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Wrap

Assembly Source File | 1986-05-22 | 28.4 KB | 1,100 lines

page 66, 132 ;--- nansi.asm ---------------------------------------------------------- ; New ANSI terminal driver. ; Optimized for speed in the case of multi-character write requests. ; (C) 1986 Daniel Kegel, Pasadena, CA ; May be distributed for educational and personal use only ; The following files make up the driver: ; nansi.asm - all DOS function handlers except init ; nansi_p.asm - parameter parser for ANSI escape sequences ; nansi_f.asm - ANSI command handlers ; nansi_i.asm - init DOS function handler ; ; Daniel Kegel, Bellevue, Washington & Pasadena, California ; Revision history: ; 5 july 85: brought up non-ANSI portion except forgot backspace ; 6 july 85: split off ANSI stuff into other files, added backspace ; 11 july 85: fixed horrible bug in getchar; changed dosfns to subroutines ; 12 july 85: fixed some scrolling bugs, began adding compaq flag ; 9 aug 85: added cursor position reporting ; 10 aug 85: added output character translation ; 11 aug 85: added keyboard redefinition, some EGA 80x43 support ; 10 sept 85: Tandy 2000 support via compaq flag (finding refresh buffer) ; 30 Jan 86: removed Tandy 2000 stuff, added graphics mode support ; 12 feb 86: added int 29h handler, added PUSHA/POPA, added direct beep, ; direct cursor positioning, takeover of BIOS write_tty, ; noticed & squashed 2 related bugs in tab expansion ; 13 feb 86: Squashed them again, harder ; 24 feb 86: There is a bug in the timing code used by the BEEP routine. ; If the addition of the beep period to the ; BIOS low timer word results in an overflow, the beep will be ; supressed. Also made code compatible eith earlier versions ; of assembler. ;------------------------------------------------------------------------ include nansi_d.asm ; definitions ; from nansi_f.asm extrn f_escape:near, f_in_escape:near ; from nansi_p.asm extrn param_end:word, redef_end:word ; from nansi_i.asm extrn dosfn0:near ; to nansi_p.asm public f_loopdone public f_not_ansi public f_ansi_exit ; to both nansi_p.asm and nansi_f.asm public cur_x, cur_y, max_x, cur_attrib ; to nansi_f.asm public xy_to_regs, get_blank_attrib public port_6845 public wrap_flag public cur_parm_ptr public cur_coords, saved_coords, max_y public escvector, string_term public cpr_esc, cprseq public video_mode public lookup public in_g_mode ; to nansi_i.asm public req_ptr, break_handler public int_29 if takeBIOS public new_vid_bios, old_vid_bios endif ; to all modules public xlate_tab_ptr ;--- seg_cs is the CS: override prefix ; (assembler forgets cs: on second "xlat dummy_cs_byte") seg_cs macro db 2eh endm ;--- push_all, pop_all ------------------------------------------------ ; Save/restore all user registers. push_all macro if is_8088 push ax push bx push cx push dx push bp push si push di else pusha endif endm pop_all macro if is_8088 pop di pop si pop bp pop dx pop cx pop bx pop ax else popa endif endm keybuf struc ; Used in getchar len dw ? adr dw ? keybuf ends ABS40 segment at 40h org 1ah buffer_head dw ? ; Used in 'flush input buffer' dos call. buffer_tail dw ? org 49h crt_mode db ? crt_cols dw ? crt_len dw ? crt_start dw ? cursor_posn dw 8 dup (?) cursor_mode dw ? active_page db ? addr_6845 dw ? crt_mode_set db ? ; = 7 only if monochrome display adaptor crt_palette db ? org 6ch timer_low dw ? ; low word of time-of-day counter (18.2 hz) ABS40 ends page CODE segment byte public 'CODE' assume cs:code, ds:code ; Device Driver Header org 0 dd -1 ; next device dw 8013h ; attributes dw strategy ; request header pointer entry dw interrupt ; request entry point db 'CON' ; device name (8 char) db 5 dup (20h) ; ... and 5 blanks) ; Identification- in case somebody TYPEs the assembled driver db 27,'[2J' db "Nansi.sys v2.2" ife is_8088 db "(80286)" endif db ': New ANSI driver (C) Daniel Kegel, Pasadena, CA 1986' db 13, 10, 26 ;----- variable area -------------------- req_ptr label dword req_off dw ? req_seg dw ? wrap_flag db 1 ; 0 = no wrap past line end escvector dw 0 ; state vector of ESCape sequencor video_mode db 3 ; ROM BIOS video mode (2=BW, 3=color) max_y db 24 max_cur_x label word ; used to get both max & cur at once max_x db 79 ; line width (79 for 80x25 modes) cur_coords label word cur_x db 0 ; cursor position (0 = left edge) cur_y db 0 ; (0 = top edge) saved_coords dw ? ; holds XY after a SCP escape sequence string_term db 0 ; either escape or double quote cur_attrib db 7 ; current char attributes cur_page db 0 ; current display page video_seg dw ? ; segment of video card f_cptr_seg dw ? ; part of fastout write buffer pointer cur_parm_ptr dw ? ; last byte of parm area now used port_6845 dw ? ; port address of 6845 card xlate_tab_ptr dw ? ; pointer to output translation table if takeBIOS old_vid_bios dd ? ; pointer to old video bios routine endif brkkeybuf db 3 ; control C fnkeybuf db ? ; holds second byte of fn key codes cpr_buf db 8 dup (?), '[' cpr_esc db 1bh ; descending buffer for cpr function ; following four keybufs hold information about input ; Storage order determines priority- since the characters making up a function ; key code must never be separated (say, by a Control-Break), they have the ; highest priority, and so on. Keyboard keys (except ctrl-break) have the ; lowest priority. fnkey keybuf <0, fnkeybuf> ; fn key string (0 followed by scan code) cprseq keybuf <0> ; CPR string (ESC [ y;x R) brkkey keybuf <0, brkkeybuf> ; ^C xlatseq keybuf <0> ; keyboard reassignment string ;------ xy_to_regs -------------------------------------------- ; on entry: x in cur_x, y in cur_y ; on exit: dx = chars left on line, di = address ; Alters ax, bx. xy_to_regs proc near ; Find number of chars 'till end of line, keep in DX mov ax, max_cur_x mov bx, ax ; save max_x & cur_x for next block mov ah, 0 ; ax = max_x xchg dx, ax mov al, bh mov ah, 0 ; ax = cur_x sub dx, ax inc dx ; dx is # of chars till EOL ; Calculate DI = current address in text buffer mov al, bl ; al = max_x inc al mul cur_y add al, bh ; al += cur_x adc ah, 0 ; AX is # of chars into buffer add ax, ax xchg di, ax ; DI is now offset of cursor. ret xy_to_regs endp ;------- dos_fn_tab ------------- ; This table is used in "interrupt" to call the routine that handles ; the requested function. max_cmd equ 12 dos_fn_tab: dw dosfn0, nopcmd, nopcmd, badcmd, dosfn4, dosfn5, dosfn6 dw dosfn7, dosfn8, dosfn8, nopcmd, nopcmd ;------- strategy ---------------------------------------------------- ; DOS calls strategy with a request which is to be executed later. ; Strategy just saves the request. strategy proc far mov cs:req_off,BX mov cs:req_seg,ES ret strategy endp ;------ interrupt ----------------------------------------------------- ; This is where the request handed us during "strategy" is ; actually carried out. ; Calls one of 12 subroutines depending on the function requested. ; Each subroutine returns with exit status in AX. interrupt proc far sti push_all ; preserve caller's registers push ds push es ; Read requested function information into registers lds bx,cs:req_ptr mov al,[BX+02h] ; al = function code ; ; The next instruction blows up MASM 1.0 but who cares!! ; les si,[BX+0Eh] ; ES:SI = input/output buffer addr mov cx,[BX+12h] ; cx = input/output byte count cmp al, max_cmd ja unk_command ; too big, exit with error code xchg bx, ax shl bx, 1 ; form index to table of words mov ax, cs mov ds, ax call word ptr dos_fn_tab[bx] int_done: lds bx,cs:req_ptr ; report status or ax, 100h ; (always set done bit upon exit) mov [bx+03],ax pop ES ; restore caller's registers pop DS pop_all ret ; return to DOS. unk_command: call badcmd jmp int_done interrupt endp ;----- BIOS break handler ----------------------------------------- ; Called by BIOS when Control-Break is hit (vector was set up in Init). ; Simply notes that a break was hit. Flag is checked during input calls. break_handler proc mov cs:brkkey.len, 1 iret break_handler endp page ;------ badcmd ------------------------------------------------------- ; Invalid function request by DOS. badcmd proc near mov ax, 813h ; return "Error: invalid cmd" ret badcmd endp ;------ nopcmd ------------------------------------------------------- ; Unimplemented or dummy function request by DOS. nopcmd proc near xor ax, ax ; No error, not busy. ret nopcmd endp ;------- dos function #4 ---------------------------------------- ; Reads CX characters from the keyboard, places them in buffer at ; ES:SI. dosfn4 proc near jcxz dos4done mov di, si dos4lp: push cx call getchar pop cx stosb loop dos4lp dos4done: xor ax, ax ; No error, not busy. ret dosfn4 endp ;-------- dos function #5: non-destructive input, no wait ------ ; One-character lookahead into the keyboard buffer. ; If no characters in buffer, return BUSY; otherwise, get value of first ; character of buffer, stuff into request header, return DONE. dosfn5 proc near call peekchar jz dos5_busy lds bx,req_ptr mov [bx+0Dh], al xor ax, ax ; No error, not busy. jmp short dos5_exit dos5_busy: MOV ax, 200h ; No error, busy. dos5_exit: ret dosfn5 endp ;-------- dos function #6: input status -------------------------- ; Returns "busy" if no characters waiting to be read. dosfn6 proc near call peekchar mov ax, 200h ; No error, busy. jz dos6_exit xor ax, ax ; No error, not busy. dos6_exit: ret dosfn6 endp ;-------- dos function #7: flush input buffer -------------------- ; Clears the IBM keyboard input buffer. Since it is a circular ; queue, we can do this without knowing the beginning and end ; of the buffer; all we need to do is set the tail of the queue ; equal to the head (as if we had read the entire queue contents). ; Also resets all the device driver's stuffahead buffers. dosfn7 proc near xor ax, ax mov fnkey.len, ax ; Reset the stuffahead buffers. mov cprseq.len, ax mov brkkey.len, ax mov xlatseq.len, ax mov ax, abs40 mov es, ax mov ax, es:buffer_head ; clear queue by making the tail mov es:buffer_tail, ax ; equal to the head xor ax, ax ; no error, not busy. ret dosfn7 endp page if takeBIOS ;--- new_vid_bios ------------------------------------------- ; New_vid_bios simply replaces the write_tty call. ; All other calls get sent to the old video bios. ; This gives BIOS ANSI capability. ; However, it takes away the escape character. ; If this is not desired, just tell init to not take over the vector. new_vid_bios proc cmp ah, 14 jz nvb_write_tty jmp dword ptr cs:old_vid_bios nvb_write_tty: push cx mov cl, cs:cur_attrib ; If in graphics mode, BL is new color call in_g_mode ; returns carry set if text mode jc nvb_wt_text mov cs:cur_attrib, bl ; ja? nvb_wt_text: int 29h ; write AL mov cs:cur_attrib, cl ; restore color pop cx iret new_vid_bios endp endif ;------ int_29 ---------------------------------------------- ; Int 29 handles DOS quick-access putchar. ; Last device loaded with attribute bit 4 set gets accessed for ; single-character writes via int 29h instead of via interrupt. ; Must preserve all registers. ; Installed as int 29h by dosfn0 (init). int_29_buf db ? int_29 proc near sti push ds push es push_all mov cx, 1 mov bx, cs mov es, bx mov ds, bx mov si, offset int_29_buf mov byte ptr [si], al call dosfn8 pop_all pop es pop ds iret int_29 endp page ;------ dosfn8 ------------------------------------------------------- ; Handles writes to the device (with or without verify). ; Called with ; CX = number of bytes to write ; ES:SI = transfer buffer ; DS = CS, so we can access local variables. dosfn8 proc near mov f_cptr_seg, es ; save segment of char ptr ; Read the BIOS buffer address/cursor position variables. mov ax, abs40 mov ds, ax assume ds:abs40 ; Find current video mode and screen size. mov ax,word ptr crt_mode ; al = crt mode; ah = # of columns mov cs:video_mode, al dec ah ; ah = max column mov cs:max_x, ah ; Find current cursor coordinates. mov al,active_page cbw add ax,ax xchg bx,ax mov ax,cursor_posn[bx] mov cs:cur_coords,AX ; Find video buffer segment address; adjust it ; so the offset is zero; return in AX. ; DS is abs40. ; Find 6845 address. mov ax, addr_6845 mov cs:port_6845, ax ; Find video buffer address. MOV AX,crt_start shr ax, 1 shr ax, 1 shr ax, 1 shr ax, 1 add ah, 0B0h ; assume it's a monochrome card... CMP cs:video_mode,07 jz d8_gots add ah, 8 ; but if not mode 7, it's color. d8_gots: push cs pop ds assume ds:code mov video_seg, ax mov es, ax call xy_to_regs ; Set DX, DI according to cur_coords. ; | If in graphics mode, clear old pseudocursor call in_g_mode jc d8_no_cp call pseudocursor ; write block in xor d8_no_cp: mov bx, xlate_tab_ptr ; get pointer to translation table mov ah, cur_attrib mov ds, f_cptr_seg ; get segment of char ptr assume ds:nothing cld ; make sure we'll increment ; The Inner Loop: 4+12 +4+4 +4+4 +0+15 +4+4 +4+18 = 77 cycles/loop ; on 8088; at 4.77 MHz, that gives 16.1 microseconds/loop. ; At that speed, it takes 32 milliseconds to fill a screen. ; Get a character, put it on the screen, repeat 'til end of line ; or no more characters. jcxz f_loopdone ; if count = 0, we're already done. cmp cs:escvector, 0 ; If in middle of an escape sequence, jnz f_in_escapex ; jump to escape sequence handler. f_tloop:; | If in graphics mode, jump to alternate loop ; | What a massive kludge! A better approach would have been ; | to collect characters for a "write n chars" routine ; | which would handle both text and graphics modes. call in_g_mode jc f_t_cloop jmp f_g_cloop f_t_cloop: LODSB ; get char! (al = ds:[si++]) cmp al, 28 ; is it a control char? jb f_control ; maybe... f_t_nctl: seg_cs xlat STOSW ; Put Char! (es:[di++] = ax) dec dx ; count down to end of line loopnz f_t_cloop ; and go back for more. jz f_t_at_eol ; at end of line; maybe do a crlf. jmp short f_loopdone f_looploop: f_ansi_exit: ; in case we switched into loopnz f_tloop ; a graphics mode f_t_at_eol: jz f_at_eol f_loopdone: ;--------- All done with write request ----------- ; DI is cursor address; cursor position in cur_y, dl. mov ax, cs mov ds, ax ; get our segment back assume ds:code ; Restore cur_x = max_x - dx + 1. mov al, max_x inc al sub al, dl mov cur_x, al ; Set cursor position; cursor adr in DI; cursor pos in cur_x,cur_y call set_pseudocursor ; Return to DOS. xor ax, ax ; No error, not busy. ret ;---- handle control characters ---- ; Note: cur_x is not kept updated in memory, but can be ; computed from max_x and dx. ; Cur_y is kept updated in memory. f_control: cmp al, 27 ; Is it an escape? jz f_escapex cmp al, 13 ; carriage return? jz f_cr cmp al, 10 ; line feed? jz f_lf cmp al, 9 ; tab? jz f_tabx cmp al, 8 ; backspace? jz f_bs cmp al, 7 ; bell? jz f_bell jmp f_nctl ; then it is not a control char. f_tabx: jmp f_tab f_escapex: jmp f_escape f_in_escapex: jmp f_in_escape f_bs: ;----- Handle backspace ----------------- ; Moves cursor back one space without erasing. No wraparound. cmp dl, cs:max_x ; wrap around to previous line? ja fbs_wrap ; yep; disallow it. dec di ; back up one char & attrib, dec di inc dx ; and note one more char left on line. fbs_wrap: jmp f_looploop f_bell: ;----- Handle bell ---------------------- ; Use BIOS to do the beep. DX is not changed, as bell is nonprinting. call beep or al, al ; clear z ; old (more portable) version: ; mov ax, 0e07h ; "write bell to tty simulator" ; mov bx, 0 ; "page zero, color black" ; int 10h ; call BIOS ; mov ah, cs:cur_attrib ; restore current attribute ; mov bx, cs:xlate_tab_ptr ; restore translate table address ; or al, al ; al still 7; this clears Z. jmp f_looploop ; Let main loop decrement cx. f_cr: ;----- Handle carriage return ----------- ; di -= cur_x<<1; set di= address of start of line ; dx=max_x+1; set bx= chars left in line mov al, cs:max_x inc al sub al, dl ; Get cur_x into ax. mov ah, 0 sub di, ax sub di, ax mov dl, cs:max_x ; Full line ahead of us. inc dx mov ah, cs:cur_attrib ; restore current attribute or al, 1 ; clear z jmp f_looploop ; and let main loop decrement cx f_at_eol: ;----- Handle overrunning right end of screen ------- ; cx++; compensate for double loop ; if (!wrap_flag) { dx++; di-=2; } ; else do_crlf; inc cx test cs:wrap_flag, 1 jnz feol_wrap dec di dec di inc dx jmp f_looploop feol_wrap: ; dx=max_x+1; set bx= chars left in line ; di -= 2*(max_x+1); ; do_lf mov dl, cs:max_x inc dx sub di, dx sub di, dx ; fall thru to line feed routine f_lf: ;----- Handle line feed ----------------- ; if (cur_y >= max_y) scroll; scroll screen up if needed ; else { cur_y++; di += max_x<<1; else increment Y mov al, cs:max_y cmp cs:cur_y, al jb flf_noscroll call scroll_up ; preserves bx,cx,dx,si,di jmp short flf_done flf_noscroll: inc cs:cur_y mov al, cs:max_x mov ah, 0 inc ax add ax, ax add di, ax flf_done: mov ah, cs:cur_attrib ; restore current attribute or al, 1 ; clear z jmp f_looploop ; and let main loop decrement cx f_tab: ;----- Handle tab expansion ------------- ; Get cur_x into al. mov al, cs:max_x inc al sub al, dl ; Calculate number of spaces to output. push cx ; save cx mov ch, 0 mov cl, al ; get zero based x coordinate and cl, 7 neg cl add cl, 8 ; 0 -> 8, 1 -> 8, ... 7 -> 1 sub dx, cx ; update chars-to-eol, maybe set z pushf ; || save Z for main loop ; ah is still current attribute. Move CX spaces to the screen. mov al, ' ' call in_g_mode ; | graphics mode jnc f_tab_putc ; | REP STOSW popf ; || restore Z flag for main loop test pop cx ; restore cx jmp f_looploop ; Let main loop decrement cx. ;--------------- graphics mode support ----------------------- f_tab_putc: ; graphics mode- call putc to put the char add dx, cx ; move back to start of tab f_tp_lp: call putchar dec dx ; go to next cursor position loop f_tp_lp popf ; Z set if wrapped around EOL pop cx jmp f_looploop ;---- in_g_mode ------------- ; Returns Carry set if not in a graphics mode. ; Preserves all registers. in_g_mode proc near cmp cs:video_mode, 4 jb igm_stc cmp cs:video_mode, 7 jz igm_stc clc ret igm_stc: stc ret in_g_mode endp ;---- Where to go when a character turns out not to be special f_nctl: f_not_ansi: call in_g_mode jnc f_g_nctl ; graphics mode f_jmptnctl: jmp f_t_nctl ; text mode ;---- Alternate main loop for graphics mode ---- f_g_cloop: LODSB ; get char! (al = ds:[si++]) cmp al, 28 ; is it a control char? jb f_g_control ; maybe... f_g_nctl: seg_cs xlat call putchar dec dx ; count down to end of line loopnz f_g_cloop ; and go back for more. jz f_g_at_eol ; at end of line; maybe do a crlf. jmp f_loopdone f_g_control: jmp f_control f_g_at_eol: jmp f_at_eol ;---- putchar ------------------------------------------------ ; Writes char AL, attribute AH to screen at (max_x+1-dl), cur_y. ; On entry, registers set up as per xy_to_regs. ; Preserves all registers. putchar proc near push dx push cx push bx push ax ; 1. Set cursor position. mov al, cs:max_x inc al sub al, dl mov cs:cur_x, al mov dx, cs:cur_coords ; get X & Y into DX xor bx, bx ; choose dpy page 0 mov ah, 2 ; chose "Set Cursor Position" int 10h ; call ROM BIOS ; 2. Write char & attribute. mov cx, 1 pop ax ; get char in AL push ax mov bl, ah ; attribute in BL mov bh, 0 mov ah, 9 int 10h pop ax pop bx pop cx pop dx ret putchar endp ;---- set_pseudocursor ------------ ; If in graphics mode, set pseudocursor, else set real cursor. ; Destroys DS!!!! set_pseudocursor proc near call in_g_mode jnc pseudocursor ; old (more portable, but slower) version ; mov dx, cur_coords ; get X & Y into DX ; xor bx, bx ; choose dpy page 0 ; mov ah, 2 ; chose "Set Cursor Position" ; int 10h ; call ROM BIOS ; Write directly to 6845 cursor address register. mov bx, di shr bx, 1 ; convert word index to byte index mov dx, port_6845 mov al, 0eh out dx, al jmp $+2 inc dx mov al, bh out dx, al jmp $+2 dec dx mov al, 0fh out dx, al jmp $+2 inc dx mov al, bl out dx, al ; Set cursor position in low memory. assume ds:abs40 mov ax, abs40 mov ds, ax ; Does anybody ever use anything but page zero? ; mov al,active_page ; cbw ; add ax,ax ; xchg bx,ax mov ax, cs:cur_coords mov cursor_posn,ax ret assume ds:code set_pseudocursor endp ;---- pseudocursor -------------------------------------------------- ; Writes a color 15 block in XOR at the current cursor location. ; Preserves DS, ES, BX, CX, DX, SI, DI. ; Should be disableable- the pseudocursor slows down single-char ; writes by a factor of three. pseudocursor proc near mov ax, 8f16h ; xor, color 15, ^V (small block) call putchar ret pseudocursor endp ;--------------- end of graphics mode support -------------------- dosfn8 endp ;--- get_blank_attrib ------------------------------------------------ ; Determine new attribute and character for a new blank region. ; Use current attribute, just disallow blink and underline. ; (Pretty strange way to do it. Might want to disallow rev vid, too.) ; Returns result in AH, preserves all other registers. get_blank_attrib proc near mov ah, 0 call in_g_mode jnc gb_aok ; if graphics mode, 0 is bkgnd mov ah, cs:cur_attrib and ah, 7fh ; disallow blink cmp cs:video_mode, 7 ; monochrome? jnz gb_aok cmp ah, 1 ; underline? jnz gb_aok mov ah, 7 ; yep- set it to normal. gb_aok: ret get_blank_attrib endp ;---- scroll_up --------------------------------------------------- ; Scroll screen up- preserves ax, bx, cx, dx, si, di, ds, es. ; Moves screen up 1 line, fills the last line with blanks. ; Attribute of blanks is the current attribute sans blink and underline. scroll_up proc near push ax push bx push cx push dx call get_blank_attrib mov bh, ah ; color to use on new blank areas mov al, 1 ; AL is number of lines to scroll. mov ah, 6 ; BIOS: scroll up mov cl, 0 ; upper-left-x of data to scroll mov ch, 0 ; upper-left-y of data to scroll mov dl, cs:max_x ; lower-rite-x mov dh, cs:max_y ; lower-rite-y (zero based) int 10h ; call BIOS to scroll a rectangle. pop dx pop cx pop bx pop ax ret scroll_up endp ;---- lookup ----------------------------------------------- ; Called by getchar, peekchar, and key to see if a given key has ; been redefined. ; Sets AH to zero if AL is not zero (i.e. if AX is not a function key). ; Returns with Z cleared if no redefinition; otherwise, ; Z is set, SI points to redefinition string, CX is its length. ; Preseves AL, all but CX and SI. ; Redefinition table organization: ; Strings are stored in reversed order, first char last. ; The word following the string is the character to be replaced; ; the next word is the length of the string sans header. ; param_end points to the last byte used by the parameter buffer; ; redef_end points to the last word used by the redef table. lookup proc near mov si, redef_end ; Start at end of table, move down. or al, al jz lu_lp mov ah, 0 ; clear extraneous scan code lu_lp: cmp si, param_end jbe lu_notfound ; If below redef table, exit. mov cx, [si] cmp ax, [si-2] ; are you my mommy? jz lu_gotit sub si, 4 sub si, cx ; point to next header jmp lu_lp lu_notfound: or si, si ; clear Z jmp short lu_exit lu_gotit: sub si, 2 sub si, cx ; point to lowest char in memory cmp al, al ; set Z lu_exit: ret lookup endp ;---- searchbuf -------------------------------------------- ; Called by getchar and peekchar to see if any characters are ; waiting to be gotten from sources other than BIOS. ; Returns with Z set if no chars found, BX=keybuf & SI=keybuf.len otherwise. searchbuf proc near ; Search the stuffahead buffers. mov cx, 4 ; number of buffers to check for chars mov bx, offset fnkey - 4 sbloop: add bx, 4 ; point to next buffer record mov si, [bx].len or si, si ; empty? loopz sbloop ; if so, loop. ret searchbuf endp ;---- getchar ----------------------------------------------- ; Returns AL = next char. ; Trashes AX, BX, CX, BP, SI. getchar proc near gc_searchbuf: ; See if any chars are waiting in stuffahead buffers. call searchbuf jz gc_trykbd ; No chars? Try the keyboard. ; A nonempty buffer was found. dec [bx].len dec si mov bp, [bx].adr ; get pointer to string mov al, byte ptr ds:[bp][si]; get the char ; Recognize function key sequences, move them to highest priority ; queue. sub si, 1 ; set carry if si=0 jc gc_nofnkey ; no chars left -> nothing to protect. cmp bx, offset fnkey jz gc_nofnkey ; already highest priority -> done. or al, al jnz gc_nofnkey ; nonzero first byte -> not fnkey. ; Found a function key; move it to highest priority queue. dec [bx].len mov ah, byte ptr ds:[bp][si]; get the second byte of fn key code gc_fnkey: mov fnkey.len, 1 mov fnkeybuf, ah ; save it. gc_nofnkey: ; Valid char in AL. Return with it. jmp short gcdone gc_trykbd: ; Actually get a character from the keyboard. mov ah, 0 int 16h ; BIOS returns with char in AX ; If it's Ctrl-break, it has already been taken care of. or ax, ax jz gc_trykbd ; Look in the reassignment table to see if it needs translation. call lookup ; Z=found; CX=length; SI=ptr jnz gc_noredef ; Okay; set up the reassignment, and run thru the translation code. mov xlatseq.len, cx mov xlatseq.adr, si jmp gc_searchbuf gc_noredef: ; Is it a function key? cmp al, 0 jz gc_fnkey ; yep- special treatment. gcdone: ret ; with character in AL. getchar endp ;---- peekchar ----------------------------------------------- ; Returns Z if no character ready, AL=char otherwise. ; Trashes AX, BX, CX, BP, SI. peekchar proc near pc_searchbuf: call searchbuf jz pc_trykbd ; No chars? Try the keyboard. ; A nonempty buffer was found. dec si mov bp, [bx].adr ; get pointer to string mov al, byte ptr ds:[bp][si]; get the char ; Valid char from buffer in AL. Return with it. jmp short pcdone pc_trykbd: ; Actually peek at the keyboard. mov ah, 1 int 16h ; BIOS returns with char in AX jz pcexit ; If it's control-break, it's already been taken care of. or ax, ax jnz pc_notbrk mov ah, 0 int 16h ; so get rid of it! jmp short pc_trykbd pc_notbrk: ; Look in the reassignment table to see if it needs translation. call lookup ; Z=found; CX=length; SI=ptr jnz pcdone ; Nope; just return the char. ; Okay; get the first code to be returned. add si, cx mov al, [si-1] pcdone: or ah, 1 ; NZ; char ready! pcexit: ret ; with character in AL, Z true if no char waiting. peekchar endp ;---- beep ------------------------------------------------------ ; Beep speaker; period given by beep_div, duration by beep_len. ; Preserves all registers. beep_div dw 1300 ; fairly close to IBM beep beep_len dw 3 ; 3/18 sec- shorter than IBM beep proc near push_all mov al, 10110110b ; select 8253 mov dx, 43h ; control port address out dx, al dec dx ; timer 2 address mov ax, cs:beep_div jmp $+2 out dx, al ; low byte of divisor xchg ah, al jmp $+2 out dx, al ; high byte of divisor mov dx, 61h jmp $+2 in al, dx ; get current value of control bits push ax or al, 3 jmp $+2 out dx, al ; turn speaker on ; Wait for desired duration by monitoring time-of-day 18 Hz clock push es mov ax, abs40 mov es, ax assume es:abs40 mov bx, timer_low mov cx, -1 beeplp: mov ax, timer_low sub ax, bx cmp ax, cs:beep_len jg beepover loop beeplp beepover: pop es assume es:code ; Turn off speaker pop ax and al, not 3 ; turn speaker off out dx, al pop_all ret beep endp CODE ends end ; of nansi.asm