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revision 1.80 by teddy, Thu Feb 14 12:20:09 2002 UTC revision 1.92 by masse, Fri Mar 8 06:44:15 2002 UTC
# Line 1  Line 1 
1  /* printf, sscanf, fgets, fprintf */  /*
2        stack - an interactive interpreter for a stack-based language
3        Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn
4    
5        This program is free software; you can redistribute it and/or modify
6        it under the terms of the GNU General Public License as published by
7        the Free Software Foundation; either version 2 of the License, or
8        (at your option) any later version.
9    
10        This program is distributed in the hope that it will be useful,
11        but WITHOUT ANY WARRANTY; without even the implied warranty of
12        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13        GNU General Public License for more details.
14    
15        You should have received a copy of the GNU General Public License
16        along with this program; if not, write to the Free Software
17        Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18    
19        Authors: Mats Alritzson <masse@fukt.bth.se>
20                 Teddy Hogeborn <teddy@fukt.bth.se>
21    */
22    
23    /* printf, sscanf, fgets, fprintf, fopen, perror */
24  #include <stdio.h>  #include <stdio.h>
25  /* exit, EXIT_SUCCESS, malloc, free */  /* exit, EXIT_SUCCESS, malloc, free */
26  #include <stdlib.h>  #include <stdlib.h>
# Line 8  Line 30 
30  #include <dlfcn.h>  #include <dlfcn.h>
31  /* strcmp, strcpy, strlen, strcat, strdup */  /* strcmp, strcpy, strlen, strcat, strdup */
32  #include <string.h>  #include <string.h>
33    /* getopt, STDIN_FILENO, STDOUT_FILENO, usleep */
34    #include <unistd.h>
35    /* EX_NOINPUT, EX_USAGE */
36    #include <sysexits.h>
37    /* mtrace, muntrace */
38    #include <mcheck.h>
39    /* ioctl */
40    #include <sys/ioctl.h>
41    /* KDMKTONE */
42    #include <linux/kd.h>
43    
44  #define HASHTBLSIZE 2048  #include "stack.h"
   
 /* First, define some types. */  
   
 /* A value of some type */  
 typedef struct {  
   enum {  
     integer,  
     string,  
     func,                       /* Function pointer */  
     symb,  
     list  
   } type;                       /* Type of stack element */  
   
   union {  
     void *ptr;                  /* Pointer to the content */  
     int val;                    /* ...or an integer */  
   } content;                    /* Stores a pointer or an integer */  
   
   int refcount;                 /* Reference counter */  
   
 } value;  
   
 /* A symbol with a name and possible value */  
 /* (These do not need reference counters, they are kept unique by  
    hashing.) */  
 typedef struct symbol_struct {  
   char *id;                     /* Symbol name */  
   value *val;                   /* The value (if any) bound to it */  
   struct symbol_struct *next;   /* In case of hashing conflicts, a */  
 } symbol;                       /* symbol is a kind of stack item. */  
   
 /* A type for a hash table for symbols */  
 typedef symbol *hashtbl[HASHTBLSIZE]; /* Hash table declaration */  
   
 /* An item (value) on a stack */  
 typedef struct stackitem_struct  
 {  
   value *item;                  /* The value on the stack */  
                                 /* (This is never NULL) */  
   struct stackitem_struct *next; /* Next item */  
 } stackitem;  
   
 /* An environment; gives access to the stack and a hash table of  
    defined symbols */  
 typedef struct {  
   stackitem *head;              /* Head of the stack */  
   hashtbl symbols;              /* Hash table of all variable bindings */  
   int err;                      /* Error flag */  
   int non_eval_flag;  
   char *in_string;              /* Input pending to be read */  
   char *free_string;            /* Free this string when all input is  
                                    read from in_string */  
 } environment;  
   
 /* A type for pointers to external functions */  
 typedef void (*funcp)(environment *); /* funcp is a pointer to a void  
                                          function (environment *) */  
45    
46  /* Initialize a newly created environment */  /* Initialize a newly created environment */
47  void init_env(environment *env)  void init_env(environment *env)
48  {  {
49    int i;    int i;
50    
51    env->in_string= NULL;    env->gc_limit= 20;
52    env->err= 0;    env->gc_count= 0;
53    env->non_eval_flag= 0;    env->gc_ref= NULL;
54      env->gc_protect= NULL;
55    
56      env->head= NULL;
57    for(i= 0; i<HASHTBLSIZE; i++)    for(i= 0; i<HASHTBLSIZE; i++)
58      env->symbols[i]= NULL;      env->symbols[i]= NULL;
59      env->err= 0;
60      env->in_string= NULL;
61      env->free_string= NULL;
62      env->inputstream= stdin;
63      env->interactive= 1;
64  }  }
65    
66  void printerr(const char* in_string) {  void printerr(const char* in_string) {
67    fprintf(stderr, "Err: %s\n", in_string);    fprintf(stderr, "Err: %s\n", in_string);
68  }  }
69    
 /* Throw away a value */  
 void free_val(value *val){  
   stackitem *item, *temp;  
   
   val->refcount--;              /* Decrease the reference count */  
   if(val->refcount == 0){  
     switch (val->type){         /* and free the contents if necessary */  
     case string:  
       free(val->content.ptr);  
       break;  
     case list:                  /* lists needs to be freed recursively */  
       item=val->content.ptr;  
       while(item != NULL) {     /* for all stack items */  
         free_val(item->item);   /* free the value */  
         temp=item->next;        /* save next ptr */  
         free(item);             /* free the stackitem */  
         item=temp;              /* go to next stackitem */  
       }  
       free(val);                /* Free the actual list value */  
       break;  
     case integer:  
     case func:  
     case symb:  
       break;  
     }  
   }  
 }  
   
70  /* Discard the top element of the stack. */  /* Discard the top element of the stack. */
71  extern void toss(environment *env)  extern void toss(environment *env)
72  {  {
# Line 119  extern void toss(environment *env) Line 74  extern void toss(environment *env)
74    
75    if((env->head)==NULL) {    if((env->head)==NULL) {
76      printerr("Too Few Arguments");      printerr("Too Few Arguments");
77      env->err=1;      env->err= 1;
78      return;      return;
79    }    }
80        
   free_val(env->head->item);    /* Free the value */  
81    env->head= env->head->next;   /* Remove the top stack item */    env->head= env->head->next;   /* Remove the top stack item */
82    free(temp);                   /* Free the old top stack item */    free(temp);                   /* Free the old top stack item */
83    
84      gc_init(env);
85  }  }
86    
87  /* Returns a pointer to a pointer to an element in the hash table. */  /* Returns a pointer to a pointer to an element in the hash table. */
# Line 157  symbol **hash(hashtbl in_hashtbl, const Line 113  symbol **hash(hashtbl in_hashtbl, const
113    }    }
114  }  }
115    
116    value* new_val(environment *env) {
117      value *nval= malloc(sizeof(value));
118      stackitem *nitem= malloc(sizeof(stackitem));
119    
120      nval->content.ptr= NULL;
121      protect(env, nval);
122    
123      gc_init(env);
124    
125      nitem->item= nval;
126      nitem->next= env->gc_ref;
127      env->gc_ref= nitem;
128    
129      env->gc_count++;
130      unprotect(env);
131    
132      return nval;
133    }
134    
135    void gc_mark(value *val) {
136      stackitem *iterator;
137    
138      if(val==NULL || val->gc_garb==0)
139        return;
140    
141      val->gc_garb= 0;
142    
143      if(val->type==list) {
144        iterator= val->content.ptr;
145    
146        while(iterator!=NULL) {
147          gc_mark(iterator->item);
148          iterator= iterator->next;
149        }
150      }
151    }
152    
153    extern void gc_init(environment *env) {
154      stackitem *new_head= NULL, *titem, *iterator= env->gc_ref;
155      symbol *tsymb;
156      int i;
157    
158      if(env->gc_count < env->gc_limit)
159        return;
160    
161      while(iterator!=NULL) {
162        iterator->item->gc_garb= 1;
163        iterator= iterator->next;
164      }
165    
166      /* Mark */
167      iterator= env->gc_protect;
168      while(iterator!=NULL) {
169        gc_mark(iterator->item);
170        iterator= iterator->next;
171      }
172    
173      iterator= env->head;
174      while(iterator!=NULL) {
175        gc_mark(iterator->item);
176        iterator= iterator->next;
177      }
178    
179      for(i= 0; i<HASHTBLSIZE; i++) {
180        tsymb= env->symbols[i];
181        while(tsymb!=NULL) {
182          gc_mark(tsymb->val);
183          tsymb= tsymb->next;
184        }
185      }
186    
187      env->gc_count= 0;
188    
189      /* Sweep */
190      while(env->gc_ref!=NULL) {
191    
192        if(env->gc_ref->item->gc_garb) {
193          switch(env->gc_ref->item->type) {
194          case string:
195            free(env->gc_ref->item->content.ptr);
196            break;
197          case integer:
198            break;
199          case list:
200            while(env->gc_ref->item->content.ptr!=NULL) {
201              titem= env->gc_ref->item->content.ptr;
202              env->gc_ref->item->content.ptr= titem->next;
203              free(titem);
204            }
205            break;
206          default:
207            break;
208          }
209          free(env->gc_ref->item);
210          titem= env->gc_ref->next;
211          free(env->gc_ref);
212          env->gc_ref= titem;
213        } else {
214          titem= env->gc_ref->next;
215          env->gc_ref->next= new_head;
216          new_head= env->gc_ref;
217          env->gc_ref= titem;
218          env->gc_count++;
219        }
220      }
221    
222      env->gc_limit= env->gc_count*2;
223      env->gc_ref= new_head;
224    }
225    
226    void protect(environment *env, value *val)
227    {
228      stackitem *new_item= malloc(sizeof(stackitem));
229      new_item->item= val;
230      new_item->next= env->gc_protect;
231      env->gc_protect= new_item;
232    }
233    
234    void unprotect(environment *env)
235    {
236      stackitem *temp= env->gc_protect;
237      env->gc_protect= env->gc_protect->next;
238      free(temp);
239    }
240    
241  /* Push a value onto the stack */  /* Push a value onto the stack */
242  void push_val(environment *env, value *val)  void push_val(environment *env, value *val)
243  {  {
244    stackitem *new_item= malloc(sizeof(stackitem));    stackitem *new_item= malloc(sizeof(stackitem));
245    new_item->item= val;    new_item->item= val;
   val->refcount++;  
246    new_item->next= env->head;    new_item->next= env->head;
247    env->head= new_item;    env->head= new_item;
248  }  }
# Line 170  void push_val(environment *env, value *v Line 250  void push_val(environment *env, value *v
250  /* Push an integer onto the stack. */  /* Push an integer onto the stack. */
251  void push_int(environment *env, int in_val)  void push_int(environment *env, int in_val)
252  {  {
253    value *new_value= malloc(sizeof(value));    value *new_value= new_val(env);
254        
255    new_value->content.val= in_val;    new_value->content.val= in_val;
256    new_value->type= integer;    new_value->type= integer;
   new_value->refcount=1;  
257    
258    push_val(env, new_value);    push_val(env, new_value);
259  }  }
# Line 182  void push_int(environment *env, int in_v Line 261  void push_int(environment *env, int in_v
261  /* Copy a string onto the stack. */  /* Copy a string onto the stack. */
262  void push_cstring(environment *env, const char *in_string)  void push_cstring(environment *env, const char *in_string)
263  {  {
264    value *new_value= malloc(sizeof(value));    value *new_value= new_val(env);
265    
266    new_value->content.ptr= malloc(strlen(in_string)+1);    new_value->content.ptr= malloc(strlen(in_string)+1);
267    strcpy(new_value->content.ptr, in_string);    strcpy(new_value->content.ptr, in_string);
268    new_value->type= string;    new_value->type= string;
   new_value->refcount=1;  
269    
270    push_val(env, new_value);    push_val(env, new_value);
271  }  }
272    
273  /* Mangle a symbol name to a valid C identifier name */  /* Mangle a symbol name to a valid C identifier name */
274  char *mangle_str(const char *old_string){  char *mangle_str(const char *old_string){
275    char validchars[]    char validchars[]= "0123456789abcdef";
     ="0123456789abcdef";  
276    char *new_string, *current;    char *new_string, *current;
277    
278    new_string=malloc((strlen(old_string)*2)+4);    new_string= malloc((strlen(old_string)*2)+4);
279    strcpy(new_string, "sx_");    /* Stack eXternal */    strcpy(new_string, "sx_");    /* Stack eXternal */
280    current=new_string+3;    current= new_string+3;
281    while(old_string[0] != '\0'){    while(old_string[0] != '\0'){
282      current[0]=validchars[(unsigned char)(old_string[0])/16];      current[0]= validchars[(unsigned char)(old_string[0])/16];
283      current[1]=validchars[(unsigned char)(old_string[0])%16];      current[1]= validchars[(unsigned char)(old_string[0])%16];
284      current+=2;      current+= 2;
285      old_string++;      old_string++;
286    }    }
287    current[0]='\0';    current[0]= '\0';
288    
289    return new_string;            /* The caller must free() it */    return new_string;            /* The caller must free() it */
290  }  }
291    
292  extern void mangle(environment *env){  extern void mangle(environment *env){
   value *new_value;  
293    char *new_string;    char *new_string;
294    
295    if((env->head)==NULL) {    if((env->head)==NULL) {
296      printerr("Too Few Arguments");      printerr("Too Few Arguments");
297      env->err=1;      env->err= 1;
298      return;      return;
299    }    }
300    
301    if(env->head->item->type!=string) {    if(env->head->item->type!=string) {
302      printerr("Bad Argument Type");      printerr("Bad Argument Type");
303      env->err=2;      env->err= 2;
304      return;      return;
305    }    }
306    
# Line 233  extern void mangle(environment *env){ Line 309  extern void mangle(environment *env){
309    toss(env);    toss(env);
310    if(env->err) return;    if(env->err) return;
311    
312    new_value= malloc(sizeof(value));    push_cstring(env, new_string);
   new_value->content.ptr= new_string;  
   new_value->type= string;  
   new_value->refcount=1;  
   
   push_val(env, new_value);  
313  }  }
314    
315  /* Push a symbol onto the stack. */  /* Push a symbol onto the stack. */
# Line 256  void push_sym(environment *env, const ch Line 327  void push_sym(environment *env, const ch
327    const char *dlerr;            /* Dynamic linker error */    const char *dlerr;            /* Dynamic linker error */
328    char *mangled;                /* Mangled function name */    char *mangled;                /* Mangled function name */
329    
330    new_value= malloc(sizeof(value));    new_value= new_val(env);
331    
332    /* The new value is a symbol */    /* The new value is a symbol */
333    new_value->type= symb;    new_value->type= symb;
   new_value->refcount= 1;  
334    
335    /* Look up the symbol name in the hash table */    /* Look up the symbol name in the hash table */
336    new_symbol= hash(env->symbols, in_string);    new_symbol= hash(env->symbols, in_string);
# Line 283  void push_sym(environment *env, const ch Line 353  void push_sym(environment *env, const ch
353      if(handle==NULL)            /* If no handle */      if(handle==NULL)            /* If no handle */
354        handle= dlopen(NULL, RTLD_LAZY);        handle= dlopen(NULL, RTLD_LAZY);
355    
356      funcptr= dlsym(handle, in_string); /* Get function pointer */      mangled= mangle_str(in_string); /* mangle the name */
357      dlerr=dlerror();      funcptr= dlsym(handle, mangled); /* and try to find it */
358        free(mangled);
359        dlerr= dlerror();
360      if(dlerr != NULL) {         /* If no function was found */      if(dlerr != NULL) {         /* If no function was found */
361        mangled=mangle_str(in_string);        funcptr= dlsym(handle, in_string); /* Get function pointer */
362        funcptr= dlsym(handle, mangled); /* try mangling it */        dlerr= dlerror();
       free(mangled);  
       dlerr=dlerror();  
363      }      }
364      if(dlerr==NULL) {           /* If a function was found */      if(dlerr==NULL) {           /* If a function was found */
365        new_fvalue= malloc(sizeof(value)); /* Create a new value */        new_fvalue= new_val(env); /* Create a new value */
366        new_fvalue->type=func;    /* The new value is a function pointer */        new_fvalue->type= func;   /* The new value is a function pointer */
367        new_fvalue->content.ptr=funcptr; /* Store function pointer */        new_fvalue->content.ptr= funcptr; /* Store function pointer */
368        (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new        (*new_symbol)->val= new_fvalue; /* Bind the symbol to the new
369                                           function value */                                           function value */
       new_fvalue->refcount= 1;  
370      }      }
371    }    }
372    push_val(env, new_value);    push_val(env, new_value);
# Line 483  extern void rcl(environment *env) Line 552  extern void rcl(environment *env)
552      env->err=3;      env->err=3;
553      return;      return;
554    }    }
555      protect(env, val);
556    toss(env);            /* toss the symbol */    toss(env);            /* toss the symbol */
557    if(env->err) return;    if(env->err) return;
558    push_val(env, val); /* Return its bound value */    push_val(env, val); /* Return its bound value */
559      unprotect(env);
560  }  }
561    
562  /* If the top element is a symbol, determine if it's bound to a  /* If the top element is a symbol, determine if it's bound to a
# Line 520  extern void eval(environment *env) Line 591  extern void eval(environment *env)
591      in_func= (funcp)(env->head->item->content.ptr);      in_func= (funcp)(env->head->item->content.ptr);
592      toss(env);      toss(env);
593      if(env->err) return;      if(env->err) return;
594      return (*in_func)(env);      return in_func(env);
595    
596      /* If it's a list */      /* If it's a list */
597    case list:    case list:
598      temp_val= env->head->item;      temp_val= env->head->item;
599      env->head->item->refcount++;      protect(env, temp_val);
600      toss(env);      toss(env);
601      if(env->err) return;      if(env->err) return;
602      iterator= (stackitem*)temp_val->content.ptr;      iterator= (stackitem*)temp_val->content.ptr;
603        unprotect(env);
604        
605      while(iterator!=NULL) {      while(iterator!=NULL) {
606        push_val(env, iterator->item);        push_val(env, iterator->item);
607          
608        if(env->head->item->type==symb        if(env->head->item->type==symb
609          && strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {          && strcmp(";", ((symbol*)(env->head->item->content.ptr))->id)==0) {
610          toss(env);          toss(env);
611          if(env->err) return;          if(env->err) return;
612            
613          if(iterator->next == NULL){          if(iterator->next == NULL){
           free_val(temp_val);  
614            goto eval_start;            goto eval_start;
615          }          }
616          eval(env);          eval(env);
# Line 544  extern void eval(environment *env) Line 618  extern void eval(environment *env)
618        }        }
619        iterator= iterator->next;        iterator= iterator->next;
620      }      }
     free_val(temp_val);  
621      return;      return;
622    
623    default:    default:
# Line 558  extern void rev(environment *env){ Line 631  extern void rev(environment *env){
631    
632    if((env->head)==NULL) {    if((env->head)==NULL) {
633      printerr("Too Few Arguments");      printerr("Too Few Arguments");
634      env->err=1;      env->err= 1;
635      return;      return;
636    }    }
637    
638    if(env->head->item->type!=list) {    if(env->head->item->type!=list) {
639      printerr("Bad Argument Type");      printerr("Bad Argument Type");
640      env->err=2;      env->err= 2;
641      return;      return;
642    }    }
643    
644    old_head=(stackitem *)(env->head->item->content.ptr);    old_head= (stackitem *)(env->head->item->content.ptr);
645    new_head=NULL;    new_head= NULL;
646    while(old_head != NULL){    while(old_head != NULL){
647      item=old_head;      item= old_head;
648      old_head=old_head->next;      old_head= old_head->next;
649      item->next=new_head;      item->next= new_head;
650      new_head=item;      new_head= item;
651    }    }
652    env->head->item->content.ptr=new_head;    env->head->item->content.ptr= new_head;
653  }  }
654    
655  /* Make a list. */  /* Make a list. */
# Line 609  extern void pack(environment *env) Line 682  extern void pack(environment *env)
682    }    }
683    
684    /* Push list */    /* Push list */
685    pack= malloc(sizeof(value));    pack= new_val(env);
686    pack->type= list;    pack->type= list;
687    pack->content.ptr= temp;    pack->content.ptr= temp;
   pack->refcount= 1;  
688    
689    push_val(env, pack);    push_val(env, pack);
690    rev(env);    rev(env);
# Line 626  extern void expand(environment *env) Line 698  extern void expand(environment *env)
698    /* Is top element a list? */    /* Is top element a list? */
699    if(env->head==NULL) {    if(env->head==NULL) {
700      printerr("Too Few Arguments");      printerr("Too Few Arguments");
701      env->err=1;      env->err= 1;
702      return;      return;
703    }    }
704    if(env->head->item->type!=list) {    if(env->head->item->type!=list) {
705      printerr("Bad Argument Type");      printerr("Bad Argument Type");
706      env->err=2;      env->err= 2;
707      return;      return;
708    }    }
709    
# Line 643  extern void expand(environment *env) Line 715  extern void expand(environment *env)
715    /* The first list element is the new stack head */    /* The first list element is the new stack head */
716    new_head= temp= env->head->item->content.ptr;    new_head= temp= env->head->item->content.ptr;
717    
   env->head->item->refcount++;  
718    toss(env);    toss(env);
719    
720    /* Find the end of the list */    /* Find the end of the list */
# Line 664  extern void eq(environment *env) Line 735  extern void eq(environment *env)
735    
736    if((env->head)==NULL || env->head->next==NULL) {    if((env->head)==NULL || env->head->next==NULL) {
737      printerr("Too Few Arguments");      printerr("Too Few Arguments");
738      env->err=1;      env->err= 1;
739      return;      return;
740    }    }
741    
# Line 684  extern void not(environment *env) Line 755  extern void not(environment *env)
755    
756    if((env->head)==NULL) {    if((env->head)==NULL) {
757      printerr("Too Few Arguments");      printerr("Too Few Arguments");
758      env->err=1;      env->err= 1;
759      return;      return;
760    }    }
761    
762    if(env->head->item->type!=integer) {    if(env->head->item->type!=integer) {
763      printerr("Bad Argument Type");      printerr("Bad Argument Type");
764      env->err=2;      env->err= 2;
765      return;      return;
766    }    }
767    
# Line 715  extern void def(environment *env) Line 786  extern void def(environment *env)
786    /* Needs two values on the stack, the top one must be a symbol */    /* Needs two values on the stack, the top one must be a symbol */
787    if(env->head==NULL || env->head->next==NULL) {    if(env->head==NULL || env->head->next==NULL) {
788      printerr("Too Few Arguments");      printerr("Too Few Arguments");
789      env->err=1;      env->err= 1;
790      return;      return;
791    }    }
792    
793    if(env->head->item->type!=symb) {    if(env->head->item->type!=symb) {
794      printerr("Bad Argument Type");      printerr("Bad Argument Type");
795      env->err=2;      env->err= 2;
796      return;      return;
797    }    }
798    
799    /* long names are a pain */    /* long names are a pain */
800    sym=env->head->item->content.ptr;    sym= env->head->item->content.ptr;
   
   /* if the symbol was bound to something else, throw it away */  
   if(sym->val != NULL)  
     free_val(sym->val);  
801    
802    /* Bind the symbol to the value */    /* Bind the symbol to the value */
803    sym->val= env->head->next->item;    sym->val= env->head->next->item;
   sym->val->refcount++;         /* Increase the reference counter */  
804    
805    toss(env); toss(env);    toss(env); toss(env);
806  }  }
807    
 extern void clear(environment *);  
 void forget_sym(symbol **);  
   
808  /* Quit stack. */  /* Quit stack. */
809  extern void quit(environment *env)  extern void quit(environment *env)
810  {  {
811    long i;    long i;
812    
813    clear(env);    clear(env);
814    
815    if (env->err) return;    if (env->err) return;
816    for(i= 0; i<HASHTBLSIZE; i++) {    for(i= 0; i<HASHTBLSIZE; i++) {
817      while(env->symbols[i]!= NULL) {      while(env->symbols[i]!= NULL) {
# Line 755  extern void quit(environment *env) Line 819  extern void quit(environment *env)
819      }      }
820      env->symbols[i]= NULL;      env->symbols[i]= NULL;
821    }    }
822    
823      env->gc_limit= 0;
824      gc_init(env);
825    
826      if(env->free_string!=NULL)
827        free(env->free_string);
828      
829      muntrace();
830    
831    exit(EXIT_SUCCESS);    exit(EXIT_SUCCESS);
832  }  }
833    
# Line 787  void forget_sym(symbol **hash_entry) { Line 860  void forget_sym(symbol **hash_entry) {
860    temp= *hash_entry;    temp= *hash_entry;
861    *hash_entry= (*hash_entry)->next;    *hash_entry= (*hash_entry)->next;
862        
   if(temp->val!=NULL) {  
     free_val(temp->val);  
   }  
863    free(temp->id);    free(temp->id);
864    free(temp);    free(temp);
865  }  }
# Line 823  extern void errn(environment *env){ Line 893  extern void errn(environment *env){
893    push_int(env, env->err);    push_int(env, env->err);
894  }  }
895    
896  extern void read(environment*);  int main(int argc, char **argv)
   
 int main()  
897  {  {
898    environment myenv;    environment myenv;
899    
900      int c;                        /* getopt option character */
901    
902      mtrace();
903    
904    init_env(&myenv);    init_env(&myenv);
905    
906      myenv.interactive = isatty(STDIN_FILENO) && isatty(STDOUT_FILENO);
907    
908      while ((c = getopt (argc, argv, "i")) != -1)
909        switch (c)
910          {
911          case 'i':
912            myenv.interactive = 1;
913            break;
914          case '?':
915            fprintf (stderr,
916                     "Unknown option character `\\x%x'.\n",
917                     optopt);
918            return EX_USAGE;
919          default:
920            abort ();
921          }
922      
923      if (optind < argc) {
924        myenv.interactive = 0;
925        myenv.inputstream= fopen(argv[optind], "r");
926        if(myenv.inputstream== NULL) {
927          perror(argv[0]);
928          exit (EX_NOINPUT);
929        }
930      }
931    
932      if(myenv.interactive) {
933        printf("Stack version $Revision$\n\
934    Copyright (C) 2002  Mats Alritzson and Teddy Hogeborn\n\
935    Stack comes with ABSOLUTELY NO WARRANTY; for details type `warranty;'.\n\
936    This is free software, and you are welcome to redistribute it\n\
937    under certain conditions; type `copying;' for details.\n");
938      }
939    
940    while(1) {    while(1) {
941      if(myenv.in_string==NULL) {      if(myenv.in_string==NULL) {
942        nl();        if (myenv.interactive) {
943        printstack(&myenv);          if(myenv.err) {
944        printf("> ");            printf("(error %d)\n", myenv.err);
945      }          }
946      read(&myenv);          nl();
947      if(myenv.err) {          printstack(&myenv);
948        printf("(error %d) ", myenv.err);          printf("> ");
949          }
950        myenv.err=0;        myenv.err=0;
951        }
952        sx_72656164(&myenv);
953        if (myenv.err==4) {
954          return EXIT_SUCCESS;      /* EOF */
955      } else if(myenv.head!=NULL      } else if(myenv.head!=NULL
956                && myenv.head->item->type==symb                && myenv.head->item->type==symb
957                && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {                && ((symbol*)(myenv.head->item->content.ptr))->id[0]==';') {
958        toss(&myenv);             /* No error check in main */        toss(&myenv);             /* No error check in main */
959        eval(&myenv);        eval(&myenv);
960      }      }
961        gc_init(&myenv);
962    }    }
963    quit(&myenv);    quit(&myenv);
964    return EXIT_FAILURE;    return EXIT_FAILURE;
965  }  }
966    
967  /* + */  /* "+" */
968  extern void sx_2b(environment *env) {  extern void sx_2b(environment *env) {
969    int a, b;    int a, b;
970    size_t len;    size_t len;
# Line 861  extern void sx_2b(environment *env) { Line 973  extern void sx_2b(environment *env) {
973    
974    if((env->head)==NULL || env->head->next==NULL) {    if((env->head)==NULL || env->head->next==NULL) {
975      printerr("Too Few Arguments");      printerr("Too Few Arguments");
976      env->err=1;      env->err= 1;
977      return;      return;
978    }    }
979    
# Line 869  extern void sx_2b(environment *env) { Line 981  extern void sx_2b(environment *env) {
981       && env->head->next->item->type==string) {       && env->head->next->item->type==string) {
982      a_val= env->head->item;      a_val= env->head->item;
983      b_val= env->head->next->item;      b_val= env->head->next->item;
984      a_val->refcount++;      protect(env, a_val); protect(env, b_val);
     b_val->refcount++;  
985      toss(env); if(env->err) return;      toss(env); if(env->err) return;
986      toss(env); if(env->err) return;      toss(env); if(env->err) return;
987      len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;      len= strlen(a_val->content.ptr)+strlen(b_val->content.ptr)+1;
988      new_string= malloc(len);      new_string= malloc(len);
989      strcpy(new_string, b_val->content.ptr);      strcpy(new_string, b_val->content.ptr);
990      strcat(new_string, a_val->content.ptr);      strcat(new_string, a_val->content.ptr);
     free_val(a_val); free_val(b_val);  
991      push_cstring(env, new_string);      push_cstring(env, new_string);
992        unprotect(env); unprotect(env);
993      free(new_string);      free(new_string);
994      return;      return;
995    }    }
# Line 889  extern void sx_2b(environment *env) { Line 1000  extern void sx_2b(environment *env) {
1000      env->err=2;      env->err=2;
1001      return;      return;
1002    }    }
1003    a=env->head->item->content.val;    a= env->head->item->content.val;
1004    toss(env);    toss(env); if(env->err) return;
1005    if(env->err) return;    
1006    if(env->head->item->refcount == 1)    b= env->head->item->content.val;
1007      env->head->item->content.val += a;    toss(env); if(env->err) return;
1008    else {    push_int(env, a+b);
     b=env->head->item->content.val;  
     toss(env);  
     if(env->err) return;  
     push_int(env, a+b);  
   }  
1009  }  }
1010    
1011  /* - */  /* "-" */
1012  extern void sx_2d(environment *env) {  extern void sx_2d(environment *env) {
1013    int a, b;    int a, b;
1014    
# Line 918  extern void sx_2d(environment *env) { Line 1024  extern void sx_2d(environment *env) {
1024      env->err=2;      env->err=2;
1025      return;      return;
1026    }    }
1027    
1028    a=env->head->item->content.val;    a=env->head->item->content.val;
1029    toss(env);    toss(env); if(env->err) return;
1030    if(env->err) return;    b=env->head->item->content.val;
1031    if(env->head->item->refcount == 1)    toss(env); if(env->err) return;
1032      env->head->item->content.val -= a;    push_int(env, b-a);
   else {  
     b=env->head->item->content.val;  
     toss(env);  
     if(env->err) return;  
     push_int(env, b-a);  
   }  
1033  }  }
1034    
1035  /* > */  /* ">" */
1036  extern void sx_3e(environment *env) {  extern void sx_3e(environment *env) {
1037    int a, b;    int a, b;
1038    
# Line 947  extern void sx_3e(environment *env) { Line 1048  extern void sx_3e(environment *env) {
1048      env->err=2;      env->err=2;
1049      return;      return;
1050    }    }
1051    
1052    a=env->head->item->content.val;    a=env->head->item->content.val;
1053    toss(env);    toss(env); if(env->err) return;
1054    if(env->err) return;    b=env->head->item->content.val;
1055    if(env->head->item->refcount == 1)    toss(env); if(env->err) return;
1056      env->head->item->content.val = (env->head->item->content.val > a);    push_int(env, b>a);
   else {  
     b=env->head->item->content.val;  
     toss(env);  
     if(env->err) return;  
     push_int(env, b>a);  
   }  
1057  }  }
1058    
1059  /* Return copy of a value */  /* Return copy of a value */
1060  value *copy_val(value *old_value){  value *copy_val(environment *env, value *old_value){
1061    stackitem *old_item, *new_item, *prev_item;    stackitem *old_item, *new_item, *prev_item;
1062    
1063    value *new_value=malloc(sizeof(value));    value *new_value= new_val(env);
1064    
1065      protect(env, old_value);
1066      new_value->type= old_value->type;
1067    
   new_value->type=old_value->type;  
   new_value->refcount=0;        /* This is increased if/when this  
                                    value is referenced somewhere, like  
                                    in a stack item or a variable */  
1068    switch(old_value->type){    switch(old_value->type){
1069    case integer:    case integer:
1070      new_value->content.val=old_value->content.val;      new_value->content.val= old_value->content.val;
1071      break;      break;
1072    case string:    case string:
1073      (char *)(new_value->content.ptr)      (char *)(new_value->content.ptr)=
1074        = strdup((char *)(old_value->content.ptr));        strdup((char *)(old_value->content.ptr));
1075      break;      break;
1076    case func:    case func:
1077    case symb:    case symb:
1078      new_value->content.ptr=old_value->content.ptr;      new_value->content.ptr= old_value->content.ptr;
1079      break;      break;
1080    case list:    case list:
1081      new_value->content.ptr=NULL;      new_value->content.ptr= NULL;
1082    
1083      prev_item=NULL;      prev_item= NULL;
1084      old_item=(stackitem *)(old_value->content.ptr);      old_item= (stackitem*)(old_value->content.ptr);
1085    
1086      while(old_item != NULL) {   /* While list is not empty */      while(old_item != NULL) {   /* While list is not empty */
1087        new_item= malloc(sizeof(stackitem));        new_item= malloc(sizeof(stackitem));
1088        new_item->item=copy_val(old_item->item); /* recurse */        new_item->item= copy_val(env, old_item->item); /* recurse */
1089        new_item->next=NULL;        new_item->next= NULL;
1090        if(prev_item != NULL)     /* If this wasn't the first item */        if(prev_item != NULL)     /* If this wasn't the first item */
1091          prev_item->next=new_item; /* point the previous item to the          prev_item->next= new_item; /* point the previous item to the
1092                                       new item */                                       new item */
1093        else        else
1094          new_value->content.ptr=new_item;          new_value->content.ptr= new_item;
1095        old_item=old_item->next;        old_item= old_item->next;
1096        prev_item=new_item;        prev_item= new_item;
1097      }          }    
1098      break;      break;
1099    }    }
1100    
1101      unprotect(env);
1102    
1103    return new_value;    return new_value;
1104  }  }
1105    
1106  /* duplicates an item on the stack */  /* "dup"; duplicates an item on the stack */
1107  extern void dup(environment *env) {  extern void sx_647570(environment *env) {
1108    if((env->head)==NULL) {    if((env->head)==NULL) {
1109      printerr("Too Few Arguments");      printerr("Too Few Arguments");
1110      env->err=1;      env->err= 1;
1111      return;      return;
1112    }    }
1113    push_val(env, copy_val(env->head->item));    push_val(env, copy_val(env, env->head->item));
1114  }  }
1115    
1116  /* "if", If-Then */  /* "if", If-Then */
# Line 1022  extern void sx_6966(environment *env) { Line 1120  extern void sx_6966(environment *env) {
1120    
1121    if((env->head)==NULL || env->head->next==NULL) {    if((env->head)==NULL || env->head->next==NULL) {
1122      printerr("Too Few Arguments");      printerr("Too Few Arguments");
1123      env->err=1;      env->err= 1;
1124      return;      return;
1125    }    }
1126    
# Line 1082  extern void ifelse(environment *env) { Line 1180  extern void ifelse(environment *env) {
1180    eval(env);    eval(env);
1181  }  }
1182    
1183  /* while */  /* "while" */
1184  extern void sx_7768696c65(environment *env) {  extern void sx_7768696c65(environment *env) {
1185    
1186    int truth;    int truth;
# Line 1095  extern void sx_7768696c65(environment *e Line 1193  extern void sx_7768696c65(environment *e
1193    }    }
1194    
1195    loop= env->head->item;    loop= env->head->item;
1196    loop->refcount++;    protect(env, loop);
1197    toss(env); if(env->err) return;    toss(env); if(env->err) return;
1198    
1199    test= env->head->item;    test= env->head->item;
1200    test->refcount++;    protect(env, test);
1201    toss(env); if(env->err) return;    toss(env); if(env->err) return;
1202    
1203    do {    do {
# Line 1108  extern void sx_7768696c65(environment *e Line 1206  extern void sx_7768696c65(environment *e
1206            
1207      if(env->head->item->type != integer) {      if(env->head->item->type != integer) {
1208        printerr("Bad Argument Type");        printerr("Bad Argument Type");
1209        env->err=2;        env->err= 2;
1210        return;        return;
1211      }      }
1212            
# Line 1124  extern void sx_7768696c65(environment *e Line 1222  extern void sx_7768696c65(environment *e
1222        
1223    } while(truth);    } while(truth);
1224    
1225    free_val(test);    unprotect(env); unprotect(env);
   free_val(loop);  
1226  }  }
1227    
1228  /* For-loop */  
1229    /* "for"; for-loop */
1230  extern void sx_666f72(environment *env) {  extern void sx_666f72(environment *env) {
1231      value *loop;
1232      int foo1, foo2;
1233    
1234      if(env->head==NULL || env->head->next==NULL
1235         || env->head->next->next==NULL) {
1236        printerr("Too Few Arguments");
1237        env->err= 1;
1238        return;
1239      }
1240    
1241      if(env->head->next->item->type!=integer
1242         || env->head->next->next->item->type!=integer) {
1243        printerr("Bad Argument Type");
1244        env->err= 2;
1245        return;
1246      }
1247    
1248      loop= env->head->item;
1249      protect(env, loop);
1250      toss(env); if(env->err) return;
1251    
1252      foo2= env->head->item->content.val;
1253      toss(env); if(env->err) return;
1254    
1255      foo1= env->head->item->content.val;
1256      toss(env); if(env->err) return;
1257    
1258      if(foo1<=foo2) {
1259        while(foo1<=foo2) {
1260          push_int(env, foo1);
1261          push_val(env, loop);
1262          eval(env); if(env->err) return;
1263          foo1++;
1264        }
1265      } else {
1266        while(foo1>=foo2) {
1267          push_int(env, foo1);
1268          push_val(env, loop);
1269          eval(env); if(env->err) return;
1270          foo1--;
1271        }
1272      }
1273      unprotect(env);
1274    }
1275    
1276    /* Variant of for-loop */
1277    extern void foreach(environment *env) {
1278        
1279    value *loop, *foo;    value *loop, *foo;
1280    stackitem *iterator;    stackitem *iterator;
1281        
1282    if((env->head)==NULL || env->head->next==NULL) {    if((env->head)==NULL || env->head->next==NULL) {
1283      printerr("Too Few Arguments");      printerr("Too Few Arguments");
1284      env->err=1;      env->err= 1;
1285      return;      return;
1286    }    }
1287    
1288    if(env->head->next->item->type != list) {    if(env->head->next->item->type != list) {
1289      printerr("Bad Argument Type");      printerr("Bad Argument Type");
1290      env->err=2;      env->err= 2;
1291      return;      return;
1292    }    }
1293    
1294    loop= env->head->item;    loop= env->head->item;
1295    loop->refcount++;    protect(env, loop);
1296    toss(env); if(env->err) return;    toss(env); if(env->err) return;
1297    
1298    foo= env->head->item;    foo= env->head->item;
1299    foo->refcount++;    protect(env, foo);
1300    toss(env); if(env->err) return;    toss(env); if(env->err) return;
1301    
1302    iterator= foo->content.ptr;    iterator= foo->content.ptr;
# Line 1162  extern void sx_666f72(environment *env) Line 1307  extern void sx_666f72(environment *env)
1307      eval(env); if(env->err) return;      eval(env); if(env->err) return;
1308      iterator= iterator->next;      iterator= iterator->next;
1309    }    }
1310      unprotect(env); unprotect(env);
   free_val(loop);  
   free_val(foo);  
1311  }  }
1312    
1313  /* 'to' */  /* "to" */
1314  extern void to(environment *env) {  extern void to(environment *env) {
1315    int i, start, ending;    int i, start, ending;
1316    stackitem *temp_head;    stackitem *temp_head;
# Line 1202  extern void to(environment *env) { Line 1345  extern void to(environment *env) {
1345        push_int(env, i);        push_int(env, i);
1346    }    }
1347    
1348    temp_val= malloc(sizeof(value));    temp_val= new_val(env);
1349    temp_val->content.ptr= env->head;    temp_val->content.ptr= env->head;
   temp_val->refcount= 1;  
1350    temp_val->type= list;    temp_val->type= list;
1351    env->head= temp_head;    env->head= temp_head;
1352    push_val(env, temp_val);    push_val(env, temp_val);
# Line 1214  extern void to(environment *env) { Line 1356  extern void to(environment *env) {
1356  extern void readline(environment *env) {  extern void readline(environment *env) {
1357    char in_string[101];    char in_string[101];
1358    
1359    fgets(in_string, 100, stdin);    if(fgets(in_string, 100, env->inputstream)==NULL)
1360    push_cstring(env, in_string);      push_cstring(env, "");
1361      else
1362        push_cstring(env, in_string);
1363  }  }
1364    
1365  /* Read a value and place on stack */  /* "read"; Read a value and place on stack */
1366  extern void read(environment *env) {  extern void sx_72656164(environment *env) {
1367    const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";    const char symbform[]= "%[a-zA-Z0-9!$%*+./:<=>?@^_~-]%n";
1368    const char strform[]= "\"%[^\"]\"%n";    const char strform[]= "\"%[^\"]\"%n";
1369    const char intform[]= "%i%n";    const char intform[]= "%i%n";
1370    const char blankform[]= "%*[ \t]%n";    const char blankform[]= "%*[ \t]%n";
1371    const char ebrackform[]= "%*1[]]%n";    const char ebrackform[]= "]%n";
1372    const char semicform[]= "%*1[;]%n";    const char semicform[]= ";%n";
1373    const char bbrackform[]= "%*1[[]%n";    const char bbrackform[]= "[%n";
1374    
1375    int itemp, readlength= -1;    int itemp, readlength= -1;
1376    static int depth= 0;    static int depth= 0;
1377    char *rest, *match;    char *match;
1378    size_t inlength;    size_t inlength;
1379    
1380    if(env->in_string==NULL) {    if(env->in_string==NULL) {
1381      if(depth > 0) {      if(depth > 0 && env->interactive) {
1382        printf("]> ");        printf("]> ");
1383      }      }
1384      readline(env); if(env->err) return;      readline(env); if(env->err) return;
1385    
1386        if(((char *)(env->head->item->content.ptr))[0]=='\0'){
1387          env->err= 4;              /* "" means EOF */
1388          return;
1389        }
1390            
1391      env->in_string= malloc(strlen(env->head->item->content.ptr)+1);      env->in_string= malloc(strlen(env->head->item->content.ptr)+1);
1392      env->free_string= env->in_string; /* Save the original pointer */      env->free_string= env->in_string; /* Save the original pointer */
# Line 1247  extern void read(environment *env) { Line 1396  extern void read(environment *env) {
1396        
1397    inlength= strlen(env->in_string)+1;    inlength= strlen(env->in_string)+1;
1398    match= malloc(inlength);    match= malloc(inlength);
   rest= malloc(inlength);  
1399    
1400    if(sscanf(env->in_string, blankform, &readlength)!=EOF    if(sscanf(env->in_string, blankform, &readlength)!=EOF
1401       && readlength != -1) {       && readlength != -1) {
# Line 1275  extern void read(environment *env) { Line 1423  extern void read(environment *env) {
1423    } else {    } else {
1424      free(env->free_string);      free(env->free_string);
1425      env->in_string = env->free_string = NULL;      env->in_string = env->free_string = NULL;
     free(match);  
1426    }    }
1427    if ( env->in_string != NULL) {    if ( env->in_string != NULL) {
1428      env->in_string += readlength;      env->in_string += readlength;
1429    }    }
1430    
1431      free(match);
1432    
1433    if(depth)    if(depth)
1434      return read(env);      return sx_72656164(env);
1435    }
1436    
1437    extern void beep(environment *env) {
1438    
1439      int freq, dur, period, ticks;
1440    
1441      if((env->head)==NULL || env->head->next==NULL) {
1442        printerr("Too Few Arguments");
1443        env->err=1;
1444        return;
1445      }
1446    
1447      if(env->head->item->type!=integer
1448         || env->head->next->item->type!=integer) {
1449        printerr("Bad Argument Type");
1450        env->err=2;
1451        return;
1452      }
1453    
1454      dur=env->head->item->content.val;
1455      toss(env);
1456      freq=env->head->item->content.val;
1457      toss(env);
1458    
1459      period=1193180/freq;          /* convert freq from Hz to period
1460                                       length */
1461      ticks=dur*.001193180;         /* convert duration from µseconds to
1462                                       timer ticks */
1463    
1464    /*    ticks=dur/1000; */
1465    
1466      /*  if (ioctl(STDOUT_FILENO, KDMKTONE, (125<<16) + 0x637)==0) */
1467      switch (ioctl(STDOUT_FILENO, KDMKTONE, (ticks<<16) | period)){
1468      case 0:
1469        usleep(dur);
1470        return;
1471      case -1:
1472        perror("beep");
1473        env->err=5;
1474        return;
1475      default:
1476        abort();
1477      }
1478    };
1479    
1480    /* "wait" */
1481    extern void sx_77616974(environment *env) {
1482    
1483      int dur;
1484    
1485      if((env->head)==NULL) {
1486        printerr("Too Few Arguments");
1487        env->err=1;
1488        return;
1489      }
1490    
1491      if(env->head->item->type!=integer) {
1492        printerr("Bad Argument Type");
1493        env->err=2;
1494        return;
1495      }
1496    
1497      dur=env->head->item->content.val;
1498      toss(env);
1499    
1500      usleep(dur);
1501    };
1502    
1503    extern void copying(environment *env){
1504      printf("GNU GENERAL PUBLIC LICENSE\n\
1505                           Version 2, June 1991\n\
1506    \n\
1507     Copyright (C) 1989, 1991 Free Software Foundation, Inc.\n\
1508         59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\n\
1509     Everyone is permitted to copy and distribute verbatim copies\n\
1510     of this license document, but changing it is not allowed.\n\
1511    \n\
1512                                Preamble\n\
1513    \n\
1514      The licenses for most software are designed to take away your\n\
1515    freedom to share and change it.  By contrast, the GNU General Public\n\
1516    License is intended to guarantee your freedom to share and change free\n\
1517    software--to make sure the software is free for all its users.  This\n\
1518    General Public License applies to most of the Free Software\n\
1519    Foundation's software and to any other program whose authors commit to\n\
1520    using it.  (Some other Free Software Foundation software is covered by\n\
1521    the GNU Library General Public License instead.)  You can apply it to\n\
1522    your programs, too.\n\
1523    \n\
1524      When we speak of free software, we are referring to freedom, not\n\
1525    price.  Our General Public Licenses are designed to make sure that you\n\
1526    have the freedom to distribute copies of free software (and charge for\n\
1527    this service if you wish), that you receive source code or can get it\n\
1528    if you want it, that you can change the software or use pieces of it\n\
1529    in new free programs; and that you know you can do these things.\n\
1530    \n\
1531      To protect your rights, we need to make restrictions that forbid\n\
1532    anyone to deny you these rights or to ask you to surrender the rights.\n\
1533    These restrictions translate to certain responsibilities for you if you\n\
1534    distribute copies of the software, or if you modify it.\n\
1535    \n\
1536      For example, if you distribute copies of such a program, whether\n\
1537    gratis or for a fee, you must give the recipients all the rights that\n\
1538    you have.  You must make sure that they, too, receive or can get the\n\
1539    source code.  And you must show them these terms so they know their\n\
1540    rights.\n\
1541    \n\
1542      We protect your rights with two steps: (1) copyright the software, and\n\
1543    (2) offer you this license which gives you legal permission to copy,\n\
1544    distribute and/or modify the software.\n\
1545    \n\
1546      Also, for each author's protection and ours, we want to make certain\n\
1547    that everyone understands that there is no warranty for this free\n\
1548    software.  If the software is modified by someone else and passed on, we\n\
1549    want its recipients to know that what they have is not the original, so\n\
1550    that any problems introduced by others will not reflect on the original\n\
1551    authors' reputations.\n\
1552    \n\
1553      Finally, any free program is threatened constantly by software\n\
1554    patents.  We wish to avoid the danger that redistributors of a free\n\
1555    program will individually obtain patent licenses, in effect making the\n\
1556    program proprietary.  To prevent this, we have made it clear that any\n\
1557    patent must be licensed for everyone's free use or not licensed at all.\n\
1558    \n\
1559      The precise terms and conditions for copying, distribution and\n\
1560    modification follow.\n\
1561    \n\
1562                        GNU GENERAL PUBLIC LICENSE\n\
1563       TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION\n\
1564    \n\
1565      0. This License applies to any program or other work which contains\n\
1566    a notice placed by the copyright holder saying it may be distributed\n\
1567    under the terms of this General Public License.  The \"Program\", below,\n\
1568    refers to any such program or work, and a \"work based on the Program\"\n\
1569    means either the Program or any derivative work under copyright law:\n\
1570    that is to say, a work containing the Program or a portion of it,\n\
1571    either verbatim or with modifications and/or translated into another\n\
1572    language.  (Hereinafter, translation is included without limitation in\n\
1573    the term \"modification\".)  Each licensee is addressed as \"you\".\n\
1574    \n\
1575    Activities other than copying, distribution and modification are not\n\
1576    covered by this License; they are outside its scope.  The act of\n\
1577    running the Program is not restricted, and the output from the Program\n\
1578    is covered only if its contents constitute a work based on the\n\
1579    Program (independent of having been made by running the Program).\n\
1580    Whether that is true depends on what the Program does.\n\
1581    \n\
1582      1. You may copy and distribute verbatim copies of the Program's\n\
1583    source code as you receive it, in any medium, provided that you\n\
1584    conspicuously and appropriately publish on each copy an appropriate\n\
1585    copyright notice and disclaimer of warranty; keep intact all the\n\
1586    notices that refer to this License and to the absence of any warranty;\n\
1587    and give any other recipients of the Program a copy of this License\n\
1588    along with the Program.\n\
1589    \n\
1590    You may charge a fee for the physical act of transferring a copy, and\n\
1591    you may at your option offer warranty protection in exchange for a fee.\n\
1592    \n\
1593      2. You may modify your copy or copies of the Program or any portion\n\
1594    of it, thus forming a work based on the Program, and copy and\n\
1595    distribute such modifications or work under the terms of Section 1\n\
1596    above, provided that you also meet all of these conditions:\n\
1597    \n\
1598        a) You must cause the modified files to carry prominent notices\n\
1599        stating that you changed the files and the date of any change.\n\
1600    \n\
1601        b) You must cause any work that you distribute or publish, that in\n\
1602        whole or in part contains or is derived from the Program or any\n\
1603        part thereof, to be licensed as a whole at no charge to all third\n\
1604        parties under the terms of this License.\n\
1605    \n\
1606        c) If the modified program normally reads commands interactively\n\
1607        when run, you must cause it, when started running for such\n\
1608        interactive use in the most ordinary way, to print or display an\n\
1609        announcement including an appropriate copyright notice and a\n\
1610        notice that there is no warranty (or else, saying that you provide\n\
1611        a warranty) and that users may redistribute the program under\n\
1612        these conditions, and telling the user how to view a copy of this\n\
1613        License.  (Exception: if the Program itself is interactive but\n\
1614        does not normally print such an announcement, your work based on\n\
1615        the Program is not required to print an announcement.)\n\
1616    \n\
1617    These requirements apply to the modified work as a whole.  If\n\
1618    identifiable sections of that work are not derived from the Program,\n\
1619    and can be reasonably considered independent and separate works in\n\
1620    themselves, then this License, and its terms, do not apply to those\n\
1621    sections when you distribute them as separate works.  But when you\n\
1622    distribute the same sections as part of a whole which is a work based\n\
1623    on the Program, the distribution of the whole must be on the terms of\n\
1624    this License, whose permissions for other licensees extend to the\n\
1625    entire whole, and thus to each and every part regardless of who wrote it.\n\
1626    \n\
1627    Thus, it is not the intent of this section to claim rights or contest\n\
1628    your rights to work written entirely by you; rather, the intent is to\n\
1629    exercise the right to control the distribution of derivative or\n\
1630    collective works based on the Program.\n\
1631    \n\
1632    In addition, mere aggregation of another work not based on the Program\n\
1633    with the Program (or with a work based on the Program) on a volume of\n\
1634    a storage or distribution medium does not bring the other work under\n\
1635    the scope of this License.\n\
1636    \n\
1637      3. You may copy and distribute the Program (or a work based on it,\n\
1638    under Section 2) in object code or executable form under the terms of\n\
1639    Sections 1 and 2 above provided that you also do one of the following:\n\
1640    \n\
1641        a) Accompany it with the complete corresponding machine-readable\n\
1642        source code, which must be distributed under the terms of Sections\n\
1643        1 and 2 above on a medium customarily used for software interchange; or,\n\
1644    \n\
1645        b) Accompany it with a written offer, valid for at least three\n\
1646        years, to give any third party, for a charge no more than your\n\
1647        cost of physically performing source distribution, a complete\n\
1648        machine-readable copy of the corresponding source code, to be\n\
1649        distributed under the terms of Sections 1 and 2 above on a medium\n\
1650        customarily used for software interchange; or,\n\
1651    \n\
1652        c) Accompany it with the information you received as to the offer\n\
1653        to distribute corresponding source code.  (This alternative is\n\
1654        allowed only for noncommercial distribution and only if you\n\
1655        received the program in object code or executable form with such\n\
1656        an offer, in accord with Subsection b above.)\n\
1657    \n\
1658    The source code for a work means the preferred form of the work for\n\
1659    making modifications to it.  For an executable work, complete source\n\
1660    code means all the source code for all modules it contains, plus any\n\
1661    associated interface definition files, plus the scripts used to\n\
1662    control compilation and installation of the executable.  However, as a\n\
1663    special exception, the source code distributed need not include\n\
1664    anything that is normally distributed (in either source or binary\n\
1665    form) with the major components (compiler, kernel, and so on) of the\n\
1666    operating system on which the executable runs, unless that component\n\
1667    itself accompanies the executable.\n\
1668    \n\
1669    If distribution of executable or object code is made by offering\n\
1670    access to copy from a designated place, then offering equivalent\n\
1671    access to copy the source code from the same place counts as\n\
1672    distribution of the source code, even though third parties are not\n\
1673    compelled to copy the source along with the object code.\n\
1674    \n\
1675      4. You may not copy, modify, sublicense, or distribute the Program\n\
1676    except as expressly provided under this License.  Any attempt\n\
1677    otherwise to copy, modify, sublicense or distribute the Program is\n\
1678    void, and will automatically terminate your rights under this License.\n\
1679    However, parties who have received copies, or rights, from you under\n\
1680    this License will not have their licenses terminated so long as such\n\
1681    parties remain in full compliance.\n\
1682    \n\
1683      5. You are not required to accept this License, since you have not\n\
1684    signed it.  However, nothing else grants you permission to modify or\n\
1685    distribute the Program or its derivative works.  These actions are\n\
1686    prohibited by law if you do not accept this License.  Therefore, by\n\
1687    modifying or distributing the Program (or any work based on the\n\
1688    Program), you indicate your acceptance of this License to do so, and\n\
1689    all its terms and conditions for copying, distributing or modifying\n\
1690    the Program or works based on it.\n\
1691    \n\
1692      6. Each time you redistribute the Program (or any work based on the\n\
1693    Program), the recipient automatically receives a license from the\n\
1694    original licensor to copy, distribute or modify the Program subject to\n\
1695    these terms and conditions.  You may not impose any further\n\
1696    restrictions on the recipients' exercise of the rights granted herein.\n\
1697    You are not responsible for enforcing compliance by third parties to\n\
1698    this License.\n\
1699    \n\
1700      7. If, as a consequence of a court judgment or allegation of patent\n\
1701    infringement or for any other reason (not limited to patent issues),\n\
1702    conditions are imposed on you (whether by court order, agreement or\n\
1703    otherwise) that contradict the conditions of this License, they do not\n\
1704    excuse you from the conditions of this License.  If you cannot\n\
1705    distribute so as to satisfy simultaneously your obligations under this\n\
1706    License and any other pertinent obligations, then as a consequence you\n\
1707    may not distribute the Program at all.  For example, if a patent\n\
1708    license would not permit royalty-free redistribution of the Program by\n\
1709    all those who receive copies directly or indirectly through you, then\n\
1710    the only way you could satisfy both it and this License would be to\n\
1711    refrain entirely from distribution of the Program.\n\
1712    \n\
1713    If any portion of this section is held invalid or unenforceable under\n\
1714    any particular circumstance, the balance of the section is intended to\n\
1715    apply and the section as a whole is intended to apply in other\n\
1716    circumstances.\n\
1717    \n\
1718    It is not the purpose of this section to induce you to infringe any\n\
1719    patents or other property right claims or to contest validity of any\n\
1720    such claims; this section has the sole purpose of protecting the\n\
1721    integrity of the free software distribution system, which is\n\
1722    implemented by public license practices.  Many people have made\n\
1723    generous contributions to the wide range of software distributed\n\
1724    through that system in reliance on consistent application of that\n\
1725    system; it is up to the author/donor to decide if he or she is willing\n\
1726    to distribute software through any other system and a licensee cannot\n\
1727    impose that choice.\n\
1728    \n\
1729    This section is intended to make thoroughly clear what is believed to\n\
1730    be a consequence of the rest of this License.\n\
1731    \n\
1732      8. If the distribution and/or use of the Program is restricted in\n\
1733    certain countries either by patents or by copyrighted interfaces, the\n\
1734    original copyright holder who places the Program under this License\n\
1735    may add an explicit geographical distribution limitation excluding\n\
1736    those countries, so that distribution is permitted only in or among\n\
1737    countries not thus excluded.  In such case, this License incorporates\n\
1738    the limitation as if written in the body of this License.\n\
1739    \n\
1740      9. The Free Software Foundation may publish revised and/or new versions\n\
1741    of the General Public License from time to time.  Such new versions will\n\
1742    be similar in spirit to the present version, but may differ in detail to\n\
1743    address new problems or concerns.\n\
1744    \n\
1745    Each version is given a distinguishing version number.  If the Program\n\
1746    specifies a version number of this License which applies to it and \"any\n\
1747    later version\", you have the option of following the terms and conditions\n\
1748    either of that version or of any later version published by the Free\n\
1749    Software Foundation.  If the Program does not specify a version number of\n\
1750    this License, you may choose any version ever published by the Free Software\n\
1751    Foundation.\n\
1752    \n\
1753      10. If you wish to incorporate parts of the Program into other free\n\
1754    programs whose distribution conditions are different, write to the author\n\
1755    to ask for permission.  For software which is copyrighted by the Free\n\
1756    Software Foundation, write to the Free Software Foundation; we sometimes\n\
1757    make exceptions for this.  Our decision will be guided by the two goals\n\
1758    of preserving the free status of all derivatives of our free software and\n\
1759    of promoting the sharing and reuse of software generally.\n");
1760    }
1761    
1762    extern void warranty(environment *env){
1763      printf("                          NO WARRANTY\n\
1764    \n\
1765      11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY\n\
1766    FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN\n\
1767    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\n\
1768    PROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\n\
1769    OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF\n\
1770    MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS\n\
1771    TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE\n\
1772    PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,\n\
1773    REPAIR OR CORRECTION.\n\
1774    \n\
1775      12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING\n\
1776    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR\n\
1777    REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,\n\
1778    INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING\n\
1779    OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED\n\
1780    TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY\n\
1781    YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\n\
1782    PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\n\
1783    POSSIBILITY OF SUCH DAMAGES.\n");
1784    }
1785    
1786    /* "*" */
1787    extern void sx_2a(environment *env)
1788    {
1789      int a, b;
1790    
1791      if((env->head)==NULL || env->head->next==NULL) {
1792        printerr("Too Few Arguments");
1793        env->err=1;
1794        return;
1795      }
1796      
1797      if(env->head->item->type!=integer
1798         || env->head->next->item->type!=integer) {
1799        printerr("Bad Argument Type");
1800        env->err=2;
1801        return;
1802      }
1803    
1804      a=env->head->item->content.val;
1805      toss(env); if(env->err) return;
1806      b=env->head->item->content.val;
1807      toss(env); if(env->err) return;
1808      push_int(env, b*a);
1809    }
1810    
1811    /* "/" */
1812    extern void sx_2f(environment *env)
1813    {
1814      int a, b;
1815    
1816      if((env->head)==NULL || env->head->next==NULL) {
1817        printerr("Too Few Arguments");
1818        env->err=1;
1819        return;
1820      }
1821      
1822      if(env->head->item->type!=integer
1823         || env->head->next->item->type!=integer) {
1824        printerr("Bad Argument Type");
1825        env->err=2;
1826        return;
1827      }
1828    
1829      a=env->head->item->content.val;
1830      toss(env); if(env->err) return;
1831      b=env->head->item->content.val;
1832      toss(env); if(env->err) return;
1833      push_int(env, b/a);
1834    }
1835    
1836    /* "mod" */
1837    extern void mod(environment *env)
1838    {
1839      int a, b;
1840    
1841      if((env->head)==NULL || env->head->next==NULL) {
1842        printerr("Too Few Arguments");
1843        env->err=1;
1844        return;
1845      }
1846      
1847      if(env->head->item->type!=integer
1848         || env->head->next->item->type!=integer) {
1849        printerr("Bad Argument Type");
1850        env->err=2;
1851        return;
1852      }
1853    
1854      a=env->head->item->content.val;
1855      toss(env); if(env->err) return;
1856      b=env->head->item->content.val;
1857      toss(env); if(env->err) return;
1858      push_int(env, b%a);
1859  }  }
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