--- stack/stack.c	2002/01/08 12:33:57	1.6
+++ stack/stack.c	2002/03/08 06:44:15	1.92
@@ -1,46 +1,98 @@
-/* printf */
+/*
+    stack - an interactive interpreter for a stack-based language
+    Copyright (C) 2002	Mats Alritzson and Teddy Hogeborn
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+    Authors: Mats Alritzson <masse@fukt.bth.se>
+	     Teddy Hogeborn <teddy@fukt.bth.se>
+*/
+
+/* printf, sscanf, fgets, fprintf, fopen, perror */
 #include <stdio.h>
-/* EXIT_SUCCESS */
+/* exit, EXIT_SUCCESS, malloc, free */
 #include <stdlib.h>
 /* NULL */
 #include <stddef.h>
 /* dlopen, dlsym, dlerror */
 #include <dlfcn.h>
+/* strcmp, strcpy, strlen, strcat, strdup */
+#include <string.h>
+/* getopt, STDIN_FILENO, STDOUT_FILENO, usleep */
+#include <unistd.h>
+/* EX_NOINPUT, EX_USAGE */
+#include <sysexits.h>
+/* mtrace, muntrace */
+#include <mcheck.h>
+/* ioctl */
+#include <sys/ioctl.h>
+/* KDMKTONE */
+#include <linux/kd.h>
 
-#define HASHTBLSIZE 65536
+#include "stack.h"
 
-typedef struct stack_item
+/* Initialize a newly created environment */
+void init_env(environment *env)
 {
-  enum {value, string, ref, func, symbol} type;
-  union {
-    void* ptr;
-    int val;
-  } content;
+  int i;
 
-  char* id;
-  struct stack_item* next;
-} stackitem;
+  env->gc_limit= 20;
+  env->gc_count= 0;
+  env->gc_ref= NULL;
+  env->gc_protect= NULL;
 
+  env->head= NULL;
+  for(i= 0; i<HASHTBLSIZE; i++)
+    env->symbols[i]= NULL;
+  env->err= 0;
+  env->in_string= NULL;
+  env->free_string= NULL;
+  env->inputstream= stdin;
+  env->interactive= 1;
+}
 
-typedef stackitem* hashtbl[HASHTBLSIZE];
-typedef void (*funcp)(stackitem**);
+void printerr(const char* in_string) {
+  fprintf(stderr, "Err: %s\n", in_string);
+}
 
-void init_hashtbl(hashtbl out_hash)
+/* Discard the top element of the stack. */
+extern void toss(environment *env)
 {
-  long i;
+  stackitem *temp= env->head;
 
-  for(i= 0; i<HASHTBLSIZE; i++)
-    out_hash[i]= NULL;
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+  
+  env->head= env->head->next;	/* Remove the top stack item */
+  free(temp);			/* Free the old top stack item */
+
+  gc_init(env);
 }
 
-stackitem** hash(hashtbl in_hashtbl, const char* in_string)
+/* Returns a pointer to a pointer to an element in the hash table. */
+symbol **hash(hashtbl in_hashtbl, const char *in_string)
 {
-  long i= 0;
-  unsigned long out_hash= 0;
-  char key= 0;
-  stackitem** position;
+  int i= 0;
+  unsigned int out_hash= 0;
+  char key= '\0';
+  symbol **position;
   
-  while(1){
+  while(1){			/* Hash in_string */
     key= in_string[i++];
     if(key=='\0')
       break;
@@ -51,243 +103,1757 @@
   position= &(in_hashtbl[out_hash]);
 
   while(1){
-    if(*position==NULL)
+    if(*position==NULL)		/* If empty */
       return position;
     
-    if(strcmp(in_string, (*position)->id)==0)
+    if(strcmp(in_string, (*position)->id)==0) /* If match */
       return position;
 
-    position= &((*position)->next);
+    position= &((*position)->next); /* Try next */
   }
 }
 
+value* new_val(environment *env) {
+  value *nval= malloc(sizeof(value));
+  stackitem *nitem= malloc(sizeof(stackitem));
 
-int push(stackitem** stack_head, stackitem* in_item)
-{
-  in_item->next= *stack_head;
-  *stack_head= in_item;
-  return 1;
-}
+  nval->content.ptr= NULL;
+  protect(env, nval);
 
-int push_val(stackitem** stack_head, int in_val) 
-{
-  stackitem* new_item= malloc(sizeof(stackitem));
-  new_item->content.val= in_val;
-  new_item->type= value;
+  gc_init(env);
+
+  nitem->item= nval;
+  nitem->next= env->gc_ref;
+  env->gc_ref= nitem;
 
-  push(stack_head, new_item);
-  return 1;
+  env->gc_count++;
+  unprotect(env);
+
+  return nval;
 }
 
-int push_cstring(stackitem** stack_head, const char* in_string)
-{
-  stackitem* new_item= malloc(sizeof(stackitem));
-  new_item->content.ptr= malloc(strlen(in_string)+1);
-  strcpy(new_item->content.ptr, in_string);
-  new_item->type= string;
+void gc_mark(value *val) {
+  stackitem *iterator;
+
+  if(val==NULL || val->gc_garb==0)
+    return;
+
+  val->gc_garb= 0;
 
-  push(stack_head, new_item);
-  return 1;
+  if(val->type==list) {
+    iterator= val->content.ptr;
+
+    while(iterator!=NULL) {
+      gc_mark(iterator->item);
+      iterator= iterator->next;
+    }
+  }
 }
 
-int mk_hashentry(hashtbl in_hashtbl, stackitem* in_item, const char* id)
-{
-  in_item->id= malloc(strlen(id)+1);
+extern void gc_init(environment *env) {
+  stackitem *new_head= NULL, *titem, *iterator= env->gc_ref;
+  symbol *tsymb;
+  int i;
 
-  strcpy(in_item->id, id);
-  push(hash(in_hashtbl, id), in_item);
+  if(env->gc_count < env->gc_limit)
+    return;
+
+  while(iterator!=NULL) {
+    iterator->item->gc_garb= 1;
+    iterator= iterator->next;
+  }
 
-  return 1;
+  /* Mark */
+  iterator= env->gc_protect;
+  while(iterator!=NULL) {
+    gc_mark(iterator->item);
+    iterator= iterator->next;
+  }
+
+  iterator= env->head;
+  while(iterator!=NULL) {
+    gc_mark(iterator->item);
+    iterator= iterator->next;
+  }
+
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    tsymb= env->symbols[i];
+    while(tsymb!=NULL) {
+      gc_mark(tsymb->val);
+      tsymb= tsymb->next;
+    }
+  }
+
+  env->gc_count= 0;
+
+  /* Sweep */
+  while(env->gc_ref!=NULL) {
+
+    if(env->gc_ref->item->gc_garb) {
+      switch(env->gc_ref->item->type) {
+      case string:
+	free(env->gc_ref->item->content.ptr);
+	break;
+      case integer:
+	break;
+      case list:
+	while(env->gc_ref->item->content.ptr!=NULL) {
+	  titem= env->gc_ref->item->content.ptr;
+	  env->gc_ref->item->content.ptr= titem->next;
+	  free(titem);
+	}
+	break;
+      default:
+	break;
+      }
+      free(env->gc_ref->item);
+      titem= env->gc_ref->next;
+      free(env->gc_ref);
+      env->gc_ref= titem;
+    } else {
+      titem= env->gc_ref->next;
+      env->gc_ref->next= new_head;
+      new_head= env->gc_ref;
+      env->gc_ref= titem;
+      env->gc_count++;
+    }
+  }
+
+  env->gc_limit= env->gc_count*2;
+  env->gc_ref= new_head;
 }
 
-void def_func(hashtbl in_hashtbl, funcp in_func, const char* id)
+void protect(environment *env, value *val)
 {
-  stackitem* temp= malloc(sizeof(stackitem));
+  stackitem *new_item= malloc(sizeof(stackitem));
+  new_item->item= val;
+  new_item->next= env->gc_protect;
+  env->gc_protect= new_item;
+}
 
-  temp->type= func;
-  temp->content.ptr= in_func;
+void unprotect(environment *env)
+{
+  stackitem *temp= env->gc_protect;
+  env->gc_protect= env->gc_protect->next;
+  free(temp);
+}
 
-  mk_hashentry(in_hashtbl, temp, id);
+/* Push a value onto the stack */
+void push_val(environment *env, value *val)
+{
+  stackitem *new_item= malloc(sizeof(stackitem));
+  new_item->item= val;
+  new_item->next= env->head;
+  env->head= new_item;
 }
 
-void def_sym(hashtbl in_hashtbl, const char* id)
+/* Push an integer onto the stack. */
+void push_int(environment *env, int in_val) 
 {
-  stackitem* temp= malloc(sizeof(stackitem));
+  value *new_value= new_val(env);
   
-  temp->type= symbol;
+  new_value->content.val= in_val;
+  new_value->type= integer;
 
-  mk_hashentry(in_hashtbl, temp, id);
+  push_val(env, new_value);
 }
 
-int push_ref(stackitem** stack_head, hashtbl in_hash, const char* in_string)
+/* Copy a string onto the stack. */
+void push_cstring(environment *env, const char *in_string)
 {
-  static void* handle= NULL;
-  void* symbol;
+  value *new_value= new_val(env);
 
-  stackitem* new_item= malloc(sizeof(stackitem));
-  new_item->content.ptr= *hash(in_hash, in_string);
-  new_item->type= ref;
+  new_value->content.ptr= malloc(strlen(in_string)+1);
+  strcpy(new_value->content.ptr, in_string);
+  new_value->type= string;
 
-  if(handle==NULL)
-    handle= dlopen(NULL, RTLD_LAZY);
+  push_val(env, new_value);
+}
 
-  if(new_item->content.ptr==NULL) {
-    symbol= dlsym(handle, in_string);
-    if(dlerror()==NULL) 
-      def_func(in_hash, symbol, in_string);
-    else
-      def_sym(in_hash, in_string);
-      
-    new_item->content.ptr= *hash(in_hash, in_string);
-    new_item->type= ref;
+/* Mangle a symbol name to a valid C identifier name */
+char *mangle_str(const char *old_string){
+  char validchars[]= "0123456789abcdef";
+  char *new_string, *current;
+
+  new_string= malloc((strlen(old_string)*2)+4);
+  strcpy(new_string, "sx_");	/* Stack eXternal */
+  current= new_string+3;
+  while(old_string[0] != '\0'){
+    current[0]= validchars[(unsigned char)(old_string[0])/16];
+    current[1]= validchars[(unsigned char)(old_string[0])%16];
+    current+= 2;
+    old_string++;
   }
+  current[0]= '\0';
 
-  push(stack_head, new_item);
-  return 1;
+  return new_string;		/* The caller must free() it */
 }
 
-extern void toss(stackitem** stack_head)
-{
-  stackitem* temp= *stack_head;
+extern void mangle(environment *env){
+  char *new_string;
 
-  *stack_head= (*stack_head)->next;
-  free(temp);
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type!=string) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  new_string= mangle_str((const char *)(env->head->item->content.ptr));
+
+  toss(env);
+  if(env->err) return;
+
+  push_cstring(env, new_string);
 }
 
+/* Push a symbol onto the stack. */
+void push_sym(environment *env, const char *in_string)
+{
+  value *new_value;		/* A new symbol value */
+  /* ...which might point to... */
+  symbol **new_symbol;		/* (if needed) A new actual symbol */
+  /* ...which, if possible, will be bound to... */
+  value *new_fvalue;		/* (if needed) A new function value */
+  /* ...which will point to... */
+  void *funcptr;		/* A function pointer */
+
+  static void *handle= NULL;	/* Dynamic linker handle */
+  const char *dlerr;		/* Dynamic linker error */
+  char *mangled;		/* Mangled function name */
+
+  new_value= new_val(env);
+
+  /* The new value is a symbol */
+  new_value->type= symb;
+
+  /* Look up the symbol name in the hash table */
+  new_symbol= hash(env->symbols, in_string);
+  new_value->content.ptr= *new_symbol;
+
+  if(*new_symbol==NULL) { /* If symbol was undefined */
+
+    /* Create a new symbol */
+    (*new_symbol)= malloc(sizeof(symbol));
+    (*new_symbol)->val= NULL;	/* undefined value */
+    (*new_symbol)->next= NULL;
+    (*new_symbol)->id= malloc(strlen(in_string)+1);
+    strcpy((*new_symbol)->id, in_string);
+
+    /* Intern the new symbol in the hash table */
+    new_value->content.ptr= *new_symbol;
+
+    /* Try to load the symbol name as an external function, to see if
+       we should bind the symbol to a new function pointer value */
+    if(handle==NULL)		/* If no handle */
+      handle= dlopen(NULL, RTLD_LAZY);
+
+    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= new_val(env); /* Create a new value */
+      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 */
+    }
+  }
+  push_val(env, new_value);
+}
 
-/* print_stack(stack); */
-void print_st(stackitem* stack_head, long counter)
-{ 
-  if(stack_head->next != NULL)
-    print_st(stack_head->next, counter+1);
+/* Print newline. */
+extern void nl()
+{
+  printf("\n");
+}
 
-  switch(stack_head->type){
-  case value:
-    printf("%ld: %d\n", counter, (int)stack_head->content.val);
+/* Gets the type of a value */
+extern void type(environment *env){
+  int typenum;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  typenum=env->head->item->type;
+  toss(env);
+  switch(typenum){
+  case integer:
+    push_sym(env, "integer");
     break;
   case string:
-    printf("%ld: \"%s\"\n", counter, (char*)stack_head->content.ptr);
+    push_sym(env, "string");
     break;
-  case ref:
-    printf("%ld: %s\n", counter, ((stackitem*)stack_head->content.ptr)->id);
+  case symb:
+    push_sym(env, "symbol");
     break;
   case func:
-  case symbol:
-    printf("%ld: %p\n", counter, stack_head->content.ptr);
+    push_sym(env, "function");
+    break;
+  case list:
+    push_sym(env, "list");
+    break;
+  }
+}    
+
+/* Prints the top element of the stack. */
+void print_h(stackitem *stack_head, int noquote)
+{
+  switch(stack_head->item->type) {
+  case integer:
+    printf("%d", stack_head->item->content.val);
+    break;
+  case string:
+    if(noquote)
+      printf("%s", (char*)stack_head->item->content.ptr);
+    else
+      printf("\"%s\"", (char*)stack_head->item->content.ptr);
+    break;
+  case symb:
+    printf("%s", ((symbol *)(stack_head->item->content.ptr))->id);
+    break;
+  case func:
+    printf("#<function %p>", (funcp)(stack_head->item->content.ptr));
+    break;
+  case list:
+    /* A list is just a stack, so make stack_head point to it */
+    stack_head=(stackitem *)(stack_head->item->content.ptr);
+    printf("[ ");
+    while(stack_head != NULL) {
+      print_h(stack_head, noquote);
+      printf(" ");
+      stack_head=stack_head->next;
+    }
+    printf("]");
     break;
   }
 }
 
-extern void printstack(stackitem** stack_head)
+extern void print_(environment *env) {
+  if(env->head==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+  print_h(env->head, 0);
+  nl();
+}
+
+/* Prints the top element of the stack and then discards it. */
+extern void print(environment *env)
 {
-  if(*stack_head != NULL) {
-    print_st(*stack_head, 1);
-    printf("\n");
+  print_(env);
+  if(env->err) return;
+  toss(env);
+}
+
+extern void princ_(environment *env) {
+  if(env->head==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
   }
+  print_h(env->head, 1);
 }
 
+/* Prints the top element of the stack and then discards it. */
+extern void princ(environment *env)
+{
+  princ_(env);
+  if(env->err) return;
+  toss(env);
+}
 
-extern void eval(stackitem** stack_head)
+/* Only to be called by function printstack. */
+void print_st(stackitem *stack_head, long counter)
+{ 
+  if(stack_head->next != NULL)
+    print_st(stack_head->next, counter+1);
+  printf("%ld: ", counter);
+  print_h(stack_head, 0);
+  nl();
+}
+
+/* Prints the stack. */
+extern void printstack(environment *env)
+{
+  if(env->head == NULL) {
+    printf("Stack Empty\n");
+    return;
+  }
+  print_st(env->head, 1);
+}
+
+/* Swap the two top elements on the stack. */
+extern void swap(environment *env)
+{
+  stackitem *temp= env->head;
+  
+  if(env->head==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  env->head= env->head->next;
+  temp->next= env->head->next;
+  env->head->next= temp;
+} 
+
+/* Rotate the first three elements on the stack. */
+extern void rot(environment *env)
+{
+  stackitem *temp= env->head;
+  
+  if(env->head==NULL || env->head->next==NULL
+      || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  env->head= env->head->next->next;
+  temp->next->next= env->head->next;
+  env->head->next= temp;
+}
+
+/* Recall a value from a symbol, if bound */
+extern void rcl(environment *env)
+{
+  value *val;
+
+  if(env->head == NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=symb) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  val=((symbol *)(env->head->item->content.ptr))->val;
+  if(val == NULL){
+    printerr("Unbound Variable");
+    env->err=3;
+    return;
+  }
+  protect(env, val);
+  toss(env);		/* toss the symbol */
+  if(env->err) return;
+  push_val(env, val); /* Return its bound value */
+  unprotect(env);
+}
+
+/* If the top element is a symbol, determine if it's bound to a
+   function value, and if it is, toss the symbol and execute the
+   function. */
+extern void eval(environment *env)
 {
   funcp in_func;
+  value* temp_val;
+  stackitem* iterator;
 
-  if((*stack_head)==NULL || (*stack_head)->type!=ref)
+ eval_start:
+
+  if(env->head==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
     return;
+  }
 
-  if(((stackitem*)(*stack_head)->content.ptr)->type==func) {
-    in_func= (funcp)((stackitem*)(*stack_head)->content.ptr)->content.ptr;
-    toss(stack_head); 
-    (*in_func)(stack_head);
+  switch(env->head->item->type) {
+    /* if it's a symbol */
+  case symb:
+    rcl(env);			/* get its contents */
+    if(env->err) return;
+    if(env->head->item->type!=symb){ /* don't recurse symbols */
+      goto eval_start;
+    }
     return;
+
+    /* If it's a lone function value, run it */
+  case func:
+    in_func= (funcp)(env->head->item->content.ptr);
+    toss(env); 
+    if(env->err) return;
+    return in_func(env);
+
+    /* If it's a list */
+  case list:
+    temp_val= env->head->item;
+    protect(env, temp_val);
+    toss(env);
+    if(env->err) return;
+    iterator= (stackitem*)temp_val->content.ptr;
+    unprotect(env);
+    
+    while(iterator!=NULL) {
+      push_val(env, iterator->item);
+      
+      if(env->head->item->type==symb
+	&& strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
+	toss(env);
+	if(env->err) return;
+	
+	if(iterator->next == NULL){
+	  goto eval_start;
+	}
+	eval(env);
+	if(env->err) return;
+      }
+      iterator= iterator->next;
+    }
+    return;
+
+  default:
+    return;
+  }
+}
+
+/* Reverse (flip) a list */
+extern void rev(environment *env){
+  stackitem *old_head, *new_head, *item;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type!=list) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  old_head= (stackitem *)(env->head->item->content.ptr);
+  new_head= NULL;
+  while(old_head != NULL){
+    item= old_head;
+    old_head= old_head->next;
+    item->next= new_head;
+    new_head= item;
+  }
+  env->head->item->content.ptr= new_head;
+}
+
+/* Make a list. */
+extern void pack(environment *env)
+{
+  stackitem *iterator, *temp;
+  value *pack;
+
+  iterator= env->head;
+
+  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;
+    
+    if(env->head!=NULL)
+      toss(env);
+  }
+
+  /* Push list */
+  pack= new_val(env);
+  pack->type= list;
+  pack->content.ptr= temp;
+
+  push_val(env, pack);
+  rev(env);
+}
+
+/* Relocate elements of the list on the stack. */
+extern void expand(environment *env)
+{
+  stackitem *temp, *new_head;
+
+  /* Is top element a list? */
+  if(env->head==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+  if(env->head->item->type!=list) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  rev(env);
+
+  if(env->err)
+    return;
+
+  /* The first list element is the new stack head */
+  new_head= temp= env->head->item->content.ptr;
+
+  toss(env);
+
+  /* Find the end of the list */
+  while(temp->next!=NULL)
+    temp= temp->next;
+
+  /* Connect the tail of the list with the old stack head */
+  temp->next= env->head;
+  env->head= new_head;		/* ...and voila! */
+
+}
+
+/* Compares two elements by reference. */
+extern void eq(environment *env)
+{
+  void *left, *right;
+  int result;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  left= env->head->item->content.ptr;
+  swap(env);
+  right= env->head->item->content.ptr;
+  result= (left==right);
+  
+  toss(env); toss(env);
+  push_int(env, result);
+}
+
+/* Negates the top element on the stack. */
+extern void not(environment *env)
+{
+  int val;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  val= env->head->item->content.val;
+  toss(env);
+  push_int(env, !val);
+}
+
+/* Compares the two top elements on the stack and return 0 if they're the
+   same. */
+extern void neq(environment *env)
+{
+  eq(env);
+  not(env);
+}
+
+/* Give a symbol some content. */
+extern void def(environment *env)
+{
+  symbol *sym;
+
+  /* Needs two values on the stack, the top one must be a symbol */
+  if(env->head==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type!=symb) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  /* long names are a pain */
+  sym= env->head->item->content.ptr;
+
+  /* Bind the symbol to the value */
+  sym->val= env->head->next->item;
+
+  toss(env); toss(env);
+} 
+
+/* Quit stack. */
+extern void quit(environment *env)
+{
+  long i;
+
+  clear(env);
+
+  if (env->err) return;
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    while(env->symbols[i]!= NULL) {
+      forget_sym(&(env->symbols[i]));
+    }
+    env->symbols[i]= NULL;
   }
+
+  env->gc_limit= 0;
+  gc_init(env);
+
+  if(env->free_string!=NULL)
+    free(env->free_string);
+  
+  muntrace();
+
+  exit(EXIT_SUCCESS);
 }
 
-int stack_read(stackitem** stack_head, hashtbl in_hash, char* in_line) 
+/* Clear stack */
+extern void clear(environment *env)
 {
-  char *temp, *rest;
-  int itemp;
-  size_t inlength= strlen(in_line)+1;
-  int convert= 0;
+  while(env->head!=NULL)
+    toss(env);
+}
 
-  temp= malloc(inlength);
-  rest= malloc(inlength);
+/* List all defined words */
+extern void words(environment *env)
+{
+  symbol *temp;
+  int i;
+  
+  for(i= 0; i<HASHTBLSIZE; i++) {
+    temp= env->symbols[i];
+    while(temp!=NULL) {
+      printf("%s\n", temp->id);
+      temp= temp->next;
+    }
+  }
+}
 
-  if((convert= sscanf(in_line, "\"%[^\"\n\r]\" %[^\n\r]", temp, rest)) >= 1)
-    push_cstring(stack_head, temp);
-  else if((convert= sscanf(in_line, "%d %[^\n\r]", &itemp, rest)) >= 1)
-    push_val(stack_head, itemp);
-  else if((convert= sscanf(in_line, "%[^ ;\n\r]%[^\n\r]", temp, rest)) >= 1) 
-    push_ref(stack_head, in_hash, temp);
-  else if((convert= sscanf(in_line, "%c%[^\n\r]", temp, rest)) >= 1)
-    if(*temp==';')
-      eval(stack_head);
+/* Internal forget function */
+void forget_sym(symbol **hash_entry) {
+  symbol *temp;
 
+  temp= *hash_entry;
+  *hash_entry= (*hash_entry)->next;
+  
+  free(temp->id);
   free(temp);
+}
+
+/* Forgets a symbol (remove it from the hash table) */
+extern void forget(environment *env)
+{
+  char* sym_id;
+  stackitem *stack_head= env->head;
 
-  if(convert<2) {
-    free(rest);
-    return 0;
+  if(stack_head==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
   }
-   
-  stack_read(stack_head, in_hash, rest);
   
-  free(rest);
-  return 1;
+  if(stack_head->item->type!=symb) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  sym_id= ((symbol*)(stack_head->item->content.ptr))->id;
+  toss(env);
+
+  return forget_sym(hash(env->symbols, sym_id));
+}
+
+/* Returns the current error number to the stack */
+extern void errn(environment *env){
+  push_int(env, env->err);
 }
 
-extern void print(stackitem** stack_head)
+int main(int argc, char **argv)
 {
-  if((*stack_head)==NULL)
+  environment myenv;
+
+  int c;			/* getopt option character */
+
+  mtrace();
+
+  init_env(&myenv);
+
+  myenv.interactive = isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
+
+  while ((c = getopt (argc, argv, "i")) != -1)
+    switch (c)
+      {
+      case 'i':
+	myenv.interactive = 1;
+	break;
+      case '?':
+	fprintf (stderr,
+		 "Unknown option character `\\x%x'.\n",
+		 optopt);
+	return EX_USAGE;
+      default:
+	abort ();
+      }
+  
+  if (optind < argc) {
+    myenv.interactive = 0;
+    myenv.inputstream= fopen(argv[optind], "r");
+    if(myenv.inputstream== NULL) {
+      perror(argv[0]);
+      exit (EX_NOINPUT);
+    }
+  }
+
+  if(myenv.interactive) {
+    printf("Stack version $Revision: 1.92 $\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\
+under certain conditions; type `copying;' for details.\n");
+  }
+
+  while(1) {
+    if(myenv.in_string==NULL) {
+      if (myenv.interactive) {
+	if(myenv.err) {
+	  printf("(error %d)\n", myenv.err);
+	}
+	nl();
+	printstack(&myenv);
+	printf("> ");
+      }
+      myenv.err=0;
+    }
+    sx_72656164(&myenv);
+    if (myenv.err==4) {
+      return EXIT_SUCCESS;	/* EOF */
+    } else if(myenv.head!=NULL
+	      && myenv.head->item->type==symb
+	      && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {
+      toss(&myenv); 		/* No error check in main */
+      eval(&myenv);
+    }
+    gc_init(&myenv);
+  }
+  quit(&myenv);
+  return EXIT_FAILURE;
+}
+
+/* "+" */
+extern void sx_2b(environment *env) {
+  int a, b;
+  size_t len;
+  char* new_string;
+  value *a_val, *b_val;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->item->type==string
+     && 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);
+    toss(env); if(env->err) return;
+    toss(env); if(env->err) return;
+    len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
+    new_string= malloc(len);
+    strcpy(new_string, b_val->content.ptr);
+    strcat(new_string, a_val->content.ptr);
+    push_cstring(env, new_string);
+    unprotect(env); unprotect(env);
+    free(new_string);
+    return;
+  }
+  
+  if(env->head->item->type!=integer
+     || env->head->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  a= env->head->item->content.val;
+  toss(env); if(env->err) return;
+  
+  b= env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, a+b);
+}
+
+/* "-" */
+extern void sx_2d(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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  a=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b-a);
+}
+
+/* ">" */
+extern void sx_3e(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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
 
-  switch((*stack_head)->type){
-  case value:
-    printf("%d", (*stack_head)->content.val);
+  a=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b>a);
+}
+
+/* Return copy of a value */
+value *copy_val(environment *env, value *old_value){
+  stackitem *old_item, *new_item, *prev_item;
+
+  value *new_value= new_val(env);
+
+  protect(env, old_value);
+  new_value->type= old_value->type;
+
+  switch(old_value->type){
+  case integer:
+    new_value->content.val= old_value->content.val;
     break;
   case string:
-    printf("%s", (char*)(*stack_head)->content.ptr);
+    (char *)(new_value->content.ptr)= 
+      strdup((char *)(old_value->content.ptr));
     break;
-  case ref:
-    printf("%s", ((stackitem*)(*stack_head)->content.ptr)->id);
+  case func:
+  case symb:
+    new_value->content.ptr= old_value->content.ptr;
     break;
-  case symbol:
-  default:
-    printf("%p", (*stack_head)->content.ptr);
+  case list:
+    new_value->content.ptr= NULL;
+
+    prev_item= NULL;
+    old_item= (stackitem*)(old_value->content.ptr);
+
+    while(old_item != NULL) {	/* While list is not empty */
+      new_item= malloc(sizeof(stackitem));
+      new_item->item= copy_val(env, old_item->item); /* recurse */
+      new_item->next= NULL;
+      if(prev_item != NULL)	/* If this wasn't the first item */
+	prev_item->next= new_item; /* point the previous item to the
+                                     new item */
+      else
+	new_value->content.ptr= new_item;
+      old_item= old_item->next;
+      prev_item= new_item;
+    }	  
     break;
   }
 
-  toss(stack_head);
+  unprotect(env);
+
+  return new_value;
 }
 
-extern void nl()
-{
-  printf("\n");
+/* "dup"; duplicates an item on the stack */
+extern void sx_647570(environment *env) {
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+  push_val(env, copy_val(env, env->head->item));
 }
 
-extern void quit()
-{
-  exit(EXIT_SUCCESS);
+/* "if", If-Then */
+extern void sx_6966(environment *env) {
+
+  int truth;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+  
+  swap(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  toss(env);
+  if(env->err) return;
+
+  if(truth)
+    eval(env);
+  else
+    toss(env);
 }
 
-int main()
-{
-  stackitem* s= NULL;
-  hashtbl myhash;
-  char in_string[100];
+/* If-Then-Else */
+extern void ifelse(environment *env) {
 
-  init_hashtbl(myhash);
+  int truth;
 
-  printf("okidok\n ");
+  if((env->head)==NULL || env->head->next==NULL
+     || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
 
-  while(fgets(in_string, 100, stdin) != NULL) {
-    stack_read(&s, myhash, in_string);
-    printf("okidok\n ");
+  if(env->head->next->next->item->type != integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
   }
+  
+  rot(env);
+  if(env->err) return;
+  
+  truth=env->head->item->content.val;
+
+  toss(env);
+  if(env->err) return;
 
+  if(!truth)
+    swap(env);
+  if(env->err) return;
 
-  return EXIT_SUCCESS;
+  toss(env);
+  if(env->err) return;
+
+  eval(env);
 }
 
-/* Local Variables: */
-/* compile-command:"make CFLAGS=\"-Wall -g -rdynamic -ldl\" stack" */
-/* End: */
+/* "while" */
+extern void sx_7768696c65(environment *env) {
+
+  int truth;
+  value *loop, *test;
+
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  loop= env->head->item;
+  protect(env, loop);
+  toss(env); if(env->err) return;
+
+  test= env->head->item;
+  protect(env, test);
+  toss(env); if(env->err) return;
+
+  do {
+    push_val(env, test);
+    eval(env);
+    
+    if(env->head->item->type != integer) {
+      printerr("Bad Argument Type");
+      env->err= 2;
+      return;
+    }
+    
+    truth= env->head->item->content.val;
+    toss(env); if(env->err) return;
+    
+    if(truth) {
+      push_val(env, loop);
+      eval(env);
+    } else {
+      toss(env);
+    }
+  
+  } while(truth);
+
+  unprotect(env); unprotect(env);
+}
+
+
+/* "for"; for-loop */
+extern void sx_666f72(environment *env) {
+  value *loop;
+  int foo1, foo2;
+
+  if(env->head==NULL || env->head->next==NULL 
+     || env->head->next->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->next->item->type!=integer
+     || env->head->next->next->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  loop= env->head->item;
+  protect(env, loop);
+  toss(env); if(env->err) return;
+
+  foo2= env->head->item->content.val;
+  toss(env); if(env->err) return;
+
+  foo1= env->head->item->content.val;
+  toss(env); if(env->err) return;
+
+  if(foo1<=foo2) {
+    while(foo1<=foo2) {
+      push_int(env, foo1);
+      push_val(env, loop);
+      eval(env); if(env->err) return;
+      foo1++;
+    }
+  } else {
+    while(foo1>=foo2) {
+      push_int(env, foo1);
+      push_val(env, loop);
+      eval(env); if(env->err) return;
+      foo1--;
+    }
+  }
+  unprotect(env);
+}
+
+/* Variant of for-loop */
+extern void foreach(environment *env) {
+  
+  value *loop, *foo;
+  stackitem *iterator;
+  
+  if((env->head)==NULL || env->head->next==NULL) {
+    printerr("Too Few Arguments");
+    env->err= 1;
+    return;
+  }
+
+  if(env->head->next->item->type != list) {
+    printerr("Bad Argument Type");
+    env->err= 2;
+    return;
+  }
+
+  loop= env->head->item;
+  protect(env, loop);
+  toss(env); if(env->err) return;
+
+  foo= env->head->item;
+  protect(env, foo);
+  toss(env); if(env->err) return;
+
+  iterator= foo->content.ptr;
+
+  while(iterator!=NULL) {
+    push_val(env, iterator->item);
+    push_val(env, loop);
+    eval(env); if(env->err) return;
+    iterator= iterator->next;
+  }
+  unprotect(env); unprotect(env);
+}
+
+/* "to" */
+extern void to(environment *env) {
+  int i, start, ending;
+  stackitem *temp_head;
+  value *temp_val;
+  
+  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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  ending= env->head->item->content.val;
+  toss(env); if(env->err) return;
+  start= env->head->item->content.val;
+  toss(env); if(env->err) return;
+
+  temp_head= env->head;
+  env->head= NULL;
+
+  if(ending>=start) {
+    for(i= ending; i>=start; i--)
+      push_int(env, i);
+  } else {
+    for(i= ending; i<=start; i++)
+      push_int(env, i);
+  }
+
+  temp_val= new_val(env);
+  temp_val->content.ptr= env->head;
+  temp_val->type= list;
+  env->head= temp_head;
+  push_val(env, temp_val);
+}
+
+/* Read a string */
+extern void readline(environment *env) {
+  char in_string[101];
+
+  if(fgets(in_string, 100, env->inputstream)==NULL)
+    push_cstring(env, "");
+  else
+    push_cstring(env, in_string);
+}
+
+/* "read"; Read a value and place on stack */
+extern void sx_72656164(environment *env) {
+  const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
+  const char strform[]= "\"%[^\"]\"%n";
+  const char intform[]= "%i%n";
+  const char blankform[]= "%*[ \t]%n";
+  const char ebrackform[]= "]%n";
+  const char semicform[]= ";%n";
+  const char bbrackform[]= "[%n";
+
+  int itemp, readlength= -1;
+  static int depth= 0;
+  char *match;
+  size_t inlength;
+
+  if(env->in_string==NULL) {
+    if(depth > 0 && env->interactive) {
+      printf("]> ");
+    }
+    readline(env); if(env->err) return;
+
+    if(((char *)(env->head->item->content.ptr))[0]=='\0'){
+      env->err= 4;		/* "" means EOF */
+      return;
+    }
+    
+    env->in_string= malloc(strlen(env->head->item->content.ptr)+1);
+    env->free_string= env->in_string; /* Save the original pointer */
+    strcpy(env->in_string, env->head->item->content.ptr);
+    toss(env); if(env->err) return;
+  }
+  
+  inlength= strlen(env->in_string)+1;
+  match= malloc(inlength);
+
+  if(sscanf(env->in_string, blankform, &readlength)!=EOF
+     && readlength != -1) {
+    ; 
+  } else if(sscanf(env->in_string, intform, &itemp, &readlength) != EOF
+	    && readlength != -1) {
+    push_int(env, itemp);
+  } else if(sscanf(env->in_string, strform, match, &readlength) != EOF
+	    && readlength != -1) {
+    push_cstring(env, match);
+  } else if(sscanf(env->in_string, symbform, match, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, match);
+  } else if(sscanf(env->in_string, ebrackform, &readlength) != EOF
+	    && readlength != -1) {
+    pack(env); if(env->err) return;
+    if(depth != 0) depth--;
+  } else if(sscanf(env->in_string, semicform, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, ";");
+  } else if(sscanf(env->in_string, bbrackform, &readlength) != EOF
+	    && readlength != -1) {
+    push_sym(env, "[");
+    depth++;
+  } else {
+    free(env->free_string);
+    env->in_string = env->free_string = NULL;
+  }
+  if ( env->in_string != NULL) {
+    env->in_string += readlength;
+  }
+
+  free(match);
+
+  if(depth)
+    return sx_72656164(env);
+}
+
+extern void beep(environment *env) {
+
+  int freq, dur, period, ticks;
+
+  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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  dur=env->head->item->content.val;
+  toss(env);
+  freq=env->head->item->content.val;
+  toss(env);
+
+  period=1193180/freq;		/* convert freq from Hz to period
+                                   length */
+  ticks=dur*.001193180;		/* convert duration from µseconds to
+				   timer ticks */
+
+/*    ticks=dur/1000; */
+
+  /*  if (ioctl(STDOUT_FILENO, KDMKTONE, (125<<16) + 0x637)==0) */
+  switch (ioctl(STDOUT_FILENO, KDMKTONE, (ticks<<16) | period)){
+  case 0:
+    usleep(dur);
+    return;
+  case -1:
+    perror("beep");
+    env->err=5;
+    return;
+  default:
+    abort();
+  }
+};
+
+/* "wait" */
+extern void sx_77616974(environment *env) {
+
+  int dur;
+
+  if((env->head)==NULL) {
+    printerr("Too Few Arguments");
+    env->err=1;
+    return;
+  }
+
+  if(env->head->item->type!=integer) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  dur=env->head->item->content.val;
+  toss(env);
+
+  usleep(dur);
+};
+
+extern void copying(environment *env){
+  printf("GNU GENERAL PUBLIC LICENSE\n\
+		       Version 2, June 1991\n\
+\n\
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.\n\
+     59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\n\
+ Everyone is permitted to copy and distribute verbatim copies\n\
+ of this license document, but changing it is not allowed.\n\
+\n\
+			    Preamble\n\
+\n\
+  The licenses for most software are designed to take away your\n\
+freedom to share and change it.  By contrast, the GNU General Public\n\
+License is intended to guarantee your freedom to share and change free\n\
+software--to make sure the software is free for all its users.  This\n\
+General Public License applies to most of the Free Software\n\
+Foundation's software and to any other program whose authors commit to\n\
+using it.  (Some other Free Software Foundation software is covered by\n\
+the GNU Library General Public License instead.)  You can apply it to\n\
+your programs, too.\n\
+\n\
+  When we speak of free software, we are referring to freedom, not\n\
+price.  Our General Public Licenses are designed to make sure that you\n\
+have the freedom to distribute copies of free software (and charge for\n\
+this service if you wish), that you receive source code or can get it\n\
+if you want it, that you can change the software or use pieces of it\n\
+in new free programs; and that you know you can do these things.\n\
+\n\
+  To protect your rights, we need to make restrictions that forbid\n\
+anyone to deny you these rights or to ask you to surrender the rights.\n\
+These restrictions translate to certain responsibilities for you if you\n\
+distribute copies of the software, or if you modify it.\n\
+\n\
+  For example, if you distribute copies of such a program, whether\n\
+gratis or for a fee, you must give the recipients all the rights that\n\
+you have.  You must make sure that they, too, receive or can get the\n\
+source code.  And you must show them these terms so they know their\n\
+rights.\n\
+\n\
+  We protect your rights with two steps: (1) copyright the software, and\n\
+(2) offer you this license which gives you legal permission to copy,\n\
+distribute and/or modify the software.\n\
+\n\
+  Also, for each author's protection and ours, we want to make certain\n\
+that everyone understands that there is no warranty for this free\n\
+software.  If the software is modified by someone else and passed on, we\n\
+want its recipients to know that what they have is not the original, so\n\
+that any problems introduced by others will not reflect on the original\n\
+authors' reputations.\n\
+\n\
+  Finally, any free program is threatened constantly by software\n\
+patents.  We wish to avoid the danger that redistributors of a free\n\
+program will individually obtain patent licenses, in effect making the\n\
+program proprietary.  To prevent this, we have made it clear that any\n\
+patent must be licensed for everyone's free use or not licensed at all.\n\
+\n\
+  The precise terms and conditions for copying, distribution and\n\
+modification follow.\n\
+\n\
+		    GNU GENERAL PUBLIC LICENSE\n\
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION\n\
+\n\
+  0. This License applies to any program or other work which contains\n\
+a notice placed by the copyright holder saying it may be distributed\n\
+under the terms of this General Public License.  The \"Program\", below,\n\
+refers to any such program or work, and a \"work based on the Program\"\n\
+means either the Program or any derivative work under copyright law:\n\
+that is to say, a work containing the Program or a portion of it,\n\
+either verbatim or with modifications and/or translated into another\n\
+language.  (Hereinafter, translation is included without limitation in\n\
+the term \"modification\".)  Each licensee is addressed as \"you\".\n\
+\n\
+Activities other than copying, distribution and modification are not\n\
+covered by this License; they are outside its scope.  The act of\n\
+running the Program is not restricted, and the output from the Program\n\
+is covered only if its contents constitute a work based on the\n\
+Program (independent of having been made by running the Program).\n\
+Whether that is true depends on what the Program does.\n\
+\n\
+  1. You may copy and distribute verbatim copies of the Program's\n\
+source code as you receive it, in any medium, provided that you\n\
+conspicuously and appropriately publish on each copy an appropriate\n\
+copyright notice and disclaimer of warranty; keep intact all the\n\
+notices that refer to this License and to the absence of any warranty;\n\
+and give any other recipients of the Program a copy of this License\n\
+along with the Program.\n\
+\n\
+You may charge a fee for the physical act of transferring a copy, and\n\
+you may at your option offer warranty protection in exchange for a fee.\n\
+\n\
+  2. You may modify your copy or copies of the Program or any portion\n\
+of it, thus forming a work based on the Program, and copy and\n\
+distribute such modifications or work under the terms of Section 1\n\
+above, provided that you also meet all of these conditions:\n\
+\n\
+    a) You must cause the modified files to carry prominent notices\n\
+    stating that you changed the files and the date of any change.\n\
+\n\
+    b) You must cause any work that you distribute or publish, that in\n\
+    whole or in part contains or is derived from the Program or any\n\
+    part thereof, to be licensed as a whole at no charge to all third\n\
+    parties under the terms of this License.\n\
+\n\
+    c) If the modified program normally reads commands interactively\n\
+    when run, you must cause it, when started running for such\n\
+    interactive use in the most ordinary way, to print or display an\n\
+    announcement including an appropriate copyright notice and a\n\
+    notice that there is no warranty (or else, saying that you provide\n\
+    a warranty) and that users may redistribute the program under\n\
+    these conditions, and telling the user how to view a copy of this\n\
+    License.  (Exception: if the Program itself is interactive but\n\
+    does not normally print such an announcement, your work based on\n\
+    the Program is not required to print an announcement.)\n\
+\n\
+These requirements apply to the modified work as a whole.  If\n\
+identifiable sections of that work are not derived from the Program,\n\
+and can be reasonably considered independent and separate works in\n\
+themselves, then this License, and its terms, do not apply to those\n\
+sections when you distribute them as separate works.  But when you\n\
+distribute the same sections as part of a whole which is a work based\n\
+on the Program, the distribution of the whole must be on the terms of\n\
+this License, whose permissions for other licensees extend to the\n\
+entire whole, and thus to each and every part regardless of who wrote it.\n\
+\n\
+Thus, it is not the intent of this section to claim rights or contest\n\
+your rights to work written entirely by you; rather, the intent is to\n\
+exercise the right to control the distribution of derivative or\n\
+collective works based on the Program.\n\
+\n\
+In addition, mere aggregation of another work not based on the Program\n\
+with the Program (or with a work based on the Program) on a volume of\n\
+a storage or distribution medium does not bring the other work under\n\
+the scope of this License.\n\
+\n\
+  3. You may copy and distribute the Program (or a work based on it,\n\
+under Section 2) in object code or executable form under the terms of\n\
+Sections 1 and 2 above provided that you also do one of the following:\n\
+\n\
+    a) Accompany it with the complete corresponding machine-readable\n\
+    source code, which must be distributed under the terms of Sections\n\
+    1 and 2 above on a medium customarily used for software interchange; or,\n\
+\n\
+    b) Accompany it with a written offer, valid for at least three\n\
+    years, to give any third party, for a charge no more than your\n\
+    cost of physically performing source distribution, a complete\n\
+    machine-readable copy of the corresponding source code, to be\n\
+    distributed under the terms of Sections 1 and 2 above on a medium\n\
+    customarily used for software interchange; or,\n\
+\n\
+    c) Accompany it with the information you received as to the offer\n\
+    to distribute corresponding source code.  (This alternative is\n\
+    allowed only for noncommercial distribution and only if you\n\
+    received the program in object code or executable form with such\n\
+    an offer, in accord with Subsection b above.)\n\
+\n\
+The source code for a work means the preferred form of the work for\n\
+making modifications to it.  For an executable work, complete source\n\
+code means all the source code for all modules it contains, plus any\n\
+associated interface definition files, plus the scripts used to\n\
+control compilation and installation of the executable.  However, as a\n\
+special exception, the source code distributed need not include\n\
+anything that is normally distributed (in either source or binary\n\
+form) with the major components (compiler, kernel, and so on) of the\n\
+operating system on which the executable runs, unless that component\n\
+itself accompanies the executable.\n\
+\n\
+If distribution of executable or object code is made by offering\n\
+access to copy from a designated place, then offering equivalent\n\
+access to copy the source code from the same place counts as\n\
+distribution of the source code, even though third parties are not\n\
+compelled to copy the source along with the object code.\n\
+\n\
+  4. You may not copy, modify, sublicense, or distribute the Program\n\
+except as expressly provided under this License.  Any attempt\n\
+otherwise to copy, modify, sublicense or distribute the Program is\n\
+void, and will automatically terminate your rights under this License.\n\
+However, parties who have received copies, or rights, from you under\n\
+this License will not have their licenses terminated so long as such\n\
+parties remain in full compliance.\n\
+\n\
+  5. You are not required to accept this License, since you have not\n\
+signed it.  However, nothing else grants you permission to modify or\n\
+distribute the Program or its derivative works.  These actions are\n\
+prohibited by law if you do not accept this License.  Therefore, by\n\
+modifying or distributing the Program (or any work based on the\n\
+Program), you indicate your acceptance of this License to do so, and\n\
+all its terms and conditions for copying, distributing or modifying\n\
+the Program or works based on it.\n\
+\n\
+  6. Each time you redistribute the Program (or any work based on the\n\
+Program), the recipient automatically receives a license from the\n\
+original licensor to copy, distribute or modify the Program subject to\n\
+these terms and conditions.  You may not impose any further\n\
+restrictions on the recipients' exercise of the rights granted herein.\n\
+You are not responsible for enforcing compliance by third parties to\n\
+this License.\n\
+\n\
+  7. If, as a consequence of a court judgment or allegation of patent\n\
+infringement or for any other reason (not limited to patent issues),\n\
+conditions are imposed on you (whether by court order, agreement or\n\
+otherwise) that contradict the conditions of this License, they do not\n\
+excuse you from the conditions of this License.  If you cannot\n\
+distribute so as to satisfy simultaneously your obligations under this\n\
+License and any other pertinent obligations, then as a consequence you\n\
+may not distribute the Program at all.  For example, if a patent\n\
+license would not permit royalty-free redistribution of the Program by\n\
+all those who receive copies directly or indirectly through you, then\n\
+the only way you could satisfy both it and this License would be to\n\
+refrain entirely from distribution of the Program.\n\
+\n\
+If any portion of this section is held invalid or unenforceable under\n\
+any particular circumstance, the balance of the section is intended to\n\
+apply and the section as a whole is intended to apply in other\n\
+circumstances.\n\
+\n\
+It is not the purpose of this section to induce you to infringe any\n\
+patents or other property right claims or to contest validity of any\n\
+such claims; this section has the sole purpose of protecting the\n\
+integrity of the free software distribution system, which is\n\
+implemented by public license practices.  Many people have made\n\
+generous contributions to the wide range of software distributed\n\
+through that system in reliance on consistent application of that\n\
+system; it is up to the author/donor to decide if he or she is willing\n\
+to distribute software through any other system and a licensee cannot\n\
+impose that choice.\n\
+\n\
+This section is intended to make thoroughly clear what is believed to\n\
+be a consequence of the rest of this License.\n\
+\n\
+  8. If the distribution and/or use of the Program is restricted in\n\
+certain countries either by patents or by copyrighted interfaces, the\n\
+original copyright holder who places the Program under this License\n\
+may add an explicit geographical distribution limitation excluding\n\
+those countries, so that distribution is permitted only in or among\n\
+countries not thus excluded.  In such case, this License incorporates\n\
+the limitation as if written in the body of this License.\n\
+\n\
+  9. The Free Software Foundation may publish revised and/or new versions\n\
+of the General Public License from time to time.  Such new versions will\n\
+be similar in spirit to the present version, but may differ in detail to\n\
+address new problems or concerns.\n\
+\n\
+Each version is given a distinguishing version number.  If the Program\n\
+specifies a version number of this License which applies to it and \"any\n\
+later version\", you have the option of following the terms and conditions\n\
+either of that version or of any later version published by the Free\n\
+Software Foundation.  If the Program does not specify a version number of\n\
+this License, you may choose any version ever published by the Free Software\n\
+Foundation.\n\
+\n\
+  10. If you wish to incorporate parts of the Program into other free\n\
+programs whose distribution conditions are different, write to the author\n\
+to ask for permission.  For software which is copyrighted by the Free\n\
+Software Foundation, write to the Free Software Foundation; we sometimes\n\
+make exceptions for this.  Our decision will be guided by the two goals\n\
+of preserving the free status of all derivatives of our free software and\n\
+of promoting the sharing and reuse of software generally.\n");
+}
+
+extern void warranty(environment *env){
+  printf("			    NO WARRANTY\n\
+\n\
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\n\
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN\n\
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\n\
+PROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\n\
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF\n\
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS\n\
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE\n\
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,\n\
+REPAIR OR CORRECTION.\n\
+\n\
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING\n\
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR\n\
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,\n\
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING\n\
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED\n\
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY\n\
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\n\
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\n\
+POSSIBILITY OF SUCH DAMAGES.\n");
+}
+
+/* "*" */
+extern void sx_2a(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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  a=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b*a);
+}
+
+/* "/" */
+extern void sx_2f(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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  a=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b/a);
+}
+
+/* "mod" */
+extern void mod(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) {
+    printerr("Bad Argument Type");
+    env->err=2;
+    return;
+  }
+
+  a=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  b=env->head->item->content.val;
+  toss(env); if(env->err) return;
+  push_int(env, b%a);
+}