TITLE 'FAST CIRCLE ROUTINE' BIOSCALL MACRO INT 10H ;BIOS service id in AH ENDM STACK SEGMENT PARA STACK 'STACK' DB 64 DUP('STACK ') STACK ENDS CSEG SEGMENT PARA 'CODE' ;--------------------------------------------- ;PROCEDURE CIRCLE (X,Y,RADIUS,NUMER,DEMON, ; COLOR:INTEGER) ;Dan Lee July 1, 1982 ;SourceWare ; ;draws a circle at center (x,y) with aspect ;ratio numer/denom; radius in column units ; ;assumes entry via inter-segment call ; ;FRAME: VALUE X : BP+16 ; VALUE Y : BP+14 ; VALUE RADIUS: BP+12 ; VALUE NUMER : BP+10 ; VALUE DENOM : BP+8 ; VALUE COLOR : BP+6 ;--------------------------------------------- CIRCLE PROC FAR ASSUME CS:CSEG,SS:STACK PUBLIC CIRCLE PUSH BP ;caller's frame pntr MOV BP,SP ;set proc frame pntr MOV AX,[BP+10] ;get aspect numer and MOV BX,1000 ;scale it by 1000 IMUL BX MOV CX,[BP+8] ;get aspect denom IDIV CX ;AX=aspect*1000 PUSH AX ;store aspect*1000 XCHG AX,CX ;get denom in AX MOV CX,[BP+10] ;get numer in CX IMUL BX ;AX=denom*1000 IDIV CX ;AX=inv aspect*1000 MOV [BP+8],AX ;store it POP AX ;get aspect*1000 MOV [BP+10],AX ;and store it ; ;start by incrementing Y by one unit and ;decrementing X by TAN units*inv aspect ;start at (RADIUS,Y) and plot to 45 deg ; MOV AX,[BP+12] ;get radius for MOV BX,1000 ;initial X and scale IMUL BX ;up by 1000 XOR DI,DI ;zero initial Y value CR5: PUSH AX ;save lo word x*1000 PUSH DX ;save hi word x*1000 XOR BX,BX ;begin round process ADD AX,500 ;`one-half' ADC DX,BX MOV BX,1000 ;rescale X by 1000 IDIV BX ;to graph MOV BX,AX ;BX=1st quad X ADD AX,[BP+16] ;add X origin MOV DX,[BP+14] ;get Y origin SUB DX,DI ;and sub Y to plot MOV CX,AX ;get X to plot MOV AL,[BP+6] ;get color MOV AH,12 ;write dot funct select PUSH AX ;save write dot parms BIOSCALL ;write 1st quad point POP AX ;restore write dot parms SUB CX,BX ;get 2nd quad SUB CX,BX ;X+origin PUSH AX ;save write dot parms BIOSCALL ;write 2nd quad point POP AX ;restore write dot parms ADD DX,DI ;get 3rd quad ADD DX,DI ;Y+origin PUSH AX ;save write dot parms BIOSCALL ;plot 3rd quad point POP AX ;restore write dot parms ADD CX,BX ;get 4th quad ADD CX,BX ;X+origin BIOSCALL ;plot 4th quad point ; ;cx now at original point ; XCHG CX,BX ;get 1st quad X INC DI ;get new Y MOV AX,DI ;AX=Y MOV BX,[BP+8] ;BX=inv aspect*1000 IMUL BX ;AX=Y*inv aspect*1000 IDIV CX ;AX=TAN*inv aspect*1000 XOR DX,DX ;zero remainder MOV SI,AX ;SI=TAN*inv aspect*1000 IDIV BX ;AX=TAN CMP AX,1 ;TAN=1? POP DX ;DX=hi word X*1000 POP AX ;AX=lo word X*1000 JAE CR7 ;yes, go to next sector NEG SI ;to decrement *X MOV BX,-1 ;negative carry ADD AX,SI ;new X value ADC DX,BX ;hi word carry JMP SHORT CR5 ;plot new point ; ;plot 45 to 90 degrees ;now decrease X by one unit and ;increase Y by COT units*aspect ratio ; CR7: MOV AX,DI ;get nest Y to plot and MOV BX,1000 ;scale by 1000 IMUL BX ;DX:AX=Y*1000 MOV DI,CX ;DI=last X value DEC DI ;next X to plot CR8: PUSH AX ;save lo word Y*1000 PUSH DX ;save hi word Y*1000 XOR BX,BX ;begin round process ADD AX,500 ;'one-half' ADC DX,BX MOV BX,1000 ;rescale Y to plot IDIV BX ;AX=Y MOV BX,AX ;BX=1st quad Y coord ADD AX,[BP+14] ;add Y origin MOV CX,[BP+16] ;CX=X origin ADD CX,DI ;X to plot MOV DX,AX ;Y to plot MOV AL,[BP+6] ;get color MOV AH,12 ;write dot funct select PUSH AX ;save write dot parms BIOSCALL ;write 1st quad point POP AX ;restore write dot parms SUB CX,DI ;get 2nd quad SUB CX,DI ;X to plot PUSH AX ;save write dot parms BIOSCALL ;plot 2nd quad point POP AX ;restore write dot parms SUB DX,BX ;get 3rd quad SUB DX,BX ;Y to plot PUSH AX ;save write dot parms BIOSCALL ;write 3rd quad point POP AX ;restore write dot parms ADD CX,DI ;get 4th quad ADD CX,DI ;X to plot BIOSCALL ;plot 4th quad point SUB DX,[BP+14] ;DX=Y-Y origin NEG DX ;Y origin adjust XCHG CX,DX ;CX=Y OR DI,DI ;90 deg? JS CR11 ;yes,exit DEC DI ;get new X MOV AX,DI ;AX=X MOV BX,[BP+10] ;BX=aspect*1000 IMUL BX ;AX=aspect*1000*X IDIV CX ;AX=aspect*1000*COT MOV SI,AX ;SI=change in Y POP DX ;DX=hi word Y*1000 POP AX ;AX=lo word Y*1000 XOR BX,BX OR SI,SI ;for sign check JNS CR10 ;positive MOV BX,-1 ;negitive carry CR10: ADD AX,SI ;AX=new X value ADC DX,BX ;hi word carry JMP SHORT CR8 ;plot next point ; ; exit ; CR11: ADD SP,4 ;adjust stack pntr POP BP ;caller's frame pntr RET 12 ;release parms CIRCLE ENDP CSEG ENDS END TPZvtVPjv4V!PZFF;F|1PvVvt^ƉƊ^;t v4XF+F