From 494ed088e84b92af85d2f7260d242b06615fab69 Mon Sep 17 00:00:00 2001
From: Yves Fischer <yvesf-git@xapek.org>
Date: Tue, 28 Feb 2012 22:38:10 +0100
Subject: ebus-racket: layer7: parse bit,data1b,data2b

---
 ebus-racket/layer7.rkt | 60 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 7 deletions(-)

(limited to 'ebus-racket/layer7.rkt')

diff --git a/ebus-racket/layer7.rkt b/ebus-racket/layer7.rkt
index 5b8f496..8f8f39e 100644
--- a/ebus-racket/layer7.rkt
+++ b/ebus-racket/layer7.rkt
@@ -1,16 +1,19 @@
 #lang racket
-(require (planet lizorkin/sxml:2:1/sxml))
-(require (planet lizorkin/ssax:2:0/ssax))
+(require (planet lizorkin/sxml:2:1/sxml)
+         (planet lizorkin/ssax:2:0/ssax)
+         "layer2.rkt")
 
 (define definition
   (ssax:xml->sxml (open-input-file "../ebus-xml/ebus.xml")
                   '[(#f . "http://xapek.org/ebus/0.1")]))
 
 
-(define (ebus-paket primaryCommand secondaryCommand)
-  ((sxpath (string-append "//packet[@primary=" (number->string primaryCommand)
-                          " and @secondary=" (number->string secondaryCommand) "]"))
-           definition))
+(define (paket ebus-paket)
+  (let ([primaryCommand (layer2-ebus-paket-primaryCommand ebus-paket)]
+        [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)
@@ -21,6 +24,49 @@
 (define (device-name address)
   ((sxpath "@name/text()") (device address)))
 
-(provide (prefix-out layer7- ebus-paket)
+
+(define (paket-fields ebus-paket)
+  (let* ([paket-definition (paket ebus-paket)]
+         [paket-name (first ((sxpath "@name/text()") paket-definition))]
+         [fields ((sxpath "fields/*") paket-definition)]
+         [values (for/list ([field fields])
+                        (let ([datatype ((sxpath "name()") field)]
+                              [name (string-append paket-name "." (first ((sxpath "@name/text()") field)))]
+                              [offset (string->number (first ((sxpath "@offset/text()") field)))])
+                          (cond ((string=? "bit" datatype)
+                                 (list name datatype offset
+                                       (field-decoder-bit (list-ref (layer2-ebus-paket-payload ebus-paket) offset))))
+                                ((string=? "data1b" datatype)
+                                 (list name datatype offset
+                                       (field-decoder-data1b (list-ref (layer2-ebus-paket-payload ebus-paket) offset))))
+                                ((string=? "data2b" datatype)
+                                 (list name datatype offset
+                                       (field-decoder-data2b (list-ref (layer2-ebus-paket-payload ebus-paket) offset)
+                                                             (list-ref (layer2-ebus-paket-payload ebus-paket) (+ offset 1)))))
+                                (else (display (string-append "unknown datatype: " datatype))
+                                      (void)))
+                          ))])
+    ; filter invalid values
+    (for/list ([value values] #:when (not (void? value)))
+      value)))
+  
+;; type bit
+(define (field-decoder-bit value)
+  (cond ((= value 1) 1)
+        (else 0)))
+
+;; type data1b
+(define (field-decoder-data1b value)
+  value)
+
+;; type data2b
+(define (field-decoder-data2b lowByte highByte)
+  (cond ((= (bitwise-and highByte 128) 128)
+         (* -1 (+ (+ 256 (bitwise-not highByte))
+                  (/ (+ 256 (bitwise-not (+ lowByte 1))) 256.0))))
+         (else (+ highByte (/ lowByte 256.0)))))
+
+(provide (prefix-out layer7- paket)
+         (prefix-out layer7- paket-fields)
          (prefix-out layer7- device)
          (prefix-out layer7- device-name))
\ No newline at end of file
-- 
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