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