þa‹RþwQþ m^9þhý oPþ nSystem-wide NAME UNtdc data struc oldBP DW ? ; space for BP retAdd DW ? ; caller's return address pEDCBlock DD ? ; parameters passed to us pReturnData DD ? pTDCData DD ? data ends CGroup GROUP Code ASSUME cs:cGroup CODE segment public 'CODE' public UNtdc ; ; calling sequence for UNtdc: ; CALL UNtdc (pTDCData, pReturnData, pEDCBlock); ; UNtdc PROC near push bp mov bp,sp push ax push bx push cx push dx push es push di push ds push si les si,[bp].pTDCData ; ES:SI = pTDCData lds di,[bp].pReturnData ; DS:DI = pActualData mov cx,1 ; for edc loop push cx xor ax,ax mov cx,8 push cx zeroArray: mov ds:[di],ax ; zero out ActualData area inc di ; di points @ end of table inc di loop zeroArray pop cx push di ; save di for Ascii data lds di,[bp].pEDCBlock ; get address for UNedc area zeroEDC: mov ds:[di],ax ; zero the edc area inc di inc di loop zeroEDC dec di ; adjust di for end of block xchg di,bx pop di push bx ; save edc ptr for below ; begin unTDCing the ascii data dec di ; adjust di for end of Ascii nextColumn: mov bx,7 ; bit count nextByte: add si,13 ; si points to end of tdc area mov cx,7 nextBit: mov al,es:[si] ; get byte j of tdc'd data xchg cx,bx shr al,cl ;get bit i of byte j to undo xchg cx,bx and al,1 jz zero dec cx shl al,cl ; move bit to correct weight inc cx or ds:[di],al ;store bit in output array zero: sub si,2 loop nextBit inc si dec di ; point to next byte sub bx,1 jnc nextbyte ; now unTDC the EDC data mov dx,7 pop bx ; bx contains di from above push di ; save Ascii pointers push si xchg di,bx add si,13 ; set indexes for EDC data UNedc: add si,10 ;adjust si to end of tdc'd edc mov cx,4 ; only 5 edc bits per byte UNedc1: mov al,es:[si] ; byte j of edc code xchg dx,cx shr al,cl xchg dx,cx and al,1 jz around shl al,cl or ds:[di],al ; store bit in edc array around: sub si,2 sub cx,1 ; move to next bit weight jnc UNedc1 dec di sub dx,1 ; DX keeps track of whether jnc UNedc ; we are doing the even or odd ; bytes xchg di,bx pop si ; get indexes for Ascii data dec si pop di pop dx sub dx,1 push dx push bx jnc nextColumn pop bx pop dx pop si pop ds pop di pop es pop dx pop cx pop bx pop ax pop bp ret 12 ; remove ptrs passed in untdc endp code ends end