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Avoid unnecessary timeout checks.

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On the Apple II the timer_read function is actually a delay function. Therefore we want to avoid calling it if we're busy processing incoming data. Fortunately timer_read is only necessary to trigger a TCP keep alive message. But if we're busy processing incoming data then we for sure need no TCP keep alive. So we simply mark if we just processed incoming data and skip the timeout check.
This commit is contained in:
Oliver Schmidt 2017-05-21 22:39:10 +02:00
parent 7586cc1651
commit 29587a1ebe
1 changed files with 17 additions and 12 deletions
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29
apps/telnet65.s
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@ -166,22 +166,27 @@ telnet_main_entry:
lda #0
sta connection_close_requested
sta connection_closed
sta data_received
sta iac_response_buffer_length
ldax #cursor_on
jsr print_vt100
@main_polling_loop:
jsr timer_read
txa
txa ; 1/1000 * 256 = ~ 1/4 seconds
adc #$20 ; 32 x 1/4 = ~ 8 seconds
sta telnet_timeout
@wait_for_keypress:
@check_timeout:
lda data_received
bne :+
jsr timer_read
cpx telnet_timeout
bne :+
jsr tcp_send_keep_alive
jmp @main_polling_loop
: jsr ip65_process
: lda #0
sta data_received
jsr ip65_process
lda connection_close_requested
beq :+
jsr tcp_close
@ -201,7 +206,7 @@ telnet_main_entry:
ldax #iac_response_buffer
jsr tcp_send
: jsr get_key_if_available
beq @wait_for_keypress
beq @check_timeout
ldx #0
stx tcp_send_data_len
stx tcp_send_data_len+1
@ -286,18 +291,17 @@ send_char:
; tcp callback - will be executed whenever data arrives on the TCP connection
telnet_callback:
lda tcp_inbound_data_length+1
cmp #$ff
bne :+
lda #1
ldx tcp_inbound_data_length+1
cpx #$ff
bne :+
sta connection_closed
rts
: ldax tcp_inbound_data_ptr
stax buffer_ptr
: sta data_received
lda tcp_inbound_data_length
sta buffer_length
lda tcp_inbound_data_length+1
sta buffer_length+1
stax buffer_length
ldax tcp_inbound_data_ptr
stax buffer_ptr
@next_byte:
ldy #0
@ -527,6 +531,7 @@ telnet_port: .res 2 ; port number to connect to
telnet_timeout: .res 1
connection_close_requested: .res 1
connection_closed: .res 1
data_received: .res 1
buffer_offset: .res 1
telnet_command: .res 1
telnet_option: .res 1