mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-19 01:46:09 +00:00
484 lines
22 KiB
NASM
484 lines
22 KiB
NASM
|
VECTORS SEGMENT AT 0H ;Set up segment to intercept Interrupts
|
||
|
|
ORG 9H*4 ;The keyboard Interrupt
|
||
|
|
KEYBOARD_INT LABEL DWORD
|
||
|
|
ORG 1CH*4 ;Timer Interrupt
|
||
|
|
TIMER_VECTOR LABEL DWORD
|
||
|
|
VECTORS ENDS
|
||
|
|
|
||
|
|
SCREEN SEGMENT AT 0B000H ;A dummy segment to use as the
|
||
|
|
SCREEN ENDS ;Extra Segment
|
||
|
|
|
||
|
|
ROM_BIOS_DATA SEGMENT AT 40H ;BIOS statuses held here, also keyboard buffer
|
||
|
|
|
||
|
|
ORG 1AH
|
||
|
|
HEAD DW ? ;Unread chars go from Head to Tail
|
||
|
|
TAIL DW ?
|
||
|
|
BUFFER DW 16 DUP (?) ;The buffer itself
|
||
|
|
BUFFER_END LABEL WORD
|
||
|
|
|
||
|
|
ROM_BIOS_DATA ENDS
|
||
|
|
|
||
|
|
CODE_SEG SEGMENT
|
||
|
|
ASSUME CS:CODE_SEG
|
||
|
|
ORG 100H ;ORG = 100H to make this into a .COM file
|
||
|
|
FIRST: JMP LOAD_KEEPER ;First time through
|
||
|
|
|
||
|
|
COPY_RIGHT DB '(C)1985 S.HOLZNER' ;Ascii autograph
|
||
|
|
PAD DB 20*102 DUP(0) ;Memory storage for pad
|
||
|
|
PAD_CURSOR DW 9*102 ;Current position in pad
|
||
|
|
ATTRIBUTE DB 112 ;Pad Attribute -- reverse video
|
||
|
|
LINE_ATTRIBUTE DB 240 ;Flashing Rev video
|
||
|
|
OLD_ATTRIBUTE DB 7 ;Original screen attrib: normal
|
||
|
|
PAD_OFFSET DW 0 ;Chooses 1st 250 bytes or 2nd
|
||
|
|
FIRST_POSITION DW ? ;Position of 1st char on screen
|
||
|
|
TRIGGER_FLAG DW 0 ;Trigger on or off
|
||
|
|
FULL_FLAG DB 0 ;Buffer Full Flag
|
||
|
|
LINE DW 9 ;Line number, 0-9
|
||
|
|
SCREEN_SEG_OFFSET DW 0 ;0 for mono, 8000H for graphics
|
||
|
|
IO_CHAR DW ? ;Holds addr of Put or Get_Char
|
||
|
|
STATUS_PORT DW ? ;Video controller status port
|
||
|
|
OLD_KEYBOARD_INT DD ? ;Location of old kbd interrupt
|
||
|
|
FINISHED_FLAG DB 1 ;If not finished,f buffer
|
||
|
|
COMMAND_INDEX DW 1 ;Stores positior timer)
|
||
|
|
ROM_TIMER DD 1 ;The Timer interrupt's address
|
||
|
|
OLD_HEAD DW 0
|
||
|
|
|
||
|
|
KEEPER PROC NEAR ;The keyboard interrupt will now come here.
|
||
|
|
ASSUME CS:CODE_SEG
|
||
|
|
PUSH AX ;Save the used registers for good form
|
||
|
|
PUSH BX
|
||
|
|
PUSH CX
|
||
|
|
PUSH DX
|
||
|
|
PUSH DI
|
||
|
|
PUSH SI
|
||
|
|
PUSH DS
|
||
|
|
PUSH ES
|
||
|
|
PUSHF ;First, call old keyboard interrupt
|
||
|
|
CALL OLD_KEYBOARD_INT
|
||
|
|
ASSUME DS:ROM_BIOS_DATA ;Examine the char just put in
|
||
|
|
MOV BX,ROM_BIOS_DATA
|
||
|
|
MOV DS,BX
|
||
|
|
MOV BX,TAIL ;Point to current tail
|
||
|
|
CMP BX,HEAD ;If at head, kbd int has deleted char
|
||
|
|
JE BYE ;So leave
|
||
|
|
MOV DX,HEAD
|
||
|
|
SUB DX,2 ;Point to just read in character
|
||
|
|
CMP DX,OFFSET BUFFER ;Did we undershoot buffer?
|
||
|
|
JAE NOWRAP ;Nope
|
||
|
|
MOV DX,OFFSET BUFFER_END ;Yes -- move to buffer top
|
||
|
|
SUB DX,2 ;Compare two bytes back from head
|
||
|
|
NOWRAP: CMP DX,TAIL ;If it's the tail, buffer is full
|
||
|
|
JNE NOTFULL ;We're OK, jump to NotFull
|
||
|
|
CMP FULL_FLAG,1 ;Check if keyboard buffer full
|
||
|
|
JE BYE ;Yep, leave
|
||
|
|
MOV FULL_FLAG,1 ;Oops, full, set flag and take
|
||
|
|
JMP CHK ; this last character
|
||
|
|
NOTFULL:MOV FULL_FLAG,0 ;Always reset Full_Flag when buff clears
|
||
|
|
CHK: CMP TRIGGER_FLAG,0 ;Is the window on (triggered?)
|
||
|
|
JNE SUBT ;Yep, keep going
|
||
|
|
MOV DX,OLD_HEAD ;Check position of buffer head
|
||
|
|
CMP DX,HEAD
|
||
|
|
JNE CONT
|
||
|
|
MOV OLD_HEAD,0
|
||
|
|
BYE: JMP OUT
|
||
|
|
CONT: MOV DX,HEAD
|
||
|
|
MOV OLD_HEAD,DX
|
||
|
|
SUBT: SUB BX,2 ;Point to just read in character
|
||
|
|
CMP BX,OFFSET BUFFER ;Did we undershoot buffer?
|
||
|
|
JAE NO_WRAP ;Nope
|
||
|
|
MOV BX,OFFSET BUFFER_END ;Yes -- move to buffer top
|
||
|
|
SUB BX,2 ;
|
||
|
|
NO_WRAP:MOV DX,[BX] ;Char in DX now
|
||
|
|
;------ CHAR IN DX NOW -------
|
||
|
|
CMP FINISHED_FLAG,0
|
||
|
|
JE IN
|
||
|
|
CMP DX,310EH ;Default trigger is a ^N here.
|
||
|
|
JNE NOT_TRIGGER ;No
|
||
|
|
MOV TAIL,BX
|
||
|
|
NOT TRIGGER_FLAG ;Switch Modes
|
||
|
|
CMP TRIGGER_FLAG,0 ;Trigger off?
|
||
|
|
JNE TRIGGER_ON ;No, only other choice is on
|
||
|
|
TRIGGER_OFF:
|
||
|
|
MOV OLD_HEAD,0 ;Reset old head
|
||
|
|
MOV AH,OLD_ATTRIBUTE ;Get ready to restore screen
|
||
|
|
MOV ATTRIBUTE,AH ;Pad and blinking line set to orig.
|
||
|
|
MOV LINE_ATTRIBUTE,AH ; values
|
||
|
|
MOV PAD_OFFSET,10*102 ;Point to 2nd half of pad
|
||
|
|
LEA AX,PUT_CHAR ;Make IO call Put_Char as it scans
|
||
|
|
MOV IO_CHAR,AX ;over all locations in pad on screen
|
||
|
|
CALL IO ;Restore screen
|
||
|
|
CMP LINE,9 ;Was the window turned off without
|
||
|
|
JE IN ; using up-down keys? If so, exit
|
||
|
|
MOV AX,LINE ;No, there is a line to stuff in
|
||
|
|
MOV CL,102 ; keyboard buffer
|
||
|
|
MUL CL ;Find its location in Pad
|
||
|
|
MOV COMMAND_INDEX,AX ;And send to Put
|
||
|
|
CALL PUT ;Which will do actual stuffing
|
||
|
|
IN: JMP OUT ;Done
|
||
|
|
TRIGGER_ON: ;Window just turned on
|
||
|
|
MOV LINE,9 ;Set blinking line to bottom
|
||
|
|
MOV PAD_OFFSET,10*102 ;Point to screen storage part of pad
|
||
|
|
LEA AX,GET_CHAR ;Make IO use Get_char so current screen
|
||
|
|
MOV IO_CHAR,AX ;is stored
|
||
|
|
CALL IO ;Store Screen
|
||
|
|
CALL DISPLAY ;And put up the pad
|
||
|
|
JMP OUT ;Done here.
|
||
|
|
NOT_TRIGGER:
|
||
|
|
TEST TRIGGER_FLAG,1 ;Is Trigger on?
|
||
|
|
JZ RUBOUT_TEST
|
||
|
|
MOV TAIL,BX ;Yes, delete this char from buffer
|
||
|
|
UP: CMP DX,4800H ;An Up cursor key?
|
||
|
|
JNE DOWN ;No, try Down
|
||
|
|
DEC LINE ;Move blinker up one line
|
||
|
|
CMP LINE,0 ;At top? If so, reset
|
||
|
|
JGE NOT_TOP
|
||
|
|
MOV LINE,9
|
||
|
|
NOT_TOP:CALL DISPLAY ;Display result
|
||
|
|
JMP OUT ;And leave
|
||
|
|
DOWN: CMP DX,5000H ;Perhaps Down cusor key pushed
|
||
|
|
JNE IN ;If not, ignore key
|
||
|
|
INC LINE ;If so, move down one
|
||
|
|
CMP LINE,9 ;If at bottom, wrap to top
|
||
|
|
JLE NOT_BOT
|
||
|
|
MOV LINE,0
|
||
|
|
NOT_BOT:CALL DISPLAY ;Show results
|
||
|
|
JMP OUT ;And exit
|
||
|
|
RUBOUT_TEST:
|
||
|
|
CMP DX,0E08H ;Is it a Rubout?
|
||
|
|
JNE CHAR_TEST ;No -- try carriage return-line feed
|
||
|
|
MOV BX,PAD_CURSOR ;Yes -- get current pad location
|
||
|
|
CMP BX,9*102 ;Are we at beginning of last line?
|
||
|
|
JLE NEVER_MIND ;Yes -- can't rubout past beginning
|
||
|
|
SUB PAD_CURSOR,2 ;No, rubout this char
|
||
|
|
MOV PAD[BX-2],20H ;Move a space in instead (3920H)
|
||
|
|
MOV PAD[BX-1],39H
|
||
|
|
NEVER_MIND:
|
||
|
|
JMP OUT ;Done here.
|
||
|
|
CHAR_TEST:
|
||
|
|
CMP DL,13 ;Is this a carriage return?
|
||
|
|
JE PLUG ;If yes, plug this line into Pad
|
||
|
|
CMP DL,32 ;If this char < Ascii 32, delete line
|
||
|
|
JGE PLUG
|
||
|
|
MOV PAD_CURSOR,9*102 ;Clear the current line
|
||
|
|
MOV CX,51
|
||
|
|
MOV BX,9*102
|
||
|
|
CLEAR: MOV WORD PTR PAD[BX],0
|
||
|
|
ADD BX,2
|
||
|
|
LOOP CLEAR
|
||
|
|
JMP OUT ;And exit
|
||
|
|
|
||
|
|
PLUG: MOV BX,PAD_CURSOR ;Get current pad location
|
||
|
|
CMP BX,10*102-2 ;Are we past the end of the pad?
|
||
|
|
JGE CRLF_TEST ;Yes -- throw away char
|
||
|
|
MOV WORD PTR PAD[BX],DX ;No -- move ASCII code into pad
|
||
|
|
ADD PAD_CURSOR,2 ;Increment pad location
|
||
|
|
CRLF_TEST:
|
||
|
|
CMP DX,1C0DH ;Is it a carriage return-line feed?
|
||
|
|
JNE OUT ;No -- put it in the pad
|
||
|
|
CALL CRLF ;Yes -- move everything up in pad
|
||
|
|
OUT: POP ES ;Having done Pushes, here are the Pops
|
||
|
|
POP DS
|
||
|
|
POP SI
|
||
|
|
POP DI
|
||
|
|
POP DX
|
||
|
|
POP CX
|
||
|
|
POP BX
|
||
|
|
POP AX
|
||
|
|
IRET ;An interrupt needs an IRET
|
||
|
|
KEEPER ENDP
|
||
|
|
|
||
|
|
DISPLAY PROC NEAR ;Puts the whole pad on the screen
|
||
|
|
PUSH AX
|
||
|
|
MOV ATTRIBUTE,112 ;Use reverse video
|
||
|
|
MOV LINE_ATTRIBUTE,240
|
||
|
|
MOV PAD_OFFSET,0 ;Use 1st 250 bytes of pad memory
|
||
|
|
LEA AX,PUT_CHAR ;Make IO use Put-Char so it does
|
||
|
|
MOV IO_CHAR,AX
|
||
|
|
CALL IO ;Put result on screen
|
||
|
|
POP AX
|
||
|
|
RET ;Leave
|
||
|
|
DISPLAY ENDP
|
||
|
|
|
||
|
|
CRLF PROC NEAR ;This handles carriage returns
|
||
|
|
PUSH BX ;Push everything conceivable
|
||
|
|
PUSH CX
|
||
|
|
PUSH DI
|
||
|
|
PUSH SI
|
||
|
|
PUSH DS
|
||
|
|
PUSH ES
|
||
|
|
ASSUME DS:CODE_SEG ;Set DS to Code_Seg here
|
||
|
|
PUSH CS
|
||
|
|
POP DS
|
||
|
|
ASSUME ES:CODE_SEG ;And ES too
|
||
|
|
PUSH DS
|
||
|
|
POP ES
|
||
|
|
LEA DI,PAD ;Get ready to move contents of Pad
|
||
|
|
MOV SI,DI ; up one line
|
||
|
|
ADD SI,102 ;DI-top line, SI-one below top line
|
||
|
|
MOV CX,9*51
|
||
|
|
MOV BX,PAD_CURSOR ;But first finish line with a 0
|
||
|
|
CMP BX,9*102+2 ; as a flag letting Put know line is
|
||
|
|
JE POPS ; done.
|
||
|
|
MOV WORD PTR PAD[BX],0
|
||
|
|
REP MOVSW ;Move up Pad contents
|
||
|
|
MOV CX,51 ;Now fill the last line with spaces
|
||
|
|
MOV AX,3920H
|
||
|
|
REP STOSW ;Using Stosw
|
||
|
|
POPS: MOV PAD_CURSOR,9*102 ;And finally reset Cursor to beginning
|
||
|
|
POP ES ; of the last line again.
|
||
|
|
POP DS
|
||
|
|
POP SI
|
||
|
|
POP DI
|
||
|
|
POP CX
|
||
|
|
POP BX
|
||
|
|
DONE: RET ;And out.
|
||
|
|
CRLF ENDP
|
||
|
|
|
||
|
|
GET_CHAR PROC NEAR ;Gets a char from screen and advances position
|
||
|
|
ASSUME ES:SCREEN,DS:ROM_BIOS_DATA
|
||
|
|
PUSH DX
|
||
|
|
MOV SI,2 ;Loop twice, once for char, once for attribute
|
||
|
|
MOV DX,STATUS_PORT ;Get ready to read video controller status
|
||
|
|
G_WAIT_LOW: ;Start waiting for a new horizontal scan -
|
||
|
|
IN AL,DX ;Make sure the video controller scan status
|
||
|
|
TEST AL,1 ;is low
|
||
|
|
JNZ G_WAIT_LOW
|
||
|
|
G_WAIT_HIGH: ;After port has gone low, it must go high
|
||
|
|
IN AL,DX ;before it is safe to read directly from
|
||
|
|
TEST AL,1 ;the screen buffer in memory
|
||
|
|
JZ G_WAIT_HIGH
|
||
|
|
MOV AH,ES:[DI] ;Do the move from the screen, one byte at a time
|
||
|
|
INC DI ;Move to next screen location
|
||
|
|
DEC SI ;Decrement loop counter
|
||
|
|
CMP SI,0 ;Are we done?
|
||
|
|
JE LEAVE ;Yes
|
||
|
|
MOV PAD[BX],AH ;No -- put char we got into the pad
|
||
|
|
JMP G_WAIT_LOW ;Do it again
|
||
|
|
LEAVE: MOV OLD_ATTRIBUTE,AH
|
||
|
|
ADD BX,2
|
||
|
|
POP DX
|
||
|
|
RET
|
||
|
|
GET_CHAR ENDP
|
||
|
|
|
||
|
|
PUT_CHAR PROC NEAR ;Puts one char on screen and advances position
|
||
|
|
PUSH DX
|
||
|
|
MOV AH,PAD[BX] ;Get the char to be put onto the screen
|
||
|
|
CMP AH,32
|
||
|
|
JAE GO
|
||
|
|
MOV AH,32
|
||
|
|
GO: MOV SI,2 ;Loop twice, once for char, once for attribute
|
||
|
|
MOV DX,STATUS_PORT ;Get ready to read video controller status
|
||
|
|
P_WAIT_LOW: ;Start waiting for a new horizontal scan -
|
||
|
|
IN AL,DX ;Make sure the video controller scan status
|
||
|
|
TEST AL,1 ;is low
|
||
|
|
JNZ P_WAIT_LOW
|
||
|
|
P_WAIT_HIGH: ;After port has gone low, it must go high
|
||
|
|
IN AL,DX ;before it is safe to write directly to
|
||
|
|
TEST AL,1 ;the screen buffer in memory
|
||
|
|
JZ P_WAIT_HIGH
|
||
|
|
MOV ES:[DI],AH ;Move to screen, one byte at a time
|
||
|
|
MOV AH,ATTRIBUTE ;Load attribute byte for second pass
|
||
|
|
INC DI ;Point to next screen postion
|
||
|
|
DEC SI ;Decrement loop counter
|
||
|
|
JNZ P_WAIT_LOW ;If not zero, do it one more time
|
||
|
|
ADD BX,2
|
||
|
|
POP DX
|
||
|
|
RET ;Exeunt
|
||
|
|
PUT_CHAR ENDP
|
||
|
|
|
||
|
|
IO PROC NEAR ;This scans over all screen positions of the pad
|
||
|
|
ASSUME ES:SCREEN ;Use screen as extra segment
|
||
|
|
MOV BX,SCREEN
|
||
|
|
MOV ES,BX
|
||
|
|
|
||
|
|
PUSH DS
|
||
|
|
MOV BX,ROM_BIOS_DATA
|
||
|
|
MOV DS,BX
|
||
|
|
MOV BX,4AH
|
||
|
|
MOV BX,DS:[BX]
|
||
|
|
SUB BX,51
|
||
|
|
ADD BX,BX
|
||
|
|
MOV FIRST_POSITION,BX
|
||
|
|
POP DS
|
||
|
|
|
||
|
|
MOV DI,SCREEN_SEG_OFFSET ;DI will be pointer to screen postion
|
||
|
|
ADD DI,FIRST_POSITION ;Add width of screen minus pad width
|
||
|
|
MOV BX,PAD_OFFSET ;BX will be pad location pointer
|
||
|
|
MOV CX,10 ;There will be 10 lines
|
||
|
|
|
||
|
|
LINE_LOOP:
|
||
|
|
PUSH WORD PTR ATTRIBUTE
|
||
|
|
PUSH CX ;Figure out whether this is blinking
|
||
|
|
NEG CX ; line and if so, temporarily change
|
||
|
|
ADD CX,10 ; display attribute
|
||
|
|
CMP CX,LINE
|
||
|
|
JNE NOLINE
|
||
|
|
MOV CL,LINE_ATTRIBUTE
|
||
|
|
MOV ATTRIBUTE,CL
|
||
|
|
NOLINE: POP CX
|
||
|
|
MOV DX,51 ;And 51 spaces across
|
||
|
|
CHAR_LOOP:
|
||
|
|
CALL IO_CHAR ;Call Put-Char or Get-Char
|
||
|
|
DEC DX ;Decrement character loop counter
|
||
|
|
JNZ CHAR_LOOP ;If not zero, scan over next character
|
||
|
|
ADD DI,FIRST_POSITION ;Add width of screen minus pad width
|
||
|
|
|
||
|
|
POP WORD PTR ATTRIBUTE
|
||
|
|
LOOP LINE_LOOP ;And now go back to do next line
|
||
|
|
RET ;Finished
|
||
|
|
IO ENDP
|
||
|
|
|
||
|
|
PUT PROC NEAR ;Here it is.
|
||
|
|
ASSUME DS:ROM_BIOS_DATA ;Free DS
|
||
|
|
PUSH DS ;Save all used registers
|
||
|
|
PUSH SI
|
||
|
|
PUSH DI
|
||
|
|
PUSH DX
|
||
|
|
PUSH CX
|
||
|
|
PUSH BX
|
||
|
|
PUSH AX
|
||
|
|
MOV AX,ROM_BIOS_DATA ;Just to make sure
|
||
|
|
MOV DS,AX ;Set DS correctly
|
||
|
|
FIN: MOV FINISHED_FLAG,1 ;Assume we'll finish
|
||
|
|
MOV BX,TAIL ;Prepare to move to buffer's tail
|
||
|
|
MOV SI,COMMAND_INDEX ;Get our source index
|
||
|
|
|
||
|
|
STUFF: MOV AX,WORD PTR PAD[SI]
|
||
|
|
ADD SI,2 ;Point to the command's next character
|
||
|
|
CMP AX,0 ;Is it a zero? (End of command)
|
||
|
|
JE NO_NEW_CHARACTERS ;Yes, leave with Finished_Flag=1
|
||
|
|
MOV DX,BX ;Find position in buffer from BX
|
||
|
|
ADD DX,2 ;Move to next position for this word
|
||
|
|
CMP DX,OFFSET BUFFER_END ;Are we past the end?
|
||
|
|
JL NO_WRAP2 ;No, don't wrap
|
||
|
|
MOV DX,OFFSET BUFFER ;Wrap
|
||
|
|
NO_WRAP2:
|
||
|
|
CMP DX,HEAD ;Buffer full but not yet done?
|
||
|
|
JE BUFFER_FULL ;Time to leave, set Finished_Flag=0.
|
||
|
|
ADD COMMAND_INDEX,2 ;Move to next word in command
|
||
|
|
MOV [BX],AX ;Put it into the buffer right here.
|
||
|
|
ADD BX,2 ;Point to next space in buffer
|
||
|
|
CMP BX,OFFSET BUFFER_END ;Wrap here?
|
||
|
|
JL NO_WRAP3 ;No, readjust buffer tail
|
||
|
|
MOV BX,OFFSET BUFFER ;Yes, wrap
|
||
|
|
NO_WRAP3:
|
||
|
|
MOV TAIL,BX ;Reset buffer tail
|
||
|
|
JMP STUFF ;Back to stuff in another character.
|
||
|
|
BUFFER_FULL: ;If buffer is full, let timer take over
|
||
|
|
MOV FINISHED_FLAG,0 ; by setting Finished_Flag to 0.
|
||
|
|
NO_NEW_CHARACTERS:
|
||
|
|
POP AX ;Restore everything before departure.
|
||
|
|
POP BX
|
||
|
|
POP CX
|
||
|
|
POP DX
|
||
|
|
POP DI
|
||
|
|
POP SI
|
||
|
|
POP DS
|
||
|
|
STI
|
||
|
|
RET
|
||
|
|
PUT ENDP
|
||
|
|
|
||
|
|
ASSUME DS:CODE_SEG
|
||
|
|
INTERCEPT_TIMER PROC NEAR ;This completes filling the buffer
|
||
|
|
PUSHF ;Store used flags
|
||
|
|
PUSH DS ;Save DS since we'll change it
|
||
|
|
PUSH CS ;Put current value of CS into DS
|
||
|
|
POP DS
|
||
|
|
CALL ROM_TIMER ;Make obligatory call
|
||
|
|
PUSHF
|
||
|
|
CMP FINISHED_FLAG,1 ;Do we have to do anything?
|
||
|
|
JE OUT1 ;No, leave
|
||
|
|
CLI ;Yes, start by clearing interrupts
|
||
|
|
PUSH DS ;Save these.
|
||
|
|
PUSH SI
|
||
|
|
PUSH DX
|
||
|
|
PUSH BX
|
||
|
|
PUSH AX
|
||
|
|
ASSUME DS:ROM_BIOS_DATA ;Point to the keyboard buffer again.
|
||
|
|
MOV AX,ROM_BIOS_DATA
|
||
|
|
MOV DS,AX
|
||
|
|
MOV BX,TAIL ;Prepare to put characters in at tail
|
||
|
|
MOV FINISHED_FLAG,1 ;Assume we'll finish
|
||
|
|
MOV SI,COMMAND_INDEX ;Find where we left ourselves
|
||
|
|
|
||
|
|
STUFF2: MOV AX,WORD PTR PAD[SI] ;The same stuff loop as above.
|
||
|
|
ADD SI,2 ;Point to next command character.
|
||
|
|
CMP AX,0 ;Is it zero? (end of command)
|
||
|
|
JNE OVER ;No, continue.
|
||
|
|
JMP NO_NEW_CHARACTERS2 ;Yes, leave with Finished_Flag=1
|
||
|
|
OVER: MOV DX,BX ;Find position in buffer from BX
|
||
|
|
ADD DX,2 ;Move to next position for this word
|
||
|
|
CMP DX,OFFSET BUFFER_END ;Are we past the end?
|
||
|
|
JL NO_WRAP4 ;No, don't wrap
|
||
|
|
MOV DX,OFFSET BUFFER ;Do the Wrap rap.
|
||
|
|
NO_WRAP4:
|
||
|
|
CMP DX,HEAD ;Buffer full but not yet done?
|
||
|
|
JE BUFFER_FULL2 ;Time to leave, come back later.
|
||
|
|
ADD COMMAND_INDEX,2 ;Point to next word of command.
|
||
|
|
MOV [BX],AX ;Put into buffer
|
||
|
|
ADD BX,2 ;Point to next space in buffer
|
||
|
|
CMP BX,OFFSET BUFFER_END ;Wrap here?
|
||
|
|
JL NO_WRAP5 ;No, readjust buffer tail
|
||
|
|
MOV BX,OFFSET BUFFER ;Yes, wrap
|
||
|
|
NO_WRAP5:
|
||
|
|
MOV TAIL,BX ;Reset buffer tail
|
||
|
|
JMP STUFF2 ;Back to stuff in another character
|
||
|
|
BUFFER_FULL2:
|
||
|
|
MOV FINISHED_FLAG,0 ;Set flag to not-done-yet.
|
||
|
|
NO_NEW_CHARACTERS2:
|
||
|
|
POP AX ;Restore these.
|
||
|
|
POP BX
|
||
|
|
POP DX
|
||
|
|
POP SI
|
||
|
|
POP DS
|
||
|
|
OUT1: POPF ;And Exit.
|
||
|
|
POP DS
|
||
|
|
IRET ;With customary IRET
|
||
|
|
INTERCEPT_TIMER ENDP
|
||
|
|
|
||
|
|
LOAD_KEEPER PROC NEAR ;This procedure intializes everything
|
||
|
|
ASSUME DS:VECTORS ;The data segment will be the Interrupt area
|
||
|
|
MOV AX,VECTORS
|
||
|
|
MOV DS,AX
|
||
|
|
|
||
|
|
MOV AX,KEYBOARD_INT ;Get the old interrupt service routine
|
||
|
|
MOV OLD_KEYBOARD_INT,AX ;address and put it into our location
|
||
|
|
MOV AX,KEYBOARD_INT[2] ;OLD_KEYBOARD_INT so we can call it.
|
||
|
|
MOV OLD_KEYBOARD_INT[2],AX
|
||
|
|
|
||
|
|
MOV KEYBOARD_INT,OFFSET KEEPER ;Now load the address of our notepad
|
||
|
|
MOV KEYBOARD_INT[2],CS ;routine into the keyboard interrupt
|
||
|
|
|
||
|
|
MOV AX,TIMER_VECTOR ;Now same for timer
|
||
|
|
MOV ROM_TIMER,AX
|
||
|
|
MOV AX,TIMER_VECTOR[2]
|
||
|
|
MOV ROM_TIMER[2],AX
|
||
|
|
|
||
|
|
MOV TIMER_VECTOR,OFFSET INTERCEPT_TIMER
|
||
|
|
MOV TIMER_VECTOR[2],CS ;And intercept that too.
|
||
|
|
|
||
|
|
ASSUME DS:ROM_BIOS_DATA
|
||
|
|
MOV AX,ROM_BIOS_DATA
|
||
|
|
MOV DS,AX
|
||
|
|
MOV BX,OFFSET BUFFER ;Clear the keyboard buffer.
|
||
|
|
MOV HEAD,BX
|
||
|
|
MOV TAIL,BX
|
||
|
|
MOV AH,15 ;Ask for service 15 of INT 10H
|
||
|
|
INT 10H ;This tells us how display is set up
|
||
|
|
MOV STATUS_PORT,03BAH ;Assume this is a monochrome display
|
||
|
|
TEST AL,4 ;Is it?
|
||
|
|
JNZ EXIT ;Yes - jump out
|
||
|
|
MOV SCREEN_SEG_OFFSET,8000H ;No - set up for graphics display
|
||
|
|
MOV STATUS_PORT,03DAH
|
||
|
|
|
||
|
|
EXIT: MOV DX,OFFSET LOAD_KEEPER ;Set up everything but LOAD_PAD to
|
||
|
|
INT 27H ;stay and attach itself to DOS
|
||
|
|
LOAD_KEEPER ENDP
|
||
|
|
|
||
|
|
CODE_SEG ENDS
|
||
|
|
|
||
|
|
END FIRST ;END "FIRST" so 8088 will go to FIRST first.
|
||
|
|
|
||
|
|
|
||
|
|
|