dae1c7ed38
Type: improvement Change-Id: I57a9f85f7df1fc48656b72592349f4c544302f77 Signed-off-by: Damjan Marion <damarion@cisco.com>
126 lines
2.4 KiB
C
126 lines
2.4 KiB
C
/*
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* Copyright (c) 2016 Cisco and/or its affiliates.
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <vppinfra/ptclosure.h>
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__clib_export u8 **
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clib_ptclosure_alloc (int n)
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{
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u8 **rv = 0;
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u8 *row;
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int i;
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ASSERT (n > 0);
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vec_validate (rv, n - 1);
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for (i = 0; i < n; i++)
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{
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row = 0;
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vec_validate (row, n - 1);
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rv[i] = row;
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}
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return rv;
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}
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__clib_export void
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clib_ptclosure_free (u8 ** ptc)
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{
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u8 *row;
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int n = vec_len (ptc);
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int i;
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ASSERT (n > 0);
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for (i = 0; i < n; i++)
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{
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row = ptc[i];
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vec_free (row);
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}
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vec_free (ptc);
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}
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void
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clib_ptclosure_copy (u8 ** dst, u8 ** src)
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{
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int i, n;
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u8 *src_row, *dst_row;
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n = vec_len (dst);
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for (i = 0; i < vec_len (dst); i++)
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{
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src_row = src[i];
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dst_row = dst[i];
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clib_memcpy (dst_row, src_row, n);
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}
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}
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/*
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* compute the positive transitive closure
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* of a relation via Warshall's algorithm.
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*
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* Ref:
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* Warshall, Stephen (January 1962). "A theorem on Boolean matrices".
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* Journal of the ACM 9 (1): 11–12.
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*
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* foo[i][j] = 1 means that item i
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* "bears the relation" to item j.
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*
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* For example: "item i must be before item j"
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*
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* You could use a bitmap, but since the algorithm is
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* O(n**3) in the first place, large N is inadvisable...
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*
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*/
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__clib_export u8 **
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clib_ptclosure (u8 ** orig)
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{
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int i, j, k;
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int n;
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u8 **prev, **cur;
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n = vec_len (orig);
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prev = clib_ptclosure_alloc (n);
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cur = clib_ptclosure_alloc (n);
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clib_ptclosure_copy (prev, orig);
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for (k = 0; k < n; k++)
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{
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for (i = 0; i < n; i++)
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{
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for (j = 0; j < n; j++)
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{
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cur[i][j] = prev[i][j] || (prev[i][k] && prev[k][j]);
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}
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}
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clib_ptclosure_copy (prev, cur);
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}
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clib_ptclosure_free (prev);
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return cur;
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}
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/*
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* fd.io coding-style-patch-verification: ON
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*
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* Local Variables:
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* eval: (c-set-style "gnu")
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* End:
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*/
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