1. No Profile Picture
    Registered User
    Devshed Newbie (0 - 499 posts)

    Join Date
    Apr 2010
    Rep Power

    Simple assembly code review help! seems like this problem should be simple

    The code below is supposed to take a string of ascii 0s and 1s (representing bits) that follows this format: 1byte start of transmission (can be ignored), 4 byte ip address and up to 8 bytes of text, then an ending byte 03H, then there is an address saved in a WORD

    I encounter these errors when trying to link it:
    ***3.o: In function `sipo':
    ***3.asm.text+0x73): undefined reference to `proc_PutStr'
    ***3.o: In function `aLoop':
    ***3.asm.text+0x8a): undefined reference to `proc_GetCh'
    ***3.o: In function `inner_loop':
    ***3.asm.text+0xcb): undefined reference to `proc_GetCh'
    ***3.o: In function `receiveCheckSum':
    ***3.asm.text+0x169): undefined reference to `proc_GetCh'

    %include "io.mac"
    	char_prompt    db  "Please input a string of 0s and 1s that represents the XXY protocol ",0
    	IP_prompt   db  "The IP address is: ",0
    	message_prompt   db  "The message is: ",0
    	char_prompt2   db  "Error in Transmission",0
    	query_msg        db  "Do you want to quit (Y/N): ",0
    	input		resb 1
    	address		resb 4
    	message		resb 8
    	checksum	resw 1
    	counter		resb 1
    	savingCheckSum	resb 1
    	locationInCheckSum	resb 1
    	currentByte	resb 1
    		push	input
    		push	address
    		push	checksum
    		mov	[savingCheckSum], byte 0
    		call	sipo
    		PutStr	IP_prompt
    			;output actual ip address TODO
    		PutStr	message_prompt
    		PutStr	message
    		push	message
    		push	address
    		call	checker
    		test	AX,[savingCheckSum]
    		je	the_end
    		PutStr	char_prompt2
    	sipo:		;paramters:
    		PutStr	char_prompt             ; request a char. input
    		                     					; 1) an array called "address" which contains the 4 bytes of the address .
    		pop	ECX			;save call stack			; 2) An array called "message" which contains the bytes of the message.
     		pop	EAX			;save checksum location 		;3) a word variable called "checksum" which contains the checksum.	
    		pop	EBX			;save ip address location
    		pop	ESI			;save message address
    		push	ECX			;put back the call address		
    		mov	ECX, 8
    		GetCh	[input]			;get the first 8 characters and do nothing with them
    		loop	aLoop
    		mov	[counter], byte 7
    		mov	AL, 0			;current byte
    		mov	ECX, 8			;loop 8 times for 8 bits
    		mov	AH, 80H			;mask byte
    		inc	AL
    		mov	[currentByte], AL	;save currentbyte so that at the end we know how many bytes were read excluding checksum
    		inc	byte [counter]
    		test	[savingCheckSum], byte 0
    		je	receiveCheckSum
    		GetCh	[input]
    		cmp	[counter], byte 40
    		jl	receiveIP
    		jmp	receiveMessage
    		test	[input], byte 0
    		je	endof_innerLoop		;if it's 0, let's finish this loop!
    		mov	EDX, EBX
    		dec	EDX
    		add	EDX, [currentByte]
    		OR	[EDX], AH		;use the mask to set the bit to 1
    		jmp	endof_innerLoop
    		mov	EDX,ESI
    		add	ESI,[currentByte]
    		sub	EDX,6
    		cmp	[EDX],byte 03H		;check for termination char, put a NULL at the end of message if it is (done below in ready)
    		je	ready
    		test	[input], byte 0
    		je	endof_innerLoop
    		mov	EDX,[currentByte]
    		add	EDX,ESI
    		sub	EDX, 5
    		OR	[EDX], AH		;use the mask to set the bit to 1
    		jmp	endof_innerLoop
    	ready:					;get ready to save the checksum
    		mov	EDX,ESI
    		add	ESI,[currentByte]
    		sub	EDX,6
    		mov	[EDX], byte ''	;put null character	
    		mov 	[locationInCheckSum], byte 0
    		mov	[savingCheckSum], byte 1
    		jmp	endof_innerLoop
    		test	[locationInCheckSum],byte 16	; THIS IS THE ONLY PLACE TO EXIT THE LOOP, after we read 16 bits from the checksum, we exit the loop
    		je	finish_loop
    		GetCh	[input]	
    		test	[input], byte 0
    		inc	byte [locationInCheckSum]
    		je	endof_innerLoop
    		OR	[EAX], AH
    		shr	AH, 1
    		cmp	ECX,1
    		je	endOf_OuterLoop
    		dec	ECX
    		jmp	inner_loop
    		jmp	outer_loop
    		dec	byte [currentByte]
    		dec	byte [currentByte]
    		pop	ECX		;get everything into the registers and return the stack to the way it was before it was setup for this function
    		pop	EDX		;address
    		pop	ESI		;message
    		mov	EBX, 0
    		push	ECX
    		mov	AX,  0
    		mov	ECX, 2	;check 2 bytes for a WORD
    		push	ECX	
    		mov	ECX, 8
    		mov	AH, 80H			;mask byte
    		test	AH, [EDX+EDI]	;EDI is stack pointer -- CONFIRM THIS
    		jz	endThisLoopAlready
    		inc	AX
    		shr	AH, 1
    		loop	check_address_inner
    		pop	ECX
    		loop	check_address_outer
    		mov	ECX, [currentByte]
    		dec	ECX
    		dec	ECX
    		dec	ECX
    	anotherOuterLoop:			;goes through the message
    		push	ECX
    		mov	AH, 80H			;mask byte
    		mov	ECX, 8			;8 bits
    		test	[ESI+EBX], AH
    		jz	endInner
    		inc	AX
    		shr	AH, 1
    		loop	anotherInnerLoop
    		pop	ECX
    		inc	EBX
    		loop	anotherOuterLoop
    If you see any other problems please let me know!! this code has never been compiled/tested because I haven't gotten past this stage so I'm sure there are other flaws in it.

    and PS: it's obvious because I didn't even bother to remove the references that this is an assignment and to be clear I'm not asking for answers I'd just like some help

    Thanks in advance!!
  2. #2
  3. No Profile Picture
    Contributing User
    Devshed Novice (500 - 999 posts)

    Join Date
    May 2007
    Rep Power
    The PutStr and GetCh procedures that you're using are from some library which you need to tell the linker to include.

    The documentation for that library should tell you what library you need to include and the documentation for your linker will tell you how to specify additional libraries on the command line. Or you can check your textbook / examples / talk to your instructor.
    sub{*{$::{$_}}{CODE}==$_[0]&& print for(%:: )}->(\&Meh);

IMN logo majestic logo threadwatch logo seochat tools logo