diff --git a/whalesong/selfhost/base64.rkt b/whalesong/selfhost/base64.rkt
new file mode 100644
index 0000000..fc79bd6
--- /dev/null
+++ b/whalesong/selfhost/base64.rkt
@@ -0,0 +1,74 @@
+#lang whalesong
+(require whalesong/lang/for)
+
+; Implements http://en.wikipedia.org/wiki/Base64
+
+(provide base64-encode) ; string -> string
+
+(define (bytes-ref bs i)
+  (define c (string-ref bs i))
+  (char->integer c))
+
+(define (string->bytes s)
+  (for/list ([c (in-string s)])
+    (char->integer c)))
+
+; 
+(define ranges '(["AZ" 0]    ;  0 to 25
+                 ["az" 26]   ; 16 to 51
+                 ["09" 52]   ; 52 to 61
+                 ["++" 62]   ; 62 
+                 ["//" 63])) ; 63
+
+; > (vector-ref base64-digit (char->integer #\A)) 
+; 0
+; > (vector-ref digit-base64 0) 
+; 65 (which is #\A)
+
+(define-values (base64-digit digit-base64)
+  (let ([bd (make-vector 256 #f)] 
+        [db (make-vector 64 #f)]) 
+    (for ([r ranges] #:when #t
+                     [i (in-range (bytes-ref (car r) 0) (add1 (bytes-ref (car r) 1)))]
+                     [n (in-naturals (cadr r))])
+      (vector-set! bd i n)
+      (vector-set! db n i))
+    (values bd db)))
+
+(define (3bytes->24bit a b c)
+  ; convert 3 bytes into  a single 24 bit number
+  (+ (* a 65536) (* b 256) c))
+
+(define (24bit->base64 n)
+  ; convert a 24 bit number into base 64
+  (define a  (remainder n      64))
+  (define n1 (quotient  n      64))
+  (define b  (remainder n1     64))
+  (define n2 (quotient  n1     64))
+  (define c  (remainder n2     64))
+  (define d  (quotient  n2     64))
+  (list d c b a))
+
+(define =byte (bytes-ref "=" 0))
+
+(define (base64-encode s)
+  (define sn (string-length s))
+  (define (encode s)
+    (define n sn)
+    (define ds
+      (for/list ([i (in-range 0 n 3)])
+        (define a (bytes-ref s i))
+        (define b (bytes-ref s (+ i 1)))
+        (define c (bytes-ref s (+ i 2)))
+        (for/list ([digit (24bit->base64 (3bytes->24bit a b c))])
+          (integer->char (vector-ref digit-base64 digit)))))
+    (define padding  (case (remainder sn 3) [(0) 0]   [(1) 2]              [(2) 1]))
+    (define padding= (case (remainder sn 3) [(0) '()] [(1) (list #\= #\=)] [(2) (list #\=)]))
+    (define ds* (apply append ds))
+    (list->string (reverse (append padding= (drop (reverse ds*) padding)))))
+
+  (case (remainder sn 3)
+    [(0) (encode s)]
+    [(1) (encode (string-append s (string (integer->char 0) (integer->char 0))))]
+    [(2) (encode (string-append s (string (integer->char 0))))]))
+
diff --git a/whalesong/selfhost/js-assembler/assemble-structs.rkt b/whalesong/selfhost/js-assembler/assemble-structs.rkt
new file mode 100644
index 0000000..124baa7
--- /dev/null
+++ b/whalesong/selfhost/js-assembler/assemble-structs.rkt
@@ -0,0 +1,21 @@
+#lang whalesong (require "../selfhost-lang.rkt")
+; #lang typed/racket/base
+
+(provide (all-defined-out))
+
+
+(require "../compiler/il-structs.rkt")
+
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Assembly
+
+(define-struct: BasicBlock ([name : Symbol] 
+                            [stmts : (Listof UnlabeledStatement)]) 
+  #:transparent)
+
+
+
+;; Represents a hashtable from symbols to basic blocks
+(define-type Blockht (HashTable Symbol BasicBlock))
diff --git a/whalesong/selfhost/selfhost-lang.rkt b/whalesong/selfhost/selfhost-lang.rkt
index c2d0145..ea68ba6 100644
--- a/whalesong/selfhost/selfhost-lang.rkt
+++ b/whalesong/selfhost/selfhost-lang.rkt
@@ -15,6 +15,7 @@
          path?
          sort
          natural?
+         vector-copy
          ; no-ops
          :
          log-debug
@@ -73,4 +74,15 @@
 
 (define (log-debug . _) (void))
 
-(define (natural? o) (and (number? o) (integer? o) (not (negative? o))))
\ No newline at end of file
+(define (natural? o) (and (number? o) (integer? o) (not (negative? o))))
+
+(require whalesong/lang/for)
+
+(define (vector-copy vec [start 0] [end (vector-length vec)])
+  (define n (- end start))
+  (define v (make-vector n #\space))
+  (for ([i (in-range start end)]
+        [j (in-range 0 n)])
+    (vector-set! v j (vector-ref vec i)))
+  v)
+