upscheme/scheme-core/compiler.scm

(define Instructions
  (let ((e (table))
        (keys
         [nop dup pop call tcall jmp brf brt jmp.l brf.l brt.l ret

          eq? eqv? equal? atom? not null? boolean? symbol?
          number? bound? pair? builtin? vector? fixnum? function?

          cons list car cdr set-car! set-cdr!
          apply

          + - * / div0 = < compare

          vector aref aset!

          loadt loadf loadnil load0 load1 loadi8
          loadv loadv.l
          loadg loadg.l
          loada loada.l loadc loadc.l
          setg setg.l
          seta seta.l setc setc.l

          closure argc vargc trycatch for tapply
          add2 sub2 neg largc lvargc
          loada0 loada1 loadc00 loadc01 call.l tcall.l
          brne brne.l cadr brnn brnn.l brn brn.l
          optargs brbound keyargs

          dummy_t dummy_f dummy_nil]))
    (for 0 (1- (length keys))
         (lambda (i)
           (put! e (aref keys i) i)))))

(define arg-counts
  (table eq?      2      eqv?     2
         equal?   2      atom?    1
         not      1      null?    1
         boolean? 1      symbol?  1
         number?  1      bound?   1
         pair?    1      builtin? 1
         vector?  1      fixnum?  1
         cons     2      car      1
         cdr      1      set-car! 2
         set-cdr! 2      =        2
         <        2      compare  2
         aref     2      aset!    3
         div0     2))

(define (make-code-emitter) (vector () (table) 0 +inf.0))
(define (bcode:code   b) (aref b 0))
(define (bcode:ctable b) (aref b 1))
(define (bcode:nconst b) (aref b 2))
(define (bcode:cdepth b d) (aset! b 3 (min (aref b 3) d)))
; get an index for a referenced value in a bytecode object
(define (bcode:indexfor b v)
  (let ((const-to-idx (bcode:ctable b))
        (nconst       (bcode:nconst b)))
    (if (has? const-to-idx v)
        (get const-to-idx v)
        (begin (put! const-to-idx v nconst)
               (prog1 nconst
                      (aset! b 2 (+ nconst 1)))))))
(define (emit e inst . args)
  (if (null? args)
      (if (and (eq? inst 'car) (pair? (aref e 0))
               (eq? (car (aref e 0)) 'cdr))
          (set-car! (aref e 0) 'cadr)
          (aset! e 0 (cons inst (aref e 0))))
      (begin
        (if (memq inst '(loadv loadg setg))
            (set! args (list (bcode:indexfor e (car args)))))
        (let ((longform
               (assq inst '((loadv loadv.l) (loadg loadg.l) (setg setg.l)
                            (loada loada.l) (seta  seta.l)))))
          (if (and longform
                   (> (car args) 255))
              (set! inst (cadr longform))))
        (let ((longform
               (assq inst '((loadc loadc.l) (setc setc.l)))))
          (if (and longform
                   (or (> (car  args) 255)
                       (> (cadr args) 255)))
              (set! inst (cadr longform))))
        (if (eq? inst 'loada)
            (cond ((equal? args '(0))
                   (set! inst 'loada0)
                   (set! args ()))
                  ((equal? args '(1))
                   (set! inst 'loada1)
                   (set! args ()))))
        (if (eq? inst 'loadc)
            (cond ((equal? args '(0 0))
                   (set! inst 'loadc00)
                   (set! args ()))
                  ((equal? args '(0 1))
                   (set! inst 'loadc01)
                   (set! args ()))))

        (let ((lasti (if (pair? (aref e 0))
                         (car (aref e 0)) ()))
              (bc (aref e 0)))
          (cond ((and
                  (eq? inst 'brf)
                  (cond ((and (eq? lasti 'not)
                              (eq? (cadr bc) 'null?))
                         (aset! e 0 (cons (car args) (cons 'brn (cddr bc)))))
                        ((eq? lasti 'not)
                         (aset! e 0 (cons (car args) (cons 'brt (cdr bc)))))
                        ((eq? lasti 'eq?)
                         (aset! e 0 (cons (car args) (cons 'brne (cdr bc)))))
                        ((eq? lasti 'null?)
                         (aset! e 0 (cons (car args) (cons 'brnn (cdr bc)))))
                        (else #f))))
                ((and (eq? inst 'brt) (eq? lasti 'null?))
                 (aset! e 0 (cons (car args) (cons 'brn (cdr bc)))))
                (else
                 (aset! e 0 (nreconc (cons inst args) bc)))))))
  e)

(define (make-label e)   (gensym))
(define (mark-label e l) (emit e 'label l))

; convert symbolic bytecode representation to a byte array.
; labels are fixed-up.
(define (encode-byte-code e)
  (let* ((cl (reverse! e))
         (v  (list->vector cl))
         (long? (>= (+ (length v)  ; 1 byte for each entry, plus...
                       ; at most half the entries in this vector can be
                       ; instructions accepting 32-bit arguments
                       (* 3 (div0 (length v) 2)))
                    65536)))
    (let ((n              (length v))
          (i              0)
          (label-to-loc   (table))
          (fixup-to-label (table))
          (bcode          (buffer))
          (vi             #f)
          (nxt            #f))
      (io.write bcode #int32(0))
      (while (< i n)
        (begin
          (set! vi (aref v i))
          (if (eq? vi 'label)
              (begin (put! label-to-loc (aref v (+ i 1)) (sizeof bcode))
                     (set! i (+ i 2)))
              (begin
                (io.write bcode
                          (byte
                           (get Instructions
                                (if long?
                                    (case vi
                                      (jmp  'jmp.l)
                                      (brt  'brt.l)
                                      (brf  'brf.l)
                                      (brne 'brne.l)
                                      (brnn 'brnn.l)
                                      (brn  'brn.l)
                                      (else vi))
                                    vi))))
                (set! i (+ i 1))
                (set! nxt (if (< i n) (aref v i) #f))
                (cond ((memq vi '(jmp brf brt brne brnn brn))
                       (put! fixup-to-label (sizeof bcode) nxt)
                       (io.write bcode ((if long? int32 int16) 0))
                       (set! i (+ i 1)))
                      ((eq? vi 'brbound)
                       (io.write bcode (int32 nxt))
                       (set! i (+ i 1)))
                      ((number? nxt)
                       (case vi
                         ((loadv.l loadg.l setg.l loada.l seta.l
                           largc lvargc call.l tcall.l)
                          (io.write bcode (int32 nxt))
                          (set! i (+ i 1)))

                         ((loadc setc)  ; 2 uint8 args
                          (io.write bcode (uint8 nxt))
                          (set! i (+ i 1))
                          (io.write bcode (uint8 (aref v i)))
                          (set! i (+ i 1)))

                         ((loadc.l setc.l optargs keyargs)  ; 2 int32 args
                          (io.write bcode (int32 nxt))
                          (set! i (+ i 1))
                          (io.write bcode (int32 (aref v i)))
                          (set! i (+ i 1))
                          (if (eq? vi 'keyargs)
                              (begin (io.write bcode (int32 (aref v i)))
                                     (set! i (+ i 1)))))

                         (else
                          ; other number arguments are always uint8
                          (io.write bcode (uint8 nxt))
                          (set! i (+ i 1)))))
                      (else #f))))))

      (table.foreach
       (lambda (addr labl)
         (begin (io.seek bcode addr)
                (io.write bcode ((if long? int32 int16)
                                 (- (get label-to-loc labl)
                                    addr)))))
       fixup-to-label)
      (io.tostring! bcode))))

(define (const-to-idx-vec e)
  (let ((cvec (vector.alloc (bcode:nconst e))))
    (table.foreach (lambda (val idx) (aset! cvec idx val))
                   (bcode:ctable e))
    cvec))

(define (index-of item lst start)
  (cond ((null? lst) #f)
        ((eq? item (car lst)) start)
        (else (index-of item (cdr lst) (+ start 1)))))

(define (in-env? s env)
  (and (pair? env)
       (or (memq s (car env))
           (in-env? s (cdr env)))))

(define (lookup-sym s env lev arg?)
  (if (null? env)
      '(global)
      (let* ((curr (car env))
             (i    (index-of s curr 0)))
        (if i
            (if arg?
                i
                (cons lev i))
            (lookup-sym s
                        (cdr env)
                        (if (or arg? (null? curr)) lev (+ lev 1))
                        #f)))))

; number of non-nulls
(define (nnn e) (count (lambda (x) (not (null? x))) e))

(define (printable? x) (not (or (iostream? x)
                                (eof-object? x))))

(define (compile-sym g env s Is)
  (let ((loc (lookup-sym s env 0 #t)))
    (cond ((number? loc)
           (emit g (aref Is 0) loc))
          ((number? (car loc))
           (emit g (aref Is 1) (car loc) (cdr loc))
           ;; update index of most distant captured frame
           (bcode:cdepth
            g (- (nnn (cdr env)) 1 (car loc))))
          (else
           (if (and (constant? s)
                    (printable? (top-level-value s)))
               (emit g 'loadv (top-level-value s))
               (emit g (aref Is 2) s))))))

(define (compile-if g env tail? x)
  (let ((elsel (make-label g))
        (endl  (make-label g))
        (test  (cadr x))
        (then  (caddr x))
        (else  (cond ((null? (cdddr x))
                      (void))
                     ((null? (cddddr x))
                      (cadddr x))
                     (else
                      (error "compile error: if expects 2-3 arguments.")))))
    (cond ((eq? test #t)
           (compile-in g env tail? then))
          ((eq? test #f)
           (compile-in g env tail? else))
          (else
           (compile-in g env #f test)
           (emit g 'brf elsel)
           (compile-in g env tail? then)
           (if tail?
               (emit g 'ret)
               (emit g 'jmp endl))
           (mark-label g elsel)
           (compile-in g env tail? else)
           (mark-label g endl)))))

(define (compile-begin g env tail? forms)
  (cond ((atom? forms) (compile-in g env tail? (void)))
        ((atom? (cdr forms))
         (compile-in g env tail? (car forms)))
        (else
         (compile-in g env #f (car forms))
         (emit g 'pop)
         (compile-begin g env tail? (cdr forms)))))

(define (compile-prog1 g env x)
  (compile-in g env #f (cadr x))
  (if (pair? (cddr x))
      (begin (compile-begin g env #f (cddr x))
             (emit g 'pop))))

(define (compile-while g env cond body)
  (let ((top  (make-label g))
        (end  (make-label g)))
    (compile-in g env #f (void))
    (mark-label g top)
    (compile-in g env #f cond)
    (emit g 'brf end)
    (emit g 'pop)
    (compile-in g env #f body)
    (emit g 'jmp top)
    (mark-label g end)))

(define (1arg-lambda? func)
  (and (pair? func)
       (eq? (car func) 'lambda)
       (pair? (cdr func))
       (pair? (cadr func))
       (length= (cadr func) 1)))

(define (compile-for g env lo hi func)
  (if (1arg-lambda? func)
      (begin (compile-in g env #f lo)
             (compile-in g env #f hi)
             (compile-in g env #f func)
             (emit g 'for))
      (error "for: third form must be a 1-argument lambda")))

(define (compile-short-circuit g env tail? forms default branch)
  (cond ((atom? forms)        (compile-in g env tail? default))
        ((atom? (cdr forms))  (compile-in g env tail? (car forms)))
        (else
         (let ((end  (make-label g)))
           (compile-in g env #f (car forms))
           (emit g 'dup)
           (emit g branch end)
           (emit g 'pop)
           (compile-short-circuit g env tail? (cdr forms) default branch)
           (mark-label g end)))))

(define (compile-and g env tail? forms)
  (compile-short-circuit g env tail? forms #t 'brf))
(define (compile-or g env tail? forms)
  (compile-short-circuit g env tail? forms #f 'brt))

(define (compile-arglist g env lst)
  (for-each (lambda (a)
              (compile-in g env #f a))
            lst)
  (length lst))

(define (argc-error head count)
  (error "compile error: " head " expects " count
         (if (= count 1)
             " argument."
             " arguments.")))

(define builtin->instruction
  (let ((b2i (table number? 'number?  cons 'cons
                    fixnum? 'fixnum?  equal? 'equal?
                    eq? 'eq?  symbol? 'symbol?
                    div0 'div0  builtin? 'builtin?
                    aset! 'aset!  - '-  boolean? 'boolean?  not 'not
                    apply 'apply  atom? 'atom?
                    set-cdr! 'set-cdr!  / '/
                    function? 'function?  vector 'vector
                    list 'list  bound? 'bound?
                    < '<  * '* cdr 'cdr  null? 'null?
                    + '+  eqv? 'eqv? compare 'compare  aref 'aref
                    set-car! 'set-car!  car 'car
                    pair? 'pair?  = '=  vector? 'vector?)))
    (lambda (b)
      (get b2i b #f))))

(define (compile-builtin-call g env tail? x head b nargs)
  (let ((count (get arg-counts head #f)))
    (if (and count
             (not (length= (cdr x) count)))
        (argc-error b count))
    (case b  ; handle special cases of vararg builtins
      (list (if (= nargs 0) (emit g 'loadnil) (emit g b nargs)))
      (+    (cond ((= nargs 0) (emit g 'load0))
                  ((= nargs 2) (emit g 'add2))
                  (else (emit g b nargs))))
      (-    (cond ((= nargs 0) (argc-error b 1))
                  ((= nargs 1) (emit g 'neg))
                  ((= nargs 2) (emit g 'sub2))
                  (else (emit g b nargs))))
      (*    (if (= nargs 0) (emit g 'load1)
                (emit g b nargs)))
      (/    (if (= nargs 0)
                (argc-error b 1)
                (emit g b nargs)))
      (vector   (if (= nargs 0)
                    (emit g 'loadv [])
                    (emit g b nargs)))
      (apply    (if (< nargs 2)
                    (argc-error b 2)
                    (emit g (if tail? 'tapply 'apply) nargs)))
      (else      (emit g b)))))

(define (compile-app g env tail? x)
  (let ((head  (car x)))
    (let ((head
           (if (and (symbol? head)
                    (not (in-env? head env))
                    (bound? head)
                    (constant? head)
                    (builtin? (top-level-value head)))
               (top-level-value head)
               head)))
      (if (length> (cdr x) 255)
          ; more than 255 arguments, need long versions of instructions
          (begin (compile-in g env #f head)
                 (let ((nargs (compile-arglist g env (cdr x))))
                   (emit g (if tail? 'tcall.l 'call.l) nargs)))
          (let ((b (and (builtin? head)
                        (builtin->instruction head))))
            (if (and (eq? head 'cadr)
                     (not (in-env? head env))
                     (equal? (top-level-value 'cadr) cadr)
                     (length= x 2))
                (begin (compile-in g env #f (cadr x))
                       (emit g 'cadr))
                (begin
                  (if (not b)
                      (compile-in g env #f head))
                  (let ((nargs (compile-arglist g env (cdr x))))
                    (if b
                        (compile-builtin-call g env tail? x head b nargs)
                        (emit g (if tail? 'tcall 'call) nargs))))))))))

(define (expand-define x)
  (let ((form (cadr x))
        (body (if (pair? (cddr x))
                  (cddr x)
                  (if (symbol? (cadr x))
                      `(,(void))
                      (error "compile error: invalid syntax "
                             (write-to-string x))))))
    (if (symbol? form)
        `(set! ,form ,(car body))
        `(set! ,(car form)
               (lambda ,(cdr form) ,@body . ,(car form))))))

(define (fits-i8 x) (and (fixnum? x) (>= x -128) (<= x 127)))

(define (compile-in g env tail? x)
  (cond ((symbol? x) (compile-sym g env x [loada loadc loadg]))
        ((atom? x)
         (cond ((eq? x 0)   (emit g 'load0))
               ((eq? x 1)   (emit g 'load1))
               ((eq? x #t)  (emit g 'loadt))
               ((eq? x #f)  (emit g 'loadf))
               ((eq? x ())  (emit g 'loadnil))
               ((fits-i8 x) (emit g 'loadi8 x))
               ((eof-object? x)
                (compile-in g env tail? (list (top-level-value 'eof-object))))
               (else        (emit g 'loadv x))))
        ((or (not (symbol? (car x))) (bound? (car x)) (in-env? (car x) env))
         (compile-app g env tail? x))
        (else
         (case (car x)
           (quote    (if (self-evaluating? (cadr x))
                         (compile-in g env tail? (cadr x))
                         (emit g 'loadv (cadr x))))
           (if       (compile-if g env tail? x))
           (begin    (compile-begin g env tail? (cdr x)))
           (prog1    (compile-prog1 g env x))
           (lambda   (receive (the-f dept) (compile-f- env x)
                       (begin (emit g 'loadv the-f)
                              (bcode:cdepth g dept)
                              (if (< dept (nnn env))
                                  (emit g 'closure)))))
           (and      (compile-and g env tail? (cdr x)))
           (or       (compile-or  g env tail? (cdr x)))
           (while    (compile-while g env (cadr x) (cons 'begin (cddr x))))
           (for      (compile-for   g env (cadr x) (caddr x) (cadddr x)))
           (return   (compile-in g env #t (cadr x))
                     (emit g 'ret))
           (set!     (compile-in g env #f (caddr x))
                     (or (symbol? (cadr x))
                         (error "set!: second argument must be a symbol"))
                     (compile-sym g env (cadr x) [seta setc setg]))
           (define   (compile-in g env tail?
                                 (expand-define x)))
           (trycatch (compile-in g env #f `(lambda () ,(cadr x)))
                     (unless (1arg-lambda? (caddr x))
                       (error
                        "trycatch: second form must be a 1-argument lambda"))
                     (compile-in g env #f (caddr x))
                     (emit g 'trycatch))
           (else   (compile-app g env tail? x))))))

(define (compile-f env f)
  (receive (ff ignore)
           (compile-f- env f)
           ff))

(define get-defined-vars
  (letrec ((get-defined-vars-
            (lambda (expr)
              (cond ((atom? expr) ())
                    ((and (eq? (car expr) 'define)
                          (pair? (cdr expr)))
                     (or (and (symbol? (cadr expr))
                              (list (cadr expr)))
                         (and (pair? (cadr expr))
                              (symbol? (caadr expr))
                              (list (caadr expr)))
                         ()))
                    ((eq? (car expr) 'begin)
                     (apply nconc (map get-defined-vars- (cdr expr))))
                    (else ())))))
    (lambda (expr) (delete-duplicates (get-defined-vars- expr)))))

(define (keyword-arg? x) (and (pair? x) (keyword? (car x))))
(define (keyword->symbol k)
  (if (keyword? k)
      (symbol (let ((s (string k)))
                (string.sub s 0 (string.dec s (length s)))))
      k))

(define (lambda-arg-names argl)
  (map! (lambda (s) (if (pair? s) (keyword->symbol (car s)) s))
        (to-proper argl)))

(define (lambda-vars l)
  (define (check-formals l o opt kw)
    (cond ((or (null? l) (symbol? l)) #t)
          ((and (pair? l) (symbol? (car l)))
           (if (or opt kw)
               (error "compile error: invalid argument list "
                      o ". optional arguments must come after required.")
               (check-formals (cdr l) o opt kw)))
          ((and (pair? l) (pair? (car l)))
           (unless (and (length= (car l) 2)
                        (symbol? (caar l)))
                   (error "compile error: invalid optional argument " (car l)
                          " in list " o))
           (if (keyword? (caar l))
               (check-formals (cdr l) o opt #t)
               (if kw
                   (error "compile error: invalid argument list "
                          o ". keyword arguments must come last.")
                   (check-formals (cdr l) o #t kw))))
          ((pair? l)
           (error "compile error: invalid formal argument " (car l)
                  " in list " o))
          (else
           (if (eq? l o)
               (error "compile error: invalid argument list " o)
               (error "compile error: invalid formal argument " l
                      " in list " o)))))
  (check-formals l l #f #f)
  (lambda-arg-names l))

(define (emit-optional-arg-inits g env opta vars i)
  ; i is the lexical var index of the opt arg to process next
  (if (pair? opta)
      (let ((nxt (make-label g)))
        (emit g 'brbound i)
        (emit g 'brt nxt)
        (compile-in g (cons (list-head vars i) env) #f (cadar opta))
        (emit g 'seta i)
        (emit g 'pop)
        (mark-label g nxt)
        (emit-optional-arg-inits g env (cdr opta) vars (+ i 1)))))

#;(define (free-vars e)
  (cond ((symbol? e) (list e))
        ((or (atom? e) (eq? (car e) 'quote)) ())
        ((eq? (car e) 'lambda)
         (diff (free-vars (cddr e))
               (nconc (get-defined-vars (cons 'begin (cddr e)))
                      (lambda-arg-names (cadr e)))))
        (else (delete-duplicates (apply nconc (map free-vars (cdr e)))))))

(define compile-f-
  (let ((*defines-processed-token* (gensym)))
    ; to eval a top-level expression we need to avoid internal define
    (set-top-level-value!
     'compile-thunk
     (lambda (expr)
       (compile `(lambda () ,expr . ,*defines-processed-token*))))

    (lambda (env f)
      ; convert lambda to one body expression and process internal defines
      (define (lambda-body e)
        (let ((B (if (pair? (cddr e))
                     (if (pair? (cdddr e))
                         (cons 'begin (cddr e))
                         (caddr e))
                     (void))))
          (let ((V (get-defined-vars B)))
            (if (null? V)
                B
                (cons (list* 'lambda V B *defines-processed-token*)
                      (map (lambda (x) (void)) V))))))
      (define (lam:body f)
        (if (eq? (lastcdr f) *defines-processed-token*)
            (caddr f)
            (lambda-body f)))

      (let ((g    (make-code-emitter))
            (args (cadr f))
            (atail (lastcdr (cadr f)))
            (vars (lambda-vars (cadr f)))
            (opta (filter pair? (cadr f)))
            (name (if (eq? (lastcdr f) *defines-processed-token*)
                      'lambda
                      (lastcdr f))))
        (let* ((nargs (if (atom? args) 0 (length args)))
               (nreq  (- nargs (length opta)))
               (kwa   (filter keyword-arg? opta)))

          ; emit argument checking prologue
          (if (not (null? opta))
              (begin
                (if (null? kwa)
                    (emit g 'optargs nreq
                          (if (null? atail) nargs (- nargs)))
                    (begin
                      (bcode:indexfor g (make-perfect-hash-table
                                         (map cons
                                              (map car kwa)
                                              (iota (length kwa)))))
                      (emit g 'keyargs nreq (length kwa)
                            (if (null? atail) nargs (- nargs)))))
                (emit-optional-arg-inits g env opta vars nreq)))

          (cond ((> nargs 255)           (emit g (if (null? atail)
                                                     'largc 'lvargc)
                                               nargs))
                ((not (null? atail))     (emit g 'vargc nargs))
                ((null? opta)            (emit g 'argc  nargs)))

          ; compile body and return
          (compile-in g (cons vars env) #t (lam:body f))
          (emit g 'ret)
          (values (function (encode-byte-code (bcode:code g))
                            (const-to-idx-vec g) name)
                  (aref g 3)))))))

(define (compile f) (compile-f () f))

(define (ref-int32-LE a i)
  (int32 (+ (ash (aref a (+ i 0)) 0)
            (ash (aref a (+ i 1)) 8)
            (ash (aref a (+ i 2)) 16)
            (ash (aref a (+ i 3)) 24))))

(define (ref-int16-LE a i)
  (int16 (+ (ash (aref a (+ i 0)) 0)
            (ash (aref a (+ i 1)) 8))))

(define (hex5 n)
  (string.lpad (number->string n 16) 5 #\0))

(define (disassemble f . lev?)
  (if (null? lev?)
      (begin (disassemble f 0)
             (newline)
             (return #t)))
  (let ((lev (car lev?))
        (code (function:code f))
        (vals (function:vals f)))
    (define (write-val v)
      (if (and (function? v) (not (builtin? v)))
          (begin (display "\n")
                 (disassemble v (+ lev 1)))
          (write v)))
    (dotimes (xx lev) (display "  "))
    (display "maxstack ")
    (display (ref-int32-LE code 0))
    (newline)
    (let ((i 4)
          (N (length code)))
      (while (< i N)
             ; find key whose value matches the current byte
             (let ((inst (table.foldl (lambda (k v z)
                                        (or z (and (eq? v (aref code i))
                                                   k)))
                                      #f Instructions)))
               (if (> i 4) (newline))
               (dotimes (xx lev) (display "  "))
               (display (hex5 (- i 4)))
               (display ":  ")
               (display (string inst))
               (display "  ")
               (set! i (+ i 1))
               (case inst
                 ((loadv.l loadg.l setg.l)
                  (write-val (aref vals (ref-int32-LE code i)))
                  (set! i (+ i 4)))

                 ((loadv loadg setg)
                  (write-val (aref vals (aref code i)))
                  (set! i (+ i 1)))

                 ((loada seta call tcall list + - * / vector
                   argc vargc loadi8 apply tapply)
                  (display (number->string (aref code i)))
                  (set! i (+ i 1)))

                 ((loada.l seta.l largc lvargc call.l tcall.l)
                  (display (number->string (ref-int32-LE code i)))
                  (set! i (+ i 4)))

                 ((loadc setc)
                  (display (number->string (aref code i)))
                  (display " ")
                  (set! i (+ i 1))
                  (display (number->string (aref code i)))
                  (set! i (+ i 1)))

                 ((loadc.l setc.l optargs keyargs)
                  (display (number->string (ref-int32-LE code i)))
                  (display " ")
                  (set! i (+ i 4))
                  (display (number->string (ref-int32-LE code i)))
                  (set! i (+ i 4))
                  (if (eq? inst 'keyargs)
                      (begin
                        (display " ")
                        (display (number->string (ref-int32-LE code i)))
                        (display " ")
                        (set! i (+ i 4)))))

                 ((brbound)
                  (display (number->string (ref-int32-LE code i)))
                  (display " ")
                  (set! i (+ i 4)))

                 ((jmp brf brt brne brnn brn)
                  (display "@")
                  (display (hex5 (+ i -4 (ref-int16-LE code i))))
                  (set! i (+ i 2)))

                 ((jmp.l brf.l brt.l brne.l brnn.l brn.l)
                  (display "@")
                  (display (hex5 (+ i -4 (ref-int32-LE code i))))
                  (set! i (+ i 4)))

                 (else #f)))))))

; From SRFI 89 by Marc Feeley (http://srfi.schemers.org/srfi-89/srfi-89.html)
; Copyright (C) Marc Feeley 2006. All Rights Reserved.
;
; "alist" is a list of pairs of the form "(keyword . value)"
; The result is a perfect hash-table represented as a vector of
; length 2*N, where N is the hash modulus.  If the keyword K is in
; the hash-table it is at index
;
;   X = (* 2 ($hash-keyword K N))
;
; and the associated value is at index X+1.
(define (make-perfect-hash-table alist)
  (define ($hash-keyword key n) (mod0 (abs (hash key)) n))
  (let loop1 ((n (length alist)))
    (let ((v (vector.alloc (* 2 n) #f)))
      (let loop2 ((lst alist))
        (if (pair? lst)
            (let ((key (caar lst)))
              (let ((x (* 2 ($hash-keyword key n))))
                (if (aref v x)
                    (loop1 (+ n 1))
                    (begin
                      (aset! v x key)
                      (aset! v (+ x 1) (cdar lst))
                      (loop2 (cdr lst))))))
            v)))))

#t