isl_scan.c

   1 /*
   2  * Copyright 2008-2009 Katholieke Universiteit Leuven
   3  *
   4  * Use of this software is governed by the MIT license
   5  *
   6  * Written by Sven Verdoolaege, K.U.Leuven, Departement
   7  * Computerwetenschappen, Celestijnenlaan 200A, B-3001 Leuven, Belgium
   8  */
   9
  10 #include <isl_ctx_private.h>
  11 #include <isl_map_private.h>
  12 #include "isl_basis_reduction.h"
  13 #include "isl_scan.h"
  14 #include <isl/seq.h>
  15 #include "isl_tab.h"
  16
  17 struct isl_counter {
  18         struct isl_scan_callback callback;
  19         isl_int count;
  20         isl_int max;
  21 };
  22
  23 static int increment_counter(struct isl_scan_callback *cb,
  24         __isl_take isl_vec *sample)
  25 {
  26         struct isl_counter *cnt = (struct isl_counter *)cb;
  27
  28         isl_int_add_ui(cnt->count, cnt->count, 1);
  29
  30         isl_vec_free(sample);
  31
  32         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  33                 return 0;
  34         return -1;
  35 }
  36
  37 static int increment_range(struct isl_scan_callback *cb, isl_int min, isl_int max)
  38 {
  39         struct isl_counter *cnt = (struct isl_counter *)cb;
  40
  41         isl_int_add(cnt->count, cnt->count, max);
  42         isl_int_sub(cnt->count, cnt->count, min);
  43         isl_int_add_ui(cnt->count, cnt->count, 1);
  44
  45         if (isl_int_is_zero(cnt->max) || isl_int_lt(cnt->count, cnt->max))
  46                 return 0;
  47         isl_int_set(cnt->count, cnt->max);
  48         return -1;
  49 }
  50
  51 /* Call callback->add with the current sample value of the tableau "tab".
  52  */
  53 static int add_solution(struct isl_tab *tab, struct isl_scan_callback *callback)
  54 {
  55         struct isl_vec *sample;
  56
  57         if (!tab)
  58                 return -1;
  59         sample = isl_tab_get_sample_value(tab);
  60         if (!sample)
  61                 return -1;
  62
  63         return callback->add(callback, sample);
  64 }
  65
  66 static int scan_0D(struct isl_basic_set *bset,
  67         struct isl_scan_callback *callback)
  68 {
  69         struct isl_vec *sample;
  70
  71         sample = isl_vec_alloc(bset->ctx, 1);
  72         isl_basic_set_free(bset);
  73
  74         if (!sample)
  75                 return -1;
  76
  77         isl_int_set_si(sample->el[0], 1);
  78
  79         return callback->add(callback, sample);
  80 }
  81
  82 /* Look for all integer points in "bset", which is assumed to be bounded,
  83  * and call callback->add on each of them.
  84  *
  85  * We first compute a reduced basis for the set and then scan
  86  * the set in the directions of this basis.
  87  * We basically perform a depth first search, where in each level i
  88  * we compute the range in the i-th basis vector direction, given
  89  * fixed values in the directions of the previous basis vector.
  90  * We then add an equality to the tableau fixing the value in the
  91  * direction of the current basis vector to each value in the range
  92  * in turn and then continue to the next level.
  93  *
  94  * The search is implemented iteratively.  "level" identifies the current
  95  * basis vector.  "init" is true if we want the first value at the current
  96  * level and false if we want the next value.
  97  * Solutions are added in the leaves of the search tree, i.e., after
  98  * we have fixed a value in each direction of the basis.
  99  */
 100 int isl_basic_set_scan(struct isl_basic_set *bset,
 101         struct isl_scan_callback *callback)
 102 {
 103         unsigned dim;
 104         struct isl_mat *B = NULL;
 105         struct isl_tab *tab = NULL;
 106         struct isl_vec *min;
 107         struct isl_vec *max;
 108         struct isl_tab_undo **snap;
 109         int level;
 110         int init;
 111         enum isl_lp_result res;
 112
 113         if (!bset)
 114                 return -1;
 115
 116         dim = isl_basic_set_total_dim(bset);
 117         if (dim == 0)
 118                 return scan_0D(bset, callback);
 119
 120         min = isl_vec_alloc(bset->ctx, dim);
 121         max = isl_vec_alloc(bset->ctx, dim);
 122         snap = isl_alloc_array(bset->ctx, struct isl_tab_undo *, dim);
 123
 124         if (!min || !max || !snap)
 125                 goto error;
 126
 127         tab = isl_tab_from_basic_set(bset, 0);
 128         if (!tab)
 129                 goto error;
 130         if (isl_tab_extend_cons(tab, dim + 1) < 0)
 131                 goto error;
 132
 133         tab->basis = isl_mat_identity(bset->ctx, 1 + dim);
 134         if (1)
 135                 tab = isl_tab_compute_reduced_basis(tab);
 136         if (!tab)
 137                 goto error;
 138         B = isl_mat_copy(tab->basis);
 139         if (!B)
 140                 goto error;
 141
 142         level = 0;
 143         init = 1;
 144
 145         while (level >= 0) {
 146                 int empty = 0;
 147                 if (init) {
 148                         res = isl_tab_min(tab, B->row[1 + level],
 149                                     bset->ctx->one, &min->el[level], NULL, 0);
 150                         if (res == isl_lp_empty)
 151                                 empty = 1;
 152                         if (res == isl_lp_error || res == isl_lp_unbounded)
 153                                 goto error;
 154                         isl_seq_neg(B->row[1 + level] + 1,
 155                                     B->row[1 + level] + 1, dim);
 156                         res = isl_tab_min(tab, B->row[1 + level],
 157                                     bset->ctx->one, &max->el[level], NULL, 0);
 158                         isl_seq_neg(B->row[1 + level] + 1,
 159                                     B->row[1 + level] + 1, dim);
 160                         isl_int_neg(max->el[level], max->el[level]);
 161                         if (res == isl_lp_empty)
 162                                 empty = 1;
 163                         if (res == isl_lp_error || res == isl_lp_unbounded)
 164                                 goto error;
 165                         snap[level] = isl_tab_snap(tab);
 166                 } else
 167                         isl_int_add_ui(min->el[level], min->el[level], 1);
 168
 169                 if (empty || isl_int_gt(min->el[level], max->el[level])) {
 170                         level--;
 171                         init = 0;
 172                         if (level >= 0)
 173                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 174                                         goto error;
 175                         continue;
 176                 }
 177                 if (level == dim - 1 && callback->add == increment_counter) {
 178                         if (increment_range(callback,
 179                                             min->el[level], max->el[level]))
 180                                 goto error;
 181                         level--;
 182                         init = 0;
 183                         if (level >= 0)
 184                                 if (isl_tab_rollback(tab, snap[level]) < 0)
 185                                         goto error;
 186                         continue;
 187                 }
 188                 isl_int_neg(B->row[1 + level][0], min->el[level]);
 189                 if (isl_tab_add_valid_eq(tab, B->row[1 + level]) < 0)
 190                         goto error;
 191                 isl_int_set_si(B->row[1 + level][0], 0);
 192                 if (level < dim - 1) {
 193                         ++level;
 194                         init = 1;
 195                         continue;
 196                 }
 197                 if (add_solution(tab, callback) < 0)
 198                         goto error;
 199                 init = 0;
 200                 if (isl_tab_rollback(tab, snap[level]) < 0)
 201                         goto error;
 202         }
 203
 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 0;
 211 error:
 212         isl_tab_free(tab);
 213         free(snap);
 214         isl_vec_free(min);
 215         isl_vec_free(max);
 216         isl_basic_set_free(bset);
 217         isl_mat_free(B);
 218         return -1;
 219 }
 220
 221 int isl_set_scan(__isl_take isl_set *set, struct isl_scan_callback *callback)
 222 {
 223         int i;
 224
 225         if (!set || !callback)
 226                 goto error;
 227
 228         set = isl_set_cow(set);
 229         set = isl_set_make_disjoint(set);
 230         set = isl_set_compute_divs(set);
 231         if (!set)
 232                 goto error;
 233
 234         for (i = 0; i < set->n; ++i)
 235                 if (isl_basic_set_scan(isl_basic_set_copy(set->p[i]),
 236                                         callback) < 0)
 237                         goto error;
 238
 239         isl_set_free(set);
 240         return 0;
 241 error:
 242         isl_set_free(set);
 243         return -1;
 244 }
 245
 246 int isl_basic_set_count_upto(__isl_keep isl_basic_set *bset,
 247         isl_int max, isl_int *count)
 248 {
 249         struct isl_counter cnt = { { &increment_counter } };
 250
 251         if (!bset)
 252                 return -1;
 253
 254         isl_int_init(cnt.count);
 255         isl_int_init(cnt.max);
 256
 257         isl_int_set_si(cnt.count, 0);
 258         isl_int_set(cnt.max, max);
 259         if (isl_basic_set_scan(isl_basic_set_copy(bset), &cnt.callback) < 0 &&
 260             isl_int_lt(cnt.count, cnt.max))
 261                 goto error;
 262
 263         isl_int_set(*count, cnt.count);
 264         isl_int_clear(cnt.max);
 265         isl_int_clear(cnt.count);
 266
 267         return 0;
 268 error:
 269         isl_int_clear(cnt.count);
 270         return -1;
 271 }
 272
 273 int isl_set_count_upto(__isl_keep isl_set *set, isl_int max, isl_int *count)
 274 {
 275         struct isl_counter cnt = { { &increment_counter } };
 276
 277         if (!set)
 278                 return -1;
 279
 280         isl_int_init(cnt.count);
 281         isl_int_init(cnt.max);
 282
 283         isl_int_set_si(cnt.count, 0);
 284         isl_int_set(cnt.max, max);
 285         if (isl_set_scan(isl_set_copy(set), &cnt.callback) < 0 &&
 286             isl_int_lt(cnt.count, cnt.max))
 287                 goto error;
 288
 289         isl_int_set(*count, cnt.count);
 290         isl_int_clear(cnt.max);
 291         isl_int_clear(cnt.count);
 292
 293         return 0;
 294 error:
 295         isl_int_clear(cnt.count);
 296         return -1;
 297 }
 298
 299 int isl_set_count(__isl_keep isl_set *set, isl_int *count)
 300 {
 301         if (!set)
 302                 return -1;
 303         return isl_set_count_upto(set, set->ctx->zero, count);
 304 }