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<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"/><link rel="stylesheet" type="text/css" href="ca65-doc-style.css"/></head><body><a href="ref_index.html"><h1>ip65 technical reference</h1></a><h1>File : ip65/xmodem.s</h1><pre> XMODEM file transfer
</pre><h2 id="functions">functions</h2><table><tr><th>function</th><th>description</th></tr><tr><td id="xmodem_receive">xmodem_receive</td><td><pre>recieve a file via XMODEM (checksum mode only, not CRC)
assumes that a tcp connection has already been set up, and that the other end is waiting to start sending
inputs: AX points to routine to call once for each byte in downloaded file (e.g. save to disk, print to screen, whatever) - byte will be in A
xmodem_iac_escape should be set to non-zero if the remote end escapes $FF bytes (i.e. if it is a real telnet server)
outputs: none
</pre></td></tr><tr><td id="xmodem_send">xmodem_send</td><td><pre>send a file via XMODEM (checksum mode only, not CRC)
assumes that a tcp connection has already been set up, and that the other end is waiting to start receiving
inputs: AX points to routine to call once for each byte in file to send (e.g. save to disk, print to screen, whatever) - byte will be in A, carry flag set means EOF
xmodem_iac_escape should be set to non-zero if the remote end escapes $FF bytes (i.e. if it is a real telnet server)
outputs: none
</pre></td></tr></table><h2 id="variables">variables</h2><table><tr><th>variable</th><th>description</th><th>size (bytes)</th></tr><tr><td id="xmodem_iac_escape">xmodem_iac_escape</td><td>are IAC bytes ($FF) escaped?
</td><td>1</td></tr></table><h2>implementation</h2><pre id="code">; XMODEM file transfer
.include "../inc/common.i"
.ifndef KPR_API_VERSION_NUMBER
.define EQU =
.include "../inc/kipper_constants.i"
.endif
XMODEM_BLOCK_SIZE=$80 ;how many bytes (excluding header & checksum) in each block?
XMODEM_TIMEOUT_SECONDS=5
XMODEM_MAX_ERRORS=10
SOH = $01
EOT = $04
ACK = $06
NAK = $15
CAN = $18
PAD = $1A ;padding added to end of file
.export xmodem_receive
.export xmodem_send
.export xmodem_iac_escape ;are IAC bytes ($FF) escaped?
.import ip65_process
.import ip65_error
.import tcp_callback
.import copymem
.importzp copy_src
.importzp copy_dest
.import tcp_send
.import tcp_send_data_len
.import tcp_inbound_data_ptr
.import tcp_inbound_data_length
.import check_for_abort_key
.import print_a
.import print_cr
.import print_ascii_as_native
.import print_hex
.import timer_seconds
.segment "SELF_MODIFIED_CODE"
got_byte:
jmp $ffff
get_byte:
jmp $ffff
next_char:
lda buffer_length
bne @not_eof
lda buffer_length+1
bne @not_eof
sec
rts
@not_eof:
next_char_ptr=*+1
lda $ffff
pha
inc next_char_ptr
bne :+
inc next_char_ptr+1
:
sec
lda buffer_length
sbc #1
sta buffer_length
lda buffer_length+1
sbc #0
sta buffer_length+1
pla
clc
rts
emit_a:
;put a byte to the output buffer
;if the byte is $FF, and xmodem_iac_escape is not zero, it is doubled
jsr @real_emit_a
cmp #$ff
bne exit_emit_a
ldx xmodem_iac_escape
beq exit_emit_a
@real_emit_a:
emit_a_ptr=*+1
sta $ffff
inc emit_a_ptr
bne :+
inc emit_a_ptr+1
:
inc xmodem_block_buffer_length
bne :+
inc xmodem_block_buffer_length+1
:
exit_emit_a:
rts
.bss
original_tcp_callback: .res 2
getc_timeout_end: .res 1
getc_timeout_seconds: .res 1
buffer_length: .res 2
.code
;send a file via XMODEM (checksum mode only, not CRC)
;assumes that a tcp connection has already been set up, and that the other end is waiting to start receiving
;inputs: AX points to routine to call once for each byte in file to send (e.g. save to disk, print to screen, whatever) - byte will be in A, carry flag set means EOF
; xmodem_iac_escape should be set to non-zero if the remote end escapes $FF bytes (i.e. if it is a real telnet server)
;outputs: none
xmodem_send:
stax get_byte+1
jsr xmodem_transfer_setup
lda #0
sta at_eof
@send_block:
ldax #sending
jsr print_ascii_as_native
ldax #block_number_msg
jsr print_ascii_as_native
lda expected_block_number
jsr print_hex
jsr print_cr
@wait_for_ack_or_nak:
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcs @synch_error
cmp #ACK
beq @got_ack
cmp #NAK
beq @got_nak
@synch_error:
pha
lda user_abort
beq @no_user_abort
pla
jmp xmodem_transfer_exit
@no_user_abort:
;flush the input buffer
lda #0
sta buffer_length
lda buffer_length+1
lda #'('
jsr print_a
pla
jsr print_hex
lda #')'
jsr print_a
inc error_number
ldax #sync_error_msg
jsr print_ascii_as_native
ldax #error_count_msg
jsr print_ascii_as_native
lda error_number
jsr print_hex
jsr print_cr
lda error_number
cmp #XMODEM_MAX_ERRORS
bcc @wait_for_ack_or_nak
lda #KPR_ERROR_TOO_MANY_ERRORS
sta ip65_error
jmp xmodem_transfer_exit
@got_ack:
inc expected_block_number
lda at_eof
bne @send_eot
@got_nak:
lda #0
sta checksum
sta xmodem_block_buffer_length
sta xmodem_block_buffer_length+1
ldax #xmodem_block_buffer
stax emit_a_ptr
lda #SOH
jsr emit_a
lda expected_block_number
jsr emit_a
eor #$ff
jsr emit_a
lda #$80
sta block_ptr
@copy_one_byte:
lda at_eof
bne @add_pad_byte
jsr get_byte
bcc @got_byte
;sec indicates EOF
lda block_ptr
cmp #$80 ;have we sent any data at all?
bne @add_pad_byte
@send_eot:
;if we get here, we should send an EOT, then read an ACK
ldax #1
stax tcp_send_data_len
ldax #eot_packet
jsr tcp_send
lda #XMODEM_TIMEOUT_SECONDS
jsr getc ;should be an ACK coming back, doesn't really matter if we don't see it though
jmp xmodem_transfer_exit
@add_pad_byte:
lda #PAD
@got_byte:
pha
clc
adc checksum
sta checksum
pla
jsr emit_a
dec block_ptr
bne @copy_one_byte
lda checksum
jsr emit_a
ldax xmodem_block_buffer_length
stax tcp_send_data_len
ldax #xmodem_block_buffer
jsr tcp_send
bcc @send_ok
ldax #send_error
jsr print_ascii_as_native
lda ip65_error
jsr print_hex
jsr print_cr
@send_ok:
jmp @send_block
rts
xmodem_transfer_setup:
lda #0
sta buffer_length
sta buffer_length+1
sta error_number
sta user_abort
lda #1
sta expected_block_number
ldax tcp_callback
stax original_tcp_callback
ldax #xmodem_tcp_callback
stax tcp_callback
rts
;recieve a file via XMODEM (checksum mode only, not CRC)
;assumes that a tcp connection has already been set up, and that the other end is waiting to start sending
;inputs: AX points to routine to call once for each byte in downloaded file (e.g. save to disk, print to screen, whatever) - byte will be in A
; xmodem_iac_escape should be set to non-zero if the remote end escapes $FF bytes (i.e. if it is a real telnet server)
;outputs: none
xmodem_receive:
stax got_byte+1
jsr xmodem_transfer_setup
jsr send_nak
@next_block:
lda #0
sta block_ptr
sta checksum
ldax #expecting
jsr print_ascii_as_native
ldax #block_number_msg
jsr print_ascii_as_native
lda expected_block_number
jsr print_hex
jsr print_cr
@wait_for_block_start:
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcc @got_block_start
lda user_abort
beq @no_user_abort
sec
jmp xmodem_transfer_exit
@no_user_abort:
jsr send_nak
inc error_number
ldax #timeout_msg
jsr print_ascii_as_native
ldax #error_count_msg
jsr print_ascii_as_native
lda error_number
jsr print_hex
jsr print_cr
lda error_number
cmp #XMODEM_MAX_ERRORS
bcc @wait_for_block_start
lda #KPR_ERROR_TOO_MANY_ERRORS
sta ip65_error
jmp xmodem_transfer_exit
@got_block_start:
cmp #EOT
bne :+
ldax #got_eot
jsr print_ascii_as_native
jsr send_ack
clc
jmp xmodem_transfer_exit
:
cmp #$81 ;jamming signal BBS seems to use $81 not $01 as SOH
beq @got_soh
cmp #SOH
beq @got_soh
lda #'!' ;we got an unexpected character
jsr print_a
jsr print_hex
;we need to clear the input buffer
@clear_input_buffer:
lda #'!' ;we got an unexpected character
jsr print_a
lda #1
jsr getc
bcc @clear_input_buffer
jmp @wait_for_block_start
@got_soh:
;now get block number
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcc :+
jsr send_nak
lda #'.'
jmp print_a
jmp @wait_for_block_start
:
sta actual_block_number
;now get block number check
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcc :+
lda #'.'
jmp print_a
jsr send_nak
jmp @wait_for_block_start
:
adc actual_block_number
cmp #$ff
beq :+
lda #'?'
jsr print_a
jmp @wait_for_block_start
:
ldax #receiving
jsr print_ascii_as_native
ldax #block_number_msg
jsr print_ascii_as_native
lda actual_block_number
jsr print_hex
jsr print_cr
@next_byte:
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcc :+
jmp xmodem_transfer_exit
:
ldx block_ptr
sta xmodem_block_buffer,x
adc checksum
sta checksum
inc block_ptr
lda block_ptr
bpl @next_byte
ldax #checksum_msg
jsr print_ascii_as_native
lda checksum
jsr print_hex
lda #'/'
jsr print_a
lda #XMODEM_TIMEOUT_SECONDS
jsr getc
bcs xmodem_transfer_exit
sta received_checksum
jsr print_hex
jsr print_cr
lda received_checksum
cmp checksum
beq @checksum_ok
;checksum error :-(
inc error_number
ldax #checksum_error_msg
jsr print_ascii_as_native
ldax #error_count_msg
jsr print_ascii_as_native
lda error_number
jsr print_hex
jsr print_cr
lda error_number
cmp #XMODEM_MAX_ERRORS
bcs :+
jmp @wait_for_block_start
:
lda #KPR_ERROR_TOO_MANY_ERRORS
sta ip65_error
jmp xmodem_transfer_exit
jsr send_nak
jmp @next_block
@checksum_ok:
lda expected_block_number
cmp actual_block_number
bne @skip_block_output
lda #0
sta block_ptr
@output_byte:
ldx block_ptr
lda xmodem_block_buffer,x
jsr got_byte
inc block_ptr
lda block_ptr
bpl @output_byte
inc expected_block_number
@skip_block_output:
jsr send_ack
jmp @next_block
clc
xmodem_transfer_exit:
ldax original_tcp_callback
stax tcp_callback
rts
xmodem_tcp_callback:
lda tcp_inbound_data_length+1
cmp #$ff
bne @not_eof
rts
@not_eof:
ldax tcp_inbound_data_ptr
stax copy_src
ldax #xmodem_stream_buffer
stax copy_dest
stax next_char_ptr
ldax tcp_inbound_data_length
stax buffer_length
jsr copymem
rts
send_nak:
ldax #1
stax tcp_send_data_len
ldax #nak_packet
jmp tcp_send
send_ack:
ldax #1
stax tcp_send_data_len
ldax #ack_packet
jmp tcp_send
getc:
jsr @real_getc
bcc :+ ;of we got an error, then bail
rts
:
cmp #$ff
beq @got_ff
clc
rts
@got_ff:
lda xmodem_iac_escape
bne @real_getc ;need to skip over the $FF and go read another byte
lda #$ff
clc
rts
@real_getc:
sta getc_timeout_seconds
clc
jsr timer_seconds ;time of day clock: seconds (in BCD)
sed
adc getc_timeout_seconds
cmp #$60
bcc @timeout_set
sec
sbc #$60
@timeout_set:
cld
sta getc_timeout_end
@poll_loop:
jsr next_char
bcs @no_char
rts ;done!
@no_char:
jsr check_for_abort_key
bcc @no_abort
lda #KPR_ERROR_ABORTED_BY_USER
sta ip65_error
inc user_abort
rts
@no_abort:
jsr ip65_process
jsr timer_seconds ;time of day clock: seconds
cmp getc_timeout_end
bne @poll_loop
lda #00
sec
rts
.rodata
ack_packet: .byte ACK
nak_packet: .byte NAK
eot_packet: .byte EOT
block_number_msg: .byte " block $",0
expecting: .byte "expecting",0
receiving: .byte "receiving",0
sending: .byte "sending",0
got_eot: .byte "end of transmission",10,0
bad_block_number: .byte "bad block number",0
checksum_msg: .byte "checksum $",0
checksum_error_msg : .byte "checksum",0
timeout_msg: .byte "timeout error",0
sync_error_msg: .byte "sync",0
error_count_msg: .byte " error - error count $",0
send_error: .byte " send error - $",0
.segment "APP_SCRATCH"
xmodem_stream_buffer: .res 1600
xmodem_block_buffer: .res 300
xmodem_block_buffer_length: .res 2
expected_block_number: .res 1
actual_block_number: .res 1
checksum: .res 1
received_checksum: .res 1
block_ptr: .res 1
error_number: .res 1
user_abort: .res 1
xmodem_iac_escape: .res 1
at_eof: .res 1
;-- LICENSE FOR xmodem.s --
; The contents of this file are subject to the Mozilla Public License
; Version 1.1 (the "License"); you may not use this file except in
; compliance with the License. You may obtain a copy of the License at
; http://www.mozilla.org/MPL/
;
; Software distributed under the License is distributed on an "AS IS"
; basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
; License for the specific language governing rights and limitations
; under the License.
;
; The Original Code is ip65.
;
; The Initial Developer of the Original Code is Jonno Downes,
; jonno@jamtronix.com.
; Portions created by the Initial Developer are Copyright (C) 2009
; Jonno Downes. All Rights Reserved.
; -- LICENSE END --
</pre></body></html>
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