exptable.c

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#include "exptable.h"
#include "table.h"
/* Implementation of a hashtable [exponent vectors, of fixed length] -->
 * unsigned long int. */
/* The implementation uses table.{h,c}, which was written by David R. Hanson */
 
#include "interface/m2-mem.h"
 
/*these next lines added by MES, July 2002, to use our gc routines..*/
#define  NEW(p) ((p) = (void *) getmem((long)sizeof *(p)))
#define FREE(ptr) ((void)(freemem((ptr)), (ptr) = 0))
 
struct exponent_table
{
  int nvars;
  Table_T *table;
};
 
static int table_nvars; /* Set this before calling 'hash' */
 
unsigned int exp_hash(const void *x)
/* exp has type 'exponent' */
{
  int i;
  const int *xx = x;
  unsigned int result = 0;
  for (i = 0; i < table_nvars; i++) result += (xx[i] << 3);
  return result;
}
 
int exp_cmp(const void *x, const void *y)
/* x, y are both of type 'exponent' */
{
  int i;
  const int *xx = x;
  const int *yy = y;
  for (i = 0; i < table_nvars; i++)
    {
      int cmp = xx[i] - yy[i];
      if (cmp != 0) return cmp;
    }
  return 0;
}
 
exponent_table *exponent_table_new(int hint, int nvars)
{
  exponent_table *result;
  NEW(result);
  result->nvars = nvars;
  result->table = Table_new(hint, exp_cmp, exp_hash);
  return result;
}
 
int exponent_table_length(exponent_table *E) { return Table_length(E->table); }
void exponent_table_free(exponent_table **E)
{
  Table_free(&((*E)->table));
  FREE(*E);
  *E = 0;
}
 
long exponent_table_put(exponent_table *E, const exponent expon, long value)
/* Puts the element 'expon => value' into the table, and if an element is
   already there, its value is returned, otherwise 0 is returned.
   Thus, it is a good idea to not insert zero values into the table */
{
  table_nvars = E->nvars;
  return (long)Table_put(E->table, expon, (void *)value);
}
 
long exponent_table_get(exponent_table *E, const exponent expon)
/* Returns the value associated to 'expon', returning zero, if 'expon'
   is not in the table */
{
  table_nvars = E->nvars;
  return (long)Table_get(E->table, expon);
}
 
const void **exponent_table_to_array(exponent_table *E)
{
  return Table_toArray(E->table, NULL);
}
 
/*
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
*/