--- stack/stack.c	2002/03/08 16:09:30	1.93
+++ stack/stack.c	2002/03/10 13:00:01	1.101
@@ -48,10 +48,9 @@
 {
   int i;
 
-  env->gc_limit= 20;
+  env->gc_limit= 400000;
   env->gc_count= 0;
   env->gc_ref= NULL;
-  env->gc_protect= NULL;
 
   env->head= NULL;
   for(i= 0; i<HASHTBLSIZE; i++)
@@ -63,7 +62,8 @@
   env->interactive= 1;
 }
 
-void printerr(const char* in_string) {
+void printerr(const char* in_string)
+{
   fprintf(stderr, "Err: %s\n", in_string);
 }
 
@@ -80,8 +80,6 @@
   
   env->head= env->head->next;	/* Remove the top stack item */
   free(temp);			/* Free the old top stack item */
-
-  gc_init(env);
 }
 
 /* Returns a pointer to a pointer to an element in the hash table. */
@@ -113,7 +111,9 @@
   }
 }
 
-value* new_val(environment *env) {
+/* Create new value */
+value* new_val(environment *env)
+{
   value *nval= malloc(sizeof(value));
   stackitem *nitem= malloc(sizeof(stackitem));
 
@@ -123,22 +123,23 @@
   nitem->next= env->gc_ref;
   env->gc_ref= nitem;
 
-  env->gc_count++;
-
-  protect(env, nval);
-  gc_init(env);
-  unprotect(env);
+  env->gc_count += sizeof(value);
+  nval->gc.flag.mark= 0;
+  nval->gc.flag.protect= 0;
 
   return nval;
 }
 
-void gc_mark(value *val) {
+/* Mark values recursively. 
+   Marked values are not collected by the GC. */
+inline void gc_mark(value *val)
+{
   stackitem *iterator;
 
-  if(val==NULL || val->gc_garb==0)
+  if(val->gc.flag.mark)
     return;
 
-  val->gc_garb= 0;
+  val->gc.flag.mark= 1;
 
   if(val->type==list) {
     iterator= val->content.ptr;
@@ -150,53 +151,57 @@
   }
 }
 
-extern void gc_init(environment *env) {
+inline void gc_maybe(environment *env)
+{
+  if(env->gc_count < env->gc_limit)
+    return;
+  else
+    return gc_init(env);
+}
+
+/* Start GC */
+extern void gc_init(environment *env)
+{
   stackitem *new_head= NULL, *titem, *iterator;
   symbol *tsymb;
   int i;
 
-  if(env->gc_count < env->gc_limit)
-    return;
-
-  /* Garb by default */
-  iterator= env->gc_ref;
-  while(iterator!=NULL) {
-    iterator->item->gc_garb= 1;
-    iterator= iterator->next;
+  if(env->interactive){
+    printf("Garbage collecting.");
   }
 
-  /* Mark protected values */
-  iterator= env->gc_protect;
+  /* Mark values on stack */
+  iterator= env->head;
   while(iterator!=NULL) {
     gc_mark(iterator->item);
     iterator= iterator->next;
   }
 
-  /* Mark values in stack */
-  iterator= env->head;
-  while(iterator!=NULL) {
-    gc_mark(iterator->item);
-    iterator= iterator->next;
+  if(env->interactive){
+    printf(".");
   }
 
   /* Mark values in hashtable */
   for(i= 0; i<HASHTBLSIZE; i++) {
     tsymb= env->symbols[i];
     while(tsymb!=NULL) {
-      gc_mark(tsymb->val);
+      if (tsymb->val != NULL)
+	gc_mark(tsymb->val);
       tsymb= tsymb->next;
     }
   }
 
+  if(env->interactive){
+    printf(".");
+  }
+
   env->gc_count= 0;
 
-  /* Sweep */
-  while(env->gc_ref!=NULL) {
+  while(env->gc_ref!=NULL) {	/* Sweep unused values */
 
-    if(env->gc_ref->item->gc_garb) {
+    if(!(env->gc_ref->item->gc.no_gc)){ /* neither mark nor protect */
 
-      /* Remove content */
-      switch(env->gc_ref->item->type) {	
+      switch(env->gc_ref->item->type) {	/* Remove content */
       case string:
 	free(env->gc_ref->item->content.ptr);
 	break;
@@ -206,40 +211,76 @@
 	  env->gc_ref->item->content.ptr= titem->next;
 	  free(titem);
 	}
-	break;
       default:
-	break;
       }
       free(env->gc_ref->item);	/* Remove from gc_ref */
       titem= env->gc_ref->next;
       free(env->gc_ref);	/* Remove value */
       env->gc_ref= titem;
-    } else {			/* Save */
-      titem= env->gc_ref->next;
-      env->gc_ref->next= new_head;
-      new_head= env->gc_ref;
-      env->gc_ref= titem;
-      env->gc_count++;
+      continue;
+    } else {
+      env->gc_count += sizeof(value);
+      if(env->gc_ref->item->type == string)
+	env->gc_count += strlen(env->gc_ref->item->content.ptr);
     }
+    
+    /* Keep values */
+    titem= env->gc_ref->next;
+    env->gc_ref->next= new_head;
+    new_head= env->gc_ref;
+    new_head->item->gc.flag.mark= 0;
+    env->gc_ref= titem;
   }
 
-  env->gc_limit= env->gc_count*2;
+  if (env->gc_limit < env->gc_count*2)
+    env->gc_limit= env->gc_count*2;
+
   env->gc_ref= new_head;
+
+  if(env->interactive){
+    printf("done\n");
+  }
+
 }
 
-void protect(environment *env, value *val)
+/* Protect values from GC */
+void protect(value *val)
 {
-  stackitem *new_item= malloc(sizeof(stackitem));
-  new_item->item= val;
-  new_item->next= env->gc_protect;
-  env->gc_protect= new_item;
+  stackitem *iterator;
+
+  if(val->gc.flag.protect)
+    return;
+
+  val->gc.flag.protect= 1;
+
+  if(val->type==list) {
+    iterator= val->content.ptr;
+
+    while(iterator!=NULL) {
+      protect(iterator->item);
+      iterator= iterator->next;
+    }
+  }
 }
 
-void unprotect(environment *env)
+/* Unprotect values from GC */
+void unprotect(value *val)
 {
-  stackitem *temp= env->gc_protect;
-  env->gc_protect= env->gc_protect->next;
-  free(temp);
+  stackitem *iterator;
+
+  if(!(val->gc.flag.protect))
+    return;
+
+  val->gc.flag.protect= 0;
+
+  if(val->type==list) {
+    iterator= val->content.ptr;
+
+    while(iterator!=NULL) {
+      unprotect(iterator->item);
+      iterator= iterator->next;
+    }
+  }
 }
 
 /* Push a value onto the stack */
@@ -251,7 +292,7 @@
   env->head= new_item;
 }
 
-/* Push an integer onto the stack. */
+/* Push an integer onto the stack */
 void push_int(environment *env, int in_val) 
 {
   value *new_value= new_val(env);
@@ -262,6 +303,7 @@
   push_val(env, new_value);
 }
 
+/* Push a floating point number onto the stack */
 void push_float(environment *env, float in_val)
 {
   value *new_value= new_val(env);
@@ -276,8 +318,10 @@
 void push_cstring(environment *env, const char *in_string)
 {
   value *new_value= new_val(env);
+  int length= strlen(in_string)+1;
 
-  new_value->content.ptr= malloc(strlen(in_string)+1);
+  new_value->content.ptr= malloc(length);
+  env->gc_count += length;
   strcpy(new_value->content.ptr, in_string);
   new_value->type= string;
 
@@ -285,7 +329,8 @@
 }
 
 /* Mangle a symbol name to a valid C identifier name */
-char *mangle_str(const char *old_string){
+char *mangle_str(const char *old_string)
+{
   char validchars[]= "0123456789abcdef";
   char *new_string, *current;
 
@@ -303,7 +348,8 @@
   return new_string;		/* The caller must free() it */
 }
 
-extern void mangle(environment *env){
+extern void mangle(environment *env)
+{
   char *new_string;
 
   if((env->head)==NULL) {
@@ -342,9 +388,9 @@
   char *mangled;		/* Mangled function name */
 
   new_value= new_val(env);
-  protect(env, new_value);
+  protect(new_value);
   new_fvalue= new_val(env);
-  protect(env, new_fvalue);
+  protect(new_fvalue);
 
   /* The new value is a symbol */
   new_value->type= symb;
@@ -372,21 +418,25 @@
 
     mangled= mangle_str(in_string); /* mangle the name */
     funcptr= dlsym(handle, mangled); /* and try to find it */
-    free(mangled);
+
     dlerr= dlerror();
     if(dlerr != NULL) {		/* If no function was found */
       funcptr= dlsym(handle, in_string); /* Get function pointer */
       dlerr= dlerror();
     }
+
     if(dlerr==NULL) {		/* If a function was found */
       new_fvalue->type= func;	/* The new value is a function pointer */
       new_fvalue->content.ptr= funcptr; /* Store function pointer */
       (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
                                          function value */
     }
+
+    free(mangled);
   }
+
   push_val(env, new_value);
-  unprotect(env); unprotect(env);
+  unprotect(new_value); unprotect(new_fvalue);
 }
 
 /* Print newline. */
@@ -396,7 +446,8 @@
 }
 
 /* Gets the type of a value */
-extern void type(environment *env){
+extern void type(environment *env)
+{
   int typenum;
 
   if((env->head)==NULL) {
@@ -464,7 +515,8 @@
   }
 }
 
-extern void print_(environment *env) {
+extern void print_(environment *env)
+{
   if(env->head==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
@@ -482,7 +534,8 @@
   toss(env);
 }
 
-extern void princ_(environment *env) {
+extern void princ_(environment *env)
+{
   if(env->head==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
@@ -516,6 +569,7 @@
     printf("Stack Empty\n");
     return;
   }
+
   print_st(env->head, 1);
 }
 
@@ -575,11 +629,11 @@
     env->err=3;
     return;
   }
-  protect(env, val);
+  protect(val);
   toss(env);		/* toss the symbol */
   if(env->err) return;
   push_val(env, val); /* Return its bound value */
-  unprotect(env);
+  unprotect(val);
 }
 
 /* If the top element is a symbol, determine if it's bound to a
@@ -593,6 +647,8 @@
 
  eval_start:
 
+  gc_maybe(env);
+
   if(env->head==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
@@ -619,7 +675,7 @@
     /* If it's a list */
   case list:
     temp_val= env->head->item;
-    protect(env, temp_val);
+    protect(temp_val);
 
     toss(env); if(env->err) return;
     iterator= (stackitem*)temp_val->content.ptr;
@@ -628,7 +684,7 @@
       push_val(env, iterator->item);
       
       if(env->head->item->type==symb
-	&& strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
+	 && (((symbol*)(env->head->item->content.ptr))->id[0] == ';')) {
 	toss(env);
 	if(env->err) return;
 	
@@ -640,7 +696,7 @@
       }
       iterator= iterator->next;
     }
-    unprotect(env);
+    unprotect(temp_val);
     return;
 
   default:
@@ -649,7 +705,8 @@
 }
 
 /* Reverse (flip) a list */
-extern void rev(environment *env){
+extern void rev(environment *env)
+{
   stackitem *old_head, *new_head, *item;
 
   if((env->head)==NULL) {
@@ -683,7 +740,7 @@
 
   iterator= env->head;
   pack= new_val(env);
-  protect(env, pack);
+  protect(pack);
 
   if(iterator==NULL
      || (iterator->item->type==symb
@@ -714,7 +771,7 @@
   push_val(env, pack);
   rev(env);
 
-  unprotect(env);
+  unprotect(pack);
 }
 
 /* Relocate elements of the list on the stack. */
@@ -835,7 +892,7 @@
 /* Quit stack. */
 extern void quit(environment *env)
 {
-  long i;
+  int i;
 
   clear(env);
 
@@ -848,7 +905,7 @@
   }
 
   env->gc_limit= 0;
-  gc_init(env);
+  gc_maybe(env);
 
   if(env->free_string!=NULL)
     free(env->free_string);
@@ -881,7 +938,8 @@
 }
 
 /* Internal forget function */
-void forget_sym(symbol **hash_entry) {
+void forget_sym(symbol **hash_entry)
+{
   symbol *temp;
 
   temp= *hash_entry;
@@ -916,7 +974,8 @@
 }
 
 /* Returns the current error number to the stack */
-extern void errn(environment *env){
+extern void errn(environment *env)
+{
   push_int(env, env->err);
 }
 
@@ -957,7 +1016,7 @@
   }
 
   if(myenv.interactive) {
-    printf("Stack version $Revision: 1.93 $\n\
+    printf("Stack version $Revision: 1.101 $\n\
 Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn\n\
 Stack comes with ABSOLUTELY NO WARRANTY; for details type `warranty;'.\n\
 This is free software, and you are welcome to redistribute it\n\
@@ -985,14 +1044,15 @@
       toss(&myenv); 		/* No error check in main */
       eval(&myenv);
     }
-    gc_init(&myenv);
+    gc_maybe(&myenv);
   }
   quit(&myenv);
   return EXIT_FAILURE;
 }
 
 /* "+" */
-extern void sx_2b(environment *env) {
+extern void sx_2b(environment *env)
+{
   int a, b;
   float fa, fb;
   size_t len;
@@ -1009,7 +1069,7 @@
      && env->head->next->item->type==string) {
     a_val= env->head->item;
     b_val= env->head->next->item;
-    protect(env, a_val); protect(env, b_val);
+    protect(a_val); protect(b_val);
     toss(env); if(env->err) return;
     toss(env); if(env->err) return;
     len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
@@ -1017,7 +1077,7 @@
     strcpy(new_string, b_val->content.ptr);
     strcat(new_string, a_val->content.ptr);
     push_cstring(env, new_string);
-    unprotect(env); unprotect(env);
+    unprotect(a_val); unprotect(b_val);
     free(new_string);
     
     return;
@@ -1072,7 +1132,8 @@
 }
 
 /* "-" */
-extern void sx_2d(environment *env) {
+extern void sx_2d(environment *env)
+{
   int a, b;
   float fa, fb;
 
@@ -1131,7 +1192,8 @@
 }
 
 /* ">" */
-extern void sx_3e(environment *env) {
+extern void sx_3e(environment *env)
+{
   int a, b;
   float fa, fb;
 
@@ -1190,31 +1252,35 @@
 }
 
 /* "<" */
-extern void sx_3c(environment *env) {
+extern void sx_3c(environment *env) 
+{
   swap(env); if(env->err) return;
   sx_3e(env);
 }
 
 /* "<=" */
-extern void sx_3c3d(environment *env) {
+extern void sx_3c3d(environment *env)
+{
   sx_3e(env); if(env->err) return;
   not(env);
 }
 
 /* ">=" */
-extern void sx_3e3d(environment *env) {
+extern void sx_3e3d(environment *env)
+{
   sx_3c(env); if(env->err) return;
   not(env);
 }
 
 /* Return copy of a value */
-value *copy_val(environment *env, value *old_value){
+value *copy_val(environment *env, value *old_value)
+{
   stackitem *old_item, *new_item, *prev_item;
   value *new_value;
 
-  protect(env, old_value);
+  protect(old_value);
   new_value= new_val(env);
-  protect(env, new_value);
+  protect(new_value);
   new_value->type= old_value->type;
 
   switch(old_value->type){
@@ -1249,13 +1315,14 @@
     break;
   }
 
-  unprotect(env); unprotect(env);
+  unprotect(old_value); unprotect(new_value);
 
   return new_value;
 }
 
 /* "dup"; duplicates an item on the stack */
-extern void sx_647570(environment *env) {
+extern void sx_647570(environment *env)
+{
   if((env->head)==NULL) {
     printerr("Too Few Arguments");
     env->err= 1;
@@ -1265,8 +1332,8 @@
 }
 
 /* "if", If-Then */
-extern void sx_6966(environment *env) {
-
+extern void sx_6966(environment *env)
+{
   int truth;
 
   if((env->head)==NULL || env->head->next==NULL) {
@@ -1296,8 +1363,8 @@
 }
 
 /* If-Then-Else */
-extern void ifelse(environment *env) {
-
+extern void ifelse(environment *env)
+{
   int truth;
 
   if((env->head)==NULL || env->head->next==NULL
@@ -1332,8 +1399,8 @@
 }
 
 /* "while" */
-extern void sx_7768696c65(environment *env) {
-
+extern void sx_7768696c65(environment *env)
+{
   int truth;
   value *loop, *test;
 
@@ -1344,11 +1411,11 @@
   }
 
   loop= env->head->item;
-  protect(env, loop);
+  protect(loop);
   toss(env); if(env->err) return;
 
   test= env->head->item;
-  protect(env, test);
+  protect(test);
   toss(env); if(env->err) return;
 
   do {
@@ -1373,12 +1440,13 @@
   
   } while(truth);
 
-  unprotect(env); unprotect(env);
+  unprotect(loop); unprotect(test);
 }
 
 
 /* "for"; for-loop */
-extern void sx_666f72(environment *env) {
+extern void sx_666f72(environment *env)
+{
   value *loop;
   int foo1, foo2;
 
@@ -1397,7 +1465,7 @@
   }
 
   loop= env->head->item;
-  protect(env, loop);
+  protect(loop);
   toss(env); if(env->err) return;
 
   foo2= env->head->item->content.i;
@@ -1421,12 +1489,12 @@
       foo1--;
     }
   }
-  unprotect(env);
+  unprotect(loop);
 }
 
 /* Variant of for-loop */
-extern void foreach(environment *env) {
-  
+extern void foreach(environment *env)
+{  
   value *loop, *foo;
   stackitem *iterator;
   
@@ -1443,11 +1511,11 @@
   }
 
   loop= env->head->item;
-  protect(env, loop);
+  protect(loop);
   toss(env); if(env->err) return;
 
   foo= env->head->item;
-  protect(env, foo);
+  protect(foo);
   toss(env); if(env->err) return;
 
   iterator= foo->content.ptr;
@@ -1458,15 +1526,16 @@
     eval(env); if(env->err) return;
     iterator= iterator->next;
   }
-  unprotect(env); unprotect(env);
+  unprotect(loop); unprotect(foo);
 }
 
 /* "to" */
-extern void to(environment *env) {
-  int i, start, ending;
-  stackitem *temp_head;
-  value *temp_val;
-  
+extern void to(environment *env)
+{
+  int ending, start, i;
+  stackitem *iterator, *temp;
+  value *pack;
+
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
     env->err=1;
@@ -1485,8 +1554,7 @@
   start= env->head->item->content.i;
   toss(env); if(env->err) return;
 
-  temp_head= env->head;
-  env->head= NULL;
+  push_sym(env, "[");
 
   if(ending>=start) {
     for(i= ending; i>=start; i--)
@@ -1496,19 +1564,44 @@
       push_int(env, i);
   }
 
-  temp_val= new_val(env);
-  protect(env, temp_val);
+  iterator= env->head;
+  pack= new_val(env);
+  protect(pack);
 
-  temp_val->content.ptr= env->head;
-  temp_val->type= list;
-  env->head= temp_head;
-  push_val(env, temp_val);
+  if(iterator==NULL
+     || (iterator->item->type==symb
+     && ((symbol*)(iterator->item->content.ptr))->id[0]=='[')) {
+    temp= NULL;
+    toss(env);
+  } else {
+    /* Search for first delimiter */
+    while(iterator->next!=NULL
+	  && (iterator->next->item->type!=symb
+	  || ((symbol*)(iterator->next->item->content.ptr))->id[0]!='['))
+      iterator= iterator->next;
+    
+    /* Extract list */
+    temp= env->head;
+    env->head= iterator->next;
+    iterator->next= NULL;
 
-  unprotect(env);
+    pack->type= list;
+    pack->content.ptr= temp;
+    
+    if(env->head!=NULL)
+      toss(env);
+  }
+
+  /* Push list */
+
+  push_val(env, pack);
+
+  unprotect(pack);
 }
 
 /* Read a string */
-extern void readline(environment *env) {
+extern void readline(environment *env)
+{
   char in_string[101];
 
   if(fgets(in_string, 100, env->inputstream)==NULL)
@@ -1518,7 +1611,8 @@
 }
 
 /* "read"; Read a value and place on stack */
-extern void sx_72656164(environment *env) {
+extern void sx_72656164(environment *env)
+{
   const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
   const char strform[]= "\"%[^\"]\"%n";
   const char intform[]= "%i%n";
@@ -1597,8 +1691,8 @@
     return sx_72656164(env);
 }
 
-extern void beep(environment *env) {
-
+extern void beep(environment *env)
+{
   int freq, dur, period, ticks;
 
   if((env->head)==NULL || env->head->next==NULL) {
@@ -1638,11 +1732,11 @@
   default:
     abort();
   }
-};
+}
 
 /* "wait" */
-extern void sx_77616974(environment *env) {
-
+extern void sx_77616974(environment *env)
+{
   int dur;
 
   if((env->head)==NULL) {
@@ -1661,9 +1755,10 @@
   toss(env);
 
   usleep(dur);
-};
+}
 
-extern void copying(environment *env){
+extern void copying(environment *env)
+{
   printf("GNU GENERAL PUBLIC LICENSE\n\
 		       Version 2, June 1991\n\
 \n\
@@ -1922,7 +2017,8 @@
 of promoting the sharing and reuse of software generally.\n");
 }
 
-extern void warranty(environment *env){
+extern void warranty(environment *env)
+{
   printf("			    NO WARRANTY\n\
 \n\
   11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\n\
@@ -2073,7 +2169,7 @@
 
   if((env->head)==NULL || env->head->next==NULL) {
     printerr("Too Few Arguments");
-    env->err=1;
+    env->err= 1;
     return;
   }
   
@@ -2091,3 +2187,29 @@
   printerr("Bad Argument Type");
   env->err=2;
 }
+
+/* "div" */
+extern void sx_646976(environment *env)
+{
+  int a, b;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type==integer
+     && env->head->next->item->type==integer) {
+    a= env->head->item->content.i;
+    toss(env); if(env->err) return;
+    b= env->head->item->content.i;
+    toss(env); if(env->err) return;
+    push_int(env, (int)b/a);
+
+    return;
+  }
+
+  printerr("Bad Argument Type");
+  env->err= 2;
+}