mirror of
https://github.com/bobbimanners/emailler.git
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250 lines
5.9 KiB
ArmAsm
250 lines
5.9 KiB
ArmAsm
;TCP (transmission control protocol) functions
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.include "../inc/common.i"
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.ifndef NB65_API_VERSION_NUMBER
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.define EQU =
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.include "../inc/nb65_constants.i"
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.endif
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.import ip65_error
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.export tcp_init
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.export tcp_process
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.export tcp_listen
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.export tcp_connect
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.export tcp_callback
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.export tcp_remote_ip
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.import ip_calc_cksum
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.import ip_send
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.import ip_create_packet
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.import ip_inp
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.import ip_outp
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.importzp ip_cksum_ptr
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.importzp ip_header_cksum
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.importzp ip_src
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.importzp ip_dest
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.importzp ip_data
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.importzp ip_proto
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.importzp ip_proto_tcp
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.importzp ip_id
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.importzp ip_len
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.import copymem
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.importzp copy_src
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.importzp copy_dest
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.import cfg_ip
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.segment "TCP_VARS"
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tcp_cxn_state_listening = 1 ;(waiting for an inbound SYN)
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tcp_cxn_state_syn_sent = 2 ;(waiting for an inbound SYN/ACK)
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; tcp packet offsets
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tcp_inp = ip_inp + ip_data ;pointer to tcp packet inside inbound ethernet frame
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tcp_outp = ip_outp + ip_data ;pointer to tcp packet inside outbound ethernet frame
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tcp_src_port = 0 ;offset of source port field in tcp packet
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tcp_dest_port = 2 ;offset of destination port field in tcp packet
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tcp_seq = 4 ;offset of sequence number field in tcp packet
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tcp_ack = 8 ;offset of acknowledgement field in tcp packet
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tcp_header_length = 12 ;offset of header length field in tcp packet
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tcp_flags_field = 13 ;offset of flags field in tcp packet
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tcp_window_size = 14 ; offset of window size field in tcp packet
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tcp_checksum = 16 ; offset of checksum field in tcp packet
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tcp_urgent_pointer = 18 ; offset of urgent pointer field in tcp packet
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tcp_data=20 ;offset of data in tcp packet
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; virtual header
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tcp_vh = tcp_outp - 12
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tcp_vh_src = 0
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tcp_vh_dest = 4
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tcp_vh_zero = 8
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tcp_vh_proto = 9
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tcp_vh_len = 10
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;
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tcp_flag_FIN =1
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tcp_flag_SYN =2
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tcp_flag_RST =4
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tcp_flag_PSH =8
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tcp_flag_ACK =16
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tcp_flag_URG =32
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.segment "TCP_VARS"
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tcp_state: .res 1
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tcp_local_port: .res 2
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tcp_remote_port: .res 2
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tcp_remote_ip: .res 4
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tcp_sequence_number: .res 4
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tcp_ack_number: .res 4
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tcp_data_ptr: .res 2
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tcp_data_len: .res 2
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tcp_callback: .res 2
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tcp_flags: .res 1
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.data
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tcp_client_port: .word $0004 ;=$0400 in network byte order
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.code
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tcp_init:
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rts
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;make outbound tcp connection
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;inputs:
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; tcp_remote_ip: destination ip address (4 bytes)
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; AX: destination port (2 bytes)
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; tcp_callback: vector to call when data arrives on this connection
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;outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_connect:
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stax tcp_remote_port
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inc tcp_client_port
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ldax tcp_client_port
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stax tcp_local_port
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lda #tcp_cxn_state_syn_sent
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sta tcp_state
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lda #tcp_flag_SYN
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sta tcp_flags
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ldax #0
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stax tcp_data_len
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stax tcp_ack_number
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stax tcp_ack_number+2
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jsr tcp_send_packet
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rts
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;send a single tcp packet
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;inputs:
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; tcp_remote_ip: IP address of destination server
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; tcp_remote_port: destination tcp port
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; tcp_local_port: source tcp port
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; tcp_flags: 6 bit flags
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; tcp_data_ptr: pointer to data to include in this packet
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; tcp_data_len: length of data pointed at by tcp_data_ptr
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;outputs:
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; carry flag is set if an error occured, clear otherwise
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tcp_send_packet:
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ldax tcp_data_ptr
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stax copy_src ; copy data to output buffer
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ldax #tcp_outp + tcp_data
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stax copy_dest
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ldax tcp_data_len
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jsr copymem
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ldx #3 ; copy virtual header addresses
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: lda tcp_remote_ip,x
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sta tcp_vh + tcp_vh_dest,x ; set virtual header destination
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lda cfg_ip,x
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sta tcp_vh + tcp_vh_src,x ; set virtual header source
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dex
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bpl :-
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lda tcp_local_port ; copy source port
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sta tcp_outp + tcp_src_port + 1
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lda tcp_local_port + 1
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sta tcp_outp + tcp_src_port
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lda tcp_remote_port ; copy destination port
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sta tcp_outp + tcp_dest_port + 1
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lda tcp_remote_port + 1
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sta tcp_outp + tcp_dest_port
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ldx #3 ; copy sequence and ack numbers (in reverse order)
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ldy #0
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: lda tcp_sequence_number,x
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sta tcp_outp + tcp_seq,y
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lda tcp_ack_number,x
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sta tcp_outp + tcp_ack,y
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iny
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dex
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bpl :-
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lda #$50 ;4 bit header length in 32bit words + 4 bits of zero
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sta tcp_outp+tcp_header_length
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lda tcp_flags
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sta tcp_outp+tcp_flags_field
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lda #ip_proto_tcp
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sta tcp_vh + tcp_vh_proto
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ldax #$1000
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stax tcp_outp+tcp_window_size
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lda #0 ; clear checksum
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sta tcp_outp + tcp_checksum
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sta tcp_outp + tcp_checksum + 1
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sta tcp_vh + tcp_vh_zero ; clear virtual header zero byte
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ldax #tcp_vh ; checksum pointer to virtual header
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stax ip_cksum_ptr
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lda tcp_data_len ; copy length + 20
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clc
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adc #20
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sta tcp_vh + tcp_vh_len + 1 ; lsb for virtual header
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tay
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lda tcp_data_len + 1
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adc #0
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sta tcp_vh + tcp_vh_len ; msb for virtual header
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tax ; length to A/X
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tya
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clc ; add 12 bytes for virtual header
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adc #12
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bcc :+
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inx
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:
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jsr ip_calc_cksum ; calculate checksum
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stax tcp_outp + tcp_checksum
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ldx #3 ; copy addresses
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: lda tcp_remote_ip,x
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sta ip_outp + ip_dest,x ; set ip destination address
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dex
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bpl :-
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jsr ip_create_packet ; create ip packet template
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lda tcp_outp + tcp_data_len + 1 ; ip len = tcp data length +20 byte ip header + 20 byte tcp header
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ldx tcp_outp + tcp_data_len
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clc
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adc #40
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bcc :+
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inx
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: sta ip_outp + ip_len + 1 ; set length
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stx ip_outp + ip_len
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ldax #$1234 ; set ID
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stax ip_outp + ip_id
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lda #ip_proto_tcp ; set protocol
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sta ip_outp + ip_proto
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jmp ip_send ; send packet, sec on error
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;listen on the tcp port specified
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; tcp_callback: vector to call when data arrives on specified port
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; AX: set to tcp port to listen on
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tcp_listen:
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rts
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tcp_process:
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;process incoming tcp packet
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;inputs:
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; eth_inp: should contain an ethernet frame encapsulating an inbound tcp packet
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;outputs:
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; carry flag set if any error occured (including if packet not part of
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; existing connection)
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; carry flag clear if no error
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; if connection was found, an outbound message may be created, overwriting eth_outp
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rts
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