PsL Monthly 1993 December

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/ PsL Monthly 1993 December / PSL Monthly Shareware CD-ROM (December 1993).iso / prgmming / dos / c / execbep.com / EXECBEEP.ASM < prev next >

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Assembly Source File | 1988-10-30 | 11.6 KB | 329 lines

name execbeep dp equ dword ptr of equ offset code segment assume cs:code, ds:code org 2CH ENV_SEG dw ? org 80h TAIL_LENGTH db ? org 100h begin: jmp start prg_nam db 'EXECBEEP 3.0'; beep proc ; beep the speaker push ax ; save push cx in al,97 ; get port values and al,0feh ; turn speaker on out 97,al mov cx,bx ; cycles to cx more_sound: push cx ; save cycles xor al,2 ; flip push/pull out 97,al mov cx,dx ; wait part1: loop part1 xor al,2 ; flip push/pull out 97,al mov cx,dx ; wait part2: loop part2 pop cx loop more_sound pop cx ; restore pop ax ret beep endp beep_low proc push bx push dx mov bx,50 ; number of cycles mov dx,100 ; half cycle time call beep pop dx pop bx ret beep_low endp beep_high proc push bx push dx mov bx,100 ; number of cycles mov dx,50 ; half cycle time call beep pop dx pop bx ret beep_high endp ; +++ EDR 2/27/88 space db ' ',0 ; just a space cr_lf db 13,10,0 ; carriage return/line feed tty_str proc ; show string in ES:SI, max of CX chars jmp short load ; make sure string isn't null write: mov ah,0EH ; write TTY service (char in AL) int 10H ; kick BIOS inc si ; point to next char dec cx ; and decrement count load: mov al,es:[si] ; load char to show or al,al ; is it end of asciiz string? jz done ; yes cmp cx,0 ; did we reach max char count? jnz write ; no- write it done: ret tty_str endp show_cmd proc ; show the exec command line push ax ; save the world push cx push dx push si push di push es push bx mov ax,ds ; show command name from ds:dx mov es,ax mov si,dx mov cx,64 call tty_str mov ax,cs ; followed by a space (just in case) mov es,ax mov si,offset space mov cx,64 call tty_str pop bx ; get original es:bx back pop es push es push bx mov si,es:[bx+2] ; set es:si to command arguments mov ax,es:[bx+4] mov es,ax mov cl,es:[si] ; get char count in cx xor ch,ch inc si ; skip to actual command chars call tty_str ; and show 'em mov ax,cs ; skip up a line mov es,ax mov si,offset cr_lf mov cx,64 call tty_str pop bx ; restore the world pop es pop di pop si pop dx pop cx pop ax ret ; back to caller show_cmd endp ; --- EDR old_dos_int label dword ; address old_int21 dw 2 dup(?) ; former int 21h address new_int21 proc far cmp ah,4bh ; EXEC function? je exec_beep ; yes, beep, then call EXEC cmp ah,4dh ; request to get return code? je retc_beep ; yes, beep then get return code jmp dp cs:old_int21 ; no, pass it on exec_beep: call beep_low ; beep before EXEC call show_cmd ; show the command (EDR) jmp dp cs:old_int21 ; go do EXEC retc_beep: call beep_high ; beep after EXEC jmp dp cs:old_int21 ; go get return code new_int21 endp END_OF_RES label word HELP1 DB 'Cannot Uninstall - Did not find copy in memory$' HELP2 DB 'Cannot Install - Found copy already in memory$' help3 db 'ExecBeep Uninstalled$' help10 db 'Cannot Uninstall - INT 21 in wrong segment$' help11 db 'Error - Dos Free Memory function failed$' help12 db 'Error - Restore of old INT 21 failed$' help20 db 'ExecBeep Installed$' alrdy_in_mem db 0 other_seg dw 0 start: assume cs:code, ds:code, es:code, ss:code ; Deallocate environment block push es mov es,env_seg ; get the segment from the PSP assume es:nothing mov ah,49h int 21h ; call DOS release memory function pop es assume es:code ; check for other copies of this program in memory find_copies: xor bx,bx mov word ptr [begin],bx mov ax,cs find_loop: inc bx ; check next segment mov es,bx ; use ES as segment pointer assume es:nothing cmp ax,bx ; have we found ourselves? je no_copies mov si,offset begin ; si is the offset pointer mov di,si ; look the same place in both segs mov cx,16 ; compare for 16 bytes cld ; increment pointers during compare repe cmpsb ; compabe bytes jne find_loop ; no match, keep looking inc alrdy_in_mem ; set already installed flag no_copies: mov other_seg,es ; save the segment for the copy ; that is already resident push cs pop es assume es:code mov di,offset tail_length ; use di to point to cmd line mov ax,1234h ; set ax to 1234h to indicate if ; a command was ever found find_command: inc di ; dec tail_length ; jl find_command_done ; are we at end of command line? cmp byte ptr [di],'u' ; je un_install cmp byte ptr [di],'U' ; je un_install jmp find_command ; un_install: cmp alrdy_in_mem,0 ; is there a resident copy? je disp_help1 ; No, so we cannot uninstall assume es:nothing mov ax,other_seg ; Make sure that ES points mov es,ax ; to the segment of the resident copy. call uninstall jc help_routine ; if CF set, error on uninstall mov dx,offset help3 ; "ExecBeep Uninstalled" jmp help_routine ;----------------------------------------------------------------------------- ;Print help lines. ;----------------------------------------------------------------------------- DISP_HELP1: MOV DX,OFFSET HELP1 ; Cannot Uninstall - not in memory HELP_ROUTINE: PUSH DX ;Save offset to message MOV AH,2 ;Output a carrage return MOV DL,10 ; to put a space between INT 21H ; the messages. POP DX ;Get back offset. MOV AH,9 ;DOS print string routine INT 21H mov ax,4c00h int 21h find_command_done: cmp alrdy_in_mem,0 je carry_on mov dx,offset help2 jmp help_routine carry_on: mov ax,3521h ; get int 21h int 21h mov old_int21,bx ; store offset mov old_int21+2,es ; store segment mov dx,of new_int21 ; ds:dx -> new int 21h mov ax,2521h int 21h mov dx,offset help20 mov ah,9 int 21h mov dx,of end_of_res ; discard excess add dx,0fh shr dx,1 shr dx,1 shr dx,1 shr dx,1 mov ax,3100h ; keep process int 21h ;----------------------------------------------------------------------------- ; UNINSTALL deallocates the memory block addressed by ES and restores the ; interrupt 21 vector displaced on installation. ; Exit: CF clear - program uninstalled ; CF set - can't uninstall ;----------------------------------------------------------------------------- UNINSTALL PROC NEAR ASSUME DS:CODE PUSH ES MOV AX,3521H ;Get int 21 vector INT 21H MOV AX,ES ;Compare vector segment with CMP AX,OTHER_SEG ; segment of installed code. JNE REMOVE_ERR1 ;If not the same, can't remove. ;----------------------------------------------------------------------------- ;Release the memory occupied by the program. ES already has proper segment. ;----------------------------------------------------------------------------- MOV AH,49H ;DOS free memory function INT 21H JC REMOVE_ERR2 ;If carry, error on removal ;----------------------------------------------------------------------------- ;Restore interrupt 21h vector. ;----------------------------------------------------------------------------- PUSH DS LDS DX,ES:[OLD_DOS_INT] ;Get old vector from installed MOV AX,2521H ; code. INT 21H ;Set int 21 to old vector. POP DS JC REMOVE_ERR3 ;If error, report and exit. ;----------------------------------------------------------------------------- ;Destroy the ASCII fingerprint that identifies the code and exit. ;----------------------------------------------------------------------------- NOT WORD PTR ES:[BEGIN] CLC ;Clear error flag REMOVE_EXIT: POP ES RET ;----------------------------------------------------------------------------- ;The program can't be uninstalled. Set CF and exit. ;----------------------------------------------------------------------------- REMOVE_ERR1: MOV DX,OFFSET HELP10 ;Point to error message. STC ;Set error flag JMP SHORT REMOVE_EXIT remove_err2: mov dx,offset help11 stc jmp short remove_exit remove_err3: mov dx,offset help12 stc jmp short remove_exit UNINSTALL ENDP code ends end begin