change function of vapp & README update

README.md

@@ -86,13 +86,13 @@ for(var i=0;i<4000000;i+=1);
 .number 1
 .symbol i
 0x00000000: pzero  0x00000000
-0x00000001: load   0x00000000 (i)
-0x00000002: call   0x00000000 (i)
+0x00000001: loadg  0x00000000 (i)
+0x00000002: callg  0x00000000 (i)
 0x00000003: pnum   0x00000001 (4e+006)
 0x00000004: less   0x00000000
 0x00000005: jf     0x0000000b
 0x00000006: pone   0x00000000
-0x00000007: mcall  0x00000000 (i)
+0x00000007: mcallg 0x00000000 (i)
 0x00000008: addeq  0x00000000
 0x00000009: pop    0x00000000
 0x0000000a: jmp    0x00000002
@@ -107,6 +107,20 @@ Because it takes more than 1.5s to count i from 0 to 4000000-1.This is not effic
 
 2021/1/23 update: Now it can count from 0 to 4000000-1 in 1.5s.
 
+## Version 6.0
+
+Use loadg loadl callg calll mcallg mcalll to avoid branches.
+
+Delete type vm_scop.
+
+Use const vm_num to avoid frequently new & delete.
+
+Change garbage collector from reference-counting to mark-sweep.
+
+Vapp and newf operand use .num to reduce the size of exec_code.
+
+2021/4/3 update: Now it can count from 0 to 4000000-1 in 0.8s.
+
 # How to Use Nasal to Program
 
 ## basic value type
@@ -299,13 +313,13 @@ If you want to add your own built-in functions,define the function in nasal_buil
 Definition:
 
 ```C++
-nasal_val* builtin_chr(nasal_val*,nasal_gc&);
+nasal_val* builtin_chr(std::unordered_map<int,nasal_val*>&,nasal_gc&);
 ```
 
 Then complete this function using C++:
 
 ```C++
-nasal_val* builtin_print(nasal_val* local_scope_addr,nasal_gc& gc)
+nasal_val* builtin_print(std::unordered_map<int,nasal_val*>& local_scope_addr,nasal_gc& gc)
 {
     // get arguments by using in_builtin_find
     nasal_val* vector_value_addr=in_builtin_find("elements");
@@ -329,7 +343,7 @@ nasal_val* builtin_print(nasal_val* local_scope_addr,nasal_gc& gc)
     // if a nasal value is not in use,use gc::del_reference to delete it
     // if get a new reference of a nasal value,use gc::add_reference
     // generate return value,use gc::gc_alloc(type) to make a new value
-    return gc.gc_alloc(vm_nil);
+    return nil_addr;
 }
 ```
 
@@ -339,7 +353,7 @@ After that, write the built-in function's name(in nasal) and the function's poin
 struct FUNC_TABLE
 {
     std::string func_name;
-    nasal_val* (*func_pointer)(nasal_val* x,nasal_gc& gc);
+    nasal_val* (*func_pointer)(std::unordered_map<int,nasal_val*>&,nasal_gc&);
 } builtin_func_table[]=
 {
     {"__builtin_std_cout",builtin_print},
@@ -352,7 +366,7 @@ At last,warp the 'nasal_call_builtin_std_cout' in a nasal file:
 ```javascript
 var print=func(elements...)
 {
-    nasal_call_builtin_std_cout(elements);
+    __builtin_std_cout(elements);
     return nil;
 };
 ```

nasal_codegen.h

@@ -334,10 +334,8 @@ void nasal_codegen::vec_gen(nasal_ast& ast)
     int size=ast.get_children().size();
     gen(op_newv,0);
     for(int i=0;i<size;++i)
-    {
         calc_gen(ast.get_children()[i]);
-        gen(op_vapp,0);
-    }
+    gen(op_vapp,size);
     return;
 }
 

nasal_vm.h

@@ -211,8 +211,10 @@ void nasal_vm::opr_newf()
 }
 void nasal_vm::opr_vapp()
 {
-    nasal_val* val=*stack_top--;
-    (*stack_top)->ptr.vec->elems.push_back(val);
+    nasal_val* vec=*(stack_top-exec_code[pc].num);
+    for(nasal_val** i=stack_top-exec_code[pc].num+1;i<=stack_top;++i)
+        vec->ptr.vec->elems.push_back(*i);
+    stack_top-=exec_code[pc].num;
     return;
 }
 void nasal_vm::opr_happ()