diff --git a/pitfall/fontkit/font.rkt b/pitfall/fontkit/font.rkt
index 53a3b16e..802aaa88 100644
--- a/pitfall/fontkit/font.rkt
+++ b/pitfall/fontkit/font.rkt
@@ -35,9 +35,9 @@ https://github.com/mbutterick/fontkit/blob/master/src/TTFFont.js
     (define table-decoder (hash-ref table-decoders table-tag
                                     (λ () (raise-argument-error '_decodeTable "decodable table" table-tag))))
     (define offset (· (hash-ref (· directory tables) table-tag) offset))
-    (define length (· (hash-ref (· directory tables) table-tag) length))
-    (set-port-position! stream offset)
-    (send table-decoder decode (make-object RDecodeStream stream) this length))
+    (define len (· (hash-ref (· directory tables) table-tag) length))
+    (set-port-position! stream 0)
+    (send table-decoder decode (make-object RDecodeStream (peek-bytes len offset stream)) this length))
 
   (define/public (_decodeDirectory)
     (set! directory (directory-decode stream (mhash '_startOffset 0)))
diff --git a/pitfall/fontkit/loca.rkt b/pitfall/fontkit/loca.rkt
index fb5c02c2..54651f2c 100644
--- a/pitfall/fontkit/loca.rkt
+++ b/pitfall/fontkit/loca.rkt
@@ -2,7 +2,9 @@
 (require restructure)
 (provide (all-defined-out))
 
-(define short-style 0)
+(define 16bit-style 0)
+(define 32bit-style 1)
+(define max-32-bit-value #xffff)
 
 #|
 approximates
@@ -13,10 +15,24 @@ https://github.com/mbutterick/fontkit/blob/master/src/tables/loca.js
   (define/override (process res stream)
     ;; in `restructure` `process` method, `res` is aliased as `this`
     ;; 
-    (when (= short-style (· res version))
-      ;; in a short-style loca table, actual offset values are divided by 2 (to fit into 16 bits)
+    (when (= 16bit-style (· res version))
+      ;; in a 16bits-style loca table, actual 32bit offset values are divided by 2 (to fit into 16 bits)
       ;; so we re-inflate them.
-      (hash-update! res 'offsets (λ (offsets) (map (curry * 2) offsets))))))
+      (hash-update! res 'offsets (λ (offsets) (map (curry * 2) offsets)))))
+
+  (define/override (preEncode this-val stream)
+    ;; this = val to be encoded
+    (loca-preEncode this-val stream)))
+
+;; make "static method"
+(define (loca-preEncode this-val . args)
+  ;; this = val to be encoded
+  (unless (hash-has-key? this-val 'version)
+    (hash-set! this-val 'version (if (> (last (· this-val offsets)) max-32-bit-value)
+                                     32bit-style
+                                     16bit-style))
+    (when (= 16bit-style (· this-val version))
+      (hash-update! this-val 'offsets (λ (offsets) (map (curryr / 2) offsets))))))
 
 (define loca (make-object Rloca
                (λ (parent) (hash-ref (send parent _getTable 'head) 'indexToLocFormat)) 
diff --git a/pitfall/fontkit/subset.rkt b/pitfall/fontkit/subset.rkt
index 0848f905..2df6b7cd 100644
--- a/pitfall/fontkit/subset.rkt
+++ b/pitfall/fontkit/subset.rkt
@@ -1,5 +1,5 @@
 #lang fontkit/racket
-(require "clone.rkt" "ttfglyphencoder.rkt")
+(require "clone.rkt" "ttfglyphencoder.rkt" "loca.rkt")
 (provide Subset CFFSubset TTFSubset)
 
 #|
@@ -70,20 +70,20 @@ https://github.com/mbutterick/fontkit/blob/master/src/subset/TTFSubset.js
        (send this _addGlyph gid))
 
   (define maxp (cloneDeep (send (· this font) _getTable 'maxp)))
-  (hash-set! maxp 'numGlyphs (length (· this glyf))) ; todo
+  (hash-set! maxp 'numGlyphs (length (· this glyf)))
 
-  ;; todo
-  (report 'boing)
-  (report (send (· this font) _getTable 'loca) 'offsets)
-  #;(hash-update! (report (send (· this font) _getTable 'loca)) 'offsets (λ (val) (push-end! val (· this offset))))
-  ;; Tables.loca.preEncode.call(this.loca);
+  ;; populate the new loca table
+  (hash-update! (· this loca) 'offsets (λ (vals) (append vals (list (· this offset)))))
+  (loca-preEncode (· this loca))
 
-  #;(define head (cloneDeep (send (· this font) _getTable 'head)))
-  ;;    head.indexToLocFormat = this.loca.version; ; todo
-
-  #;(define hhea (cloneDeep (send (· this font) _getTable 'hhea)))
-  ;; hhea.numberOfMetrics = this.hmtx.metrics.length;
+  (define head (cloneDeep (send (· this font) _getTable 'head)))
+  (hash-set! head 'indexToLocFormat (· this loca version))
+  
+  (define hhea (cloneDeep (send (· this font) _getTable 'hhea)))
+  (hash-set! hhea 'numberOfMetrics (length (· this hmtx metrics)))
 
+  ;; todo: final encoding of directory, with all tables.
+  
   (unfinished)
   )
 
diff --git a/pitfall/restructure/array.rkt b/pitfall/restructure/array.rkt
index 41595e1e..fd1117ec 100644
--- a/pitfall/restructure/array.rkt
+++ b/pitfall/restructure/array.rkt
@@ -10,10 +10,16 @@ https://github.com/mbutterick/restructure/blob/master/src/Array.coffee
 (define-subclass RStreamcoder (RArray type [length #f] [lengthType 'count])
           
   (define/augment (decode stream [parent #f])
-    (let ([length (if length
-                      (resolveLength length stream parent)
+    (let ([length (cond
+                    [length
+                      (resolveLength length stream parent)]
+                    [else
+                     (define num (send stream length))
+                     (define denom (send type size))
+                     (unless (andmap (λ (x) (and x (number? x))) (list num denom))
+                       (raise-argument-error 'RArray:decode "valid length and size" (list num denom)))
                       ;; implied length: length of stream divided by size of item
-                      (report* (send stream length) (send type size) (floor (/ (send stream length) (send type size)))))])
+                      (floor (/ (send stream length) (send type size)))])])
     
       (caseq lengthType
              [(count) (for/list ([i (in-range length)])
diff --git a/pitfall/restructure/decodestream.rkt b/pitfall/restructure/decodestream.rkt
index 83aff5ad..d50a3385 100644
--- a/pitfall/restructure/decodestream.rkt
+++ b/pitfall/restructure/decodestream.rkt
@@ -27,14 +27,13 @@ https://github.com/mbutterick/restructure/blob/master/src/DecodeStream.coffee
                                (values (string->symbol (format "~a~a" key endian)) value))))
 
 ;; basically just a wrapper for a Racket port
-(define-subclass object% (RDecodeStream [buffer-in #f])
-  (field [_port (cond
-                  [(not buffer-in) (open-input-bytes (bytes))]
-                  [(bytes? buffer-in) (open-input-bytes buffer-in)]
-                  [(input-port? buffer-in) buffer-in]
-                  [else (raise-argument-error 'RDecodeStream "bytes or input port" buffer-in)])])
+;; but needs to start with a buffer so length can be found
+(define-subclass object% (RDecodeStream [buffer #""])
+  (field [_port (if (bytes? buffer)
+                    (open-input-bytes buffer)
+                    (raise-argument-error 'RDecodeStream "bytes" buffer))])
   (getter-field [pos (port-position _port)])
-  (getter-field [length (and (bytes? buffer-in) (bytes-length buffer-in))])
+  (getter-field [length (bytes-length buffer)])
 
   (define/public (read count)
     (read-bytes-exact count _port)))
\ No newline at end of file
diff --git a/pitfall/restructure/helper.rkt b/pitfall/restructure/helper.rkt
index 99098b58..291e88e1 100644
--- a/pitfall/restructure/helper.rkt
+++ b/pitfall/restructure/helper.rkt
@@ -9,6 +9,8 @@
     (abstract encode)
     (define/public (process . args)
       (void))
+    (define/public (preEncode . args)
+      (void))
     #;(abstract size)))
 
 
diff --git a/pitfall/restructure/streamcoder.rkt b/pitfall/restructure/streamcoder.rkt
index 8d0e8c3b..eab72303 100644
--- a/pitfall/restructure/streamcoder.rkt
+++ b/pitfall/restructure/streamcoder.rkt
@@ -8,7 +8,6 @@
     (let loop ([x x])
       (cond
         [(bytes? x) (loop (open-input-bytes x))]
-        [(input-port? x) (loop (make-object RDecodeStream x))]
         [(is-a? x RDecodeStream) (inner (void) decode x . args)]
         [else (raise-argument-error 'decode "item that can become RDecodeStream" x)])))
 
diff --git a/pitfall/restructure/struct.rkt b/pitfall/restructure/struct.rkt
index 3db94a1e..6f96a5f8 100644
--- a/pitfall/restructure/struct.rkt
+++ b/pitfall/restructure/struct.rkt
@@ -13,7 +13,7 @@ https://github.com/mbutterick/restructure/blob/master/src/Struct.coffee
   (for ([(k v) (in-dict assocs)])
        (hash-set! fields k v))
 
-  (define/public (make-key-index! [fields assocs])
+  (define/public-final (make-key-index! [fields assocs])
     (set! key-index (map car fields)))
   (make-key-index!)
   
@@ -25,6 +25,7 @@ https://github.com/mbutterick/restructure/blob/master/src/Struct.coffee
     res)
 
   (define/override (encode stream val [parent #f])
+    (send this preEncode val stream)
     (for ([key (in-list key-index)])
          (send (hash-ref fields key) encode stream (hash-ref val key))))
 
diff --git a/pitfall/restructure/versioned-struct.rkt b/pitfall/restructure/versioned-struct.rkt
index 7c091ab0..6bd27d20 100644
--- a/pitfall/restructure/versioned-struct.rkt
+++ b/pitfall/restructure/versioned-struct.rkt
@@ -1,4 +1,4 @@
-#lang restructure/racket
+ #lang restructure/racket
 (require racket/dict "struct.rkt")
 (provide (all-defined-out))
 
@@ -8,11 +8,10 @@ https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
 |#
 
 (define-subclass RStruct (RVersionedStruct type [versions (dictify)])
-
   (define/override (decode stream [parent #f] [length 0] #:version [maybe-version #f])
     (define res (send this _setup stream parent length))
     (define version (cond
-                      [maybe-version]
+                      [maybe-version] ; for testing purposes: pass an explicit version
                       [(procedure? type) (type parent)]
                       [(is-a? type RBase) (send type decode stream)]
                       [else (raise-argument-error 'decode "way of finding version" type)]))
@@ -24,6 +23,4 @@ https://github.com/mbutterick/restructure/blob/master/src/VersionedStruct.coffee
       [else
        (send this _parseFields stream res fields)
        (send this process res stream)
-       res]))
-
- )
\ No newline at end of file
+       res])))
\ No newline at end of file