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Assembly Source File | 1992-09-12 | 29.1 KB | 1,295 lines

page ,132 ; (C) Copyright Microsoft Corp. 1991. All rights reserved. ; ; You have a royalty-free right to use, modify, reproduce and ; distribute the Sample Files (and/or any modified version) in ; any way you find useful, provided that you agree that ; Microsoft has no warranty obligations or liability for any ; Sample Application Files which are modified. .xlist include cmacros.inc include windows.inc .list externA __WinFlags ; in KERNEL externA __AHSHIFT externA __AHINCR LONG struc lo dw ? hi dw ? LONG ends FARPOINTER struc off dw ? sel dw ? FARPOINTER ends ; DDA structure DDASTRUC struc pixCur dw ? ; current X position pixXinc dw ? ; amount to add to X (-1, 0, or 1) pixSlope dw ? ; BOOL: non-zero if DX <= DY pixError dw ? ; current amount of error pixErrReset dw ? ; amount to add to update error pixRem dw ? ; amount to add to reset error DDASTRUC ends smov macro segreg1,segreg2 push segreg2 pop segreg1 endm jmps macro there jmp short there endm wptr equ word ptr bptr equ byte ptr sBegin DATA sEnd DATA sBegin CODE assumes CS,CODE assumes DS,DATA externFP PatBlt ; ; Draw a triangle using GID's PatBlit. ; ; This code was the source for the DIBTriangle and is left here ; as an example. ; ; There is a lot of duplication between the routines, but that is ; because they are meant to be stand-alond examples ; cProc Triangle,<FAR,PUBLIC>,<si,di> parmW hDC parmD lpPoints localD dummy localW wNextScan localW nScans ; # scans in first part of triangle localW curY ; current scan localW pLineToChange ; address of DDA struct that will ; be updated for the second part of ; triangle localV pts, %(3*(size POINT)) ; local (sorted) copy of points localV lineL, %(size DDASTRUC) ; DDA info for left line localV lineR, %(size DDASTRUC) ; DDA info for right line cBegin ;--------------------------------------------------------------------------- ; Sort the points by increasing Y order. Points are assumed to be in device ; coordinates by now. ;--------------------------------------------------------------------------- smov es, ss ; point es:di to pts buffer lea di, pts lds si, lpPoints ; point ds:si to input points lodsw ; get first point in cx, dx xchg cx, ax ; lodsw ; xchg dx, ax ; cx = X1 dx = Y1 lodsw ; get second point in bx, ax xchg bx, ax ; lodsw ; bx = X2 ax = Y2 xchg ax, bx ; ax = X2 bx = Y2 cmp bx, dx ; sort so that (ax, bx) <= (cx, dx) jle @F ; if Y1 <= Y2 then we're fine xchg ax, cx ; swap Y1 and Y2 xchg bx, dx ; swap X1 and X2 @@: cmp bx, [si+2] ; is (ax, bx) min coordinate? jle @F movsw ; copy smallest point to buffer movsw ; jmps trisort10 ; copy remainder to buffer @@: stosw ; copy smallest point to buffer xchg ax, bx ; stosw ; lodsw ; get third point in (ax, bx) xchg ax, bx lodsw xchg ax, bx ; ax = X3 bx = Y3 cmp bx, dx ; sort so that (ax, bx) <= (cx, dx) jle trisort10 ; if Y1 <= Y2 then we're fine xchg ax, cx ; swap Y1 and Y2 xchg bx, dx ; swap X1 and X2 trisort10: stosw ; copy middle point to buffer xchg ax, bx ; stosw ; xchg ax, cx ; copy largest point to buffer stosw ; xchg ax, dx ; stosw ; EndTriSort: ;--------------------------------------------------------------------------- ; Initialize the DDA structures so that we can fill between lineL and lineR. ;--------------------------------------------------------------------------- smov ds, ss ; point DS to stack lea si, pts ; point DS:SI to points lodsw ; get first two points: xchg bx, ax ; (dx,ax) = pt 2, (bx,cx) = pt 1 lodsw ; xchg cx, ax ; lodsw ; xchg dx, ax ; lodsw ; mov curY, cx ; start at top scan of triangle lea si, lineL ; point SI to left DDA structure lea di, lineR ; point DI to right DDA structure cmp dx, bx ; is X2 > X1 ? jle @F ; no, we chose correctly xchg si, di ; switch left/right pointers @@: mov pLineToChange, si ; remember which DDA structure will ; need to be updated at the cut. call TriInitDDA ; fill in left DDA structure mov nScans, ax ; save # scans to first endpoint push si lea si, pts ; point DS:SI to points lodsw ; get first & third points: xchg bx, ax ; (dx,ax) = pt 3, (bx,cx) = pt 1 lodsw ; xchg cx, ax ; add si, size POINT ; skip middle point lodsw ; xchg dx, ax ; lodsw ; pop si xchg si, di ; fill in right DDA structure call TriInitDDA ; ;--------------------------------------------------------------------------- ; Walk the DDAs of the left and right lines, which are pointed to by SI and ; BX respectively. For each scan call the routine that plots the scanline. ;--------------------------------------------------------------------------- xchg si, di ; SI = left line, DI = right line mov bx, di ; BX = right line TriRenderPiece: mov cx, nScans ; setup loop count jcxz TriNextPiece ; if current piece is TriRenderPieceLoop: push cx push bx mov ax, [si].pixCur ; Tell output routine to fill [ax,dx) mov dx, [bx].pixCur ; mov cx, curY ; on scanline cx mov bx, hDC ; ** pass in hDC for now... call OutScan ; pop bx mov cx, 2 ; two structures to update UpdateDDAs: xchg si, bx ; alternate between two structures mov ax, [si].pixXinc ; get X increment in a register or ax, ax ; is line vertical? jz EndOfDDAThing ; yes, no need to update DDA cmp [si].pixSlope, 0 ; is DX > DY? jz DoDDADXMajor ; yes, handle appropriately cmp [si].pixError, 0 ; is the error > 0 jle AddToError ; no, just add to error term add [si].pixCur, ax ; add X increment to current pixel mov ax, [si].pixErrReset ; update error term add [si].pixError, ax ; jmps EndOfDDAThing ; we're done with DDA now AddToError: mov ax, [si].pixRem ; add to error term add [si].pixError, ax ; jmps EndOfDDAThing ; we're done with DDA now DoDDADXMajor: push bx ; push cx ; mov cx, ax ; put pixXinc in cx for now mov dx, [si].pixError ; put error in dx for now mov ax, [si].pixErrReset ; update error term add dx, ax ; mov ax, [si].pixCur ; ax will have pixCur add ax, cx ; update current position mov bx, [si].pixRem ; bx will have pixRem DXMajorLoop: cmp dx, 0 ; is error <= 0? jg DoneDXMajorLoop ; no, so we're done add ax, cx ; pixCur += pixXinc add dx, bx ; pixError += pixRem jmps DXMajorLoop ; keep going DoneDXMajorLoop: mov [si].pixError, dx ; save values back in structure mov [si].pixCur, ax ; pop cx ; pop bx ; EndOfDDAThing: loop UpdateDDAs inc curY ; move to next scanline pop cx ; restore scan count loop TriRenderPieceLoop ; fill rest of triangle TriNextPiece: cmp pLineToChange, 0 ; if 0 we're done je TriDone ; push si ; save left line push bx lea si, pts + size POINT ; point si to second point lodsw ; get second & third points: xchg bx, ax ; (dx,ax) = pt 3, (bx,cx) = pt 2 lodsw ; xchg cx, ax ; lodsw ; xchg dx, ax ; lodsw ; mov si, pLineToChange ; point to DDA that will change call TriInitDDA ; and initialize for next line mov nScans, ax ; pop bx ; pop si ; mov pLineToChange, 0 ; signal this is last iteration jmp TriRenderPiece ; TriDone: cEnd ; Fill in DDA structure pointed to by DS:SI with line from (bx,cx) - (dx, ax) ; return DY in ax cProc TriInitDDA,<NEAR>,<si,di> cBegin ; Compute DX and DY, while preserving X values sub ax, cx xchg di, ax mov cx, dx sub cx, bx ; at this point the registers are as follows: ; di = DY cx = DX ; dx = iPtCur+1.X bx = iPtCur.X ; set the pixXinc xor ax, ax ; assume zero jcxz @F ; if it is great inc ax ; nope, assume it's positive or cx, cx ; is sign bit set? jns @F ; no, we chose correctly neg ax ; flip pixXinc neg cx ; force DX positive @@: ; Note: we don't need to check DY since the triangle code always passes in ; ax >= cx mov [si].pixXinc, ax ; save X increment in structure mov [si].pixCur, bx ; save pixCur in structure mov dx, di ; save DY in dx ; compute pixSlope (0 if DY > DX, non-zero otherwise) xor ax, ax ; assume DY > DX mov bx, 1 ; assume error roundup is 1 cmp cx, di ; check if DY is > DX jg @F ; yup, we picked correctly not ax ; nope, set pixSlope xchg cx, di ; swap DX and DY or di, di ; if minor axis >= 0 then error jns @F ; roundup is okay xor bx, bx ; nope, clear error roundoff @@: mov [si].pixSlope, ax shl di, 1 ; double minor axis length mov [si].pixRem, di sub di, cx add di, bx mov [si].pixError, di sub di, bx sub di, cx mov [si].pixErrReset, di mov ax, dx ; return DY cEnd ; draw line segment [ax,dx) on scanline cx on hDC in bx cProc OutScan,<NEAR>,<si,di> cBegin push bx ; hDC push ax ; X push cx ; Y sub dx, ax inc dx push dx ; nWidth mov ax, 1 push ax ; nHeight mov ax, 00F0h push ax ; PATCOPY mov ax, 0021h push ax cCall PatBlt ; use PatBlt to draw scanline cEnd ; ; This triangle code writes directly into the DIB memory ; ; ; WARNING: Known Bug: ; ; This code does not clip, and if it is asked to draw outside of image, ; it will try and usually cause GP Fault ; ; Clip points before calling this routine (or add clipping) ; ; adding clipping is left as an excercise for the reader. ; cProc DIBTriangle,<FAR,PUBLIC>,<si,di> parmD lpbi parmD lpPoints parmW crBrush localW wcrossflag ; set to 1 if sel crossing on next scan localW fnOutScan ; scanline output function localW wNextScan ; # of bytes to next scan line localW nScans ; # scans in first part of triangle localW curY ; current scan localW pLineToChange ; address of DDA struct that will ; be updated for the second part of ; triangle localV pts, %(3*(size POINT)) ; local (sorted) copy of points localV lineL, %(size DDASTRUC) ; DDA info for left line localV lineR, %(size DDASTRUC) ; DDA info for right line cBegin ;--------------------------------------------------------------------------- ; Sort the points by increasing Y order. Points are assumed to be in device ; coordinates by now. ;--------------------------------------------------------------------------- smov es, ss ; point es:di to pts buffer lea di, pts lds si, lpPoints ; point ds:si to input points lodsw ; get first point in cx, dx xchg cx, ax ; lodsw ; xchg dx, ax ; cx = X1 dx = Y1 lodsw ; get second point in bx, ax xchg bx, ax ; lodsw ; bx = X2 ax = Y2 xchg ax, bx ; ax = X2 bx = Y2 cmp bx, dx ; sort so that (ax, bx) <= (cx, dx) jle @F ; if Y1 <= Y2 then we're fine xchg ax, cx ; swap Y1 and Y2 xchg bx, dx ; swap X1 and X2 @@: cmp bx, [si+2] ; is (ax, bx) min coordinate? jle @F movsw ; copy smallest point to buffer movsw ; jmps ctrisort10 ; copy remainder to buffer @@: stosw ; copy smallest point to buffer xchg ax, bx ; stosw ; lodsw ; get third point in (ax, bx) xchg ax, bx lodsw xchg ax, bx ; ax = X3 bx = Y3 cmp bx, dx ; sort so that (ax, bx) <= (cx, dx) jle ctrisort10 ; if Y1 <= Y2 then we're fine xchg ax, cx ; swap Y1 and Y2 xchg bx, dx ; swap X1 and X2 ctrisort10: stosw ; copy middle point to buffer xchg ax, bx ; stosw ; xchg ax, cx ; copy largest point to buffer stosw ; xchg ax, dx ; stosw ; cEndTriSort: ;--------------------------------------------------------------------------- ; Initialize the DDA structures so that we can fill between lineL and lineR. ;--------------------------------------------------------------------------- smov ds, ss ; point DS to stack lea si, pts ; point DS:SI to points lodsw ; get first two points: xchg bx, ax ; (dx,ax) = pt 2, (bx,cx) = pt 1 lodsw ; xchg cx, ax ; lodsw ; xchg dx, ax ; lodsw ; mov curY, cx ; start at top scan of triangle lea si, lineL ; point SI to left DDA structure lea di, lineR ; point DI to right DDA structure cmp dx, bx ; is X2 > X1 ? jle @F ; no, we chose correctly xchg si, di ; switch left/right pointers @@: mov pLineToChange, si ; remember which DDA structure will ; need to be updated at the cut. call TriInitDDA ; fill in left DDA structure mov nScans, ax ; save # scans to first endpoint push si lea si, pts ; point DS:SI to points lodsw ; get first & third points: xchg bx, ax ; (dx,ax) = pt 3, (bx,cx) = pt 1 lodsw ; xchg cx, ax ; add si, size POINT ; skip middle point lodsw ; xchg dx, ax ; lodsw ; pop si xchg si, di ; fill in right DDA structure call TriInitDDA ; ;--------------------------------------------------------------------------- ; Walk the DDAs of the left and right lines, which are pointed to by SI and ; BX respectively. For each scan call the routine that plots the scanline. ;--------------------------------------------------------------------------- xchg si, di ; SI = left line, DI = right line mov bx, di ; BX = right line les di,lpbi mov ax,curY ; get y value of first scan line call tri_init ;;; mov ax,lpBuf.sel ; get segment of buffer ;;; mov es,ax ; into ES ;;; mov di,lpBuf.off ; lpbuf in ES:DI cTriRenderPiece: mov cx, nScans ; setup loop count jcxz cTriNextPiece ; if current piece is cTriRenderPieceLoop: push cx mov ax, [si].pixCur ; Tell output routine to fill [ax,dx) mov dx, [bx].pixCur ; ;;;;;;;;mov cx, curY ; on scanline cx cmp ax, dx ; Make sure AX <= DX jle @f xchg ax, dx ; swap point and wall pointers if not xchg bx, si ; @@: ;;;;;;;;arg lpBuf ;;;;;;;;arg <cx> ;;;;;;;;arg <ax> ;[bx].pixcur ;;;;;;;;arg <dx> ;[si].pixcur ;;;;;;;;arg crBrush push bx call [fnOutScan] pop bx ;;;;;;;; cCall DIBOutScan mov cx, 2 ; two structures to update cUpdateDDAs: xchg si, bx ; alternate between two structures mov ax, [si].pixXinc ; get X increment in a register or ax, ax ; is line vertical? jz cEndOfDDAThing ; yes, no need to update DDA cmp [si].pixSlope, 0 ; is DX > DY? jz cDoDDADXMajor ; yes, handle appropriately cmp [si].pixError, 0 ; is the error > 0 jle cAddToError ; no, just add to error term add [si].pixCur, ax ; add X increment to current pixel mov ax, [si].pixErrReset ; update error term add [si].pixError, ax ; jmps cEndOfDDAThing ; we're done with DDA now cAddToError: mov ax, [si].pixRem ; add to error term add [si].pixError, ax ; jmps cEndOfDDAThing ; we're done with DDA now cDoDDADXMajor: push bx ; push cx ; mov cx, ax ; put pixXinc in cx for now mov dx, [si].pixError ; put error in dx for now mov ax, [si].pixErrReset ; update error term add dx, ax ; mov ax, [si].pixCur ; ax will have pixCur add ax, cx ; update current position mov bx, [si].pixRem ; bx will have pixRem cDXMajorLoop: cmp dx, 0 ; is error <= 0? jg cDoneDXMajorLoop ; no, so we're done add ax, cx ; pixCur += pixXinc add dx, bx ; pixError += pixRem jmps cDXMajorLoop ; keep going cDoneDXMajorLoop: mov [si].pixError, dx ; save values back in structure mov [si].pixCur, ax ; pop cx ; pop bx ; cEndOfDDAThing: loop cUpdateDDAs inc curY ; move to next scanline pop cx ; restore scan count loop cTriRenderPieceLoop ; fill rest of triangle cTriNextPiece: cmp pLineToChange, 0 ; if 0 we're done je cTriDone ; push si ; save left line push bx lea si, pts + size POINT ; point si to second point lodsw ; get second & third points: xchg bx, ax ; (dx,ax) = pt 3, (bx,cx) = pt 2 lodsw ; xchg cx, ax ; lodsw ; xchg dx, ax ; lodsw ; mov si, pLineToChange ; point to DDA that will change call TriInitDDA ; and initialize for next line mov nScans, ax ; pop bx ; pop si ; mov pLineToChange, 0 ; signal this is last iteration jmp cTriRenderPiece ; cTriDone: cEnd if 1 ;--------------------------Private-Routine-------------------------------; ; tri_init ; ; init the bitmap pointer ES:DI to point to proper scan ; ; Entry: ; ES:DI --> BITMAPINFO ; AX - start scanline ; SS:BP --> frame of DibTriangle ; Return: ; ES:DI points to start of first scan ; carry clear ; SS:BP --> frame of DIBTriangle ; Error Returns: ; carry set ; Registers Preserved: ; none ; Registers Destroyed: ; AX,BX,CX,DX,DS,ES,SI,DI,FLAGS ; Calls: ; exclude !!! ; History: ; Mon 26-Mar-1990 -by- Todd Laney [ToddLa] ; Stole it from KenSy ;-----------------------------------------------------------------------; assumes ds,nothing assumes es,nothing ifdef DEBUG public tri_init endif tri_init proc near xor dx,dx mov wcrossflag,dx mov dx,wptr es:[di].biWidth ; compute DWORD aligned add dx,3 ; ...scan width and save it and dx,not 3 mov wNextScan,dx sub ax,wptr es:[di].biHeight ; Y = biHeight-1-Y inc ax neg ax add di,wptr es:[di].biSize add di,256 * 4 ; !!!assumes full color table mul dx ; DX:AX = offset start of scan add di,ax adc dx,0 ; DX:DI --> start of scan mov cx,__AHSHIFT ; do the selector tile stuff shl dx,cl mov ax,es add ax,dx mov es,ax ; ES:DI --> start of scan mov ax,CodeOFFSET DIBOutScan mov fnOutScan,ax tri_init_success: clc ret tri_init_fail: stc ret tri_init endp endif ;--------------------------Private-Routine-------------------------------; ; DIBOutScan ; ; output a single scanline of a triangle [ax,dx) ; ; Entry: ; AX - start X ; DX - end X (inclusive!) ; ES:DI - points to start of scanline ; SS:BP - Frame of Custom Triangle ; Return: ; ES:DI advanced to start of next scan ; Error Returns: ; none ; Registers Preserved: ; BX,DS,ES,SI,DI ; Registers Destroyed: ; AX,CX,DX,FLAGS ; Calls: ; none ; History: ; Mon 26-Mar-1990 -by- Todd Laney [ToddLa] ; Stole it from KenSy ;-----------------------------------------------------------------------; assumes ds,nothing assumes es,nothing ifdef DEBUG public diboutscan ;; for debugging endif DIBOutScan proc near mov cx,__WinFlags test cx,WF_CPU286 jnz DIBOutScan286 errn$ DIBOutScan386 DIBOutScan386: ; 386 specific version goes here. ; for now, just use 286 version ; DIBOutScan286: mov cx,dx sub cx,ax ; calc delta inc cx ; cx is # of pels cmp wcrossflag,1 je DIBOutCrossing mov dx,di sub dx,wNextScan ; advance to next scan jb DIBOutNextCrossing ; we have a seg crossing on next line DIBOutSafe: add di,ax ; point ES:DI to start of scan mov al,bptr crBrush ; get color to store in al and ah mov ah,al shr cx,1 rep stosw adc cl,cl rep stosb mov di,dx ; advance to next scan ret DIBOutNextCrossing: ;; next scan line has a crossing... mov wcrossflag,1 mov dx,di ; save old (unmodified) di ; don't update es:di, yet jmps DIBOutSafe DIBOutCrossing: ;; there is a crossing somewhere in the current scanline. mov wcrossflag,0 ; we've handled it... mov cx,dx ;; ax is start ;; cx is end ;; di is old offset ;;; mov dx,di mov di,wNextScan sub di,dx ; di = wNextScan - old offset sub dx,wNextScan ;;; still need to check for the old 'off-by-one' errors ;; di is wNextScan - old offset ;; dx is new offset ; es is old sel ; es - __AHINCR is new sel ; V-------------------wNextScan-------------------V ; ; V--wNextScan - old_offset----V----old_offset----V ; ; ; |-----------------------------------------------| ; ; current scan line es-__AHINCR:dx--> ; |----------------------------|------------------| ; es:0---^ ; ; |-----------------------------------------------| ; ; ; Three posibilities: ; ; 1 |----------------------------|------------------| ; ^ ^ ; Start End ; ; 2 |----------------------------|------------------| ; ^ ^ ; Start End ; ; 3 |----------------------------|------------------| ; ^ ^ ; Start End ; cmp ax,di ; is start > di? jg DIBOutCase2 cmp cx,di ; is end <= di? jle DIBOutCase3 ; else: ; case 1 ; do from es:0 -> end - di first sub cx,di mov di,0 ; by definition, start of seg push ax ; save start mov al,bptr crBrush mov ah,al shr cx,1 rep stosw adc cl,cl rep stosb ; now do from es-__AHINCR:dx+start -> ffff mov ax,es sub ax,__AHINCR cmp ax,lpbi.sel ; compare to buffer jl DIBOutFirstpop ; don't mod if before buffer mov es,ax pop ax ; restore start mov di,dx add di,ax ; es:di ->start mov cx,dx ; get # to move: add cx,ax ; add start offset to line not cx ; get # to end inc cx ; fill in last byte ; move the data... mov al,bptr crBrush mov ah,al shr cx,1 rep stosw adc cl,cl rep stosb mov di,dx ; setup next line... sub di,wNextScan ret DIBOutCase3: mov di,dx ; we won't cross... do it mov dx,es sub dx,__AHINCR cmp dx,lpbi.sel ; compare to buffer jl DIBOutFirst ; don't mod if before buffer mov es,dx mov dx,di sub dx,wNextScan ; setup next scan line ; (can't have another seg crossing) sub cx,ax ; get count inc cx jmp DIBOutSafe DIBOutCase2: ; we won't cross, but special calcs are needed to get next sel sub cx,ax inc cx ; cx is # of pels sub ax,di ; start - offset mov di,ax ; point ES:DI to start of scan mov al,bptr crBrush ; get color to store in al and ah mov ah,al shr cx,1 rep stosw adc cl,cl rep stosb ; fall through... DIBOutScanWrap: sub dx,wNextScan ; point to next scan line mov di,dx mov ax,es sub ax,__AHINCR cmp ax,lpbi.sel ; compare to buffer jl DIBOutFirst ; don't mod if before buffer mov es,ax DIBOutFirst: ret DIBOutFirstpop: pop ax ret DIBOutScan endp ;---------------------------Public-Routine------------------------------; ; hmemcpy ; ; copy memory ; ; Entry: ; lpSrc HPSTR to copy from ; lpDst HPSTR to copy to ; cbMem DWORD count of bytes to move ; ; NOTE: overlapped copies will work iff lpSrc.sel == lpDst.sel ; [This is a lie. They will always work.] ; ; Returns: ; destination pointer ; Error Returns: ; None ; Registers Preserved: ; BP,DS,SI,DI ; Registers Destroyed: ; AX,BX,CX,DX,FLAGS ; Calls: ; nothing ;-----------------------------------------------------------------------; cProc hmemcpy,<FAR,PASCAL,PUBLIC,NODATA>,<> ; ParmD lpDst ; ParmD lpSrc ; ParmD cbMem cBegin <nogen> mov ax,__WinFlags test ax,WF_CPU286 jz fmemcpy386 jmp FAR PTR fmemcpy286 cEnd <nogen> cProc fmemcpy386,<FAR,PASCAL,PUBLIC,NODATA>,<ds> ParmD lpDst ParmD lpSrc ParmD cbMem cBegin .386 push edi push esi cld mov ecx,cbMem jecxz mc386_exit movzx edi,di movzx esi,si lds si,lpSrc les di,lpDst ; ; calculate differance of pointers in "selector" space ; mov ax,si ; DX:AX = lpSrc mov dx,ds mov bx,es ; BX = selector of ptr B mov cx,__AHSHIFT ; number of selector bits per 64K 'segment' shr dx,cl ; linearize ptr A shr bx,cl ; linearize ptr B ; ; DX and BX contain normalized selectors ; sub ax,di sbb dx,bx ; do long subtraction. mov ecx,cbMem or dx,dx jns mc_copy_forward std add edi,ecx add esi,ecx sub edi,4 sub esi,4 push ecx shr ecx,2 ; get count in DWORDs rep movs dword ptr es:[edi], dword ptr ds:[esi] db 67H ; Fix strange 386 bug add edi,3 add esi,3 pop ecx and ecx,3 rep movs byte ptr es:[edi], byte ptr ds:[esi] db 67H ; Fix strange 386 bug jmp mc386_exit mc_copy_forward: push ecx shr ecx,2 ; get count in DWORDs rep movs dword ptr es:[edi], dword ptr ds:[esi] db 67H pop ecx and ecx,3 rep movs byte ptr es:[edi], byte ptr ds:[esi] db 67H nop mc386_exit: cld pop esi pop edi mov dx,lpDst.sel ; return destination address mov ax,lpDst.off .286 ; return to .286 mode for cEnd and 286 version ; cEnd cProc fmemcpy286,<FAR,PASCAL,PUBLIC,NODATA>,<ds,si,di> ParmD lpDst ParmD lpSrc ParmD cbMem cBegin mov cx,cbMem.lo ; CX holds count or cx,cbMem.hi ; or with high word jnz @f jmp empty_copy @@: lds si,lpSrc ; DS:SI = src les di,lpDst ; ES:DI = dst ; ; calculate differance of pointers in "selector" space ; mov ax,si ; DX:AX = lpSrc mov dx,ds mov bx,es ; BX = selector of ptr B mov cx,__AHSHIFT ; number of selector bits per 64K 'segment' shr dx,cl ; linearize ptr A shr bx,cl ; linearize ptr B ; ; DX and BX contain normalized selectors ; sub ax,di sbb dx,bx ; do long subtraction. mov cx,cbMem.lo or dx,dx jns forward_copy ; difference is positive, so copy forward ; see if the blocks intersect: is source + count > dest? ; equivalently, is source-dest + count > 0 ? ; sub ax,cx ; sbb dx,0 ; jnc next ; This looks wrong. Recheck! add ax,cx adc dx,cbMem.hi jc reverse_copy ; carry, so >0, thus they do hit. forward_copy: jmp next reverse_copy: ; first, we have to set ds:si and es:di to the _ends_ of the blocks sub cx,2 sbb cbMem.hi,0 ; subtract 2 from (long) count xor ax,ax add si,cx adc ax,cbMem.hi push cx mov cx,__AHSHIFT shl ax,cl pop cx mov bx,ds add ax,bx ; advance DS mov ds,ax xor ax,ax add di,cx adc ax,cbMem.hi push cx mov cx,__AHSHIFT shl ax,cl pop cx mov bx,es add ax,bx ; advance ES mov es,ax add cx,2 adc cbMem.hi,0 ; restore count ; ; DS:SI += Count ; ES:DI += Count ; While Count != 0 Do ; Num = MIN(Count,SI+1,DI+1) ; Reverse Copy "Num" Bytes from DS:SI to ES:DI ; (SI -= Num, DI -= Num) ; Count -= Num ; If Count == 0 Then ; BREAK ; If SI == 0xFFFF Then ; DS -= __AHINCR ; If DI == 0xFFFF Then ; ES -= __AHINCR ; next_r: mov ax,si sub ax,di sbb bx,bx and ax,bx add ax,di ; AX = MIN(SI, DI) xor bx,bx add ax,2 ; AX = Num = MIN(SI+2,DI+2) adc bx,0 ; bx==1 if exactly 64k test cbMem.hi,-1 ; is high word not zero? jnz @f ; at least 64k to go sub ax,cx sbb bx,bx and ax,bx add ax,cx ; AX = Num = MIN(Count,SI+2,DI+2) adc bx,0 @@: xchg ax,cx sub ax,cx ; Count -= Num sbb cbMem.hi,bx std shr bx,1 rcr cx,1 ; if bx==1, then cx ends up 0x8000 jnc @f inc si ; adjust pointers for byte move inc di movsb ; move first byte, if necessary dec si ; realign pointers dec di @@: rep movsw cld mov cx,ax ; restore cx or ax,cbMem.hi jz done ; If Count == 0 Then BREAK cmp si,-2 ; if SI wraps, update DS jnz @f ; mov ax,ds sub ax,__AHINCR mov ds,ax ; update DS if appropriate @@: cmp di,-2 ; if DI wraps, update ES jnz next_r ; mov ax,es sub ax,__AHINCR mov es,ax ; update ES if appropriate jmp next_r ; ; While Count != 0 Do ; If (Count + SI > 65536) OR (Count + DI > 65536) Then ; Num = Min(65536-SI, 65536-DI) ; Else ; Num = Count ; Copy "Num" Bytes from DS:SI to ES:DI (SI += Num, DI += Num) ; Count -= Num ; If Count == 0 Then ; BREAK ; If SI == 0 Then ; DS += __AHINCR ; If DI == 0 Then ; ES += __AHINCR ; next: mov ax,cx dec ax mov ax,di not ax ; AX = 65535-DI mov dx,si not dx ; DX = 65535-SI sub ax,dx sbb bx,bx and ax,bx add ax,dx ; AX = MIN(AX,DX) = MIN(65535-SI,65535-DI) ; problem: ax might have wrapped to zero test cbMem.hi,-1 jnz plentytogo ; at least 64k still to copy dec cx ; this is ok, since high word is zero sub ax,cx sbb bx,bx and ax,bx add ax,cx ; AX = MIN(AX,CX) inc cx plentytogo: xor bx,bx add ax,1 ; AX = Num = MIN(count,65536-SI,65536-DI) ; we must check the carry here! adc bx,0 ; BX could be 1 here, if CX==0 indicating ; exactly 64k to copy xchg ax,cx sub ax,cx ; Count -= Num sbb cbMem.hi,bx shr bx,1 rcr cx,1 ; if bx==1, then cx ends up 0x8000 rep movsw jnc @f movsb ; move last byte, if necessary @@: mov cx,ax ; put low word of count back in cx or ax,cbMem.hi jz done ; If Count == 0 Then BREAK or si,si ; if SI wraps, update DS jnz @f ; mov ax,ds add ax,__AHINCR mov ds,ax ; update DS if appropriate @@: or di,di ; if DI wraps, update ES jnz next ; mov ax,es add ax,__AHINCR mov es,ax ; update ES if appropriate jmp next ; ; Restore registers and return ; done: empty_copy: mov dx,lpDst.sel ; return destination address mov ax,lpDst.off cEnd sEnd CODE end