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wolf3d/ID_VL_A.ASM

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as released 1995-07-21
1995-07-21 00:00:00 +00:00
; ID_VL.ASM
IDEAL
MODEL MEDIUM,C
INCLUDE 'ID_VL.EQU'
SCREENSEG = 0a000h
DATASEG
EXTRN TimeCount:WORD ; incremented every 70th of a second
EXTRN linewidth:WORD
starttime dw ?
CODESEG
;===========================================================================
;==============
;
; VL_WaitVBL ******** NEW *********
;
; Wait for the vertical retrace (returns before the actual vertical sync)
;
;==============
PROC VL_WaitVBL num:WORD
PUBLIC VL_WaitVBL
@@wait:
mov dx,STATUS_REGISTER_1
mov cx,[num]
;
; wait for a display signal to make sure the raster isn't in the middle
; of a sync
;
@@waitnosync:
in al,dx
test al,8
jnz @@waitnosync
@@waitsync:
in al,dx
test al,8
jz @@waitsync
loop @@waitnosync
ret
ENDP
;===========================================================================
;==============
;
; VL_SetCRTC
;
;==============
PROC VL_SetCRTC crtc:WORD
PUBLIC VL_SetCRTC
;
; wait for a display signal to make sure the raster isn't in the middle
; of a sync
;
cli
mov dx,STATUS_REGISTER_1
@@waitdisplay:
in al,dx
test al,1 ;1 = display is disabled (HBL / VBL)
jnz @@waitdisplay
;
; set CRTC start
;
; for some reason, my XT's EGA card doesn't like word outs to the CRTC
; index...
;
mov cx,[crtc]
mov dx,CRTC_INDEX
mov al,0ch ;start address high register
out dx,al
inc dx
mov al,ch
out dx,al
dec dx
mov al,0dh ;start address low register
out dx,al
mov al,cl
inc dx
out dx,al
sti
ret
ENDP
;===========================================================================
;==============
;
; VL_SetScreen
;
;==============
PROC VL_SetScreen crtc:WORD, pel:WORD
PUBLIC VL_SetScreen
mov cx,[timecount] ; if timecount goes up by two, the retrace
add cx,2 ; period was missed (an interrupt covered it)
mov dx,STATUS_REGISTER_1
;
; wait for a display signal to make sure the raster isn't in the middle
; of a sync
;
@@waitdisplay:
in al,dx
test al,1 ;1 = display is disabled (HBL / VBL)
jnz @@waitdisplay
@@loop:
sti
jmp $+2
cli
cmp [timecount],cx ; will only happen if an interrupt is
jae @@setcrtc ; straddling the entire retrace period
;
; when several succesive display not enableds occur,
; the bottom of the screen has been hit
;
in al,dx
test al,8
jnz @@waitdisplay
test al,1
jz @@loop
in al,dx
test al,8
jnz @@waitdisplay
test al,1
jz @@loop
in al,dx
test al,8
jnz @@waitdisplay
test al,1
jz @@loop
in al,dx
test al,8
jnz @@waitdisplay
test al,1
jz @@loop
in al,dx
test al,8
jnz @@waitdisplay
test al,1
jz @@loop
@@setcrtc:
;
; set CRTC start
;
; for some reason, my XT's EGA card doesn't like word outs to the CRTC
; index...
;
mov cx,[crtc]
mov dx,CRTC_INDEX
mov al,0ch ;start address high register
out dx,al
inc dx
mov al,ch
out dx,al
dec dx
mov al,0dh ;start address low register
out dx,al
mov al,cl
inc dx
out dx,al
;
; set horizontal panning
;
mov dx,ATR_INDEX
mov al,ATR_PELPAN or 20h
out dx,al
jmp $+2
mov al,[BYTE pel] ;pel pan value
out dx,al
sti
ret
ENDP
;===========================================================================
;============================================================================
;
; VL_ScreenToScreen
;
; Basic block copy routine. Copies one block of screen memory to another,
; using write mode 1 (sets it and returns with write mode 0). bufferofs is
; NOT accounted for.
;
;============================================================================
PROC VL_ScreenToScreen source:WORD, dest:WORD, wide:WORD, height:WORD
PUBLIC VL_ScreenToScreen
USES SI,DI
pushf
cli
mov dx,SC_INDEX
mov ax,SC_MAPMASK+15*256
out dx,ax
mov dx,GC_INDEX
mov al,GC_MODE
out dx,al
inc dx
in al,dx
and al,NOT 3
or al,1
out dx,al
popf
mov bx,[linewidth]
sub bx,[wide]
mov ax,SCREENSEG
mov es,ax
mov ds,ax
mov si,[source]
mov di,[dest] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
mov ax,[wide]
@@lineloop:
mov cx,ax
rep movsb
add si,bx
add di,bx
dec dx
jnz @@lineloop
mov dx,GC_INDEX+1
in al,dx
and al,NOT 3
out dx,al
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
ENDP
;===========================================================================
MASM
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;
; Name: VL_VideoID
;
; Function: Detects the presence of various video subsystems
;
; int VideoID;
;
; Subsystem ID values:
; 0 = (none)
; 1 = MDA
; 2 = CGA
; 3 = EGA
; 4 = MCGA
; 5 = VGA
; 80h = HGC
; 81h = HGC+
; 82h = Hercules InColor
;
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;
; Equates
;
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VIDstruct STRUC ; corresponds to C data structure
Video0Type DB ? ; first subsystem type
Display0Type DB ? ; display attached to first subsystem
Video1Type DB ? ; second subsystem type
Display1Type DB ? ; display attached to second subsystem
VIDstruct ENDS
Device0 EQU word ptr Video0Type[di]
Device1 EQU word ptr Video1Type[di]
MDA EQU 1 ; subsystem types
CGA EQU 2
EGA EQU 3
MCGA EQU 4
VGA EQU 5
HGC EQU 80h
HGCPlus EQU 81h
InColor EQU 82h
MDADisplay EQU 1 ; display types
CGADisplay EQU 2
EGAColorDisplay EQU 3
PS2MonoDisplay EQU 4
PS2ColorDisplay EQU 5
TRUE EQU 1
FALSE EQU 0
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;
; Program
;
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Results VIDstruct <> ;results go here!
EGADisplays DB CGADisplay ; 0000b, 0001b (EGA switch values)
DB EGAColorDisplay ; 0010b, 0011b
DB MDADisplay ; 0100b, 0101b
DB CGADisplay ; 0110b, 0111b
DB EGAColorDisplay ; 1000b, 1001b
DB MDADisplay ; 1010b, 1011b
DCCtable DB 0,0 ; translate table for INT 10h func 1Ah
DB MDA,MDADisplay
DB CGA,CGADisplay
DB 0,0
DB EGA,EGAColorDisplay
DB EGA,MDADisplay
DB 0,0
DB VGA,PS2MonoDisplay
DB VGA,PS2ColorDisplay
DB 0,0
DB MCGA,EGAColorDisplay
DB MCGA,PS2MonoDisplay
DB MCGA,PS2ColorDisplay
TestSequence DB TRUE ; this list of flags and addresses
DW FindPS2 ; determines the order in which this
; program looks for the various
EGAflag DB ? ; subsystems
DW FindEGA
CGAflag DB ?
DW FindCGA
Monoflag DB ?
DW FindMono
NumberOfTests EQU ($-TestSequence)/3
PUBLIC VL_VideoID
VL_VideoID PROC
push bp ; preserve caller registers
mov bp,sp
push ds
push si
push di
push cs
pop ds
ASSUME DS:@Code
; initialize the data structure that will contain the results
lea di,Results ; DS:DI -> start of data structure
mov Device0,0 ; zero these variables
mov Device1,0
; look for the various subsystems using the subroutines whose addresses are
; tabulated in TestSequence; each subroutine sets flags in TestSequence
; to indicate whether subsequent subroutines need to be called
mov byte ptr CGAflag,TRUE
mov byte ptr EGAflag,TRUE
mov byte ptr Monoflag,TRUE
mov cx,NumberOfTests
mov si,offset TestSequence
@@L01: lodsb ; AL := flag
test al,al
lodsw ; AX := subroutine address
jz @@L02 ; skip subroutine if flag is false
push si
push cx
call ax ; call subroutine to detect subsystem
pop cx
pop si
@@L02: loop @@L01
; determine which subsystem is active
call FindActive
mov al,Results.Video0Type
mov ah,0 ; was: Results.Display0Type
pop di ; restore caller registers and return
pop si
pop ds
mov sp,bp
pop bp
ret
VL_VideoID ENDP
;
; FindPS2
;
; This subroutine uses INT 10H function 1Ah to determine the video BIOS
; Display Combination Code (DCC) for each video subsystem present.
;
FindPS2 PROC near
mov ax,1A00h
int 10h ; call video BIOS for info
cmp al,1Ah
jne @@L13 ; exit if function not supported (i.e.,
; no MCGA or VGA in system)
; convert BIOS DCCs into specific subsystems & displays
mov cx,bx
xor bh,bh ; BX := DCC for active subsystem
or ch,ch
jz @@L11 ; jump if only one subsystem present
mov bl,ch ; BX := inactive DCC
add bx,bx
mov ax,[bx+offset DCCtable]
mov Device1,ax
mov bl,cl
xor bh,bh ; BX := active DCC
@@L11: add bx,bx
mov ax,[bx+offset DCCtable]
mov Device0,ax
; reset flags for subsystems that have been ruled out
mov byte ptr CGAflag,FALSE
mov byte ptr EGAflag,FALSE
mov byte ptr Monoflag,FALSE
lea bx,Video0Type[di] ; if the BIOS reported an MDA ...
cmp byte ptr [bx],MDA
je @@L12
lea bx,Video1Type[di]
cmp byte ptr [bx],MDA
jne @@L13
@@L12: mov word ptr [bx],0 ; ... Hercules can't be ruled out
mov byte ptr Monoflag,TRUE
@@L13: ret
FindPS2 ENDP
;
; FindEGA
;
; Look for an EGA. This is done by making a call to an EGA BIOS function
; which doesn't exist in the default (MDA, CGA) BIOS.
FindEGA PROC near ; Caller: AH = flags
; Returns: AH = flags
; Video0Type and
; Display0Type updated
mov bl,10h ; BL := 10h (return EGA info)
mov ah,12h ; AH := INT 10H function number
int 10h ; call EGA BIOS for info
; if EGA BIOS is present,
; BL <> 10H
; CL = switch setting
cmp bl,10h
je @@L22 ; jump if EGA BIOS not present
mov al,cl
shr al,1 ; AL := switches/2
mov bx,offset EGADisplays
xlat ; determine display type from switches
mov ah,al ; AH := display type
mov al,EGA ; AL := subystem type
call FoundDevice
cmp ah,MDADisplay
je @@L21 ; jump if EGA has a monochrome display
mov CGAflag,FALSE ; no CGA if EGA has color display
jmp short @@L22
@@L21: mov Monoflag,FALSE ; EGA has a mono display, so MDA and
; Hercules are ruled out
@@L22: ret
FindEGA ENDP
;
; FindCGA
;
; This is done by looking for the CGA's 6845 CRTC at I/O port 3D4H.
;
FindCGA PROC near ; Returns: VIDstruct updated
mov dx,3D4h ; DX := CRTC address port
call Find6845
jc @@L31 ; jump if not present
mov al,CGA
mov ah,CGADisplay
call FoundDevice
@@L31: ret
FindCGA ENDP
;
; FindMono
;
; This is done by looking for the MDA's 6845 CRTC at I/O port 3B4H. If
; a 6845 is found, the subroutine distinguishes between an MDA
; and a Hercules adapter by monitoring bit 7 of the CRT Status byte.
; This bit changes on Hercules adapters but does not change on an MDA.
;
; The various Hercules adapters are identified by bits 4 through 6 of
; the CRT Status value:
;
; 000b = HGC
; 001b = HGC+
; 101b = InColor card
;
FindMono PROC near ; Returns: VIDstruct updated
mov dx,3B4h ; DX := CRTC address port
call Find6845
jc @@L44 ; jump if not present
mov dl,0BAh ; DX := 3BAh (status port)
in al,dx
and al,80h
mov ah,al ; AH := bit 7 (vertical sync on HGC)
mov cx,8000h ; do this 32768 times
@@L41: in al,dx
and al,80h ; isolate bit 7
cmp ah,al
loope @@L41 ; wait for bit 7 to change
jne @@L42 ; if bit 7 changed, it's a Hercules
mov al,MDA ; if bit 7 didn't change, it's an MDA
mov ah,MDADisplay
call FoundDevice
jmp short @@L44
@@L42: in al,dx
mov dl,al ; DL := value from status port
and dl,01110000b ; mask bits 4 thru 6
mov ah,MDADisplay ; assume it's a monochrome display
mov al,HGCPlus ; look for an HGC+
cmp dl,00010000b
je @@L43 ; jump if it's an HGC+
mov al,HGC ; look for an InColor card or HGC
cmp dl,01010000b
jne @@L43 ; jump if it's not an InColor card
mov al,InColor ; it's an InColor card
mov ah,EGAColorDisplay
@@L43: call FoundDevice
@@L44: ret
FindMono ENDP
;
; Find6845
;
; This routine detects the presence of the CRTC on a MDA, CGA or HGC.
; The technique is to write and read register 0Fh of the chip (cursor
; low). If the same value is read as written, assume the chip is
; present at the specified port addr.
;
Find6845 PROC near ; Caller: DX = port addr
; Returns: cf set if not present
mov al,0Fh
out dx,al ; select 6845 reg 0Fh (Cursor Low)
inc dx
in al,dx ; AL := current Cursor Low value
mov ah,al ; preserve in AH
mov al,66h ; AL := arbitrary value
out dx,al ; try to write to 6845
mov cx,100h
@@L51: loop @@L51 ; wait for 6845 to respond
in al,dx
xchg ah,al ; AH := returned value
; AL := original value
out dx,al ; restore original value
cmp ah,66h ; test whether 6845 responded
je @@L52 ; jump if it did (cf is reset)
stc ; set carry flag if no 6845 present
@@L52: ret
Find6845 ENDP
;
; FindActive
;
; This subroutine stores the currently active device as Device0. The
; current video mode determines which subsystem is active.
;
FindActive PROC near
cmp word ptr Device1,0
je @@L63 ; exit if only one subsystem
cmp Video0Type[di],4 ; exit if MCGA or VGA present
jge @@L63 ; (INT 10H function 1AH
cmp Video1Type[di],4 ; already did the work)
jge @@L63
mov ah,0Fh
int 10h ; AL := current BIOS video mode
and al,7
cmp al,7 ; jump if monochrome
je @@L61 ; (mode 7 or 0Fh)
cmp Display0Type[di],MDADisplay
jne @@L63 ; exit if Display0 is color
jmp short @@L62
@@L61: cmp Display0Type[di],MDADisplay
je @@L63 ; exit if Display0 is monochrome
@@L62: mov ax,Device0 ; make Device0 currently active
xchg ax,Device1
mov Device0,ax
@@L63: ret
FindActive ENDP
;
; FoundDevice
;
; This routine updates the list of subsystems.
;
FoundDevice PROC near ; Caller: AH = display #
; AL = subsystem #
; Destroys: BX
lea bx,Video0Type[di]
cmp byte ptr [bx],0
je @@L71 ; jump if 1st subsystem
lea bx,Video1Type[di] ; must be 2nd subsystem
@@L71: mov [bx],ax ; update list entry
ret
FoundDevice ENDP
IDEAL
END
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