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333 lines
6.9 KiB
ArmAsm
333 lines
6.9 KiB
ArmAsm
;UDP (user datagram protocol) functions
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.include "../inc/common.i"
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;.import dbg_dump_udp_header
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.export udp_init
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.export udp_process
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.export udp_add_listener
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.export udp_remove_listener
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.export udp_send
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.export udp_callback
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.export udp_inp
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.export udp_outp
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.exportzp udp_src_port
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.exportzp udp_dest_port
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.exportzp udp_len
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.exportzp udp_cksum
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.exportzp udp_data
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.export udp_send_dest
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.export udp_send_src_port
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.export udp_send_dest_port
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.export udp_send_len
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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_udp
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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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.bss
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; argument for udp_add_listener
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udp_callback: .res 2 ;vector to routine to be called when a udp packet arrives
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; arguments for udp_send
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udp_send_dest: .res 4 ;set to ip address that udp packet will be sent to
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udp_send_src_port: .res 2 ;set to port that udp packet will be sent from
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udp_send_dest_port: .res 2 ;set to port that udp packet will be sent to
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udp_send_len: .res 2 ;set to length of data to be sent in udp packet (excluding ethernet,ip & udp headers)
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; udp listener callbacks
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udp_cbmax = 4
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udp_cbtmp: .res 3 ; temporary vector
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udp_cbveclo: .res udp_cbmax ; table of listener vectors (lsb)
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udp_cbvechi: .res udp_cbmax ; table of listener vectors (msb)
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udp_cbportlo: .res udp_cbmax ; table of ports (lsb)
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udp_cbporthi: .res udp_cbmax ; table of ports (msb)
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udp_cbcount: .res 1 ; number of active listeners
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; udp packet offsets
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udp_inp = ip_inp + ip_data ;pointer to udp packet inside inbound ethernet frame
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udp_outp = ip_outp + ip_data ;pointer to udp packet inside outbound ethernet frame
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udp_src_port = 0 ;offset of source port field in udp packet
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udp_dest_port = 2 ;offset of destination port field in udp packet
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udp_len = 4 ;offset of length field in udp packet
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udp_cksum = 6 ;offset of checksum field in udp packet
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udp_data = 8 ;offset of data in udp packet
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; virtual header
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udp_vh = udp_outp - 12
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udp_vh_src = 0
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udp_vh_dest = 4
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udp_vh_zero = 8
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udp_vh_proto = 9
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udp_vh_len = 10
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; temp for port comparison
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port: .res 2
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.code
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; initialize udp
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; inputs: none
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; outputs: none
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udp_init:
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lda #0
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sta udp_cbcount
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lda #$4c ; jmp addr
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sta udp_cbtmp
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rts
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;process incoming udp packet
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;inputs:
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; eth_inp: should contain an ethernet frame encapsulating an inbound udp packet
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;outputs:
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; carry flag set if any error occured (including if no handler for specified port
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; was found)
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; carry flag clear if no error
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; if handler was found, an outbound message may be created, overwriting eth_outp
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udp_process:
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lda udp_cbcount ; any installed udp listeners?
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beq @drop
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tax ; check ports
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dex
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@checkport:
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lda udp_cbportlo,x
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cmp udp_inp + udp_dest_port + 1
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bne :+
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lda udp_cbporthi,x
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cmp udp_inp + udp_dest_port
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beq @handle
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: dex
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bpl @checkport
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@drop:
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sec
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rts
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@handle:
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lda udp_cbveclo,x ; copy vector
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sta udp_cbtmp + 1
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lda udp_cbvechi,x
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sta udp_cbtmp + 2
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jsr udp_cbtmp ; call listener
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clc
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rts
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;add a udp listener
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;inputs:
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; udp_callback: vector to call when udp packet arrives on specified port
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; AX: set to udp port to listen on
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;outputs:
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; carry flag set if too may listeners already installed, clear otherwise
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udp_add_listener:
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sta port
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stx port + 1
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ldy udp_cbcount ; any listeners at all?
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beq @add
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cpy #udp_cbmax ; max?
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beq @full
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ldy #0
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@check:
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lda udp_cbportlo,y ; check if port is already handled
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cmp port
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bne :+
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lda udp_cbporthi,y
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cmp port + 1
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beq @busy
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: iny
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cpy udp_cbcount
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bne @check
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@add:
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inc udp_cbcount ; increase counter
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sta udp_cbportlo,y ; add port
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txa
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sta udp_cbporthi,y ; add port
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lda udp_callback ; and vector
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sta udp_cbveclo,y
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lda udp_callback + 1
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sta udp_cbvechi,y
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clc
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rts
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@full:
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@busy:
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sec
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rts
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; remove an udp listener
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; inputs:
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; AX = port to stop listening on
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; outputs:
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; carry flag clear of handler found and removed
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; carry flag set if handler for specified port not found
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udp_remove_listener:
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sta port
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stx port + 1
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ldy udp_cbcount ; any listeners installed?
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beq @notfound
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@check:
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lda udp_cbportlo,y ; check if port is handled
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cmp port
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bne :+
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lda udp_cbporthi,y
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cmp port + 1
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beq @remove
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: iny
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cpy udp_cbcount
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bne @check
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@notfound:
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sec
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rts
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@remove:
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tya ; number of listeners below
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eor #$ff
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clc
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adc udp_cbcount
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beq @done
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@move:
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tax ; number of items to move
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: lda udp_cbportlo + 1,y ; move ports
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sta udp_cbportlo,y
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lda udp_cbporthi + 1,y
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sta udp_cbporthi,y
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lda udp_cbveclo + 1,y ; move vectors
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sta udp_cbveclo,y
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lda udp_cbvechi + 1,y
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sta udp_cbvechi,y
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iny
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dex
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bne :-
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@done:
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dec udp_cbcount ; decrement counter
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clc
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rts
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;send udp packet
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;inputs:
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; udp_send_dest: destination ip address (4 bytes)
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; udp_send_dest_port: destination port (2 bytes)
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; udp_send_src_port: source port (2 bytes)
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; udp_send_len: length of data to send (exclusive of any headers)
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; AX: pointer to buffer containing data to be sent
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;outputs:
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; carry flag is set if an error occured, clear otherwise
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udp_send:
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stax copy_src ; copy data to output buffer
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ldax #udp_outp + udp_data
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stax copy_dest
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ldax udp_send_len
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jsr copymem
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ldx #3 ; copy virtual header addresses
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: lda udp_send_dest,x
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sta udp_vh + udp_vh_dest,x ; set virtual header destination
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lda cfg_ip,x
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sta udp_vh + udp_vh_src,x ; set virtual header source
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dex
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bpl :-
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lda udp_send_src_port ; copy source port
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sta udp_outp + udp_src_port + 1
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lda udp_send_src_port + 1
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sta udp_outp + udp_src_port
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lda udp_send_dest_port ; copy destination port
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sta udp_outp + udp_dest_port + 1
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lda udp_send_dest_port + 1
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sta udp_outp + udp_dest_port
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lda #ip_proto_udp
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sta udp_vh + udp_vh_proto
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lda #0 ; clear checksum
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sta udp_outp + udp_cksum
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sta udp_outp + udp_cksum + 1
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sta udp_vh + udp_vh_zero ; clear virtual header zero byte
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ldax #udp_vh ; checksum pointer to virtual header
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stax ip_cksum_ptr
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lda udp_send_len ; copy length + 8
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clc
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adc #8
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sta udp_outp + udp_len + 1 ; lsb for udp header
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sta udp_vh + udp_vh_len + 1 ; lsb for virtual header
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tay
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lda udp_send_len + 1
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adc #0
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sta udp_outp + udp_len ; msb for udp header
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sta udp_vh + udp_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 udp_outp + udp_cksum
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ldx #3 ; copy addresses
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: lda udp_send_dest,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 udp_outp + udp_len + 1 ; ip len = udp len + 20
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ldx udp_outp + udp_len
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clc
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adc #20
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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_udp ; set protocol
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sta ip_outp + ip_proto
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;jsr dbg_dump_udp_header
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jmp ip_send ; send packet, sec on error
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