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Assembly Source File | 1986-02-19 | 18.5 KB | 552 lines

TITLE 'Wolfware Sample Program', 'Resident Time Display' ;----------------------------------------------; ; Resident Time Display ; ; ; ; A RAM resident utility which, if active, ; ; constantly displays the time in the the ; ; upper right corner. Once the utility is ; ; installed, the time is activated or ; ; deactivated with Alt-32 (hold down the Alt ; ; key and type 32 on the numeric keypad, then ; ; release the Alt key). The program is ; ; initially non-activated when first ; ; installed. Once assembled, to install, just ; ; type: ; ; ; ; RTIME ; ; ; ; The time is updated about three times a ; ; second, in the backround of whatever program ; ; is presently being executed. The time ; ; display overwrites whatever is on the screen ; ; at that location. The display can only be ; ; activated or deactivated when the foreground ; ; program does keyboard I/O via interrupt 16H. ; ; This utility uses about 1065 bytes of ; ; memory. ; ; ; ; For simplicity the program assumes that ; ; there are 65535 ticks in an hour, though ; ; there are actually 65543. This means that ; ; the displayed time is 8 ticks fast for each ; ; hour past midnight. The most it is off ; ; occurs just before midnight, when it is ; ; 8 * 23 = 184 ticks, or about 10 seconds fast.; ; As result of this the time actually runs to ; ; about 24:00:10 before switching to 00:00:00. ; ; ; ; This program may not be compatible with ; ; other RAM resident type programs. ; ;----------------------------------------------; PROC FAR JMP INSTALL ;skip to installation routine TRUE EQU -1 ;true flag FALSE EQU 0 ;false flag ;----- display location, location of first character of 8 byte string ROW EQU 1 ;row, 1 to 25 COLUMN EQU 73 ;column, 1 to 80 ;----- execution parameters KEY EQU 0020H ;int 16H key code to activate, Alt-32 ATTRIBUTE EQU 70H ;display attribute, reverse video COUNT_SET EQU 6 ;wait count, updated 18.2/COUNT_SET = 3/sec ;----- BIOS data, at segment 0 EQUIP_FLAG EQU WORD [0410H] ;equipment word SCREEN_COL EQU WORD [044AH] ;CRT columns ;----- interrupt location, at segement 0 KEYBOARD EQU [58H] ;keyboard fetch, interrupt 16 TIMER_TICK EQU [70H] ;timer tick vector location, interrupt 1C ;----- clock information TIMER_LOW EQU WORD [046CH] ;low word of timer, at segment 0 TIMER_HIGH EQU WORD [046EH] ;high word of timer, at segment 0 COUNTS_SEC EQU 18 ;counts in second COUNTS_MIN EQU 1092 ;counts in minute COUNTS_HOR EQU 0FFFFH ;counts in hour ;----- local stack size, stack has to handle local routines and overhead STACK EQU 20H + 80H ;size ;----------------------------------------------; ; INT16 ; ; Alternate interrupt 16H (keyboard I/O) to ; ; handle normal function calls while ; ; intercepting display activation/deactivation ; ; commands. Check for command only if read key ; ; or get keyboard status (functions 0 and 1). ; ;----------------------------------------------; INT16 PROC FAR STI ;interrupts on PUSHF ;save entry flags ;----- read next key OR AH,AH ;check if read key JNZ NONKEY ;jump if not I16GET SEG CS ;code segment CALL OLD_INT16 ;keyboard interrupt CMP AX,KEY ;check scan code JE SUBKEY ;jump if activate key IRET ;----- activation key on read SUBKEY CALL TOGGLE_ACT ;toggle present setting SUB SP,2 ;simulate flags for interrupt call SUB AH,AH ;read next key function JMPS I16GET ;try again ;----- keyboard status NONKEY CMP AH,1 ;check if keyboard status JNE NONSTAT ;jump if not POPF ;restore entry flags PUSHF ;flags for interrupt call SEG CS ;code segment CALL OLD_INT16 ;keyboard interrupt PUSHF JNZ I16CHKSK ;jump if key in buffer POPF RET 2 I16CHKSK CMP AX,KEY ;check scan code JE I16FACT ;jump if activate key POPF RET 2 ;----- activation key on status I16FACT SUB AH,AH ;get key function SUB SP,2 ;simulate flags for interrupt call SEG CS ;code segment CALL OLD_INT16 ;keyboard interrupt, get key CALL TOGGLE_ACT ;toggle present setting MOV AH,1 ;status function JMPS NONKEY ;try again, flags still on stack ;----- keyboard shift status or unknown function NONSTAT SEG CS ;code segment CALL OLD_INT16 ;keyboard interrupt, (flags on stack) IRET ENDP ;INT16 ;----------------------------------------------; ; TOGGLE_ACT ; ; Toggle active setting and reset screen info. ; ; Clears time display (sets to dashes). ; ;----------------------------------------------; TOGGLE_ACT PROC NEAR SEG CS CMP ACTIVATED,TRUE ;check if on JE ACTOFF ;jump if so, turn off ;----- activate SEG CS MOV ACTIVATED,TRUE ;activate SEG CS MOV COUNTER,COUNT_SET ;reset counter JMPS SCREENRES ;----- deactivate ACTOFF SEG CS MOV ACTIVATED,FALSE ;activate off ;----- reset screen information and clear display ;----- switch to local stack SCREENRES SEG CS MOV STACK_SEG,SS ;save stack segment SEG CS MOV TEMP,CS SEG CS MOV SS,TEMP ;new stack segment SEG CS MOV STACK_OFF,SP ;save stack pointer SEG CS MOV SP,LOCAL_STK ;new stack ;----- save all registers PUSH AX PUSH BX PUSH CX PUSH DX PUSH DI PUSH SI PUSH DS PUSH ES CLD ;forward direction ;----- set screen information SUB AX,AX MOV DS,AX ;segement 0 MOV BX,SCREEN_COL ;screen columns MOV AX,0B800H ;graphics segment MOV DX,EQUIP_FLAG ;get equipment flag AND DX,30H ;mask CRT bits CMP DX,30H ;check if BW card JNE NOTBW ;jump if not MOV AX,0B000H ;BW segement NOTBW MOV DX,CS MOV DS,DX MOV ES,DX ;set data segment registers MOV SCREEN_SEG,AX ;save segment ;----- calculate screen offset MOV AX,BX SUB DX,DX MUL AX,TIME_ROW ;row offset ADD AX,TIME_COL ;add for columns SHL AX ;times two, account for attribute bytes MOV SCREEN_OFF,AX ;save ;----- clear time display (set numbers to dashes) MOV AX,2D2DH ;dashes to clear time and date CLI ;interrupts off while display MOV DI,OFFSET TDISPLAY ;dislay line STOSW ;hours INC DI STOSW ;minutes INC DI STOSW ;seconds CALL DISPLAY ;display new string STI ;interrupts back on ;----- restore registers POP ES POP DS POP SI POP DI POP DX POP CX POP BX POP AX ;----- restore stack SEG CS MOV SP,STACK_OFF ;stack pointer SEG CS MOV SS,STACK_SEG ;stack segment RET ENDP ;TOGGLE_ACT ;----------------------------------------------; ; INT1C ; ; Alternate interrupt 1CH (timer tick). ; ; Executed every timer tick (about 18.2 times ; ; a second). ; ; ; ; One out of COUNT_SET cycles the time is ; ; displayed to its predetermined location, so ; ; the time is actually updated 18.2/COUNT_SET ; ; times per second. ; ; ; ; Each interrupt calls the original timer tick ; ; interrupt for the benefit of any other ; ; routines that were using it for their own ; ; execution. ; ;----------------------------------------------; INT1C PROC NEAR CLI ;interrupts off ;----- check if activated SEG CS CMP ACTIVATED,TRUE ;check if activated JE REDISCHK ;jump if so EXIT PUSHF ;flags for interrupt call SEG CS CALL OLD_INT1C ;call original interrupt IRET REDISCHK SEG CS DEC COUNTER ;decrement counter JNZ EXIT ;jump if not zero ;----- redisplay time ;----- switch to internal stack SEG CS MOV ACTIVATED,FALSE ;deactivate SEG CS MOV STACK_SEG,SS ;save stack segment SEG CS MOV TEMP,CS SEG CS MOV SS,TEMP ;new stack segment SEG CS MOV STACK_OFF,SP ;save stack pointer SEG CS MOV SP,LOCAL_STK ;new stack ;----- save all registers PUSH AX PUSH BX PUSH CX PUSH DX PUSH DI PUSH SI PUSH DS PUSH ES CLD ;forward direction ;----- get time SUB AX,AX MOV DS,AX ;segment 0 MOV DX,[TIMER_HIGH] ;timer high MOV AX,[TIMER_LOW] ;timer low ;----- set time MOV BX,CS MOV DS,BX MOV ES,BX ;set segment registers MOV COUNTER,COUNT_SET ;reset counter MOV DI,OFFSET TDISPLAY ;start of time display string MOV BX,COUNTS_HOR ;counts/hour DIV AX,BX ;divide CALL NUMBER_CON ;convert to ASCII and store INC DI ;skip colon MOV AX,DX ;remainder is new dividend SUB DX,DX MOV BX,COUNTS_MIN ;counts/minute DIV AX,BX ;divide CALL NUMBER_CON ;convert to ASCII and store INC DI ;skip colon MOV AX,DX ;remainder is new dividend SUB DX,DX MOV BX,COUNTS_SEC ;counts/second DIV AX,BX ;divide CALL NUMBER_CON ;convert to ASCII and store CALL DISPLAY ;display string to screen ;----- restore registers POP ES POP DS POP SI POP DI POP DX POP CX POP BX POP AX ;----- restore stack SEG CS MOV SP,STACK_OFF ;restore stack pointer SEG CS MOV SS,STACK_SEG ;restore stack segment SEG CS MOV ACTIVATED,TRUE ;reactivate JMP EXIT ;exit routine ENDP ;INT1C ;----------------------------------------------; ; NUMBER_CON ; ; Convert number in AL to two digit ASCII ; ; string and store result to DI. Number must ; ; be in range 0 to 99. DI returns pointing to ; ; byte after new string. ; ;----------------------------------------------; NUMBER_CON PROC NEAR SHL AL SUB AH,AH ;AX gets relative offset ADD AX,OFFSET NUMBERS ;absolute offset MOV SI,AX MOVSW ;move word (two byte digits) RET ;----- data, 00 to 99 NUMBERS LABEL BYTE DB '00010203040506070809' DB '10111213141516171819' DB '20212223242526272829' DB '30313233343536373839' DB '40414243444546474849' DB '50515253545556575859' DB '60616263646566676869' DB '70717273747576777879' DB '80818283848586878889' DB '90919293949596979899' ENDP ;NUMBER_CON ;----------------------------------------------; ; DISPLAY ; ; Display the time string to the screen by ; ; writing it directly to the screen buffer. ; ;----------------------------------------------; DISPLAY PROC NEAR MOV AH,ATTRIBUTE ;display attribute MOV CX,OFFSET TDISPLAY_END - OFFSET TDISPLAY ;length MOV DI,SCREEN_OFF ;offset into screen MOV SI,OFFSET TDISPLAY ;start of time string MOV ES,SCREEN_SEG ;segment of screen ;----- move string to screen buffer DISLOOP LODSB ;load character STOSW ;store character and attribute LOOP DISLOOP ;loop CX times RET ENDP ;DISPLAY ;----------------------------------------------; ; Data ; ;----------------------------------------------; ACTIVATED DB FALSE ;activation status, initially off COUNTER DB ? ;execution counter, set when activated TIME_ROW DW ROW - 1 ;display row TIME_COL DW COLUMN - 1 ;display column STACK_OFF DW ? ;storage for stack offset STACK_SEG DW ? ;storage for stack segment LOCAL_STK DW OFFSET END + STACK ;local stack top SCREEN_OFF DW ? ;screen offset SCREEN_SEG DW ? ;screen segment TEMP DW ? ;temporary storage ;----- display string TDISPLAY LABEL BYTE ;start of string DB '--:--:--' TDISPLAY_END LABEL BYTE ;end of string (to calculate length) ;----- original interrupts OLD_INT16 LABEL DWORD DW ? ;offset DW ? ;segment OLD_INT1C LABEL DWORD DW ? ;offset DW ? ;segment END LABEL BYTE ;end of code and data, start of stack space ;----------------------------------------------; ; INSTALL ; ; Install the alternate interrupts. ; ;----------------------------------------------; INSTALL PROC NEAR CLI ;disable interrupts ;----- install new interrupt vectors MOV AX,OFFSET INT16 ;keyboard offset MOV BX,CS ;present segement MOV CX,OFFSET INT1C ;timer offset MOV DX,CS ;present segement PUSH DS SUB BP,BP MOV DS,BP ;segment 0 XCHG AX,WORD KEYBOARD XCHG BX,WORD KEYBOARD+2 ;install int 16 XCHG CX,WORD TIMER_TICK XCHG DX,WORD TIMER_TICK+2 ;install int 1C POP DS ;----- save the old ones MOV WORD OLD_INT16,AX MOV WORD OLD_INT16+2,BX ;save int 16 MOV WORD OLD_INT1C,CX MOV WORD OLD_INT1C+2,DX ;save int 1C STI ;enable interrupts ;----- display message MOV DX,OFFSET INSTALLM ;message location MOV AH,9 ;print string function INT 21H ;execute ;----- finish up MOV DX,LOCAL_STK ;end of interrupt, top of local stack INT 27H ;terminate but stay resident ;----- message INSTALLM DB 10 DB '/-------------------------------------------\',13,10 DB '| Resident time display utility installed |',13,10 DB '|-------------------------------------------|',13,10 DB '| press ALT-32 to activate/deactivate |',13,10 DB '\-------------------------------------------/',13,10,'$' ENDP ;INSTALL ENDP