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ID_VW_AE.ASM
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ID_VW_AE.ASM
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; Catacomb Abyss Source Code
; Copyright (C) 1993-2014 Flat Rock Software
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License along
; with this program; if not, write to the Free Software Foundation, Inc.,
; 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
;=================================
;
; EGA view manager routines
;
;=================================
;============================================================================
;
; All EGA drawing routines that write out words need to have alternate forms
; for starting on even and odd addresses, because writing a word at segment
; offset 0xffff causes an exception! To work around this, write a single
; byte out to make the address even, so it wraps cleanly at the end.
;
; All of these routines assume read/write mode 0, and will allways return
; in that state.
; The direction flag should be clear
; readmap/writemask is left in an undefined state
;
;============================================================================
;============================================================================
;
; VW_Plot (int x,y,color)
;
;============================================================================
DATASEG
plotpixels db 128,64,32,16,8,4,2,1
CODESEG
PROC VW_Plot x:WORD, y:WORD, color:WORD
PUBLIC VW_Plot
USES SI,DI
mov es,[screenseg]
mov dx,SC_INDEX
mov ax,SC_MAPMASK+15*256
WORDOUT
mov dx,GC_INDEX
mov ax,GC_MODE+2*256 ;write mode 2
WORDOUT
mov di,[bufferofs]
mov bx,[y]
shl bx,1
add di,[ylookup+bx]
mov bx,[x]
mov ax,bx
shr ax,1
shr ax,1
shr ax,1
add di,ax ; di = byte on screen
and bx,7
mov ah,[plotpixels+bx]
mov al,GC_BITMASK ;mask off other pixels
WORDOUT
mov bl,[BYTE color]
xchg bl,[es:di] ; load latches and write pixel
mov dx,GC_INDEX
mov ah,0ffh ;no bit mask
WORDOUT
mov ax,GC_MODE+0*256 ;write mode 0
WORDOUT
ret
ENDP
;============================================================================
;
; VW_Vlin (int yl,yh,x,color)
;
;============================================================================
PROC VW_Vlin yl:WORD, yh:WORD, x:WORD, color:WORD
PUBLIC VW_Vlin
USES SI,DI
mov es,[screenseg]
mov dx,SC_INDEX
mov ax,SC_MAPMASK+15*256
WORDOUT
mov dx,GC_INDEX
mov ax,GC_MODE+2*256 ;write mode 2
WORDOUT
mov di,[bufferofs]
mov bx,[yl]
shl bx,1
add di,[ylookup+bx]
mov bx,[x]
mov ax,bx
shr ax,1
shr ax,1
shr ax,1
add di,ax ; di = byte on screen
and bx,7
mov ah,[plotpixels+bx]
mov al,GC_BITMASK ;mask off other pixels
WORDOUT
mov cx,[yh]
sub cx,[yl]
inc cx ;number of pixels to plot
mov bh,[BYTE color]
mov dx,[linewidth]
@@plot:
mov bl,bh
xchg bl,[es:di] ; load latches and write pixel
add di,dx
loop @@plot
mov dx,GC_INDEX
mov ah,0ffh ;no bit mask
WORDOUT
mov ax,GC_MODE+0*256 ;write mode 0
WORDOUT
ret
ENDP
;============================================================================
;===================
;
; VW_DrawTile8
;
; xcoord in bytes (8 pixels), ycoord in pixels
; All Tile8s are in one grseg, so an offset is calculated inside it
;
;===================
PROC VW_DrawTile8 xcoord:WORD, ycoord:WORD, tile:WORD
PUBLIC VW_DrawTile8
USES SI,DI
mov es,[screenseg]
mov di,[bufferofs]
add di,[xcoord]
mov bx,[ycoord]
shl bx,1
add di,[ylookup+bx]
mov [ss:screendest],di ;screen destination
mov bx,[linewidth]
dec bx
mov si,[tile]
shl si,1
shl si,1
shl si,1
shl si,1
shl si,1
mov ds,[grsegs+STARTTILE8*2] ; segment for all tile8s
mov cx,4 ;planes to draw
mov ah,0001b ;map mask
mov dx,SC_INDEX
mov al,SC_MAPMASK
;
; start drawing
;
@@planeloop:
WORDOUT
shl ah,1 ;shift plane mask over for next plane
mov di,[ss:screendest] ;start at same place in all planes
REPT 7
movsb
add di,bx
ENDM
movsb
loop @@planeloop
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
ENDP
;============================================================================
;
; VW_MaskBlock
;
; Draws a masked block shape to the screen. bufferofs is NOT accounted for.
; The mask comes first, then four planes of data.
;
;============================================================================
DATASEG
UNWOUNDMASKS = 10
maskroutines dw mask0,mask0,mask1E,mask1E,mask2E,mask2O,mask3E,mask3O
dw mask4E,mask4O,mask5E,mask5O,mask6E,mask6O
dw mask7E,mask7O,mask8E,mask8O,mask9E,mask9O
dw mask10E,mask10O
routinetouse dw ?
CODESEG
PROC VW_MaskBlock segm:WORD, ofs:WORD, dest:WORD, wide:WORD, height:WORD, planesize:WORD
PUBLIC VW_MaskBlock
USES SI,DI
mov es,[screenseg]
mov [BYTE planemask],1
mov [BYTE planenum],0
mov di,[wide]
mov dx,[linewidth]
sub dx,[wide]
mov [linedelta],dx ;amount to add after drawing each line
mov bx,[planesize] ; si+bx = data location
cmp di,UNWOUNDMASKS
jbe @@unwoundroutine
mov [routinetouse],OFFSET generalmask
jmp NEAR @@startloop
;=================
;
; use the unwound routines
;
;=================
@@unwoundroutine:
mov cx,[dest]
shr cx,1
rcl di,1 ;shift a 1 in if destination is odd
shl di,1 ;to index into a word width table
mov ax,[maskroutines+di] ;call the right routine
mov [routinetouse],ax
@@startloop:
mov ds,[segm]
@@drawplane:
mov dx,SC_INDEX
mov al,SC_MAPMASK
mov ah,[ss:planemask]
WORDOUT
mov dx,GC_INDEX
mov al,GC_READMAP
mov ah,[ss:planenum]
WORDOUT
mov si,[ofs] ;start back at the top of the mask
mov di,[dest] ;start at same place in all planes
mov cx,[height] ;scan lines to draw
mov dx,[ss:linedelta]
jmp [ss:routinetouse] ;draw one plane
planereturn: ;routine jmps back here
add bx,[ss:planesize] ;start of mask = start of next plane
inc [ss:planenum]
shl [ss:planemask],1 ;shift plane mask over for next plane
cmp [ss:planemask],10000b ;done all four planes?
jne @@drawplane
mask0:
mov ax,ss
mov ds,ax
ret ;width of 0 = no drawing
;==============
;
; General purpose masked block drawing. This could be optimised into
; four routines to use words, but few play loop sprites should be this big!
;
;==============
generalmask:
mov dx,cx
@@lineloopgen:
mov cx,[wide]
@@byteloop:
mov al,[es:di]
and al,[si]
or al,[bx+si]
inc si
stosb
loop @@byteloop
add di,[ss:linedelta]
dec dx
jnz @@lineloopgen
jmp planereturn
;=================
;
; Horizontally unwound routines to draw certain masked blocks faster
;
;=================
MACRO MASKBYTE
mov al,[es:di]
and al,[si]
or al,[bx+si]
inc si
stosb
ENDM
MACRO MASKWORD
mov ax,[es:di]
and ax,[si]
or ax,[bx+si]
inc si
inc si
stosw
ENDM
MACRO SPRITELOOP addr
add di,dx
loop addr
jmp planereturn
ENDM
EVEN
mask1E:
MASKBYTE
SPRITELOOP mask1E
EVEN
mask2E:
MASKWORD
SPRITELOOP mask2E
EVEN
mask2O:
MASKBYTE
MASKBYTE
SPRITELOOP mask2O
EVEN
mask3E:
MASKWORD
MASKBYTE
SPRITELOOP mask3E
EVEN
mask3O:
MASKBYTE
MASKWORD
SPRITELOOP mask3O
EVEN
mask4E:
MASKWORD
MASKWORD
SPRITELOOP mask4E
EVEN
mask4O:
MASKBYTE
MASKWORD
MASKBYTE
SPRITELOOP mask4O
EVEN
mask5E:
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask5E
EVEN
mask5O:
MASKBYTE
MASKWORD
MASKWORD
SPRITELOOP mask5O
EVEN
mask6E:
MASKWORD
MASKWORD
MASKWORD
SPRITELOOP mask6E
EVEN
mask6O:
MASKBYTE
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask6O
EVEN
mask7E:
MASKWORD
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask7E
EVEN
mask7O:
MASKBYTE
MASKWORD
MASKWORD
MASKWORD
SPRITELOOP mask7O
EVEN
mask8E:
MASKWORD
MASKWORD
MASKWORD
MASKWORD
SPRITELOOP mask8E
EVEN
mask8O:
MASKBYTE
MASKWORD
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask8O
EVEN
mask9E:
MASKWORD
MASKWORD
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask9E
EVEN
mask9O:
MASKBYTE
MASKWORD
MASKWORD
MASKWORD
MASKWORD
SPRITELOOP mask9O
EVEN
mask10E:
MASKWORD
MASKWORD
MASKWORD
MASKWORD
MASKWORD
SPRITELOOP mask10E
EVEN
mask10O:
MASKBYTE
MASKWORD
MASKWORD
MASKWORD
MASKWORD
MASKBYTE
SPRITELOOP mask10O
ENDP
;============================================================================
;
; VW_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 VW_ScreenToScreen source:WORD, dest:WORD, wide:WORD, height:WORD
PUBLIC VW_ScreenToScreen
USES SI,DI
pushf
cli
mov dx,SC_INDEX
mov ax,SC_MAPMASK+15*256
WORDOUT
mov dx,GC_INDEX
mov ax,GC_MODE+1*256
WORDOUT
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
mov ax,GC_MODE+0*256
WORDOUT
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
ENDP
;============================================================================
;
; VW_MemToScreen
;
; Basic block drawing routine. Takes a block shape at segment pointer source
; with four planes of width by height data, and draws it to dest in the
; virtual screen, based on linewidth. bufferofs is NOT accounted for.
; There are four drawing routines to provide the best optimized code while
; accounting for odd segment wrappings due to the floating screens.
;
;============================================================================
DATASEG
memtoscreentable dw eventoeven,eventoodd,oddtoeven,oddtoodd
CODESEG
PROC VW_MemToScreen source:WORD, dest:WORD, wide:WORD, height:WORD
PUBLIC VW_MemToScreen
USES SI,DI
mov es,[screenseg]
mov bx,[linewidth]
sub bx,[wide]
mov ds,[source]
xor si,si ;block is segment aligned
xor di,di
shr [wide],1 ;change wide to words, and see if carry is set
rcl di,1 ;1 if wide is odd
mov ax,[dest]
shr ax,1
rcl di,1 ;shift a 1 in if destination is odd
shl di,1 ;to index into a word width table
mov ax,SC_MAPMASK+0001b*256 ;map mask for plane 0
jmp [ss:memtoscreentable+di] ;call the right routine
;==============
;
; Copy an even width block to an even video address
;
;==============
eventoeven:
mov dx,SC_INDEX
WORDOUT
mov di,[dest] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
@@lineloopEE:
mov cx,[wide]
rep movsw
add di,bx
dec dx
jnz @@lineloopEE
shl ah,1 ;shift plane mask over for next plane
cmp ah,10000b ;done all four planes?
jne eventoeven
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
;==============
;
; Copy an odd width block to an even video address
;
;==============
oddtoeven:
mov dx,SC_INDEX
WORDOUT
mov di,[dest] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
@@lineloopOE:
mov cx,[wide]
rep movsw
movsb ;copy the last byte
add di,bx
dec dx
jnz @@lineloopOE
shl ah,1 ;shift plane mask over for next plane
cmp ah,10000b ;done all four planes?
jne oddtoeven
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
;==============
;
; Copy an even width block to an odd video address
;
;==============
eventoodd:
dec [wide] ;one word has to be handled seperately
EOplaneloop:
mov dx,SC_INDEX
WORDOUT
mov di,[dest] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
@@lineloopEO:
movsb
mov cx,[wide]
rep movsw
movsb
add di,bx
dec dx
jnz @@lineloopEO
shl ah,1 ;shift plane mask over for next plane
cmp ah,10000b ;done all four planes?
jne EOplaneloop
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
;==============
;
; Copy an odd width block to an odd video address
;
;==============
oddtoodd:
mov dx,SC_INDEX
WORDOUT
mov di,[dest] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
@@lineloopOO:
movsb
mov cx,[wide]
rep movsw
add di,bx
dec dx
jnz @@lineloopOO
shl ah,1 ;shift plane mask over for next plane
cmp ah,10000b ;done all four planes?
jne oddtoodd
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
ENDP
;===========================================================================
;
; VW_ScreenToMem
;
; Copies a block of video memory to main memory, in order from planes 0-3.
; This could be optimized along the lines of VW_MemToScreen to take advantage
; of word copies, but this is an infrequently called routine.
;
;===========================================================================
PROC VW_ScreenToMem source:WORD, dest:WORD, wide:WORD, height:WORD
PUBLIC VW_ScreenToMem
USES SI,DI
mov es,[dest]
mov bx,[linewidth]
sub bx,[wide]
mov ds,[screenseg]
mov ax,GC_READMAP ;read map for plane 0
xor di,di
@@planeloop:
mov dx,GC_INDEX
WORDOUT
mov si,[source] ;start at same place in all planes
mov dx,[height] ;scan lines to draw
@@lineloop:
mov cx,[wide]
rep movsb
add si,bx
dec dx
jnz @@lineloop
inc ah
cmp ah,4 ;done all four planes?
jne @@planeloop
mov ax,ss
mov ds,ax ;restore turbo's data segment
ret
ENDP
;============================================================================
;
; VWL_UpdateScreenBlocks
;
; Scans through the update matrix and copies any areas that have changed
; to the visable screen, then zeros the update array
;
;============================================================================
; AX 0/1 for scasb, temp for segment register transfers
; BX width for block copies
; CX REP counter
; DX line width deltas
; SI source for copies
; DI scas dest / movsb dest
; BP pointer to end of bufferblocks
PROC VWL_UpdateScreenBlocks
PUBLIC VWL_UpdateScreenBlocks
USES SI,DI,BP
jmp SHORT @@realstart
@@done:
;
; all tiles have been scanned
;
mov dx,GC_INDEX ; restore write mode 0
mov ax,GC_MODE+0*256
WORDOUT
xor ax,ax ; clear out the update matrix
mov cx,UPDATEWIDE*UPDATEHIGH/2
mov di,[updateptr]
rep stosw
ret
@@realstart:
mov dx,SC_INDEX
mov ax,SC_MAPMASK+15*256
WORDOUT
mov dx,GC_INDEX
mov ax,GC_MODE+1*256
WORDOUT
mov di,[updateptr] ; start of floating update screen
mov bp,di
add bp,UPDATEWIDE*UPDATEHIGH+1 ; when di = bp, all tiles have been scanned
push di
mov cx,-1 ; definately scan the entire thing
;
; scan for a 1 in the update list, meaning a tile needs to be copied
; from the master screen to the current screen
;
@@findtile:
pop di ; place to continue scaning from
mov ax,ss
mov es,ax ; search in the data segment
mov ds,ax
mov al,1
repne scasb
cmp di,bp
jae @@done
cmp [BYTE di],al
jne @@singletile
jmp @@tileblock
;============
;
; copy a single tile
;
;============
@@singletile:
inc di ; we know the next tile is nothing
push di ; save off the spot being scanned
sub di,[updateptr]
shl di,1
mov di,[blockstarts-4+di] ; start of tile location on screen
mov si,di
add si,[bufferofs]
add di,[displayofs]
mov dx,[linewidth]
sub dx,2
mov ax,[screenseg]
mov ds,ax
mov es,ax
REPT 15
movsb
movsb
add si,dx
add di,dx
ENDM
movsb
movsb
jmp @@findtile
;============
;
; more than one tile in a row needs to be updated, so do it as a group
;
;============
EVEN
@@tileblock:
mov dx,di ; hold starting position + 1 in dx
inc di ; we know the next tile also gets updated
repe scasb ; see how many more in a row
push di ; save off the spot being scanned
mov bx,di
sub bx,dx ; number of tiles in a row
shl bx,1 ; number of bytes / row
mov di,dx ; lookup position of start tile
sub di,[updateptr]
shl di,1
mov di,[blockstarts-2+di] ; start of tile location
mov si,di
add si,[bufferofs]
add di,[displayofs]
mov dx,[linewidth]
sub dx,bx ; offset to next line on screen
mov ax,[screenseg]
mov ds,ax
mov es,ax
REPT 15
mov cx,bx
rep movsb
add si,dx
add di,dx
ENDM
mov cx,bx
rep movsb
dec cx ; was 0 from last rep movsb, now $ffff for scasb
jmp @@findtile
ENDP
;===========================================================================
;
; MISC EGA ROUTINES
;
;===========================================================================
;==============
;
; VW_SetScreen
;
;==============
PROC VW_SetScreen crtc:WORD, pel:WORD
PUBLIC VW_SetScreen
if waitforvbl
mov dx,STATUS_REGISTER_1
;
; wait util the CRTC just starts scaning a diplayed line to set the CRTC start
;
cli
@@waitnodisplay:
in al,dx
test al,1
jz @@waitnodisplay
; the display is now disabled (in a HBL / VBL)
@@waitdisplay:
in al,dx
test al,1 ;1 = display is disabled (HBL / VBL)
jnz @@waitdisplay
; the display was just enabled, so a full scan line is available for CRTC set
endif
;
; set CRTC start
;
; for some reason, my XT's EGA card doesn't like word outs to the CRTC
; index...
;