     [VsyncPeriod],ax
    sub     ax,INTINADVANCE               ;We need a little extra
    mov     [ClockRate],ax                  ;time

    mov     dx,18                           ;dx:ax=1193000
    mov     ax,13352
    idiv    [VsyncPeriod]
    mov     [TicksPerSecond],ax            ;1193/VsyncPeriod

    mov     word ptr [VsyncIntTicks],0
    mov     word ptr [VsyncIntTicks+2],0
    mov     MouseRefreshFlag, 0
    mov     StartAddressFlag, 0
    mov     VSyncPaletteCount, 0

    cli

IFDEF _DPMI_
    mov     ax, dpmiGetInt
    mov     bl, TIMERVECT
    int     DPMI                          ;Get Pmode vector
    mov     ax, cs                        ;vector = cx:dx
    add     ax, SelectorInc               ;Make Es = Cs so we can write to it
    mov     es, ax
    mov     word ptr es:[OldTimerInt],dx
    mov     word ptr es:[OldTimerInt+2],cx
ELSE
    mov     ax, DOSGETVECT+TIMERVECT      ;Get address of old timer int
    int     21h                           ;vector = es:bx
    mov     ax,es
    mov     word ptr cs:[OldTimerInt],bx       ;Store in OldTimerInt
    mov     word ptr cs:[OldTimerInt+2],ax
ENDIF
    mov     [VsyncHandlerActive],TRUE      ;Mark handler as active
IFDEF _DPMI_
    mov     ax, dpmiSetInt
    mov     bl, TIMERVECT
    mov     dx, offset vsyncint
    mov     cx, cs
    int     DPMI
ELSE
    mov     ax,DOSSETVECT+TIMERVECT       ;Set the new timer int
    push    ds
    mov     dx,cs
    mov     ds,dx
    mov     dx,offset vsyncint
    int     21h
    pop     ds
ENDIF
    mov     al,TIMERMODE                   ;Reprogram timer 0
    out     TIMERCONTROL,al
    mov     ax,ClockRate
    out     TIMER0,al
    mov     al,ah
    out     TIMER0,al
    sti
@@Return:
    ret

xinstallvsynchandler endp

xremovevsynchandler proc far

    cmp     [VsyncHandlerActive],FALSE
    je      short @@Return
    mov     dx, word ptr cs:[OldTimerInt]
    mov     cx, word ptr cs:[OldTimerInt+2]
IFDEF _DPMI_
    mov     ax, dpmiSetInt
    mov     bl, TIMERVECT
    int     DPMI
ELSE
    push    ds
    mov     ds,cx
    mov     ax,DOSSETVECT+TIMERVECT       ;Restore the old timer int
    cli
    int     21h
    pop     ds
ENDIF
    mov     al,TIMERMODE                   ;Restore timer 0
    out     TIMERCONTROL,al
    mov     al,0
    out     TIMER0,al
    out     TIMER0,al
    sti
@@Return:
    ret

xremovevsynchandler endp


xsetuservsynchandler proc far handlerproc:dword
    mov     ax, word ptr [handlerproc]
    mov     dx, word ptr [handlerproc+2]
    cli
    mov     word ptr [UserVsyncHandler],ax
    mov     word ptr [UserVsyncHandler+2],dx
    sti
    ret
xsetuservsynchandler endp


END