PAGE    ,132
        TITLE   BltProp.asm
        NAME    BltProp

?WIN = 0
?PLM = 1

.286

.xlist
        include cmacros.inc
        include windows.inc
.list

; The following structure should be used to access high and low
; words of a DWORD.  This means that "word ptr foo[2]" -> "foo.hi".

LONG    struc
lo      dw      ?
hi      dw      ?
LONG    ends

FARPOINTER      struc
off     dw      ?
sel     dw      ?
FARPOINTER      ends

MAXWIDTH = 1500

externA  __AHINCR

sBegin DATA

;;externW     sColorsOut
;;externW     GrayThresh
;;externW     LoThresh
;;externW     HiThresh
;;externW     Prop
;;externW     Mult

GrayThresh  dw      128            ; 135
LoThresh    dw      128            ; 120
HiThresh    dw      192            ; 200
Prop        dw      8              ; 6
Mult        dw      32, 32, 32     ; 28, 28, 28

usPalMult   DW      3 * 256 DUP (?)

sCol        DW      0

v           DW      3 DUP (?)
val         DW      3 DUP (?)
errx        DW      3 DUP (?)
errz        DW      3 DUP (?)
erry        DW      3 * MAXWIDTH DUP (?)


; the output Color Table
;
;      The pixel values that index this table are generated by PropImage
;      as follows:
;
;          bits 7x543210
;               | ||||||
;               | |||||+-- set iff RED   > HiThresh
;               | ||||+--- set iff RED   > LoThresh
;               | |||+---- set iff GREEN > HiThresh
;               | ||+----- set iff GREEN > LoThresh
;               | |+------ set iff BLUE  > HiThresh
;               | +------- set iff BLUE  > LoThresh
;               +--------- set iff all colors > GrayThresh
;
;      The color values map to the appropriate 16 colors of the standard
;      palette.
;
;      0        - LoThresh     0
;      LoThresh - HiThresh     128
;      HiThresh - 255          255
;
;       As usual the magic grays are special cased
;

dwrgb   macro   n

        red    = 0
        green  = 0
        blue   = 0

        if n and 010101b
            rgbval = 0FFh
        else
            rgbval = 080h
        endif

        if n and 000011b
            red = rgbval
        endif

        if n and 001100b
            green = rgbval
        endif

        if n and 110000b
            blue = rgbval
        endif

        if n eq 0AAh
            red   = 0C0h
            green = 0C0h
            blue  = 0C0h
        endif

        if n eq 080h
            red   = 080h
            green = 080h
            blue  = 080h
        endif

        dw  red,green,blue

        endm

sColorsOut label word

        n = 0
        rept    256
            dwrgb n
            n = n + 1
        endm


sEnd DATA


sBegin CODE
        assumes  ds,DATA
        assumes  ss,DATA
        assumes  cs,CODE

;-------------------------------------------------------------------------;
;
; BltProp
;
;   Does error proagation on a input 8 bpp DIB producing a 8 bpp DIB
;   that only uses 16 colors.
;
;   assumes SS == DS !!
;
; Entry:
;
; Returns:
;       AX = 1
; Error Returns:
;       AX = 0  if error
; Registers Preserved:
;       SI,DI,DS,BP
; Registers Destroyed:
;       AX,BX,CX,DX,FLAGS
; Calls:
;
;-------------------------------------------------------------------------;

cProc   BltProp, <FAR, PUBLIC, PASCAL>, <ds,si,di>

        parmD   pbiSrc      ; BITMAP info for source DIB
        parmD   pbSrc       ; Source bits pointer
        parmW   SrcX        ; Source X offset
        parmW   SrcY        ; Source Y offset
        parmW   SrcXE       ; Source X extent
        parmW   SrcYE       ; Source Y extent
        parmD   pbiDst      ; BITMAP info for destination DIB
        parmD   pbDst       ; Destination bits pointer
        parmW   DstX        ; Destination X offset
        parmW   DstY        ; Destination Y offset

        localW  cbScanSrc   ; width of a source scanline
        localW  cbScanDst

        localW  cbIncS      ; next scan
        localW  cbIncD
cBegin
        mov     ax,ds
        mov     es,ax
        lea     di,erry                 ; clear out erry[]
        xor     ax,ax
        mov     cx,3 * MAXWIDTH
        rep     stosb

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
; pre-multiply the input palette by the intensity multipliers
;
; for (row = 0; row < cColorsIn; ++row)
;    for (clr = 0; clr < 3; ++clr)
;        usPalMult[row][2-clr] = rcbmIn.argbColor[row][clr] * Mult[2-clr] / 32;
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;

        les     di,pbiSrc                   ; es:[di] --> source BITMAPINFO

        mov     ax,word ptr es:[di].biWidth ; DWORD align bitmap width
        add     ax,3
        and     ax,not 3
        mov     cbScanSrc,ax

        add     di,word ptr es:[di].biSize  ; es:[di] --> color table

        lea     si,usPalMult                ; ds:[si] --> usPalMult
        mov     cx,256

PalMulLoop:

        xor     bx,bx

irp     rgbX, <rgbRed,rgbGreen,rgbBlue>
        xor     ah,ah
        mov     al,es:[di].&rgbX
        mul     Mult[bx]
        shr     ax,5
        mov     ds:[si+bx],ax
        add     bx,2
endm
        add     si,6
        add     di,4

        loop    PalMulLoop

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
; fill in the destination color table
;
;    for (inx = 0; inx < 256; ++inx)
;        for (clr = 0; clr < 3; ++clr)
;            rcbmOut.argbColor[inx][clr] = (BYTE)sColorsOut[inx][2-clr];
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;

        les     di,pbiDst                   ; es:[di] --> destination BITMAPINFO

        mov     ax,word ptr es:[di].biWidth ; DWORD align bitmap width
        add     ax,3
        and     ax,not 3
        mov     cbScanDst,ax

        add     di,word ptr es:[di].biSize  ; es:[di] --> color table

        lea     si,sColorsOut               ; ds:[si] --> sColorsOut
        mov     cx,256

sColorsOutLoop:
        lodsw
        mov     es:[di].rgbRed  ,al

        lodsw
        mov     es:[di].rgbGreen,al

        lodsw
        mov     es:[di].rgbBlue ,al

        add     di,4

        loop    sColorsOutLoop

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
;   caclulate amount to add to source/dest pointer to get the the next scanline
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
        mov     bx,SrcXE

        mov     ax,cbScanSrc
        sub     ax,bx                   ; cbIncS = source ptr inc ea. row
	mov	cbIncS,ax

        mov     ax,cbScanDst
        sub     ax,bx                   ; cbIncD = dest ptr inc ea. row
        mov     cbIncD,ax

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
;   caclulate the source/dest bitmap pointers
;
;   ds:si   --> source bitmap bits  (pbSrc + cbScanSrc * SrcY + SrcX)
;   es:di   --> dest bitmap bits    (pbDst + cbScanDst * DstY + DstX)
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;

        mov     ax, DstY                ; ax = start scan
        mul     cbScanDst               ; ax *= size of a scanline
        add     ax, DstX                ; ax += X offset
        adc     dx, 0                   ; dx = segment number

        mov     di, ax                  ; set di = offset into segment
        add     di, pbDst.off

        mov     ax,dx                   ; set es = segment
        mov     bx,__AHINCR
        mul     bx
        add     ax, pbDst.sel

        mov     es,ax
;
        mov     ax, SrcY                ; ax = start scan
        mul     cbScanSrc               ; ax *= size of a scanline
        add     ax, SrcX                ; ax += X offset
        adc     dx, 0                   ; dx = segment number

        mov     si, ax                  ; set si = offset into segment
        add     si, pbSrc.off

        mov     ax,dx                   ; set ds = segment
        mov     bx,__AHINCR
        mul     bx
        add     ax, pbSrc.sel

        mov     ds,ax

        assume  ds:nothing

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
;   start a new row
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;

RowLoop:
	xor	ax,ax			; clear X error for start of line
	mov	errx,ax
	mov	errx+2,ax
	mov	errx+4,ax
	mov	errz,ax 		; clear Z error for start of line
	mov	errz+2,ax
	mov	errz+4,ax

        mov     ax,SrcXE                ; sCol = number of cols to do
	mov	sCol,ax
	xor	bx,bx			; (bx) = initial column number

;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
;
;   start of the column loop
;
;   MOTE: bp is used in this loop!!! stack locals are not accessable.
;
;       es:di --> dest bits
;       ds:si --> source bits
;       bx    =   Current column # * 6
;       bp    =   is *NOT* stack frame
;       ss    =   DGROUP
;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;

        push    bp
ColLoop:
        lodsb                           ; get a source BYTE
	xor	ah,ah			; (ax) = dib color
	add	ax,ax			; (ax) = 2 * dib color
	mov	bp,ax			; (bp) = 2 * dib color
	add	ax,ax			; (ax) = 4 * dib color
	add	bp,ax			; (bp) = 6 * dib color (usPalMult index)

	mov	cx,80H			; CL = lointens (MSB flag)
	xor	ax,ax			; AL = output value

irpc color,<420>
	mov	dx,errz[color]		; move previous Z error to next Y
	xchg	dx,erry[bx+color]	;    and get this Y error
	add	dx,usPalMult[bp+color]	; desired intensity of this color
	add	dx,errx[color]		; plus X error
	mov	v[color],dx		; save for ClrLoop2

	cmp	LoThresh,dx		; above low threshold?
	lahf				; set bit for this color accordingly
	rol	ax,1
	cmp	HiThresh,dx		; above high threshold?
	lahf				; set bit for this color accordingly
	rol	ax,1
	cmp	GrayThresh,dx		; above gray threshold?
	lahf				; AND together gray requirements
	and	cl,ah
endm
	or	al,cl			; compose value

;	(al) =	Output color value
;	(bx) =	Column number * 6
;	(ss) =	DGROUP

        stosb                           ; write a dest byte

	xor	ah,ah
	add	ax,ax
	mov	bp,ax
	add	ax,ax
	add	bp,ax			; BP = input value * 6 (usPalMult index)

	cmp	Prop,0
      ;;jz	NoProp

irpc	color,<420>
	mov	ax,v[color]		; compute error for this color
	sub	ax,sColorsOut[bp+color]
	imul	Prop
	xor	ax,dx			; ABS error
	sub	ax,dx	;;
	shr	ax,5			; / 32
	mov	cx,ax
	shr	cx,1			; / 64 for Z
	xor	ax,dx			; unABS error
	sub	ax,dx	;;
	xor	cx,dx			; unABS error
	sub	cx,dx	;;
	add	erry[bx+color],ax	; add Y error to previous Z
	mov	errx[color],ax		; set X error
	mov	errz[color],cx		; set Z error
endm

;	We get weird, below, trying to allow the common jump cases to fall
;	through.  Since ColLoop is so large, we will use the dead space
;	after the unconditional jump to hide out-of-line code


NoProp:
        or      si,si
        jz      fixSSeg

fixDOff:
        or      di,di
        jz      fixDSeg

EndColLoop:
	add	bx,6
	dec	sCol
	jz	ColLoopDone
	jmp	ColLoop

fixSSeg:
        mov     ax,ds
        add     ax,__AHINCR
        mov     ds,ax
	jmp	fixDOff

fixDSeg:
        mov     ax,es
        add     ax,__AHINCR
        mov     es,ax
	jmp	EndColLoop
ColLoopDone:

;	End Weirdness.

        pop     bp                      ; it is safe to use locals now

        add     si,cbIncS
        jnc     @f
        mov     ax,ds
        add     ax,__AHINCR
        mov     ds,ax
@@:
        add     di,cbIncD
        jnc     @f
        mov     ax,es
        add     ax,__AHINCR
        mov     es,ax
@@:
        dec     SrcYE
	jz	@F
	jmp	RowLoop
@@:

cEnd

sEnd CODE

END