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https://github.com/vxunderground/MalwareSourceCode
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312 lines
8.6 KiB
NASM
312 lines
8.6 KiB
NASM
; MONOGRAF.DRV -- Lotus Driver for Graphics on Monochrome Display
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; ============
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;
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; (For use with Lotus 1-2-3 Version 1A)
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;
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; (C) Copyright Charles Petzold, 1985
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CSEG Segment
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Assume CS:CSEG
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Org 0
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Beginning dw Offset EndDriver,1,1,Offset Initialize
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Org 18h
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db "Monochrome Graphics (C) Charles Petzold, 1985",0
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Org 40h
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dw 40 * 8 - 1 ; Maximum Dot Column
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dw 25 * 8 - 1 ; Maximum Dot Row
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dw 10, 7, 6, 10, 7, 6, 256
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db -1 ; For one monitor
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Org 53h
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Jmp Near Ptr ClearScreen ; Call 0 -- Clear Screen
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Jmp Near Ptr ColorSet ; Call 1 -- Set Color
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Jmp Near Ptr SetAddress ; Call 2 -- Set Row/Col Addr
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Jmp Near Ptr DrawLine ; Call 3 -- Draw a Line
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Jmp Near Ptr Initialize ; Call 4 -- Write Dot (nothing)
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Jmp Near Ptr WriteChar ; Call 5 -- Write a Character
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Jmp Near Ptr DrawBlock ; Call 6 -- Draw a Block
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Jmp Near Ptr Initialize ; Call 7 -- Read Dot (nothing)
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Jmp Near Ptr Initialize ; Call 8 -- Video Reset
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; Initialization Routine
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; ----------------------
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Initialize Proc Far
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Mov AX,0 ; This is standard
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Or AX,AX ; for all drivers
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Ret
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Initialize EndP
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; Common Data Used in Routines
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; -----------------------------------
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CharacterRow dw ? ; from 0 to 24
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CharacterCol dw ? ; from 0 to 79
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ScreenAddress dw ?,0B000h ; Offset & Segment
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CurrentColor db ?,7 ; For Screen Output
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Colors db 219,219,178,177,176,219,178 ; Actually blocks
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; Row and Column Conversion of AX from graphics to character
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; ----------------------------------------------------------
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Rounder dw 0 ; Value to add before division
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Divisor db ? ; Value to divide by
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MaxDots dw ? ; Number of dots
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RowConvertRnd: Mov [Rounder],4 ; Row rounding -- add 4
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RowConvert: Mov [Divisor],8 ; Row normal -- divide by 8
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Mov [MaxDots],200 ; 25 lines times 8 dots
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Jmp Short Convert ; And do generalized conversion
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ColConvertRnd: Mov [Rounder],2 ; Column rounding -- add 2
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ColConvert: Mov [Divisor],4 ; Will divide by 4
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Mov [MaxDots],320 ; 40 columns times 4 dots
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Convert: Cmp AX,[MaxDots] ; See if graphics value OK
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Jb OKToConvert ; It is if under maximum
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Jl Negative ; But could be negative
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Sub AX,[MaxDots] ; Otherwise wrap down
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Jmp Convert ; And check again
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Negative: Add AX,[MaxDots] ; Negatives wrap up
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Jmp Convert ; And check again
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OkToConvert: Add AX,[Rounder] ; Add rounding value
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Div [Divisor] ; Divide
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Cbw ; And convert to word
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Mov [Rounder],0 ; For next time through
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Ret
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; Calc Offset -- DX, CX character positions in
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; -----------
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CalcOffset: Push AX
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Push DX
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Mov AX,80 ; Columns Per Line
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Mul DX ; AX now at beginning of row
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Add AX,CX ; Add column value
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Add AX,AX ; Double for attributes
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Mov [ScreenAddress],AX ; Save as the current address
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Pop DX
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Pop AX
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Ret
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; Address Convert -- DX, CX row and column converted to character
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; ---------------
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AddrConvert: Push AX
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Mov AX,DX ; This is graphics row
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Call RowConvert ; Convert to character row
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Mov DX,AX ; Save back in DX
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Mov [CharacterRow],AX ; And save value in memory
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Mov AX,CX ; This is graphics column
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Call ColConvert ; Convert to character column
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Mov CX,AX ; Back in CX
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Mov [CharacterCol],AX ; And value also saved
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Call CalcOffset ; Find the screen destination
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Pop AX
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Ret
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; Call 0 -- Clear Screen -- AL = 0 for B&W
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; ====================== -1 for Color
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ClearScreen Proc Far
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Mov AX,0B000h ; Monochrome Segment
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Mov ES,AX ; Set EX to it
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Sub DI,DI ; Start at zero
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Mov CX,25 * 80 ; Number of characters
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Mov AX,0720h ; Blanks only
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Cld ; Forward direction
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Rep Stosw ; Do it
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Ret
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ClearScreen EndP
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; Call 1 -- Color Set -- AL = Color (0, 1-6)
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; -------------------
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ColorSet Proc Far
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Mov BX,Offset Colors ; Blocks for 7 colors
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Xlat Colors ; Translate the bytes
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Mov [CurrentColor],AL ; And save it
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Ret
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ColorSet EndP
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; Call 2 -- Set Address -- DX = Graphics Row
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; --------------------- CX = Graphics Columns
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SetAddress Proc Far
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Call AddrConvert ; One routine does it all
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Ret
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SetAddress EndP
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; Call 3 -- Draw Line -- DX = End Row
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; ------------------- CX = End Column
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DrawLine Proc Far
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Les DI,DWord Ptr [ScreenAddress] ; Beginning address
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Mov AX,[CharacterCol] ; AX now beginning column
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Mov BX,[CharacterRow] ; BX now beginning row
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Call AddrConvert ; CX,DX now ending col, row
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Cmp AX,CX ; See if cols are the same
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Je VertLine ; If so, it's vertical line
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Cmp BX,DX ; See if rows are the same
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Jne DrawLineEnd ; If not, don't draw anything
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HorizLine: Sub CX,AX ; Find the number of bytes
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Mov BX,2 ; Increment for next byte
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Mov AL,196 ; The horizontal line
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Mov AH,179 ; The vertical line
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Jae DrawTheLine ; If CX > AX, left to right
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Jmp Short ReverseLine ; Otherwise right to left
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VertLine: Mov CX,DX ; This is the ending column
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Sub CX,BX ; Subtract beginning from it
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Mov BX,80 * 2 ; Increment for next line
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Mov AL,179 ; The vertical line
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Mov AH,196 ; The horizontal line
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Jae DrawTheLine ; If CX > BX, up to down
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ReverseLine: Neg BX ; Reverse Increment
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Neg CX ; Make a positive value
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DrawTheLine: Inc CX ; One more byte than calced
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DrawLineLoop: Cmp Byte Ptr ES:[DI],197 ; See if criss-cross there
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Je DrawLineCont ; If so, branch around
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Cmp ES:[DI],AH ; See if opposite line
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Jne NoOverLap ; If not, skip next code
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Mov Byte Ptr ES:[DI],197 ; Write out criss-cross
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Jmp Short DrawLineCont ; And continue
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NoOverLap: Mov ES:[DI],AL ; Display line chararacter
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DrawLineCont: Add DI,BX ; Next destination
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Loop DrawLineLoop ; For CX repetitions
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DrawLineEnd: Ret
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DrawLine EndP
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; Call 5 -- Write Character -- DX, CX = row, col; BX = count,
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; ------------------------- AH = direction, AL = type
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Direction db ?
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WriteChar Proc Far
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Push BX ; Save count
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Add BX,BX ; Initialize adjustment
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Mov [Direction],AH ; Save direction
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Or AL,AL ; Branch according to type
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Jz WriteType0
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Dec AL
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Jz WriteType1
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Dec AL
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Jz WriteType2
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Dec AL
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Jz WriteType3
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WriteType4: Mov AX,4 ; Adjustment to row
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Jmp Short WriteCharCont
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WriteType3: Add BX,BX ; Center on column
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WriteType2: Sub AX,AX ; No adjustment to row
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Jmp Short WriteCharCont
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WriteType1: Sub BX,BX ; No adjustment on column
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WriteType0: Mov AX,2 ; Adjustment to row
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WriteCharCont: Cmp [Direction],0 ; Check the direction
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Jz HorizChars
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Sub DX,BX ; Vertical -- adjust row
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Sub DX,BX
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Sub CX,AX ; Adjust column
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Mov AX,80 * 2 - 1 ; Increment for writes
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Jmp Short DoWriteChar
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HorizChars: Sub DX,AX ; Horizontal -- adjust row
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Sub DX,AX
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Sub CX,BX ; Adjust column
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Mov AX,1 ; Increment for writes
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DoWriteChar: Call AddrConvert ; Convert the address
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Les DI,DWord Ptr [ScreenAddress] ; Get video address
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Cld
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Pop CX ; Get back character count
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Jcxz WriteCharEnd ; Do nothing if no characters
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CharacterLoop: Movsb ; Write character to display
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Add DI,AX ; Increment address
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Loop CharacterLoop ; Do it CX times
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WriteCharEnd: Ret
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WriteChar EndP
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; Call 6 -- Draw Block -- BX,DX = Rows; AX,CX = Columns
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; --------------------
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DrawBlock Proc Far
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Call ColConvertRnd ; AX now first char col
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Xchg AX,CX ; Switch with 2nd graph col
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Call ColConvertRnd ; AX now 2nd char col
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Cmp AX,CX ; Compare two char cols
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Je DrawBlockEnd ; End routine if the same
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Ja NowDoRow ; If CX lowest, just continue
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Xchg AX,CX ; Otherwise switch them
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NowDoRow: Xchg AX,BX ; AX now 1st graph row
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Call RowConvertRnd ; AX now 1st char row
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Xchg AX,DX ; AX now 2nd graph row
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Call RowConvertRnd ; AX now 2nd char row
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Cmp AX,DX ; Compare two character columns
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Je DrawBlockEnd ; End routine if the same
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Ja BlockRowLoop ; If DX lowest, just continue
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Xchg AX,DX ; Otherwise switch them
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BlockRowLoop: Push CX ; Beginning Column
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Push BX ; Ending Column
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BlockColLoop: Call CalcOffset ; Calculate screen address
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Les DI,DWord Ptr [ScreenAddress] ; And set ES:DI
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Push Word Ptr [CurrentColor] ; Push the current color
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Pop ES:[DI] ; And Pop it on the screen
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Inc CX ; Next Column
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Cmp CX,BX ; Are we an end?
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Jb BlockColLoop ; Nope -- loop again
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Pop BX ; Get back beginning col
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Pop CX ; And the end
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Inc DX ; Prepare for next row
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Cmp DX,AX ; Are we at the end?
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Jb BlockRowLoop ; If not, loop
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DrawBlockEnd: Ret
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DrawBlock EndP
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Org $ + 16 - (($ - Beginning) Mod 16)
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EndDriver Label Byte
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CSEG EndS
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End
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