201 lines
4.4 KiB
ArmAsm
201 lines
4.4 KiB
ArmAsm
; Simple Network Time Protocol implementation - per RFC 2030
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MAX_SNTP_MESSAGES_SENT = 8
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.include "../inc/common.inc"
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.include "../inc/error.inc"
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.export sntp_ip
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.export sntp_utc_timestamp
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.export sntp_get_time
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.import ip65_process
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.import ip65_error
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.import udp_add_listener
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.import udp_remove_listener
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.import udp_callback
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.import udp_send
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.import udp_inp
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.import output_buffer
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.importzp udp_data
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.import udp_send_dest
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.import udp_send_src_port
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.import udp_send_dest_port
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.import udp_send_len
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.import check_for_abort_key
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.import timer_read
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.data
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sntp_ip: .byte $ff,$ff,$ff,$ff ; can be set to ip address of server that will be queried via sntp (default is a local LAN broadcast)
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.bss
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; sntp packet offsets
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sntp_inp = udp_inp + udp_data
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sntp_server_port = 123
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sntp_client_port = 123
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sntp_utc_timestamp: .res 4 ; will be set to seconds (only) part of utc timestamp (seconds since 00:00 on Jan 1, 1900)
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; sntp state machine
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sntp_initializing = 1 ; initial state
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sntp_query_sent = 2 ; sent a query, waiting for a response
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sntp_completed = 3 ; got a good response
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sntp_timer: .res 1
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sntp_loop_count: .res 1
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sntp_break_polling_loop: .res 1
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sntp_state: .res 1
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sntp_message_sent_count: .res 1
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.code
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; query an sntp server for current UTC time
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; inputs:
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; sntp_ip must point to an SNTP server
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; outputs:
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; carry flag is set if there was an error, clear otherwise
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; sntp_utc_timestamp: set to the number of seconds (seconds since 00:00 on Jan 1, 1900) - timezone is UTC
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sntp_get_time:
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ldax #sntp_in
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stax udp_callback
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ldax #sntp_client_port
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jsr udp_add_listener
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bcc :+
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rts
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: lda #sntp_initializing
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sta sntp_state
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lda #0 ; reset the "message sent" counter
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sta sntp_message_sent_count
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jsr send_sntp_query
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@sntp_polling_loop:
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lda sntp_message_sent_count
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adc #10
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sta sntp_loop_count
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@outer_delay_loop:
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lda #0
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sta sntp_break_polling_loop
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jsr timer_read
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stx sntp_timer ; we only care about the high byte
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@inner_delay_loop:
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jsr ip65_process
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jsr check_for_abort_key
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bcc @no_abort
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lda #IP65_ERROR_ABORTED_BY_USER
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sta ip65_error
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rts
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@no_abort:
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lda sntp_state
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cmp #sntp_completed
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beq @complete
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lda sntp_break_polling_loop
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bne @break_polling_loop
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jsr timer_read
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cpx sntp_timer ; this will tick over after about 1/4 of a second
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beq @inner_delay_loop
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dec sntp_loop_count
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bne @outer_delay_loop
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@break_polling_loop:
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jsr send_sntp_query
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inc sntp_message_sent_count
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lda sntp_message_sent_count
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cmp #MAX_SNTP_MESSAGES_SENT-1
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bpl @too_many_messages_sent
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jmp @sntp_polling_loop
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@complete:
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ldax #sntp_client_port
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jsr udp_remove_listener
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rts
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@too_many_messages_sent:
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@failed:
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ldax #sntp_client_port
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jsr udp_remove_listener
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lda #IP65_ERROR_TIMEOUT_ON_RECEIVE
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sta ip65_error
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sec ; signal an error
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rts
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send_sntp_query:
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; make a zero filled buffer
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lda #$0
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ldx #$30
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stx udp_send_len
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sta udp_send_len+1
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: sta output_buffer,x
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dex
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bpl :-
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; set the flags field
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lda #$E3 ; flags - LI=11 (unknown), VN=100 (4), MODE=011 (client)
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sta output_buffer
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ldax #sntp_client_port
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stax udp_send_src_port
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ldax #sntp_server_port
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stax udp_send_dest_port
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ldx #3 ; set destination address
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: lda sntp_ip,x
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sta udp_send_dest,x
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dex
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bpl :-
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ldax #output_buffer
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jsr udp_send
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bcs @error_on_send
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lda #sntp_query_sent
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sta sntp_state
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@error_on_send:
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rts
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sntp_in:
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ldx #3
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ldy #0
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: lda sntp_inp+$28,x ; the 'transmit' timestamp (in big end order)
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sta sntp_utc_timestamp,y
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iny
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dex
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bpl :-
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inc sntp_break_polling_loop
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lda #sntp_completed
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sta sntp_state
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rts
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; -- LICENSE FOR sntp.s --
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; The contents of this file are subject to the Mozilla Public License
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; Version 1.1 (the "License"); you may not use this file except in
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; compliance with the License. You may obtain a copy of the License at
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; http://www.mozilla.org/MPL/
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;
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; Software distributed under the License is distributed on an "AS IS"
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; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
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; License for the specific language governing rights and limitations
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; under the License.
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;
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; The Original Code is ip65.
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;
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; The Initial Developer of the Original Code is Jonno Downes,
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; jonno@jamtronix.com.
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; Portions created by the Initial Developer are Copyright (C) 2009,2011
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; Jonno Downes. All Rights Reserved.
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; -- LICENSE END --
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