More WIP on closures

diff --git a/codegen.scm b/codegen.scm
index b403939bc2122c2a4c9b5e24980955a2e329402e..571f1ef8498c0a662f3dfa7254b0cf2f535e4374 100644 (file)
--- a/codegen.scm
+++ b/codegen.scm
@@ -105,18 +105,22 @@
   (set! cur-lambda (+ 1 cur-lambda))
   (format "_lambda~a" (- cur-lambda 1)))
 
+; a closure on the heap looks like:
+; 0-x    x+0   x+4       x+12      x+20
+; label #vars var1....  var2....  var3....
 (define (codegen-closure label captured si env)
-;; (define (codegen-closure label captured si env)
-;;   (let* ((stack-offsets (map (lambda (x) (- si (* x wordsize))))
-;;                     (range 0 (length captured)))
-;;      (inner-si (- si (* (length captured) wordsize))))
-;;     (for-each (lambda (var-name new-offset)
-;;             (emit "movq ~a(%rbp), ~a(%rbp)" ; todo: do we need to copy this?
-;;                   (cdr (assoc var-name env))
-;;                   new-offset))
-;;           captured
-;;           stack-offsets)
-;; )
+  (let* ((heap-offsets (range 4 (length captured))) ; 4, 12, 20, etc.
+        (inner-si (- si (* (length captured) wordsize))))
+    (emit "movl $~a, (heap_start)")
+    (emit "add $4, (heap_start)")
+    (for-each (lambda (var-name new-offset)
+               (emit "movq ~a(%rbp), ~a(heap_start)" ; todo: do we need to copy this?
+                     (cdr (assoc var-name env))
+                     new-offset)
+               (emit "add $8, (heap_start)")
+             captured
+             stack-offsets)
+)
                                        ; for now we can only call closures
 (define (codegen-call closure args si env)
 ;  (codegen-expr closure si env)