PR#3
PREFIX /A2OSX.SRC
NEW
INC 1
AUTO 6
				.LIST OFF	
*--------------------------------------
TCP.IN			ldy #S.IP.SRC+3
				ldx #3
				
.1				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.DST.ADDR,x
				dey
				dex
				bpl .1
				
				ldy #S.TCP.SRCPORT
				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.DST.PORT+1
				iny
				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.DST.PORT
				
				ldy #S.IP.DST+3
				ldx #3
.2				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.SRC.ADDR,x
				dey
				dex
				bpl .2
				
				ldy #S.TCP.DSTPORT
				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.SRC.PORT+1
				iny
				lda (ZPFrameBase1),y
				sta TmpSocket+S.SOCKET.SRC.PORT
				
				>LDYA L.SKT.TABLE
				>STYA ZPPtrSKT
				
				ldx #0
				
.3				lda (ZPPtrSKT)
				beq .7
				cmp #S.SOCKET.SOCK.STREAM
				bne .7
				
				ldy #S.SOCKET.SRC.ADDR
				
.4				lda TmpSocket,y
				cmp (ZPPtrSKT),y
				bne .7						Not for this socket...
				iny
				cpy #S.SOCKET.SRC.PORT+2
				bne .4
				
				ldy #S.SOCKET.SO
				lda (ZPPtrSKT),y
				and #S.SOCKET.SO.ACCEPTCONN		Listening socket?
				beq .5
	
				ldy #S.TCP.OPTIONS				yes, only accept SYN packet
				lda (ZPFrameBase1),y
				cmp #S.TCP.OPTIONS.SYN
				bne .7							not for this listening socket
				jmp TCP.IN.LISTEN.NEW
			
.5				ldy #S.SOCKET.DST.ADDR

.6				lda TmpSocket,y			regular socket, check remote ADDR/PORT
				cmp (ZPPtrSKT),y
				bne .7
				iny
				cpy #S.SOCKET.DST.PORT+2
				bne .6
				
				jmp TCP.IN.ESTABLISHED
				
.7				lda ZPPtrSKT
				clc
				adc #S.SOCKET
				sta ZPPtrSKT
				bcc .8
				inc ZPPtrSKT+1
				
.8				inx
				cpx #K.SKTTABLE.SIZE
				bne .3
				
				clc						Discard frame
				rts
*--------------------------------------
TCP.IN.LISTEN.NEW
				lda #S.SOCKET.SOCK.STREAM
				sta TmpSocket
				
				stz TmpSocket+S.SOCKET.SO

				ldy #S.TCP.SEQ.NUMBER+3
				ldx #3
				
				sec
.1				lda (ZPFrameBase1),y
				adc #0
				sta TmpSocket+S.SOCKET.SQ.ACKNUM,x
				dey
				dex
				bpl .1
				
				ldx #3
.2				lda A2osX.TIMER16,x
				sta TmpSocket+S.SOCKET.SQ.SEQNUM,x
				dex
				bpl .2

				>PUSHW L.TmpSocket

				jsr SKT.NEW
				bcs .9
				
				phy
				pha
				txa
				
				jsr SKT.AddToQueueL
				
				pla
				sta ZPPtrSKT+1
				pla
				sta ZPPtrSKT
				
				bcc .3

				lda #0					error
				sta (ZPPtrSKT)			clear this socket
				lda #ERR.SKT.OOS
.9				rts
				
.3				ldy #S.SOCKET.STATUS
				lda #S.SOCKET.STATUS.SYNRCVD
				sta (ZPPtrSKT),y
				
				jmp TCP.SendSYNACK
*--------------------------------------
TCP.IN.ESTABLISHED
				stx hSocket
				ldy #S.SOCKET.STATUS
				lda (ZPPtrSKT),y
				cmp #S.SOCKET.STATUS.SYNRCVD	Waiting for ACK to establish?
				bne .1
				
				ldy #S.TCP.OPTIONS				yes, only accept ACK packet
				lda (ZPFrameBase1),y
				cmp #S.TCP.OPTIONS.ACK
				bne .8
				
				ldx #3
				ldy #S.SOCKET.SQ.SEQNUM+3
				sec
.10				lda (ZPPtrSKT),y
				adc #0
				sta TmpDWord,x
				dey
				dex
				bpl .10
				
				ldx #3
				ldy #S.TCP.ACK.NUMBER+3
.11				lda (ZPFrameBase1),y
				cmp TmpDWord,x
				bne .8
				dey
				dex
				bpl .11
				
				ldx #3
				ldy #S.SOCKET.SQ.SEQNUM+3
.12				lda TmpDWord,x
				sta (ZPPtrSKT),y
				dey
				dex
				bpl .12
				
				ldy #S.SOCKET.STATUS
				lda #S.SOCKET.STATUS.ESTBLSH
				sta (ZPPtrSKT),y
				
				>PUSHW K.TCP.WSIZE
				>PUSHBI 0
				>SYSCALL SYS.GetMem
				bcs *
				txa
				
				ldy #S.SOCKET.SQ.hInMem
				sta (ZPPtrSKT),y
				
				>PUSHW K.TCP.WSIZE
				>PUSHBI 0
				>SYSCALL SYS.GetMem
				bcs *
				txa
				
				ldy #S.SOCKET.SQ.hOutMem
				sta (ZPPtrSKT),y
				
.8				clc
				rts
				
.1				cmp #S.SOCKET.STATUS.ESTBLSH
				bne .99




				bra *
.99				clc
				rts
*--------------------------------------
TCP.SendSYNACK	ldy #S.SOCKET.SRC.ADDR+3
				ldx #3
.1				lda (ZPPtrSKT),y
				sta TCP.MSG+S.IP.SRC,x
				dey
				dex
				bpl .1
	
				ldy #S.SOCKET.SRC.PORT
				lda (ZPPtrSKT),y
				sta TCP.MSG+S.TCP.SRCPORT+1
				iny
				lda (ZPPtrSKT),y
				sta TCP.MSG+S.TCP.SRCPORT
				
				ldy #S.SOCKET.DST.ADDR+3
				ldx #3
.2				lda (ZPPtrSKT),y
				sta TCP.MSG+S.IP.DST,x
				dey
				dex
				bpl .2

				ldy #S.SOCKET.DST.PORT
				lda (ZPPtrSKT),y
				sta TCP.MSG+S.TCP.DSTPORT+1
				iny
				lda (ZPPtrSKT),y
				sta TCP.MSG+S.TCP.DSTPORT
				
				ldy #S.SOCKET.SQ.SEQNUM+7
				ldx #7
.3				lda (ZPPtrSKT),y
				sta TCP.MSG+S.TCP.SEQ.NUMBER,x
				dey
				dex
				bpl .3
				
				lda #S.TCP.OPTIONS.SYN+S.TCP.OPTIONS.ACK
				sta TCP.MSG+S.TCP.OPTIONS
				
				>PUSHW L.TCP.MSG
				jsr SEND.TCP.FRAME
				
				clc
				rts
*--------------------------------------
TCP.ComputeChecksum
				lda #0					RESET.TCP.CHECKSUM
				ldy #S.TCP.CHECKSUM
				sta (ZPFrameBase1),y
				iny
				sta (ZPFrameBase1),y
				
				>LDYA ZPFrameBase1
				>STYA ZPTmpPtr1
				
				lda ZPFrameLen1
				sec
				sbc #S.IP-2
				sta ZPDataLen
				
				lda ZPFrameLen1+1
				sbc /S.IP-2
				sta ZPDataLen+1
				
				clc
				
*				lda ZPDataLen+1
*				adc #0					RESERVED (all zero)
				sta IP.CHECKSUM

				lda ZPDataLen
				adc #S.IP.PROTOCOL.TCP
				sta IP.CHECKSUM+1
				
				ldy #S.IP.SRC
				
				ldx #4					4 words for SRC & DST IP
				
.10				lda (ZPFrameBase1),y
				adc IP.CHECKSUM
				sta IP.CHECKSUM
				iny
				lda (ZPFrameBase1),y
				adc IP.CHECKSUM+1
				sta IP.CHECKSUM+1
				iny
				dex
				bne .10
				
				ldy #S.IP
				
.1				jsr DecDataLen
				beq .8
				
				lda (ZPTmpPtr1),y
				adc IP.CHECKSUM
				sta IP.CHECKSUM

				iny
				bne .20
				inc ZPTmpPtr1+1
				
.20				jsr DecDataLen
				bne .2
				lda #0
				bra .21

.2				lda (ZPTmpPtr1),y

.21				adc IP.CHECKSUM+1
				sta IP.CHECKSUM+1
				
				iny
				bne .1
				inc ZPTmpPtr1+1
				bra .1
				
.8				ldy #S.TCP.CHECKSUM
				lda IP.CHECKSUM
				adc #0					Don't forget to add last carry!!!
				eor #$FF
				sta (ZPFrameBase1),y
				iny
				lda IP.CHECKSUM+1
				adc #0					Don't forget to add last carry!!!
				eor #$FF
				sta (ZPFrameBase1),y
				rts
*--------------------------------------
MAN
SAVE LIB/LIBTCPIP.S.TCP
LOAD LIB/LIBTCPIP.S
ASM