2 #include "isl_basis_reduction.h"
3 #include "isl_equalities.h"
7 /* The input of this program is the same as that of the "polytope_scan"
8 * program from the barvinok distribution.
10 * Constraints of set is PolyLib format.
12 * The input set is assumed to be bounded.
15 static struct isl_mat
*isl_basic_set_samples(struct isl_basic_set
*bset
);
17 static struct isl_mat
*samples_eq(struct isl_basic_set
*bset
)
20 struct isl_mat
*samples
;
22 bset
= isl_basic_set_remove_equalities(bset
, &T
, NULL
);
23 samples
= isl_basic_set_samples(bset
);
24 return isl_mat_product(samples
, isl_mat_transpose(T
));
27 /* Add the current sample value of the tableau "tab" to the list
30 static struct isl_mat
*add_solution(struct isl_mat
*samples
,
33 struct isl_vec
*sample
;
37 samples
= isl_mat_extend(samples
, samples
->n_row
+ 1, samples
->n_col
);
40 sample
= isl_tab_get_sample_value(tab
);
43 isl_seq_cpy(samples
->row
[samples
->n_row
- 1], sample
->el
, sample
->size
);
47 isl_mat_free(samples
);
51 /* Look for and return all integer points in "bset", which is assumed
54 * We first compute a reduced basis for the set and then scan
55 * the set in the directions of this basis.
56 * We basically perform a depth first search, where in each level i
57 * we compute the range in the i-th basis vector direction, given
58 * fixed values in the directions of the previous basis vector.
59 * We then add an equality to the tableau fixing the value in the
60 * direction of the current basis vector to each value in the range
61 * in turn and then continue to the next level.
63 * The search is implemented iteratively. "level" identifies the current
64 * basis vector. "init" is true if we want the first value at the current
65 * level and false if we want the next value.
66 * Solutions are added in the leaves of the search tree, i.e., after
67 * we have fixed a value in each direction of the basis.
69 static struct isl_mat
*isl_basic_set_samples(struct isl_basic_set
*bset
)
72 struct isl_mat
*B
= NULL
;
73 struct isl_tab
*tab
= NULL
;
76 struct isl_mat
*samples
;
77 struct isl_tab_undo
**snap
;
80 enum isl_lp_result res
;
83 return samples_eq(bset
);
85 dim
= isl_basic_set_total_dim(bset
);
87 min
= isl_vec_alloc(bset
->ctx
, dim
);
88 max
= isl_vec_alloc(bset
->ctx
, dim
);
89 samples
= isl_mat_alloc(bset
->ctx
, 0, 1 + dim
);
90 snap
= isl_alloc_array(bset
->ctx
, struct isl_tab_undo
*, dim
);
92 if (!min
|| !max
|| !samples
|| !snap
)
96 B
= isl_basic_set_reduced_basis(bset
);
98 B
= isl_mat_identity(bset
->ctx
, dim
);
99 B
= isl_mat_lin_to_aff(B
);
103 tab
= isl_tab_from_basic_set(bset
);
111 res
= isl_tab_min(tab
, B
->row
[1 + level
],
112 bset
->ctx
->one
, &min
->el
[level
], NULL
, 0);
113 if (res
== isl_lp_empty
)
115 if (res
== isl_lp_error
|| res
== isl_lp_unbounded
)
117 isl_seq_neg(B
->row
[1 + level
] + 1,
118 B
->row
[1 + level
] + 1, dim
);
119 res
= isl_tab_min(tab
, B
->row
[1 + level
],
120 bset
->ctx
->one
, &max
->el
[level
], NULL
, 0);
121 isl_seq_neg(B
->row
[1 + level
] + 1,
122 B
->row
[1 + level
] + 1, dim
);
123 isl_int_neg(max
->el
[level
], max
->el
[level
]);
124 if (res
== isl_lp_empty
)
126 if (res
== isl_lp_error
|| res
== isl_lp_unbounded
)
128 snap
[level
] = isl_tab_snap(tab
);
130 isl_int_add_ui(min
->el
[level
], min
->el
[level
], 1);
132 if (empty
|| isl_int_gt(min
->el
[level
], max
->el
[level
])) {
136 isl_tab_rollback(tab
, snap
[level
]);
139 isl_int_neg(B
->row
[1 + level
][0], min
->el
[level
]);
140 tab
= isl_tab_add_valid_eq(tab
, B
->row
[1 + level
]);
141 isl_int_set_si(B
->row
[1 + level
][0], 0);
142 if (level
< dim
- 1) {
147 samples
= add_solution(samples
, tab
);
149 isl_tab_rollback(tab
, snap
[level
]);
156 isl_basic_set_free(bset
);
162 isl_mat_free(samples
);
165 isl_basic_set_free(bset
);
170 int main(int argc
, char **argv
)
172 struct isl_ctx
*ctx
= isl_ctx_alloc();
173 struct isl_basic_set
*bset
;
174 struct isl_mat
*samples
;
176 bset
= isl_basic_set_read_from_file(ctx
, stdin
, 0, ISL_FORMAT_POLYLIB
);
177 samples
= isl_basic_set_samples(bset
);
178 isl_mat_dump(samples
, stdout
, 0);
179 isl_mat_free(samples
);