Optimize malloc for block reuse

heap.asm

@@ -15,7 +15,7 @@ verbose_malloc:
 ;
 ; Header:
 ;	word	ptr to next item (this implies its size)
-;	byte	00 = free, FF = in use
+;	byte	00 = free, >0 used (refcount)
 malloc:
   push ax
   mov si,heap
@@ -31,12 +31,10 @@ malloc:
   sub ax,cx
   je .reuse ; entry has exact length
   jc .next ; entry too short
-  jmp .next ; we'd have to split
+  jmp .next ; we'd have to split, not implemented yet
 .reuse: ; exact length
   mov byte [si+2],0xFF
-  add si, 0x03
-  pop ax
-  ret
+  jmp .end
 .append: ; append to last item
   mov ax, si
   add ax, 3
@@ -47,6 +45,7 @@ malloc:
   mov word si,[si]
   mov byte [si],0x0000
   pop si
+.end:
   add si, 0x03
   pop ax
   ret