Basic/source/BasicSerial.spin

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2014-05-18 19:57:12 +02:00
''*********************************************
''* Full-Duplex Serial Driver v1.1 Extended *
''* (C) 2006 Parallax, Inc. *
''*********************************************
CON
buffer_length = 64 'can be 2, 4, 8, 16, 32, 64, 128, 256
buffer_mask = buffer_length - 1
VAR
long cog 'cog flag/id
long rx_head '9 contiguous longs
long rx_tail
long tx_head
long tx_tail
long rx_pin
long tx_pin
long rxtx_mode
long bit_ticks
long buffer_ptr
byte rx_buffer[buffer_length] 'transmit and receive buffers
byte tx_buffer[buffer_length]
PUB start(rxpin, txpin, mode, baudrate) : okay
'' Start serial driver - starts a cog
'' returns false if no cog available
''
'' mode bit 0 = invert rx
'' mode bit 1 = invert tx
'' mode bit 2 = open-drain/source tx
'' mode bit 3 = ignore tx echo on rx
stop
longfill(@rx_head, 0, 4)
longmove(@rx_pin, @rxpin, 3)
bit_ticks := clkfreq / baudrate
buffer_ptr := @rx_buffer
okay := cog := cognew(@entry, @rx_head) + 1
PUB stop
'' Stop serial driver - frees a cog
if cog
cogstop(cog~ - 1)
longfill(@rx_head, 0, 9)
PUB rxflush
'' Flush receive buffer
repeat while rxcheck => 0
PUB rxcheck : rxbyte
'' Check if byte received (never waits)
'' returns -1 if no byte received, $00..$FF if byte
rxbyte--
if rx_tail <> rx_head
rxbyte := rx_buffer[rx_tail]
rx_tail := (rx_tail + 1) & buffer_mask
PUB rxtime(ms) : rxbyte | t
'' Wait ms milliseconds for a byte to be received
'' returns -1 if no byte received, $00..$FF if byte
t := cnt
repeat until (rxbyte := rxcheck) => 0 or (cnt - t) / (clkfreq / 1000) > ms
PUB rx : rxbyte
'' Receive byte (may wait for byte)
'' returns $00..$FF
repeat while (rxbyte := rxcheck) < 0
PUB tx(txbyte)
'' Send byte (may wait for room in buffer)
'Wait till there's space in the Tx buffer
repeat until (tx_tail <> (tx_head + 1) & buffer_mask)
tx_buffer[tx_head] := txbyte
tx_head := (tx_head + 1) & buffer_mask
if rxtx_mode & %1000
rx
PUB str(stringptr)
'' Send string
repeat strsize(stringptr)
tx(byte[stringptr++])
PUB dec(value) | i
'' Print a decimal number
if value < 0
-value
tx("-")
i := 1_000_000_000
repeat 10
if value => i
tx(value / i + "0")
value //= i
result~~
elseif result or i == 1
tx("0")
i /= 10
PUB hex(value, digits)
'' Print a hexadecimal number
value <<= (8 - digits) << 2
repeat digits
tx(lookupz((value <-= 4) & $F : "0".."9", "A".."F"))
PUB bin(value, digits)
'' Print a binary number
value <<= 32 - digits
repeat digits
tx((value <-= 1) & 1 + "0")
DAT
'***********************************
'* Assembly language serial driver *
'***********************************
org
'
'
' Entry
'
entry mov t1,par 'get structure address
add t1,#4 << 2 'skip past heads and tails
rdlong t2,t1 'get rx_pin
mov rxmask,#1
shl rxmask,t2
add t1,#4 'get tx_pin
rdlong t2,t1
mov txmask,#1
shl txmask,t2
add t1,#4 'get rxtx_mode
rdlong rxtxmode,t1
add t1,#4 'get bit_ticks
rdlong bitticks,t1
add t1,#4 'get buffer_ptr ...
rdlong rxbuff,t1 '... for the receiver
mov txbuff,rxbuff '... and the transmitter
add txbuff,#buffer_length
test rxtxmode,#%100 wz 'if_nz = open drain Tx
test rxtxmode,#%010 wc 'if_c = inverted output
if_z_ne_c or outa,txmask
if_z or dira,txmask
mov txcode,#transmit 'initialize ping-pong multitasking
'
'
' Receive
'
receive jmpret rxcode,txcode 'run a chunk of transmit code, then return
test rxtxmode,#%001 wz 'wait for start bit on rx pin
test rxmask,ina wc
if_z_eq_c jmp #receive
mov rxbits,#9 'ready to receive byte
mov rxcnt,bitticks
shr rxcnt,#1 'half a bit tick
add rxcnt,cnt '+ the current clock
:bit add rxcnt,bitticks 'ready for the middle of the bit period
:wait jmpret rxcode,txcode 'run a chuck of transmit code, then return
mov t1,rxcnt 'check if bit receive period done
sub t1,cnt
cmps t1,#0 wc
if_nc jmp #:wait
test rxmask,ina wc 'receive bit on rx pin into carry
rcr rxdata,#1 'shift carry into receiver
djnz rxbits,#:bit 'go get another bit till done
test rxtxmode,#%001 wz 'find out if rx is inverted
if_z_ne_c jmp #receive 'abort if no stop bit
shr rxdata,#32-9 'justify and trim received byte
and rxdata,#$FF
if_nz xor rxdata,#$FF 'if rx inverted, invert byte
rdlong t2,par 'rx_head
add t2,rxbuff 'plus the buffer offset
wrbyte rxdata,t2 'write the byte
sub t2,rxbuff
add t2,#1 'update rx_head
and t2,#buffer_mask
wrlong t2,par 'and save
jmp #receive 'byte done, receive next byte
'
'
' Transmit
'
transmit jmpret txcode,rxcode 'run a chunk of receive code, then return
mov t1,par 'check for head <> tail
add t1,#2 << 2 'tx_head
rdlong t2,t1
add t1,#1 << 2 'tx_tail
rdlong t3,t1
cmp t2,t3 wz
if_z jmp #transmit
add t3,txbuff 'get byte and inc tail
rdbyte txdata,t3
sub t3,txbuff
add t3,#1
and t3,#buffer_mask
wrlong t3,t1
or txdata,#$100 'or in a stop bit
shl txdata,#2
or txdata,#1 'or in a idle line state and a start bit
mov txbits,#11
mov txcnt,cnt
:bit test rxtxmode,#%100 wz 'output bit on tx pin according to mode
test rxtxmode,#%010 wc
if_z_and_c xor txdata,#1
shr txdata,#1 wc
if_z muxc outa,txmask
if_nz muxnc dira,txmask
add txcnt,bitticks 'ready next cnt
:wait jmpret txcode,rxcode 'run a chunk of receive code, then return
mov t1,txcnt 'check if bit transmit period done
sub t1,cnt
cmps t1,#0 wc
if_nc jmp #:wait
djnz txbits,#:bit 'another bit to transmit?
jmp #transmit 'byte done, transmit next byte
'
'
' Uninitialized data
'
t1 res 1
t2 res 1
t3 res 1
rxtxmode res 1
bitticks res 1
rxmask res 1
rxbuff res 1
rxdata res 1
rxbits res 1
rxcnt res 1
rxcode res 1
txmask res 1
txbuff res 1
txdata res 1
txbits res 1
txcnt res 1
txcode res 1