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#lang racket/base
(require racket/list
(planet lizorkin/sxml:2:1/sxml)
(planet lizorkin/ssax:2:0/ssax)
"layer2.rkt")
(define logger (make-logger 'ebus-layer7 (current-logger)))
(define definition
(ssax:xml->sxml (open-input-file "../ebus-xml/ebus.xml")
'[(#f . "http://xapek.org/ebus/0.1")]))
(define (paket ebus-paket)
(define primaryCommand (layer2-ebus-paket-primaryCommand ebus-paket))
(define secondaryCommand (layer2-ebus-paket-secondaryCommand ebus-paket))
((sxpath (string-append "//packet[@primary=" (number->string primaryCommand)
" and @secondary=" (number->string secondaryCommand) "]"))
definition))
;; returns the full device-definition
(define (device address)
((sxpath (string-append "//devices/device[@address=" (number->string address) "]"))
definition))
;; returns device-name in a list or empty-list
(define (device-name address)
(first ((sxpath "@name/text()") (device address))))
(define (paket-fields ebus-paket)
(define paket-definition (paket ebus-paket))
(cond ((> (length paket-definition) 0)
(let*
([paket-name (string-append
(device-name (layer2-ebus-paket-source ebus-paket))
"."
(first ((sxpath "@name/text()") paket-definition)))]
[fields ((sxpath "fields/*") paket-definition)]
[values
(for/list ([field fields]) (paket-fields-dispatch-decoder ebus-paket field paket-name))])
;; filter invalid values
(for/list ([value values] #:when (not (void? value)))
value)))
(else (void (log-message logger 'warning (format "Unknown Paket: ~s" ebus-paket) #t)))))
(define (paket-fields-dispatch-decoder ebus-paket field paket-name)
(define datatype ((sxpath "name()") field))
(define name (string-append paket-name "." (first ((sxpath "@name/text()") field))))
(define offset (string->number (first ((sxpath "@offset/text()") field))))
(define payload (layer2-ebus-paket-payload ebus-paket))
(cond ((string=? "bit" datatype)
(list name datatype offset
(field-decoder-bit (list-ref payload offset))))
((string=? "bcd" datatype)
(list name datatype offset
(field-decoder-bcd (list-ref payload offset))))
((string=? "data1b" datatype)
(list name datatype offset
(field-decoder-data1b (list-ref payload offset))))
((string=? "data1c" datatype)
(list name datatype offset
(field-decoder-data1c (list-ref (layer2-ebus-paket-payload ebus-paket) offset))))
((string=? "byte" datatype)
(list name datatype offset (list-ref payload offset)))
((string=? "data2b" datatype)
(list name datatype offset
(field-decoder-data2b (list-ref payload offset)
(list-ref payload (+ offset 1)))))
((string=? "data2c" datatype)
(list name datatype offset
(field-decoder-data2c (list-ref payload offset)
(list-ref payload (+ offset 1)))))
((string=? "word" datatype)
(list name datatype offset
(field-decoder-word (list-ref payload offset)
(list-ref payload (+ offset 1)))))
((string=? "byteEnum" datatype)
(list name datatype offset
(field-decoder-byteEnum (list-ref payload offset) field)))
(else (void (log-message logger 'error (format "unknown datatype: ~a" datatype) #t)))))
;; type bit
(define (field-decoder-bit value)
(cond ((= value 1) 1)
(else 0)))
;; type data1b
(define (field-decoder-data1b value)
value)
;; type data1c
(define (field-decoder-data1c value)
(/ value 2.0))
;; type data2b
(define (field-decoder-data2b lowByte highByte)
(if (= (bitwise-and highByte 128) 128)
(* -1
(+ (+ 256 (bitwise-not highByte))
(/ (+ 256 (bitwise-not (+ lowByte 1))) 256.0)))
(+ highByte (/ lowByte 256.0))))
;; type data2c
(define (field-decoder-data2c lowByte highByte)
(define (lowNibble v)
(bitwise-and v #x0f))
(define (highNibble v)
(arithmetic-shift v -4))
(define (u-not v)
(+ 256 (bitwise-not v)))
(if (= (bitwise-and highByte 128) 128)
(* -1
(+ (* 16 (u-not highByte))
(highNibble (u-not lowByte))
(/ (lowNibble (u-not lowByte) 16))))
(+ (* 16 (u-not highByte))
(highNibble lowByte)
(/ (lowNibble lowByte) 16))))
;; type byteEnum
(define (field-decoder-byteEnum value field-definition)
(define (pred l)
(= value (list-ref l 0)))
(define all-options (for/list ([option ((sxpath "option") field-definition)])
(list (string->number (first ((sxpath "@value/text()") option))) ;; value, name
(first ((sxpath "@name/text()") option)))))
(define options (filter pred all-options))
(cond ((= (length options) 1)
(list-ref (first options) 1))
(else "<undefined>")))
;; type word
(define (field-decoder-word lowByte highByte)
(+ lowByte
(arithmetic-shift highByte 8)))
;; type bcd
(define (field-decoder-bcd value)
(+ (bitwise-and value #x0f)
(arithmetic-shift value -4)))
;; read one ebus-paket or eof from input-port
;; or return #<eof>
(define (read-ebus input-port)
(define paket (layer2-read-ebus input-port))
(cond ((layer2-ebus-paket? paket)
(paket-fields paket))
(else paket)))
(provide (prefix-out layer7- paket)
(prefix-out layer7- paket-fields)
(prefix-out layer7- device)
(prefix-out layer7- device-name)
;; read ebus from port an return fields from next paket
(prefix-out layer7- read-ebus)
(prefix-out layer7- logger))
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