isl_power_templ.c

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#include <isl_val_private.h>
 
#define xFN(TYPE,NAME) TYPE ## _ ## NAME
#define FN(TYPE,NAME) xFN(TYPE,NAME)
 
/* Helper function for isl_*_fixed_power that applies (a copy of) "map2"
 * to the range of "map1" and returns the result.
 *
 * The result is coalesced in an attempt to reduce the number of disjuncts
 * that result from repeated applications.
 * Similarly, look for implicit equality constraints in an attempt
 * to reduce the number of local variables that get introduced
 * during the repeated applications.
 */
static __isl_give TYPE *FN(TYPE,fixed_power_apply)(__isl_take TYPE *map1,
  __isl_keep TYPE *map2)
{
  TYPE *res;
 
  res = FN(TYPE,apply_range)(map1, FN(TYPE,copy)(map2));
  res = FN(TYPE,detect_equalities)(res);
  res = FN(TYPE,coalesce)(res);
 
  return res;
}
 
/* Compute the given non-zero power of "map" and return the result.
 * If the exponent "exp" is negative, then the -exp th power of the inverse
 * relation is computed.
 */
__isl_give TYPE *FN(TYPE,fixed_power)(__isl_take TYPE *map, isl_int exp)
{
  isl_ctx *ctx;
  TYPE *res = NULL;
  isl_int r;
 
  if (!map)
    return NULL;
 
  ctx = FN(TYPE,get_ctx)(map);
  if (isl_int_is_zero(exp))
    isl_die(ctx, isl_error_invalid,
      "expecting non-zero exponent", goto error);
 
  if (isl_int_is_neg(exp)) {
    isl_int_neg(exp, exp);
    map = FN(TYPE,reverse)(map);
    return FN(TYPE,fixed_power)(map, exp);
  }
 
  isl_int_init(r);
  for (;;) {
    isl_int_fdiv_r(r, exp, ctx->two);
 
    if (!isl_int_is_zero(r)) {
      if (!res)
        res = FN(TYPE,copy)(map);
      else
        res = FN(TYPE,fixed_power_apply)(res, map);
      if (!res)
        break;
    }
 
    isl_int_fdiv_q(exp, exp, ctx->two);
    if (isl_int_is_zero(exp))
      break;
 
    map = FN(TYPE,fixed_power_apply)(map, map);
  }
  isl_int_clear(r);
 
  FN(TYPE,free)(map);
  return res;
error:
  FN(TYPE,free)(map);
  return NULL;
}
 
/* Compute the given non-zero power of "map" and return the result.
 * If the exponent "exp" is negative, then the -exp th power of the inverse
 * relation is computed.
 */
__isl_give TYPE *FN(TYPE,fixed_power_val)(__isl_take TYPE *map,
  __isl_take isl_val *exp)
{
  if (!map || !exp)
    goto error;
  if (!isl_val_is_int(exp))
    isl_die(FN(TYPE,get_ctx)(map), isl_error_invalid,
      "expecting integer exponent", goto error);
  map = FN(TYPE,fixed_power)(map, exp->n);
  isl_val_free(exp);
  return map;
error:
  FN(TYPE,free)(map);
  isl_val_free(exp);
  return NULL;
}