isl_scan.c

   1 /*
   2  * Copyright 2008-2009 Katholieke Universiteit Leuven
   3  *
   4  * Use of this software is governed by the GNU LGPLv2.1 license
   5  *
   6  * Written by Sven Verdoolaege, K.U.Leuven, Departement
   7  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
   8  */
   9
  10 #include "isl_basis_reduction.h"
  11 #include "isl_scan.h"
  12 #include "isl_seq.h"
  13 #include "isl_tab.h"
  14 #include <isl_map_private.h>
  15
  16 struct isl_counter {
  17         struct isl_scan_callback callback;
  18         isl_int count;
  19 };
  20
  21 static int increment_counter(struct isl_scan_callback *cb,
  22         __isl_take isl_vec *sample)
  23 {
  24         struct isl_counter *cnt = (struct isl_counter *)cb;
  25
  26         isl_int_add_ui(cnt->count, cnt->count, 1);
  27
  28         isl_vec_free(sample);
  29
  30         return 0;
  31 }
  32
  33 static int increment_range(struct isl_scan_callback *cb, isl_int min, isl_int max)
  34 {
  35         struct isl_counter *cnt = (struct isl_counter *)cb;
  36
  37         isl_int_add(cnt->count, cnt->count, max);
  38         isl_int_sub(cnt->count, cnt->count, min);
  39         isl_int_add_ui(cnt->count, cnt->count, 1);
  40
  41         return 0;
  42 }
  43
  44 /* Call callback->add with the current sample value of the tableau "tab".
  45  */
  46 static int add_solution(struct isl_tab *tab, struct isl_scan_callback *callback)
  47 {
  48         struct isl_vec *sample;
  49
  50         if (!tab)
  51                 return -1;
  52         sample = isl_tab_get_sample_value(tab);
  53         if (!sample)
  54                 return -1;
  55
  56         return callback->add(callback, sample);
  57 }
  58
  59 static int scan_0D(struct isl_basic_set *bset,
  60         struct isl_scan_callback *callback)
  61 {
  62         struct isl_vec *sample;
  63
  64         sample = isl_vec_alloc(bset->ctx, 1);
  65         isl_basic_set_free(bset);
  66
  67         if (!sample)
  68                 return -1;
  69
  70         isl_int_set_si(sample->el[0], 1);
  71
  72         return callback->add(callback, sample);
  73 }
  74
  75 /* Look for all integer points in "bset", which is assumed to be unbounded,
  76  * and call callback->add on each of them.
  77  *
  78  * We first compute a reduced basis for the set and then scan
  79  * the set in the directions of this basis.
  80  * We basically perform a depth first search, where in each level i
  81  * we compute the range in the i-th basis vector direction, given
  82  * fixed values in the directions of the previous basis vector.
  83  * We then add an equality to the tableau fixing the value in the
  84  * direction of the current basis vector to each value in the range
  85  * in turn and then continue to the next level.
  86  *
  87  * The search is implemented iteratively.  "level" identifies the current
  88  * basis vector.  "init" is true if we want the first value at the current
  89  * level and false if we want the next value.
  90  * Solutions are added in the leaves of the search tree, i.e., after
  91  * we have fixed a value in each direction of the basis.
  92  */
  93 int isl_basic_set_scan(struct isl_basic_set *bset,
  94         struct isl_scan_callback *callback)
  95 {
  96         unsigned dim;
  97         struct isl_mat *B = NULL;
  98         struct isl_tab *tab = NULL;
  99         struct isl_vec *min;
 100         struct isl_vec *max;
 101         struct isl_tab_undo **snap;
 102         int level;
 103         int init;
 104         enum isl_lp_result res;
 105
 106         if (!bset)
 107                 return -1;
 108
 109         dim = isl_basic_set_total_dim(bset);
 110         if (dim == 0)
 111                 return scan_0D(bset, callback);
 112
 113         min = isl_vec_alloc(bset->ctx, dim);
 114         max = isl_vec_alloc(bset->ctx, dim);
 115         snap = isl_alloc_array(bset->ctx, struct isl_tab_undo *, dim);
 116
 117         if (!min || !max || !snap)
 118                 goto error;
 119
 120         tab = isl_tab_from_basic_set(bset);
 121         if (!tab)
 122                 goto error;
 123         if (isl_tab_extend_cons(tab, dim + 1) < 0)
 124                 goto error;
 125
 126         tab->basis = isl_mat_identity(bset->ctx, 1 + dim);
 127         if (1)
 128                 tab = isl_tab_compute_reduced_basis(tab);
 129         if (!tab)
 130                 goto error;
 131         B = isl_mat_copy(tab->basis);
 132         if (!B)
 133                 goto error;
 134
 135         level = 0;
 136         init = 1;
 137
 138         while (level >= 0) {
 139                 int empty = 0;
 140                 if (init) {
 141                         res = isl_tab_min(tab, B->row[1 + level],
 142                                     bset->ctx->one, &min->el[level], NULL, 0);
 143                         if (res == isl_lp_empty)
 144                                 empty = 1;
 145                         if (res == isl_lp_error || res == isl_lp_unbounded)
 146                                 goto error;
 147                         isl_seq_neg(B->row[1 + level] + 1,
 148                                     B->row[1 + level] + 1, dim);
 149                         res = isl_tab_min(tab, B->row[1 + level],
 150                                     bset->ctx->one, &max->el[level], NULL, 0);
 151                         isl_seq_neg(B->row[1 + level] + 1,
 152                                     B->row[1 + level] + 1, dim);
 153                         isl_int_neg(max->el[level], max->el[level]);
 154                         if (res == isl_lp_empty)
 155                                 empty = 1;
 156                         if (res == isl_lp_error || res == isl_lp_unbounded)
 157                                 goto error;
 158                         snap[level] = isl_tab_snap(tab);
 159                 } else
 160                         isl_int_add_ui(min->el[level], min->el[level], 1);
 161
 162                 if (empty || isl_int_gt(min->el[level], max->el[level])) {
 163                         level--;
 164                         init = 0;
 165                         if (level >= 0)
 166                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 167                                         goto error;
 168                         continue;
 169                 }
 170                 if (level == dim - 1 && callback->add == increment_counter) {
 171                         if (increment_range(callback,
 172                                             min->el[level], max->el[level]))
 173                                 goto error;
 174                         level--;
 175                         init = 0;
 176                         if (level >= 0)
 177                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 178                                         goto error;
 179                         continue;
 180                 }
 181                 isl_int_neg(B->row[1 + level][0], min->el[level]);
 182                 tab = isl_tab_add_valid_eq(tab, B->row[1 + level]);
 183                 isl_int_set_si(B->row[1 + level][0], 0);
 184                 if (level < dim - 1) {
 185                         ++level;
 186                         init = 1;
 187                         continue;
 188                 }
 189                 if (add_solution(tab, callback) < 0)
 190                         goto error;
 191                 init = 0;
 192                 if (isl_tab_rollback(tab, snap[level]) < 0)
 193                         goto error;
 194         }
 195
 196         isl_tab_free(tab);
 197         free(snap);
 198         isl_vec_free(min);
 199         isl_vec_free(max);
 200         isl_basic_set_free(bset);
 201         isl_mat_free(B);
 202         return 0;
 203 error:
 204         isl_tab_free(tab);
 205         free(snap);
 206         isl_vec_free(min);
 207         isl_vec_free(max);
 208         isl_basic_set_free(bset);
 209         isl_mat_free(B);
 210         return -1;
 211 }
 212
 213 int isl_set_count(__isl_keep isl_set *set, isl_int *count)
 214 {
 215         int i;
 216         struct isl_counter cnt = { { &increment_counter } };
 217
 218         if (!set)
 219                 return -1;
 220
 221         isl_int_init(cnt.count);
 222
 223         set = isl_set_copy(set);
 224         set = isl_set_cow(set);
 225         set = isl_set_make_disjoint(set);
 226         set = isl_set_compute_divs(set);
 227         if (!set)
 228                 goto error;
 229
 230         isl_int_set_si(cnt.count, 0);
 231         for (i = 0; i < set->n; ++i)
 232                 if (isl_basic_set_scan(isl_basic_set_copy(set->p[i]),
 233                                         &cnt.callback) < 0)
 234                         goto error;
 235
 236         isl_int_set(*count, cnt.count);
 237
 238         isl_set_free(set);
 239         isl_int_clear(cnt.count);
 240
 241         return 0;
 242 error:
 243         isl_set_free(set);
 244         isl_int_clear(cnt.count);
 245         return -1;
 246 }