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Assembly Source File | 1993-03-11 | 38.6 KB | 1,302 lines

;----------------------------------------------------------------------- ; MODULE XMAIN ; ; Initialization, panning and split screen functions for all MODE X 256 ; Color resolutions ; ; Compile with Tasm. ; C callable. ; ; ; ****** XLIB - Mode X graphics library **************** ; ****** **************** ; ****** Written By Themie Gouthas **************** ; ; egg@dstos3.dsto.gov.au ; teg@bart.dsto.gov.au ; ; MODIFICATIONS: ; 26-9-92: Pel panning code added ; Dates forgotten: Numerous ;^) ;----------------------------------------------------------------------- include xlib.inc include xmain.inc .data ; Mode X CRTC register tweaks for various resolutions X320Y200 label word db 00 ; 0e3h ; dot clock db 02 ; Number of CRTC Registers to update dw 00014h ; turn off dword mode dw 0e317h ; turn on byte mode dw 320 ; width dw 200 ; height X320Y240 label word db 0e3h ; dot clock db 10 ; Number of CRTC Registers to update dw 00d06h ; vertical total dw 03e07h ; overflow (bit 8 of vertical counts) dw 04109h ; cell height (2 to double-scan) dw 0ea10h ; v sync start dw 0ac11h ; v sync end and protect cr0-cr7 dw 0df12h ; vertical displayed dw 00014h ; turn off dword mode dw 0e715h ; v blank start dw 00616h ; v blank end dw 0e317h ; turn on byte mode dw 320 ; width dw 240 ; height X360Y200 label word db 0e7h ; dot clock db 08 ; Number of CRTC Registers to update dw 06b00h ; horz total dw 05901h ; horz displayed dw 05a02h ; start horz blanking dw 08e03h ; end horz blanking dw 05e04h ; start h sync dw 08a05h ; end h sync dw 00014h ; turn off dword mode dw 0e317h ; turn on byte mode dw 360 ; width dw 200 ; height X360Y240 label word db 0e7h ; dot clock db 17 ; Number of CRTC Registers to update dw 06b00h ; horz total dw 05901h ; horz displayed dw 05a02h ; start horz blanking dw 08e03h ; end horz blanking dw 05e04h ; start h sync dw 08a05h ; end h sync dw 00d06h ; vertical total dw 03e07h ; overflow (bit 8 of vertical counts) dw 04109h ; cell height (2 to double-scan) dw 0ea10h ; v sync start dw 0ac11h ; v sync end and protect cr0-cr7 dw 0df12h ; vertical displayed dw 02d13h ; offset; dw 00014h ; turn off dword mode dw 0e715h ; v blank start dw 00616h ; v blank end dw 0e317h ; turn on byte mode dw 360 dw 240 X376Y282 label word db 0e7h db 18 dw 06e00h ; horz total dw 05d01h ; horz displayed dw 05e02h ; start horz blanking dw 09103h ; end horz blanking dw 06204h ; start h sync dw 08f05h ; end h sync dw 06206h ; vertical total dw 0f007h ; overflow dw 06109h ; cell height dw 0310fh ; dw 03710h ; v sync start dw 08911h ; v sync end and protect cr0-cr7 dw 03312h ; vertical displayed dw 02f13h ; offset dw 00014h ; turn off dword mode dw 03c15h ; v blank start dw 05c16h ; v blank end dw 0e317h ; turn on byte mode dw 376 dw 564 X320Y400 label word db 0e3h ; dot clock db 03 ; Number of CRTC Registers to update dw 04009h ; cell height dw 00014h ; turn off dword mode dw 0e317h ; turn on byte mode dw 320 ; width dw 400 ; height X320Y480 label word db 0e3h ; dotclock db 10 ; Number of CRTC Registers to update dw 00d06h ; vertical total dw 03e07h ; overflow (bit 8 of vertical counts) dw 04009h ; cell height (2 to double-scan) dw 0ea10h ; v sync start dw 0ac11h ; v sync end and protect cr0-cr7 dw 0df12h ; vertical displayed dw 00014h ; turn off dword mode dw 0e715h ; v blank start dw 00616h ; v blank end dw 0e317h ; turn on byte mode dw 320 ; width dw 480 ; height X360Y400 label word db 0e7h ; dot clock db 09 ; Number of CRTC Registers to update dw 06b00h ; horz total dw 05901h ; horz displayed dw 05a02h ; start horz blanking dw 08e03h ; end horz blanking dw 05e04h ; start h sync dw 08a05h ; end h sync dw 04009h ; cell height dw 00014h ; turn off dword mode dw 0e317h ; turn on byte mode dw 360 ; width dw 400 ; height X360Y480 label word db 0e7h db 17 dw 06b00h ; horz total dw 05901h ; horz displayed dw 05a02h ; start horz blanking dw 08e03h ; end horz blanking dw 05e04h ; start h sync dw 08a05h ; end h sync dw 00d06h ; vertical total dw 03e07h ; overflow dw 04009h ; cell height dw 0ea10h ; v sync start dw 0ac11h ; v sync end and protect cr0-cr7 dw 0df12h ; vertical displayed dw 02d13h ; offset dw 00014h ; turn off dword mode dw 0e715h ; v blank start dw 00616h ; v blank end dw 0e317h ; turn on byte mode dw 360 dw 480 X360Y360 label word db 0e7h db 15 dw 06b00h ; horz total dw 05901h ; horz displayed dw 05a02h ; start horz blanking dw 08e03h ; end horz blanking dw 05e04h ; start h sync dw 08a05h ; end h sync dw 04009h ; cell height dw 08810h ; v sync start dw 08511h ; v sync end and protect cr0-cr7 dw 06712h ; vertical displayed dw 02d13h ; offset dw 00014h ; turn off dword mode dw 06d15h ; v blank start dw 0ba16h ; v blank end dw 0e317h ; turn on byte mode dw 360 dw 360 X376Y308 label word db 0e7h db 18 dw 06e00h ; horz total dw 05d01h ; horz displayed dw 05e02h ; start horz blanking dw 09103h ; end horz blanking dw 06204h ; start h sync dw 08f05h ; end h sync dw 06206h ; vertical total dw 00f07h ; overflow dw 04009h ; dw 0310fh ; dw 03710h ; v sync start dw 08911h ; v sync end and protect cr0-cr7 dw 03312h ; vertical displayed dw 02f13h ; offset dw 00014h ; turn off dword mode dw 03c15h ; v blank start dw 05c16h ; v blank end dw 0e317h ; turn on byte mode dw 376 dw 308 X376Y564 label word db 0e7h db 18 dw 06e00h ; horz total dw 05d01h ; horz displayed dw 05e02h ; start horz blanking dw 09103h ; end horz blanking dw 06204h ; start h sync dw 08f05h ; end h sync dw 06206h ; vertical total dw 0f007h ; overflow dw 06009h ; dw 0310fh ; dw 03710h ; v sync start dw 08911h ; v sync end and protect cr0-cr7 dw 03312h ; vertical displayed dw 02f13h ; offset dw 00014h ; turn off dword mode dw 03c15h ; v blank start dw 05c16h ; v blank end dw 0e317h ; turn on byte mode dw 376 dw 564 LAST_X_MODE equ 11 ModeTable label word ; Mode X tweak table dw offset X320Y200 dw offset X320Y240 dw offset X360Y200 dw offset X360Y240 dw offset X376Y282 dw offset X320Y400 dw offset X320Y480 dw offset X360Y400 dw offset X360Y480 dw offset X360Y360 dw offset X376Y308 dw offset X376Y564 PARAMS label byte _CurrXMode dw 0 ; Current graphics mode index _InGraphics db 0 ; Flag indicating graphics activity _ScrnPhysicalByteWidth dw 0 ; Physical width in bytes of screen _ScrnPhysicalPixelWidth dw 0 ; Physical width in pixels of screen _ScrnPhysicalHeight dw 0 ; Physical Height of screen _ErrorValue db 0 ; Set after function calls _SplitScrnActive db 0 ; Flag indicating Split scrn activity _DoubleBufferActive dw 0 ; Flag indicating double buffering _SplitScrnScanLine dw 0 ; Split Screen's starting scan line _SplitScrnVisibleHeight dw 0 ; Split Screen's height on screen _SplitScrnOffs dw 0 ; Offset in video ram of Split Screen ; always = 0 _Page0_Offs dw 0 ; Ofset in video ram of Main virtual ; screen ( = 0 if no split screen ; otherwise = offset of first byte ; after split screen _Page1_Offs dw 0 ; Ofset in video ram of Second virtual ; screen ( = 0 if no split screen ; otherwise = offset of first byte ; after split screen ; = Page0_Offs if Doubble buffering ; not enabled _NonVisual_Offs dw 0 ; Ofset in video ram of first byte ; of non visible ram _ScrnLogicalByteWidth dw 0 ; Logical width in bytes of screen _ScrnLogicalPixelWidth dw 0 ; Logical width in pixels of screen _ScrnLogicalHeight dw 0 ; Logical Height of screen _MaxScrollX dw 0 ; Max X start position of Physical ; screen within virtual screen (in ; bytes) _MaxScrollY dw 0 ; Max Y start position of Physical ; screen within virtual screen _VisiblePageIdx dw 0 ; Index of currently visible D.B. ; page PageAddrTable label word _VisiblePageOffs dw 0 ; Table containing starting offsets _HiddenPageOffs dw 0 ; of the double buffer pages _TopClip dw 0 ; Clipping Rectangle _BottomClip dw 0 ; _LeftClip dw 0 ; Left/Right coordinates in bytes _RightClip dw 0 ; _PhysicalStartByteX dw 0 ; X byte coord of physical screen ; relative to virtual virtual screen _PhysicalStartPixelX dw 0 ; X pixel coord of physical screen ; relative to virtual screen _PhysicalStartY dw 0 ; Y pixel coord of physical screen ; relative to virtual screen PARAMS_END label byte PARAM_COUNT equ ($-PARAMS) ; Index/data pairs for CRT Controller registers that differ between ; mode 13h and mode X. ;Pelpan values for 0,1,2,3 pixel panning to the left, respectively PelPanMask db 000h,002h,004h,006h DoubleScanFlag db ? ; Flag to indicate double scanned mode .code ;------------------------------------------------------------------------- ; Local Logical Screen Width setting function ; cx = Requitrd Logical Width ; ; WARNING: no registers are preserved SetLogicalScrWidth proc mov dx,CRTC_INDEX mov al,CRTC_OFFSET out dx,al inc dx mov ax,cx cmp ax,[_ScrnPhysicalPixelWidth]; Is logical width >= physical width jge @@ValidLogicalWidth ; yes - continue mov ax,bx ; no - set logical width = physical @@ValidLogicalWidth: shr ax,3 out dx,al ; The EXACT logical pixel width may not have been possible since ; it should be divisible by 8. Round down to the closest possible ; width and update the status variables shl ax,1 mov bx,ax mov [_ScrnLogicalByteWidth],ax ; Store the byte width of virtual mov [_RightClip],ax ; Set default Right clip column ; screen sub ax,[_ScrnPhysicalByteWidth] ; Calculate and store Max X position shl ax,2 ; of physical screen in virtual mov [_MaxScrollX],ax ; screen in pixels mov ax,bx ; set ax to byte width of virt scrn shl ax,2 ; convert to pixels mov [_ScrnLogicalPixelWidth],ax ; store virt scrn pixel width mov cx,ax ; save ax (return value) ; calculate no. non split screen rows in video ram mov ax,0ffffh ; cx = Maximum video ram offset sub dx,dx ; DX:AX is divide operand, set DX = 0 div bx ; divide ax by ScrnLogicalByteWidth mov [_ScrnLogicalHeight],ax ; Save Screen Logical Height mov [_BottomClip],ax ; Set default bottom clip row sub ax,[_ScrnPhysicalHeight] ; Update the maximum Y position of mov [_MaxScrollY],ax ; Physical screen in logical screen mov ax,cx ; restore ax (return value) ; calculate initial NonVisual mov ax,[_ScrnLogicalByteWidth] mul [_ScrnPhysicalHeight] mov [_NonVisual_Offs],ax @@Done: ret SetLogicalScrWidth endp ;----------------------------------------------------------------------- ; Mode X graphics mode set with a virtual screen ; logical screen width. ; C near-callable as: ; ; int x_set_mode(unsigned int mode,unsigned int WidthInPixels); ; ; returns the actual width of the allocated virtual screen in pixels ; if a valid mode was selected otherwise returns -1 ; ; Saves virtual screen pixel width in _ScrnLogicalPixelWidth. ; Saves virtual screen byte width in _ScrnLogicalByteWidth. ; Physical screen dimensions are set in _ScrnPhysicalPixelWidth, ; _ScrnPhysicalByteWidth and _ScrnPhysicalHeight ; ; ; Modes: 0 = 320 x 200 (256 color) NOTE: Some of these modes require ; 1 = 320 x 240 (256 color) vertical size adjustment. ; 2 = 360 x 200 (256 color) ; 3 = 360 x 240 (256 color) ; 4 = 320 x 400 (256 color) ; 5 = 320 x 480 (256 color) ; 6 = 360 x 200 (256 color) ; 7 = 360 x 480 (256 color) ; 8 = 360 x 360 (256 color) ; 9 = 376 x 308 (256 color) ; 10 = 376 x 564 (256 color) ; ; Written by Themie Gouthas, ; parts adapted from M. Abrash code. ;------------------------------------------------------------------------ _x_set_mode proc ARG mode:word,logicalscrwidth:word push bp ;preserve caller's stack frame mov bp,sp push si ;preserve C register vars push di ; (don't count on BIOS preserving anything) cld mov ax,ds mov es,ax mov di,offset PARAMS xor ax,ax mov cx,PARAM_COUNT rep stosb mov cx,[mode] cmp cx,LAST_X_MODE ; have we selected a valid mode jle @@ValidMode ; Yes ! mov [_InGraphics],FALSE ; No return -1 mov ax,-1 pop di pop si pop bp ret @@ValidMode: mov [_CurrXMode],cx mov [_InGraphics],TRUE xor al,al cmp cx,3 jg @@SetDoubleScanFlag mov al,TRUE @@SetDoubleScanFlag: mov [DoubleScanFlag],al push cx ; some bios's dont preserve cx mov ax,13h ; let the BIOS set standard 256-color int 10h ; mode (320x200 linear) pop cx mov dx,SC_INDEX mov ax,0604h out dx,ax ; disable chain4 mode mov ax,0100h out dx,ax ; synchronous reset while setting Misc ; Output for safety, even though clock ; unchanged mov bx,offset ModeTable shl cx,1 add bx,cx mov si, word ptr [bx] lodsb or al,al jz @@DontSetDot mov dx,MISC_OUTPUT out dx,al ; select the dot clock and Horiz ; scanning rate @@DontSetDot: mov dx,SC_INDEX mov ax,0300h out dx,ax ; undo reset (restart sequencer) mov dx,CRTC_INDEX ; reprogram the CRT Controller mov al,11h ; VSync End reg contains register write out dx,al ; protect bit inc dx ; CRT Controller Data register in al,dx ; get current VSync End register setting and al,07fh ; remove write protect on various out dx,al ; CRTC registers dec dx ; CRT Controller Index cld xor cx,cx lodsb mov cl,al @@SetCRTParmsLoop: lodsw ; get the next CRT Index/Data pair out dx,ax ; set the next CRT Index/Data pair loop @@SetCRTParmsLoop mov dx,SC_INDEX mov ax,0f02h out dx,ax ; enable writes to all four planes mov ax,SCREEN_SEG ; now clear all display memory, 8 pixels mov es,ax ; at a time sub di,di ; point ES:DI to display memory sub ax,ax ; clear to zero-value pixels mov cx,8000h ; # of words in display memory rep stosw ; clear all of display memory ;Fix for single line ;mov dx,CRTC_INDEX ;mov al,MAX_SCAN_LINE ;out dx,al ;inc dx ;mov al,0C0h ;out dx,al ; Set pysical screen dimensions lodsw ; Load scrn pixel width mov [_ScrnPhysicalPixelWidth],ax ; from tweak table and store mov [_SplitScrnScanLine],ax ; No splitscrn == ; splitscrn=PhysicalscrnHeight mov bx,ax ; Copy width for later use shr ax,2 ; Convert to byte width mov [_ScrnPhysicalByteWidth],ax ; Store for later use lodsw ; Load Screen Phys. Height mov [_ScrnPhysicalHeight],ax ; Store for later use ; Mode X is set, now set the required logical page width. mov cx,[logicalscrwidth] call SetLogicalScrWidth pop di ;restore C register vars pop si pop bp ;restore caller's stack frame ret _x_set_mode endp ;---------------------------------------------------------------------- ; Mode X (256 color mode) set default access video plane ; ; C near-callable as: ; void x_select_default_plane(unsigned char plane); ; ; Enables Read/Write access to a plane using general memory access ; methods ; ; Written by Themie Gouthas ;---------------------------------------------------------------------- _x_select_default_plane proc ARG Plane:byte push bp mov bp,sp ; set up stack frame mov cl,byte ptr [Plane] ; SELECT WRITE PLANE and cl,011b ;CL = plane mov ax,0100h + MAP_MASK ;AL = index in SC of Map Mask reg shl ah,cl ;set only the bit for the required ; plane to 1 mov dx,SC_INDEX ;set the Map Mask to enable only the out dx,ax ; pixel's plane ; SELECT READ PLANE mov ah,cl ;AH = plane mov al,READ_MAP ;AL = index in GC of the Read Map reg mov dx,GC_INDEX ;set the Read Map to read the pixel's out dx,ax ; plane pop bp ret _x_select_default_plane endp ;---------------------------------------------------------------------- ; Mode X (256 color mode) Set Mode X split screen starting row ; The split screen resides on the bottom half of the screen and has a ; starting address of A000:0000 ; ; C near-callable as: ; void x_set_splitscreen(unsigned int line); ; ; Updates _Page0_Offs to reflect the existence of the split screen region ; ie _MainScrnOffset is set to the offset of the first pixel beyond the split ; screen region ; ; Written by Themie Gouthas ;---------------------------------------------------------------------- _x_set_splitscreen proc ARG Line:word push bp mov bp,sp ; set up stack frame push si xor si,si ; si=0 -> x virtual page start coord cmp [_DoubleBufferActive],0 jne @@error cmp [_SplitScrnActive],0 je @@NotPreviouslyCalled @@error: mov [_ErrorValue],ERROR pop si pop bp ; Return if previously called ret @@NotPreviouslyCalled: ; Turn on split screen pal pen suppression, so the split screen ; wo'nt be subject to pel panning as is the non split screen portion. mov dx,INPUT_STATUS_0 in al,dx ; Reset the AC Index/Data toggle to ; index state mov al,AC_MODE_CONTROL+20h ; Bit 5 set to prevent screen blanking mov dx,AC_INDEX ; Point AC to Index/Data register out dx,al inc dx ; Point to AC Data reg (for reads only) in al,dx ; Get the current AC Mode Control reg or al,20h ; Enable split scrn Pel panning suppress. dec dx ; Point to AC Index/Data reg (for writes only) out dx,al ; Write the new AC Mode Control setting ; with split screen pel panning ; suppression turned on mov [_PhysicalStartByteX],ax ; Set the Phisical screen start mov [_PhysicalStartPixelX],ax ; offset within virtual screen mov [_PhysicalStartY],ax mov [_SplitScrnActive],TRUE mov ax,[Line] jns @@NotNeg ; Check that Split Scrn start scan line is +ve mov ax,0 ; Since -ve set to 0 @@NotNeg: mov [_SplitScrnScanLine],ax ; save the scanline or [DoubleScanFlag],0 jz @@NotDoubleScanned shl ax,1 dec ax @@NotDoubleScanned: ;mov cl,[DoubleScanFlag] ;shl ax,cl ; Mode X 200 and 240 line modes are actually ; 400 and 480 lines that are double scanned ; so for start scanline multiply required ModeX ; scan line by 2 if its a double scanned mode mov bx,ax ; save the scanline WaitVsyncStart ; wait for vertical retrace cli ; Dont allow register setting to be interrupted mov dx,CRTC_INDEX mov ah,bl mov al,LINE_COMPARE out dx,ax ; Bits 7-0 of the split screen scan line mov ah,bh and ah,1 shl ah,4 mov al,OVERFLOW ; Bit 4 of overflow register = Bit 8 of split out dx,al ; screen scan line, inc dx ; So using readability of VGA registers in al,dx ; Read the OVERFLOW register, and set the and al, not 10h ; bit corresponding to Bit 8 (above) or al,ah out dx,al dec dx mov ah,bh and ah,2 ror ah,3 mov al,MAX_SCAN_LINE ; Bit 6 of max scan line register = out dx,al ; Bit 9 of split screen scan line inc dx ; As we did before, update the apropriate in al,dx ; bit without disturbing the rest and al, not 40h or al,ah out dx,al sti ; Registers are set, so interrupts are safe mov ax,[_ScrnPhysicalHeight] ; Determine where the first byte sub ax,[_SplitScrnScanLine] ; of the non split screen video ram mov [_SplitScrnVisibleHeight],bx ; starts and store it for reference mov bx,[_ScrnLogicalByteWidth] mul bx mov [_Page0_Offs],ax mov [_Page1_Offs],ax ; calculate no. non split screen rows in video ram mov cx,0ffffh ; cx = Maximum video ram offset sub cx,ax ; cx = cx - _Page0_Offs xchg cx,ax ; swap cx and ax sub dx,dx ; DX:AX is divide operand, set DX = 0 div bx ; divide ax (prev cx) by ; ScrnLogicalByteWidth mov [_ScrnLogicalHeight],ax ; Save Screen Logical Height cmp ax,[_BottomClip] jle @@BottomClipOK ; Adjust Clip Rectangle if necessary mov [_BottomClip],ax @@BottomClipOK: sub ax,[_SplitScrnScanLine] ; Update the maximum Y position of mov [_MaxScrollY],ax ; Physical screen in logical screen xchg cx,ax ; restore original ax (MainScrnOfs) mov bh,al ; Set the visible screen start address mov ch,ah ; to the top left corner of the virtual jmp short StartAddrEntry ; screen _x_set_splitscreen endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Page flip primer ; No clipping is performed. ; C near-callable as: ; ; void x_page_flip(unsigned int x, unsigned int y); ; ; Swaps visible and hidden page offsets and then executes the SetStartAddr ; to achieve a page flip. ; ; SEE x_set_start_addr below ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_page_flip proc ARG x:word,y:word push bp ;preserve caller's stack frame mov bp,sp ;point to local stack frame push si mov si,[x] mov ax,[_ScrnLogicalByteWidth] ; Calculate Offset increment mov cx,[y] mul cx ; for Y cmp [_DoubleBufferActive],TRUE ; Do we have double buffering ? jne PageFlipEntry1 mov bx,[_HiddenPageOffs] xchg bx,[_VisiblePageOffs] ; Swap the Page Offsete xchg [_HiddenPageOffs],bx xor [_VisiblePageIdx],01h ; Set the Visible page index jmp short PageFlipEntry2 _x_page_flip endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Set Mode X non split screen start address ; of logical screen. ; C near-callable as: ; ; void x_set_start_addr(unsigned int x, unsigned int y); ; ; Params: StartOffset is offset of first byte of logical screen ram ; (Useful if you want to double buffer by splitting your non ; split screen video ram into 2 pages) ; X,Y coordinates of the top left hand corner of the physical screen ; within the logical screen ; X must not exceed (Logical screen width - Physical screen width) ; Y must not exceed (Logical screen height - Physical screen height) ; ; ; Written by Themie Gouthas, ; Parts addapted from M. Abrash code published in DDJ Mag. ;------------------------------------------------------------------------ _x_set_start_addr proc ARG x:word,y:word push bp mov bp,sp push si mov si,[x] mov ax,[_ScrnLogicalByteWidth] ; Calculate Offset increment mov cx,[y] ; for Y mul cx cmp [_DoubleBufferActive],TRUE ; Do we have double buffering ? je @@PageResolution PageFlipEntry1: add ax,[_Page0_Offs] ; no - add page 0 offset jmp short @@AddColumn PageFlipEntry2: mov [_PhysicalStartPixelX],si mov [_PhysicalStartY],cx @@PageResolution: add ax,[_VisiblePageOffs] ; Add visible page offset @@AddColumn: mov cx,si shr cx,2 mov [_PhysicalStartByteX],cx add ax,cx ; add the column offset for X mov bh,al ; setup CRTC start addr regs and ; values in word registers for mov ch,ah ; fast word outs StartAddrEntry: mov bl,ADDR_LOW mov cl,ADDR_HIGH and si,0003h ; select pel pan register value for the mov ah,PelPanMask[si] ; required x coordinate mov al,PEL_PANNING+20h mov si,ax mov dx,INPUT_STATUS_0 ;Wait for trailing edge of Vsync pulse @@WaitDE: in al,dx test al,01h jnz @@WaitDE ;display enable is active low (0 = active) mov dx,CRTC_INDEX mov ax,bx out dx,ax ;start address low mov ax,cx out dx,ax ;start address high mov dx,AC_INDEX mov ax,si ; Point the attribute controller to pel pan out dx,al ; reg. Bit 5 also set to prevent blanking mov al,ah out dx,al ; load new Pel Pan setting. ; Now wait for vertical sync, so the other page will be invisible when ; we start drawing to it. mov dx,INPUT_STATUS_0 ;Wait for trailing edge of Vsync pulse @@WaitVS: in al,dx test al,08h jz @@WaitVS ;display enable is active low (0 = active) mov [_ErrorValue],OK pop si pop bp ret _x_set_start_addr endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Mode X split screen hide ; C near-callable as: ; ; void x_hide_splitscreen() ; ; Hides an existing split screen by setting its starting scan line to ; the last physical screen scan line ; ; WARNING: Only to be used if SplitScrnLine has been previously called ; WARNING: DO NOT USE with mode 5-11 (320x400-376x564). The memory for ; the initial split screen is reserved and the size limitations ; of these modes means any change in the split screen scan line ; will encroach on the split screen ram ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_hide_splitscreen proc push bp mov bp,sp cmp [_SplitScrnActive],TRUE je @@SplitScreenEnabled @@error: mov [_ErrorValue],ERROR pop bp ret @@SplitScreenEnabled: cmp [_CurrXMode],4 ; Do nothing for Modes > 2 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: ;mov cl,[DoubleScanFlag] ; Compensate for double scanned modes ;shl bx,cl WaitVsyncStart ; wait for vertical retrace cli ; Dont allow register setting to be interrupted mov dx,CRTC_INDEX mov ah,bl mov al,LINE_COMPARE out dx,ax ; Bits 7-0 of the split screen scan line mov ah,bh and ah,1 shl ah,4 mov al,OVERFLOW ; Bit 4 of overflow register = Bit 8 of split out dx,al ; screen scan line, inc dx ; So using readability of VGA registers in al,dx ; Read the OVERFLOW register, and set the and al, not 10h ; bit corresponding to Bit 8 (above) or al,ah out dx,al dec dx mov ah,bh and ah,2 ror ah,3 mov al,MAX_SCAN_LINE ; Bit 6 of max scan line register = out dx,al ; Bit 9 of split screen scan line inc dx ; As we did before, update the apropriate in al,dx ; bit without disturbing the rest and al, not 40h or al,ah out dx,al sti ; Registers are set, so interrupts are safe @@done: mov [_ErrorValue],OK pop bp ret _x_hide_splitscreen endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Mode X split screen show ; C near-callable as: ; ; void x_show_splitscreen() ; ; Restores split screen start scan line to the initial split screen ; starting scan line as set by SplitScrnLine. ; ; WARNING: Only to be used if SplitScrnLine has been previously called ; WARNING: DO NOT USE with mode 5-11 (320x400-376x564). The memory for ; the initial split screen is reserved and the size limitations ; of these modes means any change in the split screen scan line ; will encroach on the split screen ram ; Update: Now disabled for these modes ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_show_splitscreen proc push bp mov bp,sp cmp [_SplitScrnActive],TRUE je @@SplitScreenEnabled @@error: mov [_ErrorValue],ERROR pop bp ret @@SplitScreenEnabled: cmp [_CurrXMode],4 ; Do nothing for Modes > 2 jg @@error mov bx,[_SplitScrnScanLine] mov ax,[_ScrnLogicalHeight] ; Update Max Scroll Y 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: ;mov cl,[DoubleScanFlag] ; Compensate for double scanned modes ;shl bx,cl WaitVsyncStart ; wait for vertical retrace cli ; Dont allow register setting to be interrupted mov dx,CRTC_INDEX mov ah,bl mov al,LINE_COMPARE out dx,ax ; Bits 7-0 of the split screen scan line mov ah,bh and ah,1 shl ah,4 mov al,OVERFLOW ; Bit 4 of overflow register = Bit 8 of split out dx,al ; screen scan line, inc dx ; So using readability of VGA registers in al,dx ; Read the OVERFLOW register, and set the and al, not 10h ; bit corresponding to Bit 8 (above) or al,ah out dx,al dec dx mov ah,bh and ah,2 ror ah,3 mov al,MAX_SCAN_LINE ; Bit 6 of max scan line register = out dx,al ; Bit 9 of split screen scan line inc dx ; As we did before, update the apropriate in al,dx ; bit without disturbing the rest and al, not 40h or al,ah out dx,al sti ; Registers are set, so interrupts are safe @@Done: mov [_ErrorValue],0 pop bp ret _x_show_splitscreen endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Modify Mode X split screen starting scan line ; C near-callable as: ; ; void x_adjust_splitscreen(unsigned int ScanLine) ; ; Sets the split screen start scan line to a new scan line. Valid scan lines ; are between the initial split screen starting scan line and the last ; physical screen scan line. ; ; WARNING: Only to be used if SplitScrnLine has been previously called ; WARNING: DO NOT USE with mode 5-11 (320x400-376x564). The memory for ; the initial split screen is reserved and the size limitations ; of these modes means any change in the split screen scan line ; will encroach on the split screen ram ; Update: Now disabled for these modes ; ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_adjust_splitscreen proc ARG ScanLine push bp mov bp,sp cmp [_SplitScrnActive],TRUE je @@SplitScreenEnabled @@error: mov [_ErrorValue],ERROR pop bp ret @@SplitScreenEnabled: cmp [_CurrXMode],4 ; Do nothing for Modes > 2 jg @@error mov bx,[ScanLine] ; Is the required starting scan line cmp bx,[_SplitScrnScanLine] ; valid ? js @@Done ; No - Then do nothing @@ValidScanLine: mov ax,[_ScrnLogicalHeight] ; Update Max Scroll Y 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: ;mov cl,[DoubleScanFlag] ; Compensate for double scanned modes ;shl bx,cl WaitVsyncStart ; wait for vertical retrace cli ; Dont allow register setting to be interrupted mov dx,CRTC_INDEX mov ah,bl mov al,LINE_COMPARE out dx,ax ; Bits 7-0 of the split screen scan line mov ah,bh and ah,1 shl ah,4 mov al,OVERFLOW ; Bit 4 of overflow register = Bit 8 of split out dx,al ; screen scan line, inc dx ; So using readability of VGA registers in al,dx ; Read the OVERFLOW register, and set the and al, not 10h ; bit corresponding to Bit 8 (above) or al,ah out dx,al dec dx mov ah,bh and ah,2 ror ah,3 mov al,MAX_SCAN_LINE ; Bit 6 of max scan line register = out dx,al ; Bit 9 of split screen scan line inc dx ; As we did before, update the apropriate in al,dx ; bit without disturbing the rest and al, not 40h or al,ah out dx,al sti ; Registers are set, so interrupts are safe @@Done: mov [_ErrorValue],OK pop bp ret _x_adjust_splitscreen endp ;----------------------------------------------------------------------- ; Mode X (256 color mode) Enable DoubleBuffering on non split screen area ; C near-callable as: ; ; int x_set_doublebuffer(unsigned int PageHeight); ; ; Params: PageHeight is the height of the virtual screen to double buffer ; Returns the closest possible height to the specified. ; ; Sets up two double buffering virtual pages ; GLOBAL variables set: ; ; _Page1_Offs Offset of second virtual page ; _NonVisual_Offs Offset of first non visible video ram byte ; _DoubleBufferActive Flag ; _PageAddrTable Table of Double buffering pages start offsets ; _ScrnLogicalHeight Logical height of the double buffering pages ; ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_set_doublebuffer proc ARG PageHeight:word push bp mov bp,sp cmp [_DoubleBufferActive],0 je @@OkToContinue @error: mov [_ErrorValue],ERROR pop bp ret @@OkToContinue: mov [_VisiblePageIdx],0 ; Set visible Page to 0 mov ax,[_ScrnLogicalHeight] ; Set Maximum D.B. Page height to shr ax,1 ; _ScrnLogicalHeight / 2 mov bx,[PageHeight] ; Is the require D.B. Page Height cmp ax,bx ; > the Maximum D.B. Page Height ? js @@InvalidHeight ; no - jump mov ax,bx ; yes - Set the D.B. Page height to ; to the maximum allowed. @@InvalidHeight: mov [_ScrnLogicalHeight],ax ; Update logical screen height to ; reflect the height of a D.B. page cmp ax,[_BottomClip] jle @@BottomClipOK ; Adjust Clip Rectangle if necessary mov [_BottomClip],ax @@BottomClipOK: mov dx,ax mul [_ScrnLogicalByteWidth] ; Calculate the offset of the second mov cx,ax ; D.B. Page in video ram mov bx,[_Page0_Offs] mov [_VisiblePageOffs],bx add ax,bx mov [_Page1_Offs],ax ; Save it mov [_HiddenPageOffs],ax add ax,cx ; Calculate the offset of first byte mov [_NonVisual_Offs],ax ; beyond the D.B. pages and save it mov [_DoubleBufferActive],TRUE ; Set flag indicating D.B'ing mode on mov ax,dx sub ax,[_ScrnPhysicalHeight] add ax,[_SplitScrnVisibleHeight] mov [_MaxScrollY],ax mov ax,dx ; return the D.B. pages' height mov [_ErrorValue],OK pop bp ret _x_set_doublebuffer endp ;----------------------------------------------------------------------- ; Set Clipping rectangle ; C callable as: ; ; ; int x_set_cliprect(WORD left,WORD top, WORD right, WORD bottom); ; ; ; NOTE clipping is byte oriented. "left" and "right" are in bytes not pixels. ; Only selected functions perform any clipping at all. ; ; Written by Themie Gouthas ;------------------------------------------------------------------------ _x_set_cliprect proc ARG left:word,top:word,right:word,bottom:word push bp mov bp,sp 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 pop bp ret _x_set_cliprect endp ;---------------------------------------------------------------------- ; Return to text mode ; _x_text_mode proc push bp mov ax,03h ; Restore Text Mode int 10h pop bp ret _x_text_mode endp ;----------------------------------------------------------------------- ; Wait for Vertical sync _x_wait_vsync proc push bp WaitVsyncStart pop bp ret _x_wait_vsync endp end