Update dbgmon.asm

Eliminate need for 128 byte packet buffer

Source/HBIOS/dbgmon.asm

@@ -324,28 +324,27 @@ KLOP1:
 	JP	Z,SERIALCMDLOOP		; IF SO, ALL DONE
 	CALL	COUT			; OUTPUT KEY TO SCREEN
 	JR	KLOP1			; LOOP
+;
 #IF (ENA_XM)
 ;
 ;__XMLOAD_____________________________________________________________________
 ;
 ;	LOAD A FILE INTO MEMORY FROM THE SERIAL PORT USING X-MODEM PROTOCOL
 ;
-;
 SOH:	.EQU	'A'-40h			; ^A CTRL-A
 EOT:	.EQU	'D'-40h			; ^D = End of Transmission
 ACK:	.EQU	'F'-40h			; ^F = Positive Acknowledgement
 NAK:	.EQU	'U'-40h			; ^U = Negative Acknowledgement
 CAN:	.EQU	'X'-40h			; ^X = Cancel
 ;
-PKTNU	.DB	0			; CALCULATED PACKET NUMBER
-PKTNU1C	.DB	0			; CALCULATED PACKET NUMBER COMPLEMENT
+CPKTN	.DB	0			; CALCULATED PACKET NUMBER
+CPKTN1C	.DB	0			; CALCULATED PACKET NUMBER COMPLEMENT
 RETRYC	.DB	0			; RETRY COUNT
-
-PACKET:	.DB 	0			; START OF HEADER (SOH)
-	.DB	0			; RECEIVED PACKET NUMBER
-	.DB	0			; RECEIVED PACKET NUMBER COMPLEMENT
-	.FILL	128,0			; 128 BYTES OF DATA
-	.DB	0 			; CHECKSUM
+RPKTN:	.DB	0			; RECEIVED PACKET NUMBER
+RPKTN1C:.DB	0			; RECEIVED PACKET NUMBER COMPLEMENT
+PKTCS	.DB	0 			; CHECKSUM
+;
+PSADDR:	.DW	0			; START OF PACKET ADDR
 ;
 XMLOAD:	CALL	WORDPARM		; GET STARTING LOCATION
 	JP	C,ERR			; HANDLE SYNTAX ERRORS
@@ -366,13 +365,12 @@ XMLOAD:	CALL	WORDPARM		; GET STARTING LOCATION
 	ADD	A,A			; TIMEOUT DELAY
 	LD	(TMOFCT),A		; FACTOR 
 	POP	AF
-
-	LD 	A,1			; THE FIRST PACKET IS NUMBER 1
-	LD 	(PKTNU),A
-	LD 	A,255-1			; ALSO STORE THE 1-COMPLEMENT OF IT
-	LD 	(PKTNU1C),A
 ;
-	POP	DE			; POINT TO WHERE TO SAVE FILE
+	LD	BC,$FE01		; SET FIRST NUMBER TO 1
+	LD	(CPKTN),BC		; ALSO STORE THE 1-COMPLEMENT
+;
+	POP	DE			; POINT TO WHERE TO SAVE THE PACKET
+	LD	(PSADDR),DE		; SAVE IF FOR THE CHECKSUM CALCULATION
 ;
 GETNP:	LD	HL,RETRYC		; WE RETRY 20 TIMES BEFORE GIVING UP
 	LD 	(HL),20
@@ -386,7 +384,7 @@ NPLOOP:	LD 	B,6			; 6 SECONDS OF TIMEOUT BEFORE EACH NEW BLOCK
 ;
 	LD 	A,NAK			; SEND A NAK TO THE UPLOADER
 	CALL	COUT
-	JR 	NPLOOP			; GET NEXT PACKET
+	JR 	NPLOOP			; LOOP UNTIL WE GET A GET A CHARACTOR OR TIMEOUT
 ;
 NOTOUT:	CP	EOT			; DID UPLOADER SAY WE'RE FINISHED?
 	JP	Z,XMDONE		; YES, THEN WE'RE DONE
@@ -395,7 +393,7 @@ NOTOUT:	CP	EOT			; DID UPLOADER SAY WE'RE FINISHED?
 	CP	SOH			; DID WE GET A START-OF-NEW-PACKET?
 	JR	NZ,NPLOOP		; NO, GO BACK AND TRY AGAIN
 ;
-	LD	HL,PACKET+1		; SKIP SAVING SOH
+	LD	HL,RPKTN		; WE SAVE PACKET NUMBER HERE
 ;
 	CALL	GCTO1			; WAIT ONE SECOND FOR A CHARACTER
 	LD	(HL),A                  ; SHOULD BE PACKET NUMBER
@@ -403,42 +401,41 @@ NOTOUT:	CP	EOT			; DID UPLOADER SAY WE'RE FINISHED?
 	JR	C,FAILTO		; TIMOUT ERROR?
 ;
 	CALL	GCTO1			; WAIT ONE SECOND FOR A CHARACTER
-	LD	(HL),A			; SHOULD BE PACKET NUMBER
-	INC 	HL                      ; COMPLEMENT
+	LD	(HL),A			; SHOULD BE PACKET NUMBER COMPLEMENT
 	JR	C,FAILTO		; TIMOUT ERROR?
-;
-	LD 	C,0 			; GET 128 MORE CHARACTERS FOR A FULL PACKET
-PCKRCV:					; C=0=256 TO ALLOW FOR DOUBLE DECREMENT
-	CALL	GCTO1			; WAIT ONE SECOND FOR A CHARACTER
+
+	LD 	C,128			; GET 128 MORE CHARACTERS FOR A FULL PACKET
+PCKRCV:	CALL	GCTO1			; WAIT ONE SECOND FOR A CHARACTER
 	JR	C,FAILTO		; TIMOUT ERROR?
-;
-	LD	(HL),A			; SAVE THE RECEIVED CHAR INTO THE
-	LDI                		; PACKET BUFFER AND DESTINATION (DE)
-;
-	DEC	C			; C GETS DECREMENTED TWICE EACH LOOP.
+	LD	(DE),A         		; SAVE THE RECEIVED CHAR
+	INC	DE
+	DEC	C	
 	JP	NZ,PCKRCV
 ;
 	CALL	GCTO1			; WAIT ONE SECOND FOR A CHARACTER
-	LD	(HL),A                  ; SHOULD BE CHECKSUM
 	JR	C,FAILTO		; TIMOUT ERROR?
+	LD	(PKTCS),A		; SHOULD BE CHECKSUM
 ;
-	LD	HL,PACKET+3		; CALCULATE CHECKSUM FROM 128 BYTES OF DATA
+	LD	HL,(PSADDR)		; CALCULATE CHECKSUM FROM 128 BYTES OF DATA
 	LD	B,128
 	XOR	A
 CSLOOP:	ADD	A,(HL)			; JUST ADD UP THE BYTES
 	INC	HL
 	DJNZ	CSLOOP
 ;
+	LD	(PSADDR),DE		; SAVE THE NEW PACKET START ADDRESS
+;
+	LD	HL,PKTCS
 	XOR	(HL)			; HL POINTS TO THE RECEIVED CHECKSUM SO
 	JR	NZ,FAILCS		; BY XORING IT TO OUR SUM WE CHECK FOR EQUALITY
 ;
-	LD	HL,(PKTNU)		; CHECK
-	LD	BC,(PACKET+1)		; AGREEMENT
+	LD	HL,(CPKTN)		; CHECK
+	LD	BC,(RPKTN)		; AGREEMENT
 ;	XOR	A                       ; PACKET
 	SBC	HL,BC                   ; NUMBERS
 	JR	NZ,FAILPN
 ;
-	LD	HL,PKTNU		; UPDATE THE PACKET COUNTERS
+	LD	HL,CPKTN		; UPDATE THE PACKET COUNTERS
 	INC 	(HL)
 	INC	HL
 	DEC	(HL)