var_set.doc

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var_set Package, Version 1.0

Tom Shiple (original contributor: Herve' Touati)
University of California, Berkeley, 1993


Introduction -----------------------------------------------------------------

The var_set package is used to store and manipulate sets.  The var_set_t data
structure is essentially a bit array.  Its size is static.  The positions of
the array are numbered from 0 to n-1, where n is the size of the var_set. When
a bit is "set", its value is 1; when a bit is "clear", its value is 0.


Summary -----------------------------------------------------------------------

  var_set_new()
  var_set_copy()
  var_set_assign()
  var_set_free()
  var_set_n_elts()
  var_set_or()
  var_set_and()
  var_set_not()
  var_set_get_elt()
  var_set_set_elt()
  var_set_clear_elt()
  var_set_clear()
  var_set_intersect()
  var_set_is_empty()
  var_set_is_full()
  var_set_print()
  var_set_equal()
  var_set_cmp()
  var_set_hash()


Description of Functions ------------------------------------------------------

var_set_t 
*var_set_new(size)
int size;

   Allocate a new var_set data structure of size `size'.  Clears all the
   elements.

var_set_t 
*var_set_copy(set)
var_set_t *set;

   Allocate a new var_set data structure with the same contents as `set'.

var_set_t 
*var_set_assign(result, set)
var_set_t *result;
var_set_t *set;

   Assign the contents of `result' to be the same as those of `set'.  `result'
   and `set' must be the same size.

void 
var_set_free(set)
var_set_t *set;

   Free the var_set data structure `set'.

int 
var_set_n_elts(set)
var_set_t *set;

   Return the number of bits in var_set `set' which are set (i.e. the
   cardinality).

var_set_t 
*var_set_or(result, a, b)
var_set_t *result;
var_set_t *a;
var_set_t *b;

   Compute the bitwise inclusive OR of `a' and `b', and store the result in
   `result'.  Also, return a pointer to `result'.  `a', `b', and `result' 
   must be the same size.  Note that `result' can be the same as either or
   both of `a' and `b' (e.g. var_set_or(foo, foo, bar)).

var_set_t 
*var_set_and(result, a, b)
var_set_t *result;
var_set_t *a;
var_set_t *b;

   Compute the bitwise AND of `a' and `b', and store the result in `result'.
   Also, return a pointer to `result'.  `a', `b', and `result' must be the 
   same size.  Note that `result' can be the same as either or both of `a' 
   and `b' (e.g. var_set_and(foo, foo, bar)).

var_set_t 
*var_set_not(result, a)
var_set_t *result;
var_set_t *a;

   Compute the bitwise complement of `a', and store the result in `result'.
   Also, return a pointer to `result'.  `a' and `result' must be the same 
   size.  Note that `result' can be the same as `a' (e.g. 
   var_set_not(foo, foo)).

int 
var_set_get_elt(set, index)
var_set_t *set;
int index;

   Return the value of the bit at position `index' in `set'.  `index' must be
   at least zero and less than the size of `set'.

void 
var_set_set_elt(set, index)
var_set_t *set;
int index;

   Set the value of the bit at position `index' in `set'.  `index' must be at
   least zero and less than the size of `set'.

void 
var_set_clear_elt(set, index)
var_set_t *set;
int index;

   Clear the value of the bit at position `index' in `set'.  `index' must be at
   least zero and less than the size of `set'.

void 
var_set_clear(set)
var_set_t *set;

   Clear the value of all the bits in `set'.  
   
int 
var_set_intersect(a, b)
var_set_t *a;
var_set_t *b;

   Return 1 if the var_sets `a' and `b' intersect (i.e. have bits set in the
   same position); otherwise, return 0.  `a' and `b' must be the same size.

int 
var_set_is_empty(a)
var_set_t *a;

   Return 1 if every bit of var_set `a' is cleared; otherwise, return 0.
   
int 
var_set_is_full(a)
var_set_t *a;

   Return 1 if every bit of var_set `a' is set; otherwise, return 0.
   
void 
var_set_print(fp, set)
FILE *fp;
var_set_t *set;

   Print to `fp' the value of each bit in var_set `set'.  Example output 
   for a set of 4 elements: "1 0 1 1".

int 
var_set_equal(a, b)
var_set_t *a;
var_set_t *b;

   Return 1 if the var_sets `a' and `b' are equal at every bit position;
   otherwise, return 0.  `a' and `b' must be the same size.

int 
var_set_cmp(obj1, obj2)
char *obj1;
char *obj2;

   Return 0 if the var_sets `a' and `b' are equal at every bit position;
   otherwise, return 1.  `a' and `b' must be the same size.

unsigned int 
var_set_hash(set)
var_set_t *set;

   Compute a hash value for the var_set `set'.  This is to be used when
   var_sets are used as keys in hash tables.