/* $NetBSD: graph2.h,v 1.2 2021/01/07 16:03:08 joerg Exp $ */
/*-
* Copyright (c) 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Joerg Sonnenberger.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Implementation of common 2/3-graph routines:
* - build a 2/3-graph with hash-pairs as edges
* - check a 2/3-graph for acyclicness and compute an output order
*
* For each vertex in the 2/3-graph, the incidence lists need to kept.
* Avoid storing the full list by just XORing the indices of the still
* incident edges and the number of such edges as that's all the peeling
* computation needs. This is inspired by:
* Cache-Oblivious Peeling of Random Hypergraphs by Djamal Belazzougui,
* Paolo Boldi, Giuseppe Ottaviano, Rossano Venturini, and Sebastiano
* Vigna. https://arxiv.org/abs/1312.0526
*
* Unlike in the paper, we don't care about external storage and have
* the edge list at hand all the time. As such, no ordering is necessary
* and the vertices of the edge don't have to be copied.
*
* The core observation of the paper above is that for a degree of one,
* the incident edge can be obtained directly.
*/
#ifndef GRAPH_SIZE
#define GRAPH_SIZE 2
#endif
#define SIZED__(n, i) n ## i
#define SIZED_(n, i) SIZED__(n, i)
#define SIZED(n) SIZED_(n, GRAPH_SIZE)
#define SIZED2__(n, i, m) n ## i ## m
#define SIZED2_(n, i, m) SIZED2__(n, i, m)
#define SIZED2(n) SIZED2_(graph, GRAPH_SIZE, n)
struct SIZED(vertex) {
uint32_t degree, edges;
};
struct SIZED(edge) {
uint32_t vertices[GRAPH_SIZE];
};
struct SIZED(graph) {
struct SIZED(vertex) *verts;
struct SIZED(edge) *edges;
uint32_t output_index;
uint32_t *output_order;
uint8_t *visited;
uint32_t e, v;
int hash_fudge;
};
void SIZED2(_setup)(struct SIZED(graph) *, uint32_t, uint32_t);
void SIZED2(_free)(struct SIZED(graph) *);
int SIZED2(_hash)(struct nbperf *, struct SIZED(graph) *);
int SIZED2(_output_order)(struct SIZED(graph) *graph);