From b5b5dff0cbcd8163cda9af1d56113d912f61c673 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Sat, 15 Dec 2018 22:20:59 -0800
Subject: [PATCH] bitfield tests pass

---
 xenomorph/xenomorph/bitfield.rkt | 35 +++++++-------------------------
 1 file changed, 7 insertions(+), 28 deletions(-)

diff --git a/xenomorph/xenomorph/bitfield.rkt b/xenomorph/xenomorph/bitfield.rkt
index 4cd03728..3314654b 100644
--- a/xenomorph/xenomorph/bitfield.rkt
+++ b/xenomorph/xenomorph/bitfield.rkt
@@ -7,45 +7,24 @@ approximates
 https://github.com/mbutterick/restructure/blob/master/src/Bitfield.coffee
 |#
 
-#;(define/post-decode (xbitfield-decode xb [port-arg (current-input-port)] #:parent [parent #f])
-    (define port (->input-port port-arg))
-    (parameterize ([current-input-port port])
-      ))
-
-#;(define/pre-encode (xbitfield-encode xb flag-hash [port-arg (current-output-port)] #:parent [parent #f])
-    (define port (if (output-port? port-arg) port-arg (open-output-bytes)))
-    (parameterize ([current-output-port port])
-      
-      (unless port-arg (get-output-bytes port))))
-
-#;(define (xbitfield-size xb [val #f] #:parent [parent #f])
-    )
-
-#;(struct xbitfield xbase (type flags) #:transparent
-    #:methods gen:xenomorphic
-    [(define decode xbitfield-decode)
-     (define xdecode xbitfield-decode)
-     (define encode xbitfield-encode)
-     (define size xbitfield-size)])
-
 (define xbitfield%
   (class xenobase%
     (super-new)
     (init-field type flags)
 
-    (define flag-hash (mhasheq))
-
     (define/augment (xxdecode port parent)
+
+    (define flag-hash (mhasheq))
       (define val (send type xxdecode port))
-      (for ([(flag i) (in-indexed flags)]
+      (for ([(flag idx) (in-indexed flags)]
             #:when flag)
-           (hash-set! flag-hash flag (bitwise-bit-set? val i)))
+           (hash-set! flag-hash flag (bitwise-bit-set? val idx)))
       flag-hash)
 
-    (define/augment (xxencode array port [parent #f])
-      (define bit-int (for/sum ([(flag i) (in-indexed flags)]
+    (define/augment (xxencode flag-hash port [parent #f])
+      (define bit-int (for/sum ([(flag idx) (in-indexed flags)]
                                 #:when (and flag (dict-ref flag-hash flag #f)))
-                               (arithmetic-shift 1 i)))
+                               (arithmetic-shift 1 idx)))
       (send type xxencode bit-int port))
     
     (define/augment (xxsize [val #f] [parent #f])