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Assembly Source File | 1991-07-15 | 30.9 KB | 599 lines

; DISPLAY.ASM ─ contains a collection of video-related procedures and ; functions for use with Microsoft high-level languages. ; ; Author: Christy Gemmell ; For: Assembly-Language Toolbox for QuickBASIC ; Version: 5.0 ; Date: 9/6/1991 ; ; Compatible with Microsoft QuickBASIC 4.x and BASIC 6 compilers. ; Assembled using Microsoft Macro Assembler, MASM version 5.1 ; ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Global symbols and procedures. │ ;└────────────────────────────────────────────────────────────────────────┘ ; .model medium public ScreenAddress public ScreenCopy public ScreenRead public ScreenWrite public VideoType public WriteByte public Attribute public Delay public Explode public FastPrint .code ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Data Division. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; Video parameters - default to monochrome screen display ; SnowFlag db 0 ; Snow prevention flag VideoRam dw 0B000h ; Current video segment VideoPort dw 03BAh ; Current video status port Param1 label word Mode db 7 ; Current screen mode Columns db 80 ; Current screen width Param2 label word Rows db 25 ; Current screen length ActivePage db 0 ; Current video page TopLeft label word ; Upper left co-ordinates H1 db ? ; Horizontal length V1 db ? ; Vertical height BotRight label word ; Lower right co-ordinates H2 db ? ; Horizontal length V2 db ? ; Vertical height Factor label word dw 0 dw 0 Counter label word dw ? dw ? Seed label word dw 7397 dw 29447 dw 802 Multiple label word dw 179 dw 183 dw 182 Modulus label word dw 32771 dw 32779 dw 32783 ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Calculate address from a pair of row/column co-ordinates. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; Given the row/column column co-ordinate of a character on the screen, ; this function returns the segment:offset address of that character in ; video memory. The address is correctly adjusted to the start of the ; the currently active display page, but no check is made to ensure that ; the co-ordinates supplied are within the actual screen bounds. ; ; Input: AL = Row co-ordinate of character (base zero). ; AH = Column co-ordinate of character (base zero). ; ; Output: ES:DI==> Address in video display buffer of the ; character cell specified. ; DX = CRT status register port address. ; ; It is assumed that a previous call has been made to the VideoType ; function, above, to determine the screen width, the port address of ; the CRT status register and the correct video display segment. ; ScreenAddress proc far push ax ; Save working registers push bx mov bh,ah ; Column to BH mov bl,cs:Columns ; Get current screen width shl bl,1 ; Add in attribute bytes mul bl ; Multiply by row number xor bl,bl ; Calculate xchg bh,bl ; column offset shl bl,1 ; in BX add ax,bx ; Add it to the row offset mov di,ax ; and copy to DI xor ax,ax ; Index to ROM-BIOS mov es,ax ; data in low memory mov ax,es:[44Eh] ; Get offset of current page add di,ax ; Adjust target pointer mov es,cs:VideoRam ; Return segment of video RAM mov dx,cs:VideoPort ; Return CRT status port pop bx ; Clean up the stack pop ax ret ; and return to caller ScreenAddress endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Copy a character and attribute from the video display. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; If the 'snow prevention' flag is set, this routine waits until the ; beginning of the next CRT horizontal retrace period before reading ; data from the display. This is necessary only on machines fitted with ; a Colour Graphics Adaptor (CGA) which may suffer from glitches or ; screen snow if data is copied from the screen while the video buffer ; is being refreshed. ; ; Input: DS:SI==> Address of the screen location from which ; the data is to be copied. ; ES:DI==> Address of the buffer into which the data ; is to be copied. ; DX = Port address of CRT status register. ; ; Output: SI and DI Updated to point to next buffer locations. ; AX destroyed. ; ScreenCopy proc far cmp cs:SnowFlag,0 ; Snow prevention needed? cli ; Don't interrupt! jz Copy_03 ; No, don't bother Copy_01: in al,dx ; Read video port test al,1 ; Test bit zero jnz Copy_01 ; Wait until it's reset Copy_02: in al,dx ; Read port again test al,1 ; Test bit zero jz Copy_02 ; Wait until it's set Copy_03: movsw ; Transfer one word sti ; Restore interrupts ret ScreenCopy endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Read a character and attribute from the display. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; This procedure is similar to ScreenCopy, above, except that the word ; is simply loaded into AX instead of being copied into a buffer. ; ; Input: DS:SI==> address, in the video display buffer, from ; where the data is to be read ; DX = port address of the CRT status register. ; ; Output: AL = character at the specified address ; AH = display attribute given to character ; DI updated to point to the next word address ; ScreenRead proc far cmp cs:SnowFlag,0 ; Snow prevention needed? jz Read_03 ; No, don't bother cli ; Don't interrupt! Read_01: in al,dx ; Read video port test al,1 ; Test bit zero jnz Read_01 ; Wait until it's reset Read_02: in al,dx ; Read port again test al,1 ; Test bit zero jz Read_02 ; Wait until it's set Read_03: lodsw ; Get character and attribute sti ; You were saying? ret ScreenRead endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Output a character and attribute to the video display. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; If the 'snow prevention' flag is set, this routine waits until the ; beginning of the next CRT horizontal retrace period before writing ; data to the display. This is necessary only on machines fitted with ; a Colour Graphics Adaptor (CGA) which may suffer from glitches or ; screen snow if data is written to the screen while the video buffer ; is being refreshed. ; ; Input: ES:DI==> Address in the video display buffer where ; the data is to be written. ; DX = Port address of CRT status register. ; AL = Character to output. ; AH = Display attribute of character. ; ; Output: DI Updated to point to next output address. ; ScreenWrite proc far push bx ; Preserve BX cmp cs:SnowFlag,0 ; Snow prevention needed? cli ; Don't interrupt! jz Write_3 ; No, don't bother mov bx,ax ; Save byte and attribute Write_1: in al,dx ; Read video port test al,1 ; Test bit zero jnz Write_1 ; Wait until it's reset Write_2: in al,dx ; Read port again test al,1 ; Test bit zero jz Write_2 ; Wait until it's set mov ax,bx ; Recover data Write_3: stosw ; Write data to screen sti ; Restore interrupts pop bx ; Restore BX ret ScreenWrite endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Collect information about the current video display. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; Output: AL = Current display mode ; AH = Screen width in columns ; BL = Screen height in rows ; BH = Active display page ; ; The correct video display segment and CRT status port addresses are ; determined for the current system and, if necessary, the internal ; 'snow' prevention flag is set. ; VideoType proc far push bp ; Preserve these registers push cx push dx push es mov ah,0Fh ; ROM-BIOS Service 16 int 10h ; - Check video mode cmp al,7 ; Monochrome display? je Type_02 ; Yes, use defaults mov cs:VideoRam,0B800h ; Otherwise set up mov cs:VideoPort,03DAh ; for colour Type_01: mov cs:Param1,ax ; Save display mode and width push bx ; Save active display page xor bh,bh mov dl,24 ; Default to 25 rows mov ax,1130h ; ROM-BIOS Service 16 int 10h ; - get font information pop bx mov bl,dl ; DL = number of rows - 1 inc bl mov cs:Param2,bx ; Save video page and height mov bl,10h ; Test for presence mov ah,12h ; of an EGA or VGA int 10h ; display adaptor cmp bl,10h ; Any response? jne Type_02 ; Yes, can't be a CGA mov cs:SnowFlag,1 ; Set snow prevention flag Type_02: mov bx,cs:Param2 ; Recover page and height mov ax,cs:Param1 ; Recover mode and width pop es ; Clean up the stack pop dx pop cx pop bp ret VideoType endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Output a byte of data to video memory. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; This procedure is similar to ScreenWrite, above, except that only a ; single byte is written. It is used by the BackFill routine to reset ; the display attribute of a character, without changing the character ; itself. ; ; Input: ES:DI==> address, in the video display buffer, where ; the byte is to be written. ; DX = port address of the CRT status register. ; AL = the byte value to be written. ; ; Output: DI updated to point to the next byte address ; WriteByte proc far push ax ; Preserve this register cmp cs:SnowFlag,0 ; Snow prevention needed? jz Byte_03 ; No, don't bother mov ah,al ; Save character to output cli ; Don't interrupt! Byte_01: in al,dx ; Read video port test al,1 ; Test bit zero jnz Byte_01 ; Wait until it's reset Byte_02: in al,dx ; Read port again test al,1 ; Test bit zero jz Byte_02 ; Wait until it's set mov al,ah ; Retrieve character Byte_03: stosb ; Write data to the screen sti ; You were saying? pop ax ; Clean up the stack ret WriteByte endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Calculate display attribute from fore and background colours. │ ;└────────────────────────────────────────────────────────────────────────┘ ; Attribute proc far push bp ; Save Base pointer mov bp,sp ; Establish stack frame mov dx,[bp+8] ; Get foreground colour mov ax,[bp+6] ; Get background colour and ax,000Fh ; Only 0-15 allowed mov cl,4 ; Multiply it shl ax,cl ; by sixteen mov dh,dl ; Foreground to DH and dh,10h ; Only 0-31 allowed mov cl,3 ; Multiply it shl dh,cl ; by eight or al,dh ; Adjust or al,dl ; to fit pop bp ; Clean up the stack ret 4 ; Return to QuickBASIC Attribute endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Millisecond delay loop. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; The delay interval, in milliseconds, should be passed by value. ; Delay proc far push bp ; Save Base Pointer mov bp,sp ; Establish stack frame push ds ; Save all registers push bx push cx push dx mov cx,[bp+6] ; Get delay required jcxz Delay_4 ; Ignore if zero push cs ; Align code and pop ds ; data segments mov ax,Factor ; Load fudge factor mov dx,Factor[2] ; into DX:AX or ax,ax ; Has fudge been set? jnz Delay_1 ; Yes, continue call Fudge ; Otherwise set it Delay_1: mov bx,44 ; Divide by 44 to get div bx ; loop counter value Delay_2: mov Counter,ax ; Set up for 1 msec delay mov Counter[2],0 ; High word is not used Delay_3: sub Counter,1 ; Decrement count sbb Counter[2],0 jns Delay_3 ; for 1 millisecond loop Delay_2 ; for n milliseconds Delay_4: pop dx ; Clean up the stack pop cx pop bx pop ds pop bp ret 2 ; Return to QuickBASIC Delay endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Calculate delay fudge factor for host system. │ ;└────────────────────────────────────────────────────────────────────────┘ ; Fudge proc near push es ; Save this register xor ax,ax ; Zero AX mov Factor,ax ; Initialise mov Factor[2],ax ; local data mov es,ax ; Point ES to page zero mov al,es:[46Ch] ; Get current timer count Fudge_1: cmp al,es:[46Ch] ; Has it changed? je Fudge_1 ; No, wait till it does mov al,es:[46Ch] ; Yes, get new count Fudge_2: add Factor,1 ; Increment adc Factor[2],0 ; fudge factor cmp al,es:[46Ch] ; Has timer changed yet? je Fudge_2 ; No, keep incrementing mov ax,Factor ; Yes, load fudge mov dx,Factor[2] ; factor and return pop es ; Clean up the stack ret ; Return to caller Fudge endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Clear screen rectangle explosively. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; The panel is cleared, starting at the centre point, and progressively ; moving outwards until the defined borders are reached. This gives the ; impression of the clear area exploding onto the screen. ; Explode proc far push bp ; Save Base pointer mov bp,sp ; Establish stack frame push es ; Save Extra Segment, push ds ; Data segment, push si ; and index push di ; pointers call VideoType ; Get video parameters push cs ; Align Code and pop ds ; Data segments mov al,[bp+16] ; Get top-left row dec al ; Use ROM-BIOS numbering cmp al,0 ; Check for jae Exp_01 ; legal xor al,al ; values Exp_01: mov [bp+16],al ; Save it for later mov al,[bp+14] ; Get top-left column dec al ; Use ROM-BIOS numbering cmp al,0 ; Check for jae Exp_02 ; legal xor al,al ; values Exp_02: mov [bp+14],al ; Save it for later mov al,[bp+12] ; Get bottom-right row dec al ; Use ROM-BIOS numbering cmp al,Rows ; Check jb Exp_03 ; for mov al,Rows ; legal dec al ; values Exp_03: mov [bp+12],al ; Save it for later mov al,[bp+10] ; Get bottom-right column dec al ; Use ROM-BIOS numbering cmp al,Columns ; Check jb Exp_04 ; for mov al,Columns ; legal dec al ; values Exp_04: mov [bp+10],al ; Save it for later mov al,[bp+16] ; Get top-left row cmp al,[bp+12] ; Below bottom-right? jb Exp_05 ; If so, proceed jmp Exp_15 ; If not, abort Exp_05: add al,[bp+12] ; Add bottom-right row shr al,1 ; Divide by two mov V1,al ; Store the result mov V2,al ; twice mov al,[bp+14] ; Get top-left column cmp al,[bp+10] ; Left of right-hand edge? jb Exp_06 ; If so, proceed jmp Exp_15 ; If not, abort Exp_06: add al,[bp+10] ; Add bottom-right column shr al,1 ; Divide by two mov H1,al ; Store the result mov H2,al ; twice mov ax,[bp+6] ; Get delay value cmp ax,1 ; Check for jge Exp_07 ; legal mov ax,1 ; values Exp_07: mov [bp+6],ax ; Save it for later mov bh,[bp+8] ; Get display attribute Exp_08: mov al,[bp+16] ; Check top-left row cmp al,V1 ; Reached it yet? jae Exp_09 ; If not bump dec V1 ; the counter Exp_09: mov al,[bp+12] ; Check bottom-right row cmp al,V2 ; Reached it yet? jbe Exp_10 ; If not bump inc V2 ; the counter Exp_10: mov al,[bp+14] ; Check top-left column mov cx,3 ; Iteration count Exp_11: cmp al,H1 ; Reached it yet? jae Exp_12 ; If not bump dec H1 ; the counter loop Exp_11 ; Up to three times Exp_12: mov al,[bp+10] ; Check bottom-right column mov cx,3 ; Iteration count Exp_13: cmp al,H2 ; Reached it yet? jbe Exp_14 ; If not bump inc H2 ; the counter loop Exp_13 ; Up to three times Exp_14: mov dx,BotRight ; Get lower right co-ordinate mov cx,TopLeft ; Get upper left co-ordinate mov ax,0700h ; BIOS display service 7 int 10h ; - scroll down window push [bp+6] ; Get delay count call Delay ; Pause awhile mov al,[bp+16] ; Get top-left row cmp al,V1 ; Reached it? jb Exp_08 ; No, do it again mov al,[bp+14] ; Get top-left column cmp al,H1 ; Reached it? jb Exp_08 ; No, do it again mov al,[bp+12] ; Get bottom-right row cmp al,V2 ; Reached it? ja Exp_08 ; No, do it again mov al,[bp+10] ; Get bottom-right column cmp al,H2 ; Reached it? ja Exp_08 ; No, do it again Exp_15: pop di ; Clean up the stack pop si pop ds pop es pop bp ret 12 ; Return to QuickBASIC Explode endp ;┌────────────────────────────────────────────────────────────────────────┐ ;│ Fast screen printing. │ ;└────────────────────────────────────────────────────────────────────────┘ ; ; This procedure outputs text directly to the video display without ; going through DOS or ROM-BIOS services. ; FastPrint proc far push bp ; Save Base pointer mov bp,sp ; Establish stack frame push es ; Save Extra Segment, push si ; and index push di ; pointers call VideoType ; Get video parameters mov dh,ah ; Load screen dimensions mov dl,bl ; into DX mov ax,[bp+12] ; Get row number dec al ; Convert to base zero cmp al,0 ; Top screen row? jae Fast_01 ; Jump if not below xor al,al ; Don't go over the top! Fast_01: cmp al,dl ; Bottom row? jb Fast_02 ; Go no further mov al,dl dec al Fast_02: mov bx,[bp+10] ; Get column number mov ah,bl ; into AH dec ah ; Convert to base zero cmp ah,0 ; Leftmost column? jae Fast_03 ; Jump if not below xor ah,ah ; Don't go off the screen Fast_03: cmp ah,dh ; Rightmost column? jb Fast_04 ; Go no further mov ah,dh ; Don't go off the screen dec ah ; Base zero, remember? Fast_04: mov bx,[bp+8] ; Index to string descriptor mov cx,[bx] ; String length to CX jcxz Fast_06 ; Abort if a null string mov si,[bx+2] ; DS:SI==> string data call ScreenAddress ; Calculate target address mov ax,[bp+6] ; Get display attribute xchg ah,al ; into AH cld ; Clear direction flag Fast_05: lodsb ; Get a byte from the string call ScreenWrite ; Write byte and attribute loop Fast_05 ; For length of string xor ax,ax ; Report success Fast_06: pop di ; Clean up the stack pop si pop es pop bp ret 8 ; Return to QuickBASIC FastPrint endp end ;┌────────────────────────────────────────────────────────────────────────┐ ;│ (c) 1988,1991 By Christy Gemmell and Singular SoftWare. │ ;└────────────────────────────────────────────────────────────────────────┘