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Assembly Source File | 1998-10-26 | 12.9 KB | 446 lines

; ; GRDB ; ; Copyright(c) LADsoft ; ; David Lindauer, camille@bluegrass.net ; ; ; Input.asm ; ; Function: Handle input ; ; Handles numbers ; Handles segments ; Handles trapping page faults ; Handles command input ; ;MASM MODE .model small .386 include edispatc.inc include eprints.inc include emtrap.inc include eregs.inc include edump.inc include eentry.inc include eexec.inc include ebreaks.inc include edis.inc include einout.inc include eoptions.inc include ehistory.inc extrn _exit : PROC,domath : PROC, drive : PROC, fill : PROC extrn logging : PROC, help : PROC, pci : PROC extrn DoFileRead : PROC, DoFileWrite : PROC, search : PROC extrn fpcommand : PROC, move : proc, compare : proc, asm : PROC PUBLIC qerr, ReadNumber, ReadAddress, Inputhandler PUBLIC wadeSpace, GetInputLine, WadeSpaceOnly, inputbuffer PUBLIC defDS,defCS IBSIZE = 80 ;max size of iinput buffer for a line=width of screen .data inputbuffer db IBSIZE DUP (?) ;Allocate Input buffer Commands db "abcdefghilmnopqrstuwxy@?" ; List of commands comlen = $ - Commands ; Length of list inquote db 0 .code ; ; load defaults if dx is zero ; INPUT: EDX contains segment to use if not 0, OR if big real with offset 0 ; OUTPUT: DX contains segment to use, could be default DX from bucket ; defDS PROC or edx,edx ;if edx has a value jnz ddsx ;then use it sub dx,dx ; waste one instruction test [optflat0],1 ;see if default seg is 0 jnz ddsx ;if so, use EDX=0 mov dx,[RegdumpDS] ;else use default DS ddsx: ret defDS ENDP ; ; for now we just default CS to the active CS, since it is only ; used on U and A commands and since we can't do linear addressing ; with those anyway right now. ???is this true??? ; If EDX <> 0, we are starting from a specified segment location, ; so use that instead of CS. (EDX contains the segment). ; defCS PROC or edx,edx jnz dcsx mov dx,[RegdumpCS] dcsx: ret defCS ENDP ; ; Print an error if command wrong ; Apparently, SI points to some location in the input buffer. We ; need to determine how many spaces to print before we found the actual ; error to point to from the line below. I guess if the error is in the ; first or second positions, we print the character right at the start of ; the line, else we space over to where the error is found. ; qerr PROC call crlf ;new line for this sub si,offset inputbuffer-2 ; Calculate error pos mov cx,si ; jcxz short qestart ; dec cx ; jcxz short qestart ; qelp: call printspace ; Space over to error pos loop qelp qestart: mov dl,'^' ; Display error call PutChar stc ; Did an error ret qerr ENDP ; ; Read in a number. ; In at least some cases, we have ALREADY called ReadReg to find a register, ;and failed so we are looking for a number anyway. ; SI points to the input line from the user. ; OUTPUT: CY if we found 0 digits and did NOT find a register by name ; EAX contains number found if NC ; ReadNumber PROC push ebx push cx push dx call ReadReg ;find a non-number (mnemonic) clc ;ignore which type or reg found jz gotnum ;if 0, we have value of this reg ;We reach here if we found no mnemonic in our lookup table sub ebx,ebx ; Number = 0 sub cx,cx ; digits = 0 mov al,[si] ;get next user character cmp al,"'" ;if single or double quotes jz getstring ;get a string input cmp al,'"' jz getstring cmp al,'-' ;if a hyphen pushf ;save result of compare jnz rnlp ;not a hyphen, so SI is ok inc si ;else skip the hyphen rnlp: lodsb ; Get char & convert to uppercase cmp al,60h jc notlower and al,NOT 20h notlower: sub al,'0' ; Convert to binary jc short rn_done ; < '0' is an error cmp al,10 ; See if is a digit jc short gotdigit ; Yes, got it sub al,7 ; Convert letters to binary cmp al,16 ; Make sure is < 'G' jnc short rn_done ; Quit if not cmp al,10 ; MAke sure not < 'A' jc short rn_done gotdigit: shl ebx,4 ; It is a hex digit, add in or bl,al ; OR in the digit inc cx ; Set flag to indicate we got digits jmp rnlp ; go get the next digit ;We have snagged all entered digits here, and in the process SI got bumped ;past the non-digit by lodsb, so back up to look at the first non-digit ;character. the Zero flag contains the result of our hyphen compare, ZF if ;we found a hyphen, NZ if we didn't. ; NOTE also that if we found a string, EBX has up to 4 ASCII codes in it, ;NOT a value. Don't offhand see any way the caller can know this, though. rn_done: dec si ; Point at first non-digit popf ;did we find a hyphen? jnz rm_done2 ; check for negation neg ebx ;yes, negative, so negate value rm_done2: mov eax,ebx ;final result into EAX test cl,-1 ; See if got any CX=digit count jnz gotnum ;if non-0, we got at least one stc ; No, error gotnum: pop dx pop cx pop ebx ret ;return number/string in EAX ;We found a quote character at [SI], so we move past the quote to try to ;snag a quoted string. We keep sticking ASCII codes into EBX, shifting it ;left as we go, and losing all but the last 4 ASCII codes. getstring: inc si ;bump past quote character getstringl: lodsb ;get next char cmp al,13 ;if CR, end of input jz rm_done2 ;so leave SI alone? cmp al,"'" ;find end of quotes already? jz rm_done2 ;if so, check if null string cmp al,'"' jz rm_done2 inc cl ;else we got a char shl ebx,8 ;stick in BL mov bl,al jmp getstringl ;and get the next one ReadNumber ENDP ; ; Read an address, composed of a number and a possible selector ; INPUT: SI points at the input line just following the U (for unassemble). ; OUTPUT: EBX contains the address, which came either from a current ; register bucket or from a string or number ; ReadAddress PROC sub edx,edx ;EDX used for segment if found call ReadReg ;chk for seg or non-seg register ; mnemonic (like 'AX') ;ReadReg returns two flags: if NZ, we found nothing. if ZF, we found either ;a segment register or a non-segment register, so we examine the carry flag. ;CY means it was a non-segment register, and NC means we found a segment ;register. ; If we found a register at all, the value returned is what was in the ;Regdump bucket for that register, and is returned in EAX unless it was not a ;32-bit register, in which case the low word is returned in AX and the high ;word of AX is zero. (undefined for segments) jnc gotseg ;if NC, we snagged a segment reg mov ebx,eax ;else, get value into ebx jz gotaddr ;ZF if non-segment reg found ;We fall through here if we failed to find a register. The syntax from the ;user permits either REG:number, REG:REG, number:REG, number:number, or just ;number. At this point, no register was asked for by name, so we check for a ;number. readseg: call ReadNumber ; Read a number or string jc short raerr ; Quit if error - no input mov ebx,eax ;move number/string to EBX call WadeSpace ;find next input jz gotaddr ;if no more, we're done cmp al,':' ;if not a colon jnz gotaddr ;we are also done inc si ;else move past colon ; We fell through above because the user did NOT ask for any ;register by name, then fell through to here because we found a colon after ;a number or quoted string. ;EBX now contains a number of up to the last 8 digits entered, or a string ;of up to the last 4 ASCII characters entered. We take the low 4 digits or ;two characters and put them in DX, then set bit 16 of EDX mov dx,bx ;low order num/string to DX or edx,10000H ;set bit 16 for segment jmp readofs ;and go read an offset ;EAX contains the value read out of the RegdumpREG bucket, with the high ;order word zeroed out. gotseg: sub ebx,ebx ;assume seg only, so offset is 0 mov dx,ax ;get segment value into DX or edx,10000H ;set bit 16 for segment call WadeSpace ;look for more input jz gotaddr ;if no more, segment given only cmp al,':' ;else see if colon for offset jnz gotaddr ;if not, that's it inc si ;else move past colon ;We get here if the input contained a colon, indicating that there might ;be an offset following. If nothing follows the colon, assume an offset ;of 0. readofs: call WadeSpace ;any further input jz gotaddr ;ZF means we found a CR call ReadNumber ; Read in offset jc short raerr ; Quit if error - no number or ; quoted string with endquotes mov ebx,eax ;else set offset into EBX gotaddr: clc ; OK, exit ret raerr: stc ; Error on number input ret ReadAddress ENDP ; ; Get an input line ; OUTPUT: SI points to the line of input. ; GetInputLine PROC mov [inquote],0 ;say input not in quotes mov di,offset InputBuffer ;point to input buffer mov si,di ;Return buffer pointer mov cx,IBSIZE ; Size of buffer=80 bytes moreinput: call GetKey ;wait, return keystroke call CheckHistory ;check for history substitutions jc MoreInput ;and go for more input if so or al,al ; ignore function keys jz moreinput ; cmp al,9 ; is tab? jz dotab cmp al,8 ; Is delete or rubout? jz short bkspc ; Yes - go do it cmp al,7fh ;not on PC? jz short bkspc ; yes - go do it cmp al,'"' ;is it double quotes jz doquote ;if so, set flag cmp al,"'" ;is it single quotes jnz dochar ;no, must be valid char doquote: xor [inquote],1 ;invert quote flag dochar: push ax ;save keystroke test [inquote],1 ;was it quotes jnz nolc ;if so, OK cmp al,'A' ;see if below A jc nolc cmp al,'Z' ;or above Z ja nolc or al,20h ;if A-Z, force lowercase nolc: stosb pop ax cmp al,13 ; Is CR jz short endinput ; Yes, return mov dl,al ; Echo character call PutChar loop moreinput ; Loop till buffer full endinput: call EnterHistory ret bkspc: cmp di,offset InputBuffer ; Quit if nothing in buffer jz moreinput ; And get more input mov dl,8 ; Erase last echoed char call PutChar mov dl,' ' ; call PutChar mov dl,8 ; Reset pointer call PutChar dec di ; Point at last char cmp byte ptr [di],' ' ; check for multiple spaces jnz moreinput cmp byte ptr [di-1],' ' ; jz bkspc jmp moreinput ; Get more input dotab: push cx mov cx,di ; cx = current pos sub cx,si ; Minus start pos add cl,7 ; now it equals number of and cx,7 ; spaces per tab xor cx,7 inc cl ; spaces = 1 to 8 tablp: mov al,' ' stosb mov dl,' ' call PutChar loop tablp pop cx jmp moreinput GetInputLine ENDP ; ; Wade past spaces ; Whoa! By subtle implication, the carry accidentally gets set if the non- ; space of comma character was less than 13 in ASCII sequence. This means ; if we hit a tab (8), the carry gets returned set. ; Turns out this is NO ACCIDENT, and callers rely on this somehow. ; WadeSpace PROC lodsb ; Get char cmp al,' ' ; if ' ' or ',' go again je short wadeSpace ; cmp al,',' ; je short WadeSpace ; cmp al,9 ;ignore tab also je WadeSpace dec si ; Point at last space char cmp al,13 ret WadeSpace ENDP ; ; Wade through spaces only ; WadeSpaceOnly PROC lodsb ; Get a char cmp al,' ' ; Is space je WadeSpaceOnly ; Loop if so cmp al,9 ; ignore tab also je WadeSpaceOnly dec si ; Else point at char cmp al,13 ret WadeSpaceOnly ENDP ; ; Main Input routine ; InputHandler PROC call LoadHistory PRINT_MESSAGE <13,10,"->"> ; MONITOR prompt call GetInputLine ; Get an input line call WadeSpace ; Wade through spaces jz InputHandler ; blank line, so try again inc si ; Point at first non-space char mov di,offset commands ; Get command list mov cx,comlen ; Length of list repne scasb ; search for command in list jnz ierr ; Error if not in list mov ax,comlen-1 ; Calculate position sub ax,cx ; ;Dangerous practice - the list of commands is tightly coupled to the string ;of command characters. Some day, I should convert this to an array of ;structures, each containing the command and a pointer to its handler. ;Then we search through the structure list to find the command, and if found ;call the associated handler. push 0 ; Command arg = 0 call TableDispatch ; Dispatch command dw comlen-1 dw asm ;A command dw breaks ;B command dw compare ;C command dw Dump ;D command dw entry ;E command dw fill ;F command dw go ;G command dw domath ;H command dw doin ;I command dw DoFileRead ;L command dw move ;M command dw fpcommand ;N command dw doout ;O command dw proceed ;P command dw _exit ;Q command dw ModifyRegisters ;R command dw search ;S command dw trap ;T command dw diss ;U command dw DoFileWrite ;W command dw drive ;X command dw pci ;Y command dw logging ;@ command dw help ;? command jnc InputHandler ; Get more input if no err ierr: call qerr ; Display error jmp InputHandler ; Get more input InputHandler ENDP END