Desktop Publisher's Dream 1994

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Assembly Source File | 1988-12-07 | 26.6 KB | 758 lines

PAGE 63, 132 Title Interupt support for the Hercules Graphics Card CSEG SEGMENT ORG 100H ASSUME CS:CSEG, DS:CSEG, SS:CSEG START: JMP SET_UP ;------------------------ routine ---------------------- ROUTINE PROC FAR PUSHF PUSH ES PUSH DS PUSH SI PUSH DI PUSH AX PUSH BX PUSH CX PUSH DX JMP SKIP_DATA ; data section Pos_X DW ? Pos_Y DW ? Pos_Err DW ? Neg_X DW ? Neg_Y DW ? Neg_Err DW ? Line_Err DW ? LENGTH DW ? Point_Type DB ? X1 DW ? Y1 DW ? X2 DW ? Y2 DW ? DeltaX DW ? DeltaY DW ? Ten DB 0Ah Function_Table DW 8 DUP(0) Active_page DB 0 Segment_value DW ? Offset_Value DW ? ; ;++======================================================================++ ;|| || ;|| Draws the line given the present data || ;|| || ;++======================================================================++ ; DrawIt PROC Near MOV AX, 0B000h MOV BH, Active_page CMP BH, 0 JE Pg_0d MOV AX, 0B800h Pg_0d: MOV ES, AX MOV AX, Y2 ; see which is larger. if Y1 is larger, CMP AX, Y1 ; you have to swap the end points JNL No_Swap ; ( you always want to go up ) MOV AX, Y1 ; put the first Y value into the AX register MOV BX, Y2 ; put the second Y value into the BX register MOV Y2, AX ; put the first Y value into the second Y MOV Y1, BX ; put the second Y value into the first Y MOV AX, X1 ; same as above for the X values MOV BX, X2 MOV X2, AX MOV X1, BX No_Swap: MOV AX, X2 ; come up with the difference in X's SUB AX, X1 MOV DeltaX, AX MOV AX, Y2 ; come up with the difference in Y's SUB AX, Y1 MOV DeltaY, AX JNZ Not_Horiz ; if DeltaY is zero, the line is horizontal JMP Horiz Not_Horiz: CMP AX, DeltaX ; compare DeltaY to DeltaX JNE Not_Diag1 ; if they are equal, the slope is 1 JMP Diag1 Not_Diag1: XOR AX, 0FFFFh ; get negative DeltaY in AX INC AX CMP AX, DeltaX ; compare negative DeltaY to DeltaX JNE Not_Diag2 ; if they are equal, the slope is -1 JMP Diag2 Not_Diag2: CMP DeltaX, 0 ; compare DeltaX to zero JNE Not_Vert ; if there is no difference in X's, it's vert JMP Vert Not_Vert: JL Case_3_or_4 ; this line has a negative slope Case_1_or_2: XOR AX, 0FFFFh ; AX should still have -DeltaY INC AX ; so, make it positive CMP AX, DeltaX ; compare this to DeltaX JA Case2 ; if DeltaY > DeltaX the goto Case 2 Case1: MOV DX, AX ; store the negative error correction MOV SI, DeltaX ; the length of the line SUB AX, SI ; Positive error = DeltaY - DeltaX MOV CX, AX ; store it MOV BX, X1 ; get the starting point MOV AX, Y1 XOR DI, DI ; initialize the error register Plot_1: CALL Plot_pt CMP DI, 0 ; compare the error to zero JL Neg_err_1 ; if a negative error, jump pos err code ADD DI, CX ; add pos error correction INC AX ; next point is "up" and to the right INC BX JMP Chk_1 ; jump neg err code Neg_err_1: ADD DI, DX ; add neg error correction INC BX ; next point is to the right Chk_1: DEC SI ; decrement counter JNZ Plot_1 ; check to see if you are done JMP Plot_end_pts ; go to where you will plot the end points Case2: MOV SI, AX ; AX has DeltaX in it and that is the length MOV CX, DeltaX ; get DeltaX for Pos err correction SUB AX, CX ; DeltaY - DeltaX MOV DX, AX ; store the Neg err correction XOR CX, 0FFFFh ; Pos err cor is -DeltaX INC CX MOV BX, X1 MOV AX, Y1 XOR DI, DI Plot_2: CALL Plot_pt CMP DI, 0 ; compare the error to zero JL Neg_err_2 ; if a negative error, jump pos err code ADD DI, CX ; add pos error correction INC AX ; next point is "up" one point JMP Chk_2 ; jump neg err code Neg_err_2: ADD DI, DX ; add neg error correction INC AX ; next point is "up" and to the right INC BX ; Chk_2: DEC SI ; decrement counter JNZ Plot_2 ; check to see if you are done JMP Plot_end_pts ; go to where you will plot the end points Case_3_or_4: MOV AX, DeltaX ; DeltaX is negative. Invert it and add 1 for XOR AX, 0FFFFh ; 2's compliment (leave DeltaX alone use AX) INC AX CMP AX, DeltaY ; If DeltaY > DeltaX . . . JB Case4 ; this means that the slope is < -1 Case3: MOV SI, AX ; AX has DeltaX in it and that is the length MOV CX, DeltaY ; get DeltaY for neg err correction MOV DX, CX ; store it SUB CX, AX ; calculate the pos err correction: Dy - Dx MOV BX, X1 ; set initial values MOV AX, Y1 XOR DI, DI Plot_3: CALL Plot_pt CMP DI, 0 ; compare the error to zero JL Neg_err_3 ; if a negative error, jump pos err code ADD DI, CX ; add pos error correction INC AX ; next point is "up" and to the left DEC BX JMP Chk_3 ; jump neg err code Neg_err_3: ADD DI, DX ; add neg error correction DEC BX ; next point is "up" and to the left Chk_3: DEC SI ; decrement counter JNZ Plot_3 ; check to see if you are done JMP Plot_end_pts ; go to where you will plot the end points Case4: MOV SI, DeltaY ; the length of the line XOR AX, 0FFFFh ; AX had -DeltaX in it INC AX ; change it to DeltaX MOV CX, AX ; set the pos err correction register ( +Dx ) ADD AX, SI ; calculate the neg err correction ( Dy + Dx ) MOV DX, AX ; store it MOV BX, X1 ; set initial values MOV AX, Y1 XOR DI, DI Plot_4: CALL Plot_pt CMP DI, 0 ; compare the error to zero JL Neg_err_4 ; if a negative error, jump pos err code ADD DI, CX ; add pos error correction INC AX ; next point is "up" one point JMP Chk_4 ; jump neg err code Neg_err_4: ADD DI, DX ; add neg error correction INC AX ; next point is "up" and to the right DEC BX ; Chk_4: DEC SI ; decrement counter JNZ Plot_4 ; check to see if you are done JMP Plot_end_pts ; go to where you will plot the end points Horiz: MOV SI, DeltaX ; set the length variable MOV BX, X1 ; set initial values MOV AX, Y1 CMP SI, 0 ; check to see if the length var is neg JG Plot_H ; if not, skip making it neg XOR SI, 0FFFFh ; make SI ( = -DeltaX ) positive INC SI Plot_H: CALL Plot_pt ; plot the point INC BX ; move one pixel right DEC SI ; decrement the counter JNZ Plot_H ; if not done, go again JMP Plot_end_pts ; plot the end points of the line Vert: XOR AX, 0FFFFh ; AX already had -DeltaY, INC AX ; make it DeltaY and MOV SI, AX ; stick it into the length var MOV BX, X1 ; set initial values MOV AX, Y1 Plot_V: CALL Plot_pt ; plot the point INC AX ; move one pixel right DEC SI ; decrement the counter JNZ Plot_V ; if not done, go again JMP Plot_end_pts ; plot the end points of the line Diag1: MOV SI, AX ; AX still has DeltaY in it MOV BX, X1 ; the starting point MOV AX, Y1 Plot_D1: CALL Plot_pt INC AX ; next point is "up" and to the right INC BX DEC SI ; decrement the counter JNZ Plot_D1 ; if not done, go again JMP Plot_end_pts Diag2: XOR AX, 0FFFFh ; AX has -DeltaY in it, change its sign INC AX MOV SI, AX ; store it MOV BX, X1 ; initial point MOV AX, Y1 Plot_D2: CALL Plot_pt INC AX ; next point is "up" and to the left DEC BX DEC SI ; decrement counter JNZ Plot_D2 ; if not done, go again Plot_end_pts: MOV AX, Y1 ; set up for plotting the 1st end pt MOV BX, X1 CALL Plot_Pt ; plot 1st end pt MOV AX, Y2 ; set up for plotting the 2nd end pt MOV BX, X2 CALL Plot_Pt RET DrawIt ENDP ; done here ; ;++======================================================================++ ;|| || ;|| Plots a point at (BX,AX) if possible using Line_Type || ;|| || ;++======================================================================++ ; Plot_Pt PROC Near PUSH AX ; save the values of X & Y PUSH BX PUSH CX CALL AddrHGC ; get the offset in the buffer CMP AX, 1000h ; check for an error being returned from JNE No_Plot ; if an error was detected, get out MOV CH, 1 ; bit to or into the byte SHL CH, CL ; move the bit into position CMP Point_Type, 2 ; JB Or_Point ; if plotting a line... JA Del_Point ; if erasing a line... XOR ES:[BX], CH ; xor the line JMP No_Plot Or_Point: OR ES:[BX], CH ; set the bit in the video buffer JMP No_Plot Del_Point: XOR CH, 0FFFFh ; reverse the bits AND ES:[BX], CH ; erase the bit No_Plot: POP CX ; CX was altered, restore it POP BX ; get the X value back POP AX ; get the Y value back RET Plot_Pt ENDP ; ; in: AX = y ; BX = x <--------------------+ ; | ; out: AX = 1000 if value is OK or x if bad ; BX = byte offset in buffer ; CL = nuber of bits to shift left ; AddrHGC PROC Near CMP AX, 0 ; is the y value too small? JL DONE ; if so, get out of the procedure CMP AX, 347 ; is the y value too large? JG DONE ; if so, get out of the procedure CMP BX, 0 ; is the x value too small? JL DONE ; if so, get out of the procedure CMP BX, 719 ; is the x value too large? JG DONE ; if not, get out MOV CL, BL ; CL = low order byte of x SHR AX, 1 ; AX = y / 2 RCR BX, 1 ; BX = 8000h * (y&1) + x/2 SHR AX, 1 ; AX = y / 4 RCR BX, 1 ; BX = 4000h * (y&3) + x/4 SHR BX, 1 ; BX = 2000h * (y&3) + x/8 MOV AH, 90 ; bytes per line (decimal) MUL AH ; AX = bytes per line * (y/4) ADD BX, AX ; BX = 2000h * (y&3) + x/8 + ; bytes per line * (y/4) AND CL, 7 ; CL = x & 7 XOR CL, 7 ; CL = number of bits to shift left MOV AX, 1000h ; AH = unshifted bit mask DONE: RET AddrHGC ENDP ; ;++======================================================================++ ;|| || ;|| Turns on the HERCULES graphics mode || ;|| || ;++======================================================================++ ; Graphics_on PROC Near MOV AL, 02Ah ; graphics mode (Page 0) AND DH, 01 ; get visible page from the instruction byte JZ Pg_0g ; if it is page 0, don't change now MOV AL, 0AAh ; graphics mode (Page 1) Pg_0g: MOV DX, 03B8h ; HGC mode control reister OUT DX, AL ; set to graphics mode MOV AL, 03h ; code to enable graphics MOV DX, 03BFh ; HGC config switch register OUT DX, AL ; enable graphics RET Graphics_on ENDP ; ;++======================================================================++ ;|| || ;|| Turns off the HERCULES graphics mode || ;|| || ;++======================================================================++ ; Text_on PROC Near MOV AL, 028h ; text mode (page 0) AND DH, 01 ; get visible page from instruction byte JZ Pg_0 ; don't make it page 1 if page 0 MOV AL, 0A8h ; text mode (page 1) Pg_0: MOV DX, 03B8h ; HGC mode control reister OUT DX, AL ; set to graphics mode MOV AL, 03h ; code to enable HGC MOV DX, 03BFh ; HGC config switch register OUT DX, AL ; enable graphics RET Text_on ENDP ; ;++======================================================================++ ;|| || ;|| plot a point on the graphics page || ;|| || ;++======================================================================++ ; Point PROC near AND DH, 03 ; mask off the type of point MOV Point_type, DH ; set the variable MOV CX, ES:[BX] ; get the X value of the point ADD BX, 2 ; move past the data word MOV DX, ES:[BX] ; get the Y value of the point ADD BX, 2 ; move pointer past the data word MOV Offset_value, BX ; save current value MOV AX, 0B000h ; default graphics page ( page 0 ) MOV BH, Active_page ; get the number of the active page CMP BH, 0 ; check to see if page 0 IS the active page JE Pg_0p ; if so, don't change it now MOV AX, 0B800h ; if not, do change it to page 1 Pg_0p: MOV ES, AX ; plot_pt needs this MOV BX, CX ; BX is where the procedure expects the ; X value of the point MOV AX, DX ; AX is where the procedure expects the ; Y value of the point CALL Plot_Pt ; call the procedure to plot the point RET ; you're done here Point ENDP ; ;++======================================================================++ ;|| || ;|| plot a line on the graphics page || ;|| || ;++======================================================================++ ; Line PROC near MOV CX, ES:[BX] ; get the first end point's X value MOV X1, CX ; store the value ADD BX, 2 ; mov the pointer past the word MOV CX, ES:[BX] ; get the 1st pt's Y value MOV Y1, CX ; store it ADD BX, 2 MOV CX, ES:[BX] ; 2nd pt's X value MOV X2, CX ADD BX, 2 MOV CX, ES:[BX] ; 2nd pt's Y value MOV Y2, CX ADD BX, 2 MOV Offset_value, BX ; store current value of my IR AND DH, 03 ; get the line type MOV Point_type, DH ; CALL Drawit ; call the procedure to draw the line RET ; you're done Line ENDP ; ;++======================================================================++ ;|| || ;|| set the active page variable || ;|| (needed by the plot_pt proc) || ;|| || ;++======================================================================++ ; act_page PROC near AND DH, 01 ; the only pages are 0 and 1 & the LSB MOV Active_page, DH ; gives the page RET act_page ENDP ; ;++======================================================================++ ;|| || ;|| clears the given page (graphics) || ;|| || ;++======================================================================++ ; Clear_page PROC near MOV AX, 0B000h ; start of video buffer AND DH, 01 ; get the active page number JE Clr_pg_1 ; if it is zero, you don't need to change AX MOV AX, 0B800h ; second page Clr_pg_1:MOV ES, AX ; set base value XOR DI, DI ; reset offset XOR AX, AX ; value to put in buffer ( AX = 0 ) MOV CX, 8000H ; number of bytes to fill REP STOSW ; repeat storing value in memory RET Clear_page ENDP ; ;++======================================================================++ ;|| || ;|| fills the given page (graphics) || ;|| || ;++======================================================================++ ; Fill_page PROC near MOV CX, ES:[BX] ; get the value to fill the buffer ADD BX, 2 ; increment the instruction pointer MOV Offset_value, BX ; store the pointer MOV AX, 0B000h ; start of video buffer AND DH, 01 ; get the active page number JE Fil_pg_1 ; if it is zero, you don't need to change AX MOV AX, 0B800h ; second page Fil_pg_1:MOV ES, AX ; set base value XOR DI, DI ; reset offset MOV AX, CX ; value to put in buffer ( AX = 0 ) MOV CX, 8000H ; number of bytes to fill REP STOSW ; repeat storing value in memory RET Fill_page ENDP ; ;++======================================================================++ ;|| || ;|| This is the error return function || ;|| || ;++======================================================================++ ; Err_in_fn: POP AX ; the calling value of the AX register is ; on top of the stack. get it off. MOV AH, 0FFh ; signify an error return MOV AL, DH ; return erroneous function JMP Err_exit ; get out while you still can ; ;++======================================================================++ ;|| || ;|| This is the main loop of the code || ;|| || ;++======================================================================++ ; SKIP_DATA: MOV CX, CS ; set DS to the same as CS MOV DS, CX MOV Segment_value, AX ; save these important values MOV Offset_value, BX MOV ES, AX ; move data segment value into ES Go_again: MOV DH, ES:[BX] ; load the function byte INC BX ; increment my program counter MOV Offset_value, BX ; save program counter CMP DH, 0 ; compare it to 0 to see if you are done JE Quit_int ; if equal, get out CMP DH, 80h ; see if the function # is too high JAE Err_in_fn ; if so, go tell the user CMP DH, 10h ; see if the function # is too low JB Err_in_fn ; if so, go tell the user MOV CL, 3 ; bits to shift left (to find fn in table) MOV DL, DH ; XOR DH, DH MOV SI, DX ; copy function byte for manipulation SHR SI, CL ; shift byte (divide it by 8) AND SI, 0Eh ; mask off value (offset into the table) MOV DH, DL ; some of the fns require DH to have the ; instruction byte CALL Function_table[SI] ; jump to funcion offset in the table MOV BX, Segment_value ; get the segment value MOV ES, BX ; set the ES register to the proper segment MOV BX, Offset_value ; get pointer to next instruction JMP Go_again ; start over Quit_int: POP AX Err_exit: POP BX POP CX POP DX POP DI POP SI POP DS POP ES POPF IRET FINISH EQU $ ROUTINE ENDP ;----------------------- set up ----------------------- SET_UP: LEA BX, Function_Table ; set up fuction offset table LEA CX, Graphics_on MOV [BX+2], CX LEA CX, Text_on MOV [BX+4], CX LEA CX, Point MOV [BX+6], CX LEA CX, Line MOV [BX+8], CX LEA CX, Act_page MOV [BX+10], CX LEA CX, Clear_page MOV [BX+12], CX LEA CX, Fill_page MOV [BX+14], CX LEA DX, Strt_msg MOV AH, 9 INT 21H MOV DX, OFFSET ROUTINE ; start of routine MOV AL, 70H ; what interupt I plan to use MOV AH, 25H ; DOS function to set the int vector INT 21H ; set the vector LEA DX, FINISH ; end of resident routine INT 27H ; quit and routine stays resident strt_msg DB 13, 10, '╒══════════════════════════════════════════╕' DB 13, 10, '│ │' DB 13, 10, '│ Hercules video support now resident. │' DB 13, 10, '│ │' DB 13, 10, '│ INT 70h │' DB 13, 10, '│ by │' DB 13, 10, '│ │' DB 13, 10, '│ Ted O''Connor │' DB 13, 10, '│ │' DB 13, 10, '╘══════════════════════════════════════════╛' DB 13, 10, 10, '$' CSEG ENDS END START END