-static void swap_inequality(struct isl_basic_set *bset, int a, int b)
-{
- isl_int *t = bset->ineq[a];
- bset->ineq[a] = bset->ineq[b];
- bset->ineq[b] = t;
-}
-
-static struct isl_mat *independent_bounds(struct isl_ctx *ctx,
- struct isl_basic_set *bset)
-{
- int i, j, n;
- struct isl_mat *dirs = NULL;
- struct isl_mat *bounds = NULL;
- unsigned dim;
-
- if (!bset)
- return NULL;
-
- dim = isl_basic_set_n_dim(bset);
- bounds = isl_mat_alloc(ctx, 1+dim, 1+dim);
- if (!bounds)
- return NULL;
-
- isl_int_set_si(bounds->row[0][0], 1);
- isl_seq_clr(bounds->row[0]+1, dim);
- bounds->n_row = 1;
-
- if (bset->n_ineq == 0)
- return bounds;
-
- dirs = isl_mat_alloc(ctx, dim, dim);
- if (!dirs) {
- isl_mat_free(ctx, bounds);
- return NULL;
- }
- isl_seq_cpy(dirs->row[0], bset->ineq[0]+1, dirs->n_col);
- isl_seq_cpy(bounds->row[1], bset->ineq[0], bounds->n_col);
- for (j = 1, n = 1; n < dim && j < bset->n_ineq; ++j) {
- int pos;
-
- isl_seq_cpy(dirs->row[n], bset->ineq[j]+1, dirs->n_col);
-
- pos = isl_seq_first_non_zero(dirs->row[n], dirs->n_col);
- if (pos < 0)
- continue;
- for (i = 0; i < n; ++i) {
- int pos_i;
- pos_i = isl_seq_first_non_zero(dirs->row[i], dirs->n_col);
- if (pos_i < pos)
- continue;
- if (pos_i > pos)
- break;
- isl_seq_elim(dirs->row[n], dirs->row[i], pos,
- dirs->n_col, NULL);
- pos = isl_seq_first_non_zero(dirs->row[n], dirs->n_col);
- if (pos < 0)
- break;
- }
- if (pos < 0)
- continue;
- if (i < n) {
- int k;
- isl_int *t = dirs->row[n];
- for (k = n; k > i; --k)
- dirs->row[k] = dirs->row[k-1];
- dirs->row[i] = t;
- }
- ++n;
- isl_seq_cpy(bounds->row[n], bset->ineq[j], bounds->n_col);
- }
- isl_mat_free(ctx, dirs);
- bounds->n_row = 1+n;
- return bounds;
-}
-
-/* Skew into positive orthant and project out lineality space */
-static struct isl_basic_set *isl_basic_set_skew_to_positive_orthant(
- struct isl_basic_set *bset, struct isl_mat **T)
-{
- struct isl_mat *U = NULL;
- struct isl_mat *bounds = NULL;
- int i, j;
- unsigned old_dim, new_dim;
- struct isl_ctx *ctx;
-
- *T = NULL;
- if (!bset)
- return NULL;
-
- ctx = bset->ctx;
- isl_assert(ctx, isl_basic_set_n_param(bset) == 0, goto error);
- isl_assert(ctx, bset->n_div == 0, goto error);
- isl_assert(ctx, bset->n_eq == 0, goto error);
-
- old_dim = isl_basic_set_n_dim(bset);
- /* Try to move (multiples of) unit rows up. */
- for (i = 0, j = 0; i < bset->n_ineq; ++i) {
- int pos = isl_seq_first_non_zero(bset->ineq[i]+1, old_dim);
- if (pos < 0)
- continue;
- if (isl_seq_first_non_zero(bset->ineq[i]+1+pos+1,
- old_dim-pos-1) >= 0)
- continue;
- if (i != j)
- swap_inequality(bset, i, j);
- ++j;
- }
- bounds = independent_bounds(ctx, bset);
- if (!bounds)
- goto error;
- new_dim = bounds->n_row - 1;
- bounds = isl_mat_left_hermite(ctx, bounds, 1, &U, NULL);
- if (!bounds)
- goto error;
- U = isl_mat_drop_cols(ctx, U, 1 + new_dim, old_dim - new_dim);
- bset = isl_basic_set_preimage(ctx, bset, isl_mat_copy(ctx, U));
- if (!bset)
- goto error;
- *T = U;
- isl_mat_free(ctx, bounds);
- return bset;
-error:
- isl_mat_free(ctx, bounds);
- isl_mat_free(ctx, U);
- isl_basic_set_free(bset);
- return NULL;
-}
-