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Simtel MSDOS 1992 December
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NANSI.ASM
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Assembly Source File
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1989-11-19
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37KB
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1,048 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
;------------------------------------------------------------------------
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)
org 84h
crt_max_y db ? ; CJD 11/19/89 - EGA/VGA max row #
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)
; 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
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
mov al,crt_max_y ; CJD 11/19/89 - get/set max row #
mov cs:max_y,al
; 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.
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
if BIOS_cur
; 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
else
; 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
endif
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
CODE ends
end ; of nansi.asm
