emailler/client/ip65/udp.s

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;UDP (user datagram protocol) functions
.include "../inc/common.i"
.ifndef NB65_API_VERSION_NUMBER
.define EQU =
.include "../inc/nb65_constants.i"
.endif
;.import dbg_dump_udp_header
.import ip65_error
.export udp_init
.export udp_process
.export udp_add_listener
.export udp_remove_listener
.export udp_send
.export udp_callback
.export udp_inp
.export udp_outp
.exportzp udp_src_port
.exportzp udp_dest_port
.exportzp udp_len
.exportzp udp_cksum
.exportzp udp_data
.export udp_send_dest
.export udp_send_src_port
.export udp_send_dest_port
.export udp_send_len
.import ip_calc_cksum
.import ip_send
.import ip_create_packet
.import ip_inp
.import ip_outp
.importzp ip_cksum_ptr
.importzp ip_header_cksum
.importzp ip_src
.importzp ip_dest
.importzp ip_data
.importzp ip_proto
.importzp ip_proto_udp
.importzp ip_id
.importzp ip_len
.import copymem
.importzp copy_src
.importzp copy_dest
.import cfg_ip
.bss
; argument for udp_add_listener
udp_callback: .res 2 ;vector to routine to be called when a udp packet arrives
; arguments for udp_send
udp_send_dest: .res 4 ;set to ip address that udp packet will be sent to
udp_send_src_port: .res 2 ;set to port that udp packet will be sent from
udp_send_dest_port: .res 2 ;set to port that udp packet will be sent to
udp_send_len: .res 2 ;set to length of data to be sent in udp packet (excluding ethernet,ip & udp headers)
; udp listener callbacks
udp_cbmax = 4
udp_cbtmp: .res 3 ; temporary vector
udp_cbveclo: .res udp_cbmax ; table of listener vectors (lsb)
udp_cbvechi: .res udp_cbmax ; table of listener vectors (msb)
udp_cbportlo: .res udp_cbmax ; table of ports (lsb)
udp_cbporthi: .res udp_cbmax ; table of ports (msb)
udp_cbcount: .res 1 ; number of active listeners
; udp packet offsets
udp_inp = ip_inp + ip_data ;pointer to udp packet inside inbound ethernet frame
udp_outp = ip_outp + ip_data ;pointer to udp packet inside outbound ethernet frame
udp_src_port = 0 ;offset of source port field in udp packet
udp_dest_port = 2 ;offset of destination port field in udp packet
udp_len = 4 ;offset of length field in udp packet
udp_cksum = 6 ;offset of checksum field in udp packet
udp_data = 8 ;offset of data in udp packet
; virtual header
udp_vh = udp_outp - 12
udp_vh_src = 0
udp_vh_dest = 4
udp_vh_zero = 8
udp_vh_proto = 9
udp_vh_len = 10
; temp for port comparison
port: .res 2
.code
; initialize udp
; inputs: none
; outputs: none
udp_init:
lda #0
sta udp_cbcount
lda #$4c ; jmp addr
sta udp_cbtmp
rts
;process incoming udp packet
;inputs:
; eth_inp: should contain an ethernet frame encapsulating an inbound udp packet
;outputs:
; carry flag set if any error occured (including if no handler for specified port
; was found)
; carry flag clear if no error
; if handler was found, an outbound message may be created, overwriting eth_outp
udp_process:
lda udp_cbcount ; any installed udp listeners?
beq @drop
tax ; check ports
dex
@checkport:
lda udp_cbportlo,x
cmp udp_inp + udp_dest_port + 1
bne :+
lda udp_cbporthi,x
cmp udp_inp + udp_dest_port
beq @handle
: dex
bpl @checkport
@drop:
lda #NB65_ERROR_NO_SUCH_LISTENER
sta ip65_error
sec
rts
@handle:
lda udp_cbveclo,x ; copy vector
sta udp_cbtmp + 1
lda udp_cbvechi,x
sta udp_cbtmp + 2
jsr udp_cbtmp ; call listener
clc
rts
;add a udp listener
;inputs:
; udp_callback: vector to call when udp packet arrives on specified port
; AX: set to udp port to listen on
;outputs:
; carry flag set if too may listeners already installed, clear otherwise
udp_add_listener:
sta port
stx port + 1
ldy udp_cbcount ; any listeners at all?
beq @add
cpy #udp_cbmax ; max?
beq @full
ldy #0
@check:
lda udp_cbportlo,y ; check if port is already handled
cmp port
bne :+
lda udp_cbporthi,y
cmp port + 1
beq @busy
: iny
cpy udp_cbcount
bne @check
@add:
inc udp_cbcount ; increase counter
sta udp_cbportlo,y ; add port
txa
sta udp_cbporthi,y ; add port
lda udp_callback ; and vector
sta udp_cbveclo,y
lda udp_callback + 1
sta udp_cbvechi,y
clc
rts
@full:
@busy:
lda #NB65_ERROR_LISTENER_NOT_AVAILABLE
sta ip65_error
sec
sec
rts
; remove an udp listener
; inputs:
; AX = port to stop listening on
; outputs:
; carry flag clear of handler found and removed
; carry flag set if handler for specified port not found
udp_remove_listener:
sta port
stx port + 1
ldy udp_cbcount ; any listeners installed?
beq @notfound
@check:
lda udp_cbportlo,y ; check if port is handled
cmp port
bne :+
lda udp_cbporthi,y
cmp port + 1
beq @remove
: iny
cpy udp_cbcount
bne @check
@notfound:
sec
rts
@remove:
tya ; number of listeners below
eor #$ff
clc
adc udp_cbcount
beq @done
@move:
tax ; number of items to move
: lda udp_cbportlo + 1,y ; move ports
sta udp_cbportlo,y
lda udp_cbporthi + 1,y
sta udp_cbporthi,y
lda udp_cbveclo + 1,y ; move vectors
sta udp_cbveclo,y
lda udp_cbvechi + 1,y
sta udp_cbvechi,y
iny
dex
bne :-
@done:
dec udp_cbcount ; decrement counter
clc
rts
;send udp packet
;inputs:
; udp_send_dest: destination ip address (4 bytes)
; udp_send_dest_port: destination port (2 bytes)
; udp_send_src_port: source port (2 bytes)
; udp_send_len: length of data to send (exclusive of any headers)
; AX: pointer to buffer containing data to be sent
;outputs:
; carry flag is set if an error occured, clear otherwise
udp_send:
stax copy_src ; copy data to output buffer
ldax #udp_outp + udp_data
stax copy_dest
ldax udp_send_len
jsr copymem
ldx #3 ; copy virtual header addresses
: lda udp_send_dest,x
sta udp_vh + udp_vh_dest,x ; set virtual header destination
lda cfg_ip,x
sta udp_vh + udp_vh_src,x ; set virtual header source
dex
bpl :-
lda udp_send_src_port ; copy source port
sta udp_outp + udp_src_port + 1
lda udp_send_src_port + 1
sta udp_outp + udp_src_port
lda udp_send_dest_port ; copy destination port
sta udp_outp + udp_dest_port + 1
lda udp_send_dest_port + 1
sta udp_outp + udp_dest_port
lda #ip_proto_udp
sta udp_vh + udp_vh_proto
lda #0 ; clear checksum
sta udp_outp + udp_cksum
sta udp_outp + udp_cksum + 1
sta udp_vh + udp_vh_zero ; clear virtual header zero byte
ldax #udp_vh ; checksum pointer to virtual header
stax ip_cksum_ptr
lda udp_send_len ; copy length + 8
clc
adc #8
sta udp_outp + udp_len + 1 ; lsb for udp header
sta udp_vh + udp_vh_len + 1 ; lsb for virtual header
tay
lda udp_send_len + 1
adc #0
sta udp_outp + udp_len ; msb for udp header
sta udp_vh + udp_vh_len ; msb for virtual header
tax ; length to A/X
tya
clc ; add 12 bytes for virtual header
adc #12
bcc :+
inx
:
jsr ip_calc_cksum ; calculate checksum
stax udp_outp + udp_cksum
ldx #3 ; copy addresses
: lda udp_send_dest,x
sta ip_outp + ip_dest,x ; set ip destination address
dex
bpl :-
jsr ip_create_packet ; create ip packet template
lda udp_outp + udp_len + 1 ; ip len = udp len + 20
ldx udp_outp + udp_len
clc
adc #20
bcc :+
inx
: sta ip_outp + ip_len + 1 ; set length
stx ip_outp + ip_len
ldax #$1234 ; set ID
stax ip_outp + ip_id
lda #ip_proto_udp ; set protocol
sta ip_outp + ip_proto
;jsr dbg_dump_udp_header
jmp ip_send ; send packet, sec on error