Simtel MSDOS 1993 May/SIMTEL_0593.ISO/msdos/deskaces/remind.asm

Assembly Source File | 1986-06-13 | 9KB | 375 lines

---------------------------- REMIND.DOC (cut here) ----------------------------
REMIND.COM is a program that can pop up a small reminder on line 25 of
your screen at a given time.  It displays messages via the ROM BIOS, and
thus will work on any IBM BIOS-compatible machine with any display
hardware in any graphics mode.  The syntax is: REMIND time message,
where time is one or two hour digits followed by a colon and two minute
digits.  REMIND can also be entered without any arguments, in which case
the pending, or if none, the previous message is shown.  The program
works by communicating with a resident daemon that steals the timer
interrupt (1c).  This communication is via the multiplex interrupt (2f),
using multiplex number f0.  The daemon is installed as a terminate-and-
stay-resident program the first time that remind is executed.  To run on
a machine with the Microsoft system card, first use the program SETTIME
to correctly set the BIOS timer (DOS's TIME command doesn't do this when
the system card's clock.sys device driver is installed).

Written by Robert Lenoil; June/July 1985.
------------------------ end of REMIND.DOC (cut here) -------------------------

---------------------------- REMIND.ASM (cut here) ----------------------------
; Displays user-supplied message on 25th screen line at user-specified time.
; Author: Robert Lenoil        Date: June, 1985

;Placed in the public domain, June 1986.
;Author's electronic mail address:
;USENET: [e-mail]            ARPA: [e-mail]

DOSFN    MACRO    FNUM        ;macro to make DOS function call
IF    FNUM/256
    MOV    AX,FNUM
ELSE
    MOV    AH,FNUM
ENDIF
    INT    21H
    ENDM

PRINT    MACRO    TEXT        ;macro to print message at ds:text
    MOV    BX,OFFSET RESGRP:TEXT
    CALL    MSGOUT
    ENDM

ATTRIB    EQU    0F0H        ;flashing black foreground, white background

BIOSDAT    SEGMENT    AT 40H
ORG    6CH
TIMER_LOW    DW    ?    ;low word of timer count
TIMER_HIGH    DW    ?    ;high word of timer count
TIMER_OFL    DB    ?    ;timer has rolled over since last read
BIOSDAT    ENDS

RESGRP    GROUP    DATA,RESDNT,NONRES

DATA    SEGMENT
ORG    2CH
ENVSEG    DW    ?        ;seg address of environment
ORG    70H
RINT2F    DD    ?        ;address of next in int2f chain
RINT1C    DD    ?        ;address of real int1c handler
MSGON    DB    ?        ;zero if message already on
MSGLOW    DW    ?        ;when to put up message (in timer ticks)
MSGHIGH    DW    ?
MSG    DW    ?        ;ptr to start of message on command line
MSGLEN    DB    ?        ;message length
CMDLEN    DB    ?        ;command line length
CMD    LABEL    BYTE        ;command line
ORG    100H
DATA    ENDS

RESDNT    SEGMENT            ;handle timer interrupt
ASSUME    CS:RESGRP,DS:BIOSDAT

ENTRY:    JMP    NEAR PTR START

;note that on entry, caller's AX,DX are saved; DS points to BIOS data area
INT1C:    STI
    SUB    AX,AX
    CMP    MSGON,AL    ;has message already been displayed?
    JE    EXINT        ;yes, exit
    CMP    TIMER_OFL,AL    ;has timer overflowed?
    JNE    EXINT        ;yes, exit (it's after midnight)
    MOV    AX,TIMER_HIGH
    CMP    AX,MSGHIGH
    JB    EXINT
    JA    DISPLAY
    MOV    AX,TIMER_LOW
    CMP    AX,MSGLOW
    JB    EXINT

DISPLAY:            ;it's time: print message
    PUSH    BX        ;save regs
    PUSH    CX
    PUSH    DX
    PUSH    BP
    PUSH    SI
    PUSH    DI

    MOV    BL,2        ;send two beeps
BEEPLP:    MOV    AX,0E07H
    INT    10H
    DEC    BL
    JNZ    BEEPLP

    MOV    AH,15
    INT    10H        ;[BH]=active display page, [AH]=max # columns
    PUSH    AX        ;[AL]=video mode
    MOV    AH,3
    INT    10H        ;[DX] = cursorpos
    POP    AX
    PUSH    DX
    PUSH    AX
    MOV    SI,MSG        ;[SI] = ptr to msg
    MOV    CL,MSGLEN
    SUB    CH,CH        ;[CX] = msg length
    POP    AX
    CMP    CL,AH        ;check if msg longer than screen width
    JLE    DISP1
    XCHG    CL,AH        ;yes, truncate
DISP1:    MOV    BL,ATTRIB    ;load screen attribute
    CMP    AL,4        ;are we in a graphics mode (AL > 3)?
    JB    DISP2
    AND    BL,7FH        ;yes, turn off bit 7 (otherwise characters are
                ;XORed onto screen, which isn't what we want.)
DISP2:    MOV    DX,1800H    ;set cursorpos to row 24, column 0
DISPLP:    MOV    AH,2        ;set cursorpos
    INT    10H
    MOV    AH,9        ;function = write char/attrib
    MOV    AL,CS:[SI]    ;get character
    PUSH    SI
    PUSH    CX
    MOV    CX,1        ;repeat count of one
    INT    10H        ;write it
    POP    CX
    POP    SI
    INC    SI        ;position to next char
    INC    DX        ;increment cursorpos
    LOOP    DISPLP        ;loop till cx=0

    POP    DX        ;restore cursorpos
    MOV    AH,2
    INT    10H

    MOV    MSGON,CH    ;set displayed flag

    POP    DI        ;pop regs
    POP    SI
    POP    BP
    POP    DX
    POP    CX
    POP    BX

EXINT:    JMP    RINT1C        ;jump to real timer tick handler

INT2F:    CMP    AH,0F0H        ;if not our number, chain to next
    JE    OUR2F
    JMP    RINT2F

OUR2F:    CMP    AL,0        ;is function Get Installed State?
    JE    XINT2F
    PUSH    CS        ;otherwise load our segment into es
    POP    ES
XINT2F:    MOV    AL,0FFH        ;tell caller that we're installed
    IRET
RESDNT    ENDS

NONRES    SEGMENT
ASSUME    DS:RESGRP
START:    ;deallocate environment space
    MOV    AX,ENVSEG
    MOV    ES,AX
    DOSFN    49H

    ;erase 25th screen line
    MOV    AH,15
    INT    10H        ;[BH]=active display page, [AH]=max # columns
    MOV    BL,AH        ;save ah
    MOV    AH,3
    INT    10H        ;[DX] = cursorpos
    PUSH    DX
    MOV    DX,1800H    ;set cursorpos to row 24, column 0
    MOV    AH,2
    INT    10H
    SUB    CX,CX
    XCHG    BL,CL        ;[CX]=screen width, [BL]=0
    MOV    AH,9        ;write (screen width) chars w/attribute 0
    INT    10H
    POP    DX        ;restore cursorpos
    MOV    AH,2
    INT    10H

    MOV    AX,0F000H    ;perform installation check
    INT    2FH
    CMP    AL,0FFH        ;are we installed?
    JNE    INSTALL
    MOV    AX,0F001H    ;yes, get segment of resdnt in es
    INT    2FH
    XOR    CH,CH        ;reset just-installed flag
    JMP    SHORT PARSE

ASSUME    ES:RESGRP
INSTALL:            ;install resident code
    OR    AL,AL        ;can we install?
    JNZ    CANT        ;al != 0; can't install resdnt code
    MOV    MSGON,AL    ;turn off display flag until we're ready
    DOSFN    352FH        ;store address of int2f handler
    MOV    WORD PTR RINT2F,BX
    MOV    BX,ES
    MOV    WORD PTR RINT2F+2,BX
    MOV    DX,OFFSET RESGRP:INT2F    ;set int2f vector to us
    DOSFN    25H
    DOSFN    351CH        ;store address of real int1c handler
    MOV    WORD PTR RINT1C,BX
    MOV    BX,ES
    MOV    WORD PTR RINT1C+2,BX
    MOV    DX,OFFSET RESGRP:INT1C    ;set int1c vector to us
    DOSFN    25H
    PRINT    LOADED
    MOV    CH,1        ;flag that we just installed ourself

;parse command line
PARSE:    SUB    BX,BX
    MOV    CL,CMDLEN
    CALL    EAT_SPACE    ;eat initial whitespace
    JC    GETHRS
;command line is empty. show pending message
    OR    CH,CH
    JNZ    STAY0        ;just installed ourself; there is no message
    CMP    ES:MSGON,0    ;is there a pending message?
    JE    NOMSG
    PRINT    PENDING        ;yes, print "pending"
    JMP    SHORT PRCMD
NOMSG:    PRINT    LASTMSG        ;no, print "last reminder"
PRCMD:    PUSH    ES        ;get resident segment in ds
    POP    DS
    PRINT    CMD        ;print reminder
EXIT0:    XOR    AL,AL        ;exit with errorlevel = 0
EXIT:    DOSFN    4CH

CANT:    PRINT    NOLOAD
    MOV    AH,2
    JMP    SHORT EXIT

STAY0:    MOV    AL,0        ;errorlevel = 0
STAY:    MOV    DX,OFFSET RESGRP:START    ;terminate and stay resident
    MOV    CL,4
    SHR    DX,CL
    DOSFN    31H

GETHRS:    CALL    GETDIG1
    CMP    CMD[BX],':'
    JE    GOTHRS
    CALL    GETDIG2
    CMP    CMD[BX],':'
    JNE    SYNTAX
GOTHRS:    CMP    AL,24        ;check for range 0-23
    JGE    SYNTAX
    INC    BX        ;skip colon
    MOV    DX,65520
    MUL    DX        ;convert hours to timer ticks
    MOV    MSGHIGH,DX
    MOV    MSGLOW,AX

    CALL    GETDIG1        ;get seconds
    CALL    GETDIG2
    CMP    AL,60        ;check for range 0-59
    JGE    SYNTAX
    MOV    DX,1092
    MUL    DX        ;convert to timer ticks
    ADD    MSGLOW,AX    ;and add to hours
    ADC    MSGHIGH,DX

    CMP    CMD[BX],20H    ;at least one space required
    JNE    SYNTAX
    CALL    EAT_SPACE    ;consume any others
    JNC    SYNTAX

    LEA    AX,CMD[BX]    ;store start of message ptr
    MOV    MSG,AX
    MOV    DL,CL
    SUB    DL,BL        ;store message length
    MOV    MSGLEN,DL

    INC    MSGON        ;all fields are setup, set the display flag

    OR    CH,CH        ;are we the resident code?
    JNZ    STAY0        ;yes: we're done
    CMP    ES:MSGON,0    ;no: will we overwrite a pending message?
    JE    DWNLD

    PUSH    CX        ;yes, print it first
    PRINT    OVRWRT
    PUSH    ES
    POP    DS
    PRINT    CMD
    PUSH    CS
    POP    DS
    POP    CX

DWNLD:    STD            ;no: download msg to resident code
    ;we move backwards so that the display flag is the last byte written
    ADD    CL,9
    MOV    SI,OFFSET RESGRP:MSGON - 1
    ADD    SI,CX
    MOV    DI,SI
    REP    MOVSB
    JMP    EXIT0        ;we're done

SYNTAX:    PUSH    CX        ;save ch
    PRINT    SERROR
    POP    CX
    MOV    AL,1        ;errorlevel = 1
    OR    CH,CH        ;are we the resident code?
    JNZ    GOSTAY        ;yes, then stay resident
    JMP    EXIT        ;else just exit
GOSTAY:    JMP    STAY

EAT_SPACE    PROC    NEAR
;Advances cmd[bx] past any spaces.  Resets carry if ran off end of cmd.
    CMP    BL,CL
    JNC    ATE
    CMP    CMD[BX],20H
    STC
    JNE    ATE
    INC    BX
    JMP    SHORT EAT_SPACE
ATE:    RET
EAT_SPACE    ENDP

GETDIG1    PROC    NEAR
;GETDIG1 gets digit in AX.  GETDIG2 multiplies AX by 10 and adds new digit.
    SUB    AX,AX
GETDIG2:
    MOV    DL,CMD[BX]
    CMP    DL,'0'        ;check for digit range
    JL    SYNTAX
    CMP    DL,'9'
    JG    SYNTAX
    INC    BX
    SUB    DL,'0'
    MOV    DH,10
    MUL    DH
    ADD    AL,DL
    RET
GETDIG1    ENDP

MSGOUT    PROC    NEAR        ;displays string at ds:bx w/length byte at bx-1
    SUB    CH,CH        ;output message to stderr
    MOV    CL,[BX]-1
    MOV    DX,BX
    MOV    BX,2
    DOSFN    40H
    MOV    DL,0DH        ;output CRLF to console
    DOSFN    6H
    MOV    DL,0AH
    INT    21H
    RET
MSGOUT    ENDP

;Messages (each preceeded by a byte holding its length)
    DB    27
SERROR    DB    "Usage: REMIND hh:mm message"
    DB    34
NOLOAD    DB    "System error: Can't install daemon"
    DB    24
LOADED    DB    "REMIND daemon installed."
    DB    8
PENDING    DB    "Pending:"
    DB    35
LASTMSG    DB    "Nothing pending; last reminder was:"
    DB    28
OVRWRT    DB    "Overwriting pending message:"
NONRES    ENDS

END    ENTRY
------------------------ end of REMIND.ASM (cut here) -------------------------