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Assembly Source File | 1988-11-29 | 36.6 KB | 822 lines

;----------------------------------------------------------------; ; CONFIG.CTL - Allows you to dynamically change your CONFIG.SYS ; ; configuration at boot time. Add DEVICE = CONFIG.CTL [m] ; ; to your CONFIG.SYS just ahead of the first command you wish ; ; to be able to modify. m is seconds CONFIG.CTL will pause ; ; for a keystroke before booting normally. m defaults to zero. ; ; Add DEVICE = CONFIG.END after the last command you wish to be ; ; able to modify. CONFIG.END is a dummy device and must appear ; ; in CONFIG.SYS in order for CONFIG.CTL to operate. ; ; Requires MASM 2.0 or later. Remember to EXE2BIN ; ; CONFIG.CTL 1.0 (C) 1988 Ziff Communications Co. ;----------------------------------------------------------------; _TEXT SEGMENT PUBLIC 'CODE' ASSUME CS:_TEXT,DS:_TEXT ASSUME ES:_TEXT,SS:_TEXT ORG 0H ;************* DEVICE_HEADER *************; POINTER DD -1 ATTRIBUTE DW 1000000000000000B DEVICE_STAG DW STRATEGY DEVICE_INT DW INTERRUPT DEVICE_NAME DB "CONFIGURE" CR EQU 13 LF EQU 10 CTRL_Z EQU 26 SPACE EQU 32 COMMA EQU 44 FORWARD_SLASH EQU 47 BOX EQU 254 ;-------------------------; REQUEST_HEADER STRUC HEADER_LENGTH DB ? UNIT_CODE DB ? COMMAND_CODE DB ? STATUS DW ? RESERVED DQ ? REQUEST_HEADER ENDS DONE EQU 0000000100000000B ;Status codes. UNKNOWN EQU 1000000000000011B ;-------------------------; INIT STRUC HEADER DB (TYPE REQUEST_HEADER) DUP(?) UNITS DB ? ENDING_OFFSET DW ? ENDING_SEGMENT DW ? ARGUMENTS_OFF DW ? ARGUMENTS_SEG DW ? INIT ENDS REQUEST_OFFSET DW ? REQUEST_SEG DW ? ;-----------------------------------------------------------------------------; ; The only task of the strategy is to save the pointer to the request header. ; ;-----------------------------------------------------------------------------; STRATEGY PROC FAR MOV CS:REQUEST_OFFSET,BX ;Request header address is MOV CS:REQUEST_SEG,ES ; passed in ES:BX. RET STRATEGY ENDP ;------------------------------------------------------------------------; ; The interrupt procedure will be called immediately after the strategy. ; ;------------------------------------------------------------------------; INTERRUPT PROC FAR PUSH AX ;Responsible for all registers. PUSH BX PUSH CX PUSH DX PUSH DS PUSHF MOV DS,CS:REQUEST_SEG ;Retrieve request header pointer. MOV BX,CS:REQUEST_OFFSET OR STATUS[BX],DONE ;Tell DOS we are done. CMP COMMAND_CODE[BX],0 ;Is it INIT command? JZ MAKE_STACK ;If yes, do our stuff. OR STATUS[BX],UNKNOWN ;Else, exit with confused JMP SHORT UNKNOWN_EXIT ; message to DOS. MAKE_STACK: MOV CX,SS ;Save DOS stack. MOV DX,SP MOV AX,CS CLI MOV SS,AX ;Make new stack. MOV SP,0FFFEH STI PUSH CX ;Save old stack pointers on new. PUSH DX PUSH ES ;Save rest of registers. PUSH SI PUSH DI PUSH BP CALL INITIALIZE ;Go do our stuff. POP BP ;Restore registers. POP DI POP SI POP ES POP DX ;Restore old DOS stack. POP CX CLI MOV SS,CX MOV SP,DX STI UNKNOWN_EXIT: POPF ;Restore rest of registers. POP DS POP DX POP CX POP BX POP AX RET ;Far return back to DOS. INTERRUPT ENDP CONFIG_CTL_END LABEL WORD ;************* END OF RESIDENT PORTION *************; BUFFER_SEGMENT DW ? ;CONFIG.SYS buffer segment BUFFER_START DW ? ; and offset. BUFFER_END DW ? ;CONFIG.END address. END_FLAG DB 0 ;CONFIG.END found flag. CONFIG_END DB "DCONFIG.END" CONFIG_END_LEN EQU $ - CONFIG_END DELAY_MSG DB CR,LF,LF,"Press any key if you wish to modify the " DB "CONFIG.SYS configuration.",CR,LF DB "Press Esc for quick bypass of CONFIG.CTL.",CR,LF,LF,"$" NOT_FOUND_MSG DB "DEVICE=CONFIG.END has to be added as a terminating " DB CR,LF,"command in CONFIG.SYS before CONFIG.CTL can " DB "function.",CR,LF,"Press and key to continue.$" ;--------------------------; NORMAL EQU 07H ;Screen attributes. INVERSE EQU 70H HEADING LABEL BYTE DB "CONFIG.CTL 1.0 (C) 1988 Ziff Communications Co.",CR,LF DB "PC Magazine ",BOX," Michael J. Mefford",CR,LF,LF DB "Press F1 to toggle active state of highlighted command.",CR,LF DB "You may optionally edit a highlighted command.",CR,LF DB "Press F2 to accept changes and exit.",CR,LF DB "Press Esc to abort changes and exit.",CR,LF DB "Note: Permanent changes are not made to the CONFIG.SYS file.$" ;----------------------------; STRING_MAX EQU 80 DISPLAY_MAX EQU 67 LAST_RECORD EQU -1 DATA_RECORD STRUC COMMAND DB STRING_MAX DUP (?) STRING_LENGTH DW ? ADDRESS DW ? ;Command string address start. DATA_RECORD ENDS ROW_START EQU 9 COL_START EQU 12 CODES DB "CBQDXFSKL" ;DOS command codes. CODES_LENGTH EQU $ - CODES ;For example "C" = BREAK COMMAND_TABLE DB "BREAK" ,5 DUP (SPACE), "BUFFERS" ,3 DUP (SPACE) DB "COUNTRY" ,3 DUP (SPACE), "DEVICE" ,4 DUP (SPACE) DB "FCBS" ,6 DUP (SPACE), "FILES" ,5 DUP (SPACE) DB "SHELL" ,5 DUP (SPACE), "STACKS" ,4 DUP (SPACE) LAST_COMMAND DB "LASTDRIVE" ,1 DUP (SPACE) TABLE_END EQU $ COMMAND_SIZE EQU TABLE_END - LAST_COMMAND INACTIVE DB "INACTIVE" ,2 DUP (SPACE) HIGH_BIT EQU 10000000B ESC_KEY EQU 01H ENTER_KEY EQU 1CH F1_KEY EQU 3BH F2_KEY EQU 3CH BACKSPACE_KEY EQU 0EH UP_ARROW_KEY EQU 48H DN_ARROW_KEY EQU 50H LT_ARROW_KEY EQU 4BH RT_ARROW_KEY EQU 4DH HOME_KEY EQU 47H END_KEY EQU 4FH PG_UP_KEY EQU 49H PG_DN_KEY EQU 51H BS EQU 8 DISPATCH_KEY DB F1_KEY, BACKSPACE_KEY, UP_ARROW_KEY, DN_ARROW_KEY DB LT_ARROW_KEY, RT_ARROW_KEY, HOME_KEY, END_KEY DB PG_UP_KEY, PG_DN_KEY, ENTER_KEY KEY_COUNT EQU $ - DISPATCH_KEY DISPATCH_TABLE DW F1, BACKSPACE, UP_ARROW, DN_ARROW DW LT_ARROW, RT_ARROW, HOME, END_CURSOR DW PG_UP, PG_DN, DN_ARROW DISPATCH_END EQU $ - 2 ;------------------------------------------; ; INPUT ; ; DS:BX points to request header. ; ; ; ; All registers destroyed. ; ;------------------------------------------; INITIALIZE PROC NEAR MOV ENDING_OFFSET[BX],OFFSET CONFIG_CTL_END MOV ENDING_SEGMENT[BX],CS ;Resident portion setup. MOV AX,ARGUMENTS_SEG[BX] ;Retrieve CONFIG.SYS buffer MOV ES,AX ; pointers from INIT table. MOV BX,ARGUMENTS_OFF[BX] PUSH CS ;Point to our data. POP DS MOV BUFFER_SEGMENT,ES ;And save the segment. CLD ;------------------------------------; ; Parse CONFIG.CTL second parameter. ; ;------------------------------------; XOR BP,BP ;Use BP to store seconds. NEXT_NUMBER: MOV AL,ES:[BX] ;Retrieve a byte. INC BX ;Point to next byte. CMP AL,CR ;If carriage return of linefeed, JZ FIND_END ; found end of parameter. CMP AL,LF JZ FIND_END SUB AL,"0" ;ASCII to binary. JC NEXT_NUMBER ;If not between 0 and 9, skip. CMP AL,9 JA NEXT_NUMBER CBW ;Convert to word. XCHG AX,BP ;Swap old and new number. MOV CX,10 ;Shift to left by multiplying MUL CX ; last entry by ten. ADD BP,AX ;Add new number and store in BP. JMP SHORT NEXT_NUMBER ;-----------------------------------------------------------------------; ; Search for dummy CONFIG.END device as signature of end of buffer. ; ; If found, replace "D" device code with "Z" unrecognized command code. ; ;-----------------------------------------------------------------------; FIND_END: MOV BUFFER_START,BX ;Save start of first command. NEXT_BYTE: MOV SI,OFFSET CONFIG_END ;Point to CONFIG.END. MOV DI,BX ;Point to current buffer pos. MOV CX,CONFIG_END_LEN ;Is it CONFIG.END? REPZ CMPSB JZ FOUND_END ;If yes, found end. INC BX ;Else, increment buff pos. CMP BX,0FFFFH - CONFIG_END_LEN ;End of segment? JNZ NEXT_BYTE ;If no, continue. JMP SHORT PAUSE ;Else, give up search. FOUND_END: MOV END_FLAG,1 ;Flag that we found CONFIG.END. MOV BYTE PTR ES:[BX],"Z" ;"Z" out CONFIG.END command. DEC BX ;Adjust to buffer end MOV BUFFER_END,BX ; and store. ;-------------------------------------------------------------; ; See if user pressed key requesting CONFIG.SYS modification. ; ;-------------------------------------------------------------; PAUSE: CALL CK_KEY ;Key pressed? JNZ ATTENTION ;If yes, give attention. MOV CX,BP ;Else, retrieve second delay. JCXZ INIT_END ;If zero, we're done. MOV DX,OFFSET DELAY_MSG ;Else, display "Press key for CALL PRINT_STRING ; service" message. WAIT_A_SEC: CALL DELAY ;Delay a second. POLL_KEY: CALL CK_KEY ;Key pressed? JNZ ATTENTION ;If yes, give attention. LOOP WAIT_A_SEC ;Else, continue waiting until JMP SHORT INIT_END ; time out. ;--------------------------------------------------------------; ; If keystroke other than ESC was pressed and CONFIG.END dummy ; ; device found, then we're in business; otherwise exit. ;--------------------------------------------------------------; ATTENTION: PUSH AX ;Save key press. CALL CLEAR_KEY ;Clear keyboard buffer. POP AX ;Retrieve key press. CMP AH,ESC_KEY ;Was is Esc? JZ INIT_END ;If yes, we're done. CMP END_FLAG,1 ;Else, did we find CONFIG.END? JZ CONTINUE ;If yes, continue. MOV DX,OFFSET NOT_FOUND_MSG ;Else, Display CONFIG.END not CALL PRINT_STRING ; found message. CALL GET_KEY ;Wait for keystroke so it can be JMP SHORT INIT_END ; read and then exit. CONTINUE: CALL BUSINESS ;Do our thing. INIT_END: RET ;Exit. INITIALIZE ENDP ;--------------------------------------------; ; INPUT ; ; DS = CS ; ; ES = CONFIG.SYS command buffer segment. ; ; ; ; All registers destroyed. ; ;--------------------------------------------; BUSINESS PROC NEAR CALL CLS ;Clear the screen. MOV DX,OFFSET HEADING ;Display heading messages. CALL PRINT_STRING ;----------------------------------------------------------------------------; ; Retrieve the commands from CONFIG.SYS buffer and place them in our buffer. ; ;----------------------------------------------------------------------------; MOV SI,BUFFER_START ;Point to start of commands. MOV DX,BUFFER_END ;DX = end of buffer. MOV BX,OFFSET DATA_STORAGE ;Point to our storage. PUSH CS ;Destination segment our data. POP ES PUSH BUFFER_SEGMENT ;Source segment CONFIG.SYS POP DS ; command buffer. NEXT_COMMAND: CMP SI,DX ;End of buffer? JAE COMMAND_END ;If yes, done here. LODSB ;Get a byte. CMP AL,CR ;Carriage return or linefeed? JZ NEXT_COMMAND ;If yes, delimiter; skip. CMP AL,LF JZ NEXT_COMMAND PUSH AX ;Else, command code character. DEC SI ;Adjust pointer. MOV ES:ADDRESS[BX],SI ;Save starting address. MOV DI,BX ;Point to our storage. CALL RETRIEVE ;Go retrieve the command string. POP AX ;Retrieve command code. CMP AL,"Z" ;Was it unrecognized "Z" ? JZ NEXT_COMMAND ;If yes, skip. DEC CX ;Else, adjust string length less DEC CX ; code and ending linefeed. JCXZ NEXT_COMMAND ;Null string? If yes, skip. MOV ES:STRING_LENGTH[BX],CX ;Else, store length. ADD BX,TYPE DATA_RECORD ;Point to next storage record. JMP SHORT NEXT_COMMAND ;Get next command. COMMAND_END: PUSH CS ;Back to our data segment. POP DS MOV COMMAND[BX],LAST_RECORD ; -1 as end of data signature. CMP BX,OFFSET DATA_STORAGE ;Were there any commands? JZ BUSINESS_END ;If no, done here. ;--------------------------------------------------; ; Display the commands and let the user edit them. ; ;--------------------------------------------------; CALL DISPLAY CALL EDIT JC BUSINESS_END ;If carry, Esc was pressed. ;----------------------------------------------------------; ; Place the edited commands back in the CONFIG.SYS buffer. ; ;----------------------------------------------------------; MOV BX,OFFSET DATA_STORAGE ;Point to CONFIG.SYS buffer PUSH BUFFER_SEGMENT ; as destination. POP ES STORE_COMMAND: CMP COMMAND[BX],LAST_RECORD ;Is it the last record? JZ BUSINESS_END ;If yes, we're all done. TEST COMMAND[BX],HIGH_BIT ;Is command inactive? JZ REPLACE_DATA ;If no, OK. MOV COMMAND[BX],"Z" ;Else, replace with "Z". REPLACE_DATA: MOV SI,BX ;Point to command string. MOV DI,ADDRESS[BX] ;Point to destination address. CALL REPLACE ;Replace the string in buffer. ADD BX,TYPE DATA_RECORD ;Point to next record. JMP SHORT STORE_COMMAND ;And store it. BUSINESS_END: CALL CLS ;Exit with clean slate. RET BUSINESS ENDP ;---------------------------------------; ; INPUT ; ; DS:SI points to CONFIG.SYS buffer. ; ; ES:DI points to our storage. ; ; ; ; OUTPUT ; ; SI and DI at end of string. ; ; CX = string length include one byte ; ; for command code and one byte for ; ; CR or LF. ASCIIZ is stripped. ; ; ; ; AX destroyed. ; ;---------------------------------------; RETRIEVE PROC NEAR XOR CX,CX ;Zero in string length counter. NEXT_RETRIEVE: LODSB ;Get a byte. OR AL,AL ;If it's ASCIIZ zero, JZ NEXT_RETRIEVE ; skip it. STOSB ;Else, store it. INC CX ;Increment count. CMP AL,CR ;If terminating carriage return JZ RETRIEVE_END ; or linefeed, we're done. CMP AL,LF JNZ NEXT_RETRIEVE RETRIEVE_END: RET RETRIEVE ENDP ;--------------------------------------; ; INPUT ; ; DS:SI points to our storage. ; ; ES:DI points to CONFIG.SYS buffer. ; ; BX = current record. ; ; ; ; OUTPUT ; ; ASCIIZ is reinserted in string. ; ; SI and DI at end of string. ; ; ; ; AX, CX, DX, BP destroyed. ; ;--------------------------------------; REPLACE PROC NEAR MOV CX,STRING_LENGTH[BX] ;Retrieve string length. INC CX ;Include command code byte. MOV BP,-1 ;ASCIIZ flag. XOR DX,DX ;Leading space flag. NEXT_REPLACE: LODSB ;Get a byte. CMP AL,"a" ;Capitalize. JB CK_LEADING CMP AL,"z" JA CK_LEADING AND AL,5FH CK_LEADING: CMP AL,SPACE ;Is it a leading space? JNZ CK_ADD_ZERO ;If no, check if zero time. CMP DX,1 ;If command only thing stored JZ NEXT_REPLACE ; so far, then it's leading. CK_ADD_ZERO: CMP BP,-1 ;Have we stored a zero yet? JNZ CK_CR_LF ;If yes, check CR and LF. CMP AL,SPACE ;Else, if it's delimiting JZ ASCIIZ ; space, comma, slash, CR or LF CMP AL,COMMA ; then store a terminating JZ ASCIIZ ; right in front of it. CMP AL,FORWARD_SLASH JZ ASCIIZ CMP AL,CR JZ ASCIIZ CMP AL,LF JNZ STORE_BYTE ASCIIZ: XCHG AX,BP ;Swap special character. XOR AX,AX ;Store the zero. STOSB ;Retrieve the character and XCHG AX,BP ; zero in BP as flag. CK_CR_LF: CMP AL,CR ;If CR or LF we're done here. JZ PAD_SPACES CMP AL,LF JZ PAD_SPACES STORE_BYTE: STOSB ;Store the byte. INC DX ;Increment count. LOOP NEXT_REPLACE PAD_SPACES: JCXZ REPLACE_END ;If end of string, done. MOV AL,SPACE ;Else, move leading spaces REP STOSB ; to end of string. REPLACE_END: RET REPLACE ENDP ;------------------------------------------; ; Display the commands on the screen. ; ; All registers destroyed. ; ;------------------------------------------; DISPLAY PROC NEAR MOV BP,OFFSET DATA_STORAGE ;Point to data storage. MOV DH,ROW_START ;Point to first display row. NEXT_DISPLAY: XOR DL,DL ;Column zero. CALL SET_CURSOR ;Set cursor position. CMP COMMAND[BP],LAST_RECORD ;Is it the last record? JZ DISPLAY_END ;If yes, done here. CALL DECODE ;Else, decode the command. MOV AL,"=" ;Add quotes and a space. CALL WRITE_TTY MOV AL,SPACE CALL WRITE_TTY MOV SI,BP ;Point to command string. INC SI MOV CX,STRING_LENGTH[BP] ;Retrieve the string length. NEXT_ARGUMENT: LODSB ;Display the command. CALL WRITE_TTY LOOP NEXT_ARGUMENT ADD BP,TYPE DATA_RECORD ;Point to next record. INC DH ;Next cursor row. CMP DH,25 ;Is it row 25? JNZ NEXT_DISPLAY ;If no, continue. DISPLAY_END: RET DISPLAY ENDP ;-----------------------------------------; ; INPUT ; ; BP points to command. ; ; ; ; OUTPUT ; ; The command is decoded and displayed. ; ; ; ; AX, CX, SI and DI destroyed. ; ;-----------------------------------------; DECODE PROC NEAR MOV SI,OFFSET INACTIVE ;Assume command inactive. MOV AL,COMMAND[BP] ;Retrieve command. TEST AL,HIGH_BIT ;Is it marked inactive? JNZ FOUND_COMMAND ;If yes, assumed right. MOV DI,OFFSET CODES ;Else, point to codes. MOV CX,CODES_LENGTH ;Number of codes. REPNZ SCASB ;Search for match. MOV SI,OFFSET TABLE_END ;Point to interpolation table. INC CX ;Adjust count. FIND_COMMAND: SUB SI,COMMAND_SIZE ;Point to appropriate command. LOOP FIND_COMMAND FOUND_COMMAND: MOV CX,COMMAND_SIZE ;Command string length. DISPLAY_CMD: LODSB ;Display it. CALL WRITE_TTY LOOP DISPLAY_CMD RET DECODE ENDP ;----------------------------------; ; OUTPUT ; ; Carry flag = 0 if good edit. ; ; Carry flag = 1 if edit abort. ; ; ; ; All registers destroyed. ; ;----------------------------------; EDIT PROC NEAR MOV BP,OFFSET DATA_STORAGE ;Point to data storage. MOV DH,ROW_START ;Point to first row. MOV BL,INVERSE ;Highlight the first command. CALL HIGHLIGHT_BAR ;Return with DI = 1; first char. NEXT_KEY: CALL GET_KEY ;Get a keystroke. CMP AH,ESC_KEY ;Is it ESC? JZ NO_CHANGE ;If yes, exit with no change. CMP AH,F2_KEY ;Is it F2? JZ EDIT_END ;If yes, exit with changes. CMP AL,BS ;Is it backspace? JZ FUNCTION ;If yes, function. CMP AL,CR ;Is it carriage return? JZ FUNCTION ;If yes, function. CMP AH,F1_KEY ;Is it F1 or above? JAE FUNCTION ;If yes, function. ASCII: CMP AL,SPACE ;Is it space or above? JB NEXT_KEY ;If no, skip. CMP DI,STRING_LENGTH[BP] ;Else, are we at end of field? JA NEXT_KEY ;If yes, skip. MOV COMMAND[BP+DI],AL ;Else, store character. INC DI ;Point to next storage. INC DL ;Increment cursor column. CALL WRITE_TTY ;Write the character to screen. JMP SHORT NEXT_KEY ;Get next keystroke. FUNCTION: MOV AL,AH ;Scan code in AL. MOV CX,KEY_COUNT ;Count of active functions. PUSH DI ;Preserve DI. MOV DI,OFFSET DISPATCH_KEY ;Point to active keys. REPNZ SCASB ;Scan for match. POP DI ;Retrieve DI. JNZ NEXT_KEY ;If no match, next key. MOV SI,OFFSET DISPATCH_END ;Else, point to dispatch table. SHL CX,1 ;Convert to word offset. SUB SI,CX ;Point to appropriate procedure CALL DS:[SI] ; and go do it. JMP SHORT NEXT_KEY ;Get next keystroke. NO_CHANGE: STC EDIT_END: RET EDIT ENDP ;----------------------------------------------------------------------------; ; The following are the active function, arrow and backspace key procedures. ; ;----------------------------------------------------------------------------; F1 PROC NEAR PUSH DI ;Preserve DI and DX. PUSH DX XOR DL,DL ;Column zero. CALL SET_CURSOR ;Set cursor. XOR COMMAND[BP],HIGH_BIT ;Toggle active state. CALL DECODE ;Decode the command. POP DX ;Restore cursor position. CALL SET_CURSOR POP DI ;Restore DI. RET F1 ENDP ;------------------------------; BACKSPACE PROC NEAR CMP DI,1 ;Are we already at first char? JZ BACKSPACE_END ;If yes, skip. DEC DL ;Else, decrement cursor DEC DI ; and character storage position. MOV COMMAND[BP+DI],SPACE ;Store a space. MOV AL,BS ;Write a backspace, space and CALL WRITE_TTY ;backspace to screen. MOV AL,SPACE CALL WRITE_TTY MOV AL,BS CALL WRITE_TTY BACKSPACE_END: RET BACKSPACE ENDP ;------------------------------; UP_ARROW PROC NEAR CMP BP,OFFSET DATA_STORAGE ;Are we already at top row? JZ UP_ARROW_END ;If yes, skip. MOV BL,NORMAL ;Else, return to normal CALL HIGHLIGHT_BAR ; attribute current row. SUB BP,TYPE DATA_RECORD ;Move up a record. DEC DH ;Move cursor up one. MOV BL,INVERSE ;Display line in inverse video. CALL HIGHLIGHT_BAR UP_ARROW_END: RET UP_ARROW ENDP ;------------------------------; DN_ARROW PROC NEAR CMP COMMAND[BP+TYPE DATA_RECORD],LAST_RECORD JZ DN_ARROW_END CMP DH,24 ;If last record already or JZ DN_ARROW_END ; bottom of screen, skip. MOV BL,NORMAL ;Else, return current row to CALL HIGHLIGHT_BAR ; normal. ADD BP,TYPE DATA_RECORD ;Go down a record. INC DH ;And down a row. MOV BL,INVERSE ;Display the line inverse video. CALL HIGHLIGHT_BAR DN_ARROW_END: RET DN_ARROW ENDP ;------------------------------; LT_ARROW PROC NEAR CMP DI,1 ;Are we already first positon? JZ LT_ARROW_END ;If yes, skip. DEC DI ;Else, decrement storage position DEC DL ; and cursor position. CALL SET_CURSOR LT_ARROW_END: RET LT_ARROW ENDP ;------------------------------; RT_ARROW PROC NEAR CMP DI,STRING_LENGTH[BP] ;Are we already end of string? JA RT_ARROW_END ;If yes, skip. INC DI ;Else, increment storage position INC DL ; and cursor position. CALL SET_CURSOR RT_ARROW_END: RET RT_ARROW ENDP ;------------------------------; HOME PROC NEAR MOV DI,1 ;Home storage position MOV DL,COL_START ; and cursor. CALL SET_CURSOR RET HOME ENDP ;------------------------------; END_CURSOR PROC NEAR MOV DI,STRING_LENGTH[BP] ;Retrieve string length. MOV CX,DI MOV DL,CL ADD DL,COL_START ;Add to starting column. INC DI ;Adjust. CALL SET_CURSOR ;Set cursor. RET END_CURSOR ENDP ;------------------------------; PG_DN PROC NEAR MOV BL,NORMAL ;Current postion back to normal. CALL HIGHLIGHT_BAR NEXT_PG_DN: CMP COMMAND[BP+TYPE DATA_RECORD],LAST_RECORD JZ PAGE_END ADD BP,TYPE DATA_RECORD ;If not already last position, INC DH ; go to it. JMP SHORT NEXT_PG_DN PAGE_END: MOV BL,INVERSE ;And display it in inverse video. CALL HIGHLIGHT_BAR RET PG_DN ENDP ;------------------------------; PG_UP PROC NEAR MOV BL,NORMAL ;Restore current position to CALL HIGHLIGHT_BAR ; normal. MOV BP,OFFSET DATA_STORAGE ;Move to top command. MOV DH,ROW_START ;And cursor position. MOV BL,INVERSE ;And highlight. CALL HIGHLIGHT_BAR RET PG_UP ENDP ;------------------------------------------; ; INPUT ; ; BL = attribute. ; ; BP points to current command. ; ; ; ; OUTPUT ; ; DI = 1 (First storage position.) ; ; DL = cursor column start. ; ; ; ; CX, SI destroyed. ; ;------------------------------------------; HIGHLIGHT_BAR PROC NEAR MOV CX,STRING_LENGTH[BP] ;Retrieve string length. MOV SI,BP ;Point to command. INC SI ;Adjust. MOV DL,COL_START ;Point to first position. HIGHLIGHT: CALL SET_CURSOR ;Set the cursor. LODSB PUSH CX ;Preserve CX. MOV CX,1 MOV AH,9 ;Write char/attribute. INT 10H INC DL ;Increment cursor postion. POP CX LOOP HIGHLIGHT MOV DL,COL_START ;Point to first position again. CALL SET_CURSOR ;Set cursor. MOV DI,1 ;Return with DI = first storage. RET HIGHLIGHT_BAR ENDP ;---------------------------------------; ; The following are support procedures. ; ;---------------------------------------; WRITE_TTY PROC NEAR MOV AH,0EH ;Write TTY via BIOS. INT 10H RET WRITE_TTY ENDP ;------------------------------; SET_CURSOR PROC NEAR XOR BH,BH ;Enter with DX = cursor postion. MOV AH,2 ;Set cursor position via BIOS. INT 10H RET SET_CURSOR ENDP ;------------------------------; CLS PROC NEAR MOV AH,0FH ;Get current video mode. INT 10H XOR AH,AH ;Set current video mode. INT 10H ;Result is a clear screen. RET CLS ENDP ;------------------------------; DELAY PROC NEAR PUSH DS ;Preserve data segment. MOV AX,40H ;Point to BIOS data segment. MOV DS,AX MOV AX,DS:[6CH] ;Retrieve timer low. ADD AX,18 ;Add 18 counts per second. NEXT_COUNT: MOV DX,DS:[6CH] ;Retrieve timer low. CMP DX,AX ;Have we timed out? JNZ NEXT_COUNT ;If not, wait until second up. POP DS ;Restore data segment. RET DELAY ENDP ;------------------------------; GET_KEY: MOV AH,0 ;Retrieve keystroke via BIOS. INT 16H RET CK_KEY: MOV AH,1 ;Check for keystroke via BIOS. INT 16H RET CLEAR_IT: CALL GET_KEY CLEAR_KEY: CALL CK_KEY ;Clear keyboard buffer. JNZ CLEAR_IT RET ;------------------------------; PRINT_STRING: MOV AH,9 ;Print string via DOS. INT 21H RET ;------------------------------; DATA_STORAGE EQU $ _TEXT ENDS END