295 lines
8.7 KiB
Plaintext
295 lines
8.7 KiB
Plaintext
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''*********************************************
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''* Full-Duplex Serial Driver v1.1 Extended *
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''* (C) 2006 Parallax, Inc. *
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''*********************************************
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CON
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buffer_length = 64 'can be 2, 4, 8, 16, 32, 64, 128, 256
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buffer_mask = buffer_length - 1
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VAR
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long cog 'cog flag/id
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long rx_head '9 contiguous longs
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long rx_tail
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long tx_head
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long tx_tail
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long rx_pin
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long tx_pin
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long rxtx_mode
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long bit_ticks
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long buffer_ptr
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byte rx_buffer[buffer_length] 'transmit and receive buffers
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byte tx_buffer[buffer_length]
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PUB start(rxpin, txpin, mode, baudrate) : okay
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'' Start serial driver - starts a cog
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'' returns false if no cog available
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''
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'' mode bit 0 = invert rx
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'' mode bit 1 = invert tx
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'' mode bit 2 = open-drain/source tx
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'' mode bit 3 = ignore tx echo on rx
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stop
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longfill(@rx_head, 0, 4)
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longmove(@rx_pin, @rxpin, 3)
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bit_ticks := clkfreq / baudrate
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buffer_ptr := @rx_buffer
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okay := cog := cognew(@entry, @rx_head) + 1
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PUB stop
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'' Stop serial driver - frees a cog
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if cog
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cogstop(cog~ - 1)
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longfill(@rx_head, 0, 9)
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PUB rxflush
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'' Flush receive buffer
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repeat while rxcheck => 0
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PUB rxcheck : rxbyte
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'' Check if byte received (never waits)
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'' returns -1 if no byte received, $00..$FF if byte
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rxbyte--
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if rx_tail <> rx_head
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rxbyte := rx_buffer[rx_tail]
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rx_tail := (rx_tail + 1) & buffer_mask
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PUB rxtime(ms) : rxbyte | t
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'' Wait ms milliseconds for a byte to be received
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'' returns -1 if no byte received, $00..$FF if byte
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t := cnt
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repeat until (rxbyte := rxcheck) => 0 or (cnt - t) / (clkfreq / 1000) > ms
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PUB rx : rxbyte
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'' Receive byte (may wait for byte)
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'' returns $00..$FF
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repeat while (rxbyte := rxcheck) < 0
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PUB tx(txbyte)
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'' Send byte (may wait for room in buffer)
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'Wait till there's space in the Tx buffer
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repeat until (tx_tail <> (tx_head + 1) & buffer_mask)
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tx_buffer[tx_head] := txbyte
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tx_head := (tx_head + 1) & buffer_mask
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if rxtx_mode & %1000
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rx
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PUB str(stringptr)
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'' Send string
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repeat strsize(stringptr)
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tx(byte[stringptr++])
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PUB dec(value) | i
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'' Print a decimal number
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if value < 0
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-value
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tx("-")
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i := 1_000_000_000
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repeat 10
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if value => i
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tx(value / i + "0")
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value //= i
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result~~
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elseif result or i == 1
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tx("0")
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i /= 10
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PUB hex(value, digits)
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'' Print a hexadecimal number
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value <<= (8 - digits) << 2
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repeat digits
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tx(lookupz((value <-= 4) & $F : "0".."9", "A".."F"))
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PUB bin(value, digits)
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'' Print a binary number
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value <<= 32 - digits
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repeat digits
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tx((value <-= 1) & 1 + "0")
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DAT
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'***********************************
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'* Assembly language serial driver *
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'***********************************
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org
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'
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'
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' Entry
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'
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entry mov t1,par 'get structure address
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add t1,#4 << 2 'skip past heads and tails
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rdlong t2,t1 'get rx_pin
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mov rxmask,#1
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shl rxmask,t2
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add t1,#4 'get tx_pin
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rdlong t2,t1
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mov txmask,#1
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shl txmask,t2
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add t1,#4 'get rxtx_mode
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rdlong rxtxmode,t1
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add t1,#4 'get bit_ticks
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rdlong bitticks,t1
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add t1,#4 'get buffer_ptr ...
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rdlong rxbuff,t1 '... for the receiver
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mov txbuff,rxbuff '... and the transmitter
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add txbuff,#buffer_length
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test rxtxmode,#%100 wz 'if_nz = open drain Tx
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test rxtxmode,#%010 wc 'if_c = inverted output
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if_z_ne_c or outa,txmask
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if_z or dira,txmask
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mov txcode,#transmit 'initialize ping-pong multitasking
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'
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'
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' Receive
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'
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receive jmpret rxcode,txcode 'run a chunk of transmit code, then return
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test rxtxmode,#%001 wz 'wait for start bit on rx pin
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test rxmask,ina wc
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if_z_eq_c jmp #receive
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mov rxbits,#9 'ready to receive byte
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mov rxcnt,bitticks
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shr rxcnt,#1 'half a bit tick
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add rxcnt,cnt '+ the current clock
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:bit add rxcnt,bitticks 'ready for the middle of the bit period
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:wait jmpret rxcode,txcode 'run a chuck of transmit code, then return
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mov t1,rxcnt 'check if bit receive period done
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sub t1,cnt
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cmps t1,#0 wc
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if_nc jmp #:wait
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test rxmask,ina wc 'receive bit on rx pin into carry
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rcr rxdata,#1 'shift carry into receiver
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djnz rxbits,#:bit 'go get another bit till done
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test rxtxmode,#%001 wz 'find out if rx is inverted
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if_z_ne_c jmp #receive 'abort if no stop bit
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shr rxdata,#32-9 'justify and trim received byte
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and rxdata,#$FF
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if_nz xor rxdata,#$FF 'if rx inverted, invert byte
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rdlong t2,par 'rx_head
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add t2,rxbuff 'plus the buffer offset
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wrbyte rxdata,t2 'write the byte
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sub t2,rxbuff
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add t2,#1 'update rx_head
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and t2,#buffer_mask
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wrlong t2,par 'and save
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jmp #receive 'byte done, receive next byte
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'
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'
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' Transmit
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'
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transmit jmpret txcode,rxcode 'run a chunk of receive code, then return
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mov t1,par 'check for head <> tail
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add t1,#2 << 2 'tx_head
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rdlong t2,t1
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add t1,#1 << 2 'tx_tail
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rdlong t3,t1
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cmp t2,t3 wz
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if_z jmp #transmit
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add t3,txbuff 'get byte and inc tail
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rdbyte txdata,t3
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sub t3,txbuff
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add t3,#1
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and t3,#buffer_mask
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wrlong t3,t1
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or txdata,#$100 'or in a stop bit
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shl txdata,#2
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or txdata,#1 'or in a idle line state and a start bit
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mov txbits,#11
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mov txcnt,cnt
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:bit test rxtxmode,#%100 wz 'output bit on tx pin according to mode
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test rxtxmode,#%010 wc
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if_z_and_c xor txdata,#1
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shr txdata,#1 wc
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if_z muxc outa,txmask
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if_nz muxnc dira,txmask
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add txcnt,bitticks 'ready next cnt
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:wait jmpret txcode,rxcode 'run a chunk of receive code, then return
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mov t1,txcnt 'check if bit transmit period done
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sub t1,cnt
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cmps t1,#0 wc
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if_nc jmp #:wait
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djnz txbits,#:bit 'another bit to transmit?
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jmp #transmit 'byte done, transmit next byte
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'
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'
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' Uninitialized data
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'
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t1 res 1
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t2 res 1
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t3 res 1
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rxtxmode res 1
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bitticks res 1
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rxmask res 1
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rxbuff res 1
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rxdata res 1
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rxbits res 1
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rxcnt res 1
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rxcode res 1
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txmask res 1
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txbuff res 1
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txdata res 1
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txbits res 1
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txcnt res 1
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txcode res 1
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