usr.bin/nbperf/nbperf-bdz.c

/*	$NetBSD: nbperf-bdz.c,v 1.4 2011/10/21 23:47:11 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.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
__RCSID("$NetBSD: nbperf-bdz.c,v 1.4 2011/10/21 23:47:11 joerg Exp $");

#include <err.h>
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include "nbperf.h"

/*
 * A full description of the algorithm can be found in:
 * "Simple and Space-Efficient Minimal Perfect Hash Functions"
 * by Botelho, Pagh and Ziviani, proceeedings of WADS 2007.
 */

/*
 * The algorithm is based on random, acyclic 3-graphs.
 *
 * Each edge in the represents a key.  The vertices are the reminder of
 * the hash function mod n.  n = cm with c > 1.23.  This ensures that
 * an acyclic graph can be found with a very high probality.
 *
 * An acyclic graph has an edge order, where at least one vertex of
 * each edge hasn't been seen before.   It is declares the first unvisited
 * vertex as authoritive for the edge and assigns a 2bit value to unvisited
 * vertices, so that the sum of all vertices of the edge modulo 4 is
 * the index of the authoritive vertex.
 */

#include "graph3.h"

struct state {
	struct graph3 graph;
	uint32_t *visited;
	uint32_t *holes64k;
	uint16_t *holes256;
	uint8_t *holes256_64;
	uint8_t *holes256_128;
	uint8_t *holes256_192;
	uint8_t *g;
	uint32_t *result_map;
};

static void
assign_nodes(struct state *state)
{
	struct edge3 *e;
	size_t i, j;
	uint32_t t, r, holes;

	for (i = 0; i < state->graph.v; ++i)
		state->g[i] = 3;

	for (i = 0; i < state->graph.e; ++i) {
		j = state->graph.output_order[i];
		e = &state->graph.edges[j];
		if (!state->visited[e->left]) {
			r = 0;
			t = e->left;
		} else if (!state->visited[e->middle]) {
			r = 1;
			t = e->middle;
		} else {
			if (state->visited[e->right])
				abort();
			r = 2;
			t = e->right;
		}

		state->visited[t] = 2 + j;
		if (state->visited[e->left] == 0)
			state->visited[e->left] = 1;
		if (state->visited[e->middle] == 0)
			state->visited[e->middle] = 1;
		if (state->visited[e->right] == 0)
			state->visited[e->right] = 1;

		state->g[t] = (9 + r - state->g[e->left] - state->g[e->middle]
		    - state->g[e->right]) % 3;
	}

	holes = 0;
	for (i = 0; i < state->graph.v; ++i) {
		if (i % 65536 == 0)
			state->holes64k[i >> 16] = holes;

		if (i % 256 == 0)
			state->holes256[i >> 8] = holes - state->holes64k[i >> 16];

		if (i % 256 == 64)
			state->holes256_64[i >> 8] = holes - state->holes256[i >> 8] - state->holes64k[i >> 16];

		if (i % 256 == 128)
			state->holes256_128[i >> 8] = holes - state->holes256[i >> 8] - state->holes64k[i >> 16];

		if (i % 256 == 192)
			state->holes256_192[i >> 8] = holes - state->holes256[i >> 8] - state->holes64k[i >> 16];

		if (state->visited[i] > 1) {
			j = state->visited[i] - 2;
			state->result_map[j] = i - holes;
		}

		if (state->g[i] == 3)
			++holes;
	}

	if (i % 65536 != 0)
		state->holes64k[(i >> 16) + 1] = holes;

	if (i % 256 != 0)
		state->holes256[(i >> 8) + 1] = holes - state->holes64k[((i >> 8) + 1) >> 8];

	if (i % 256 != 64)
		state->holes256_64[(i >> 8) + 1] = holes - state->holes256[(i >> 8) + 1] - state->holes64k[((i >> 8) + 1) >> 8];

	if (i % 256 != 128)
		state->holes256_128[(i >> 8) + 1] = holes - state->holes256[(i >> 8) + 1] - state->holes64k[((i >> 8) + 1) >> 8];

	if (i % 256 != 192)
		state->holes256_192[(i >> 8) + 1] = holes - state->holes256[(i >> 8) + 1] - state->holes64k[((i >> 8) + 1) >> 8];
}

static void
print_hash(struct nbperf *nbperf, struct state *state)
{
	size_t i, j;
	uint32_t sum;

	fprintf(nbperf->output, "#include <stdlib.h>\n");
	fprintf(nbperf->output, "#include <strings.h>\n\n");

	fprintf(nbperf->output, "%suint32_t\n",
	    nbperf->static_hash ? "static " : "");
	fprintf(nbperf->output,
	    "%s(const void * __restrict key, size_t keylen)\n",
	    nbperf->hash_name);
	fprintf(nbperf->output, "{\n");
	fprintf(nbperf->output,
	    "\tstatic const uint32_t g[%" PRId32 "] = {\n",
	    (state->graph.v + 15) / 16);
	for (i = 0; i < state->graph.v; i += 16) {
		for (j = 0, sum = 0; j < 16; ++j)
			sum |= (uint32_t)state->g[i + j] << (2 * j);

		fprintf(nbperf->output, "%s0x%08" PRIx32 "ULL,%s",
		    (i / 16 % 4 == 0 ? "\t    " : " "),
		    sum,
		    (i / 16 % 4 == 3 ? "\n" : ""));
	}
	fprintf(nbperf->output, "%s\t};\n", (i / 16 % 4 ? "\n" : ""));

	fprintf(nbperf->output,
	    "\tstatic const uint32_t holes64k[%" PRId32 "] = {\n",
	    (state->graph.v + 65535) / 65536);
	for (i = 0; i < state->graph.v; i += 65536)
		fprintf(nbperf->output, "%s0x%08" PRIx32 ",%s",
		    (i / 65536 % 4 == 0 ? "\t    " : " "),
		    state->holes64k[i >> 16],
		    (i / 65536 % 4 == 3 ? "\n" : ""));
	fprintf(nbperf->output, "%s\t};\n", (i / 65536 % 4 ? "\n" : ""));

	fprintf(nbperf->output,
	    "\tstatic const uint16_t holes256[%" PRId32 "] = {\n",
	    (state->graph.v + 255) / 256);
	for (i = 0; i < state->graph.v; i += 256)
		fprintf(nbperf->output, "%s0x%04" PRIx32 ",%s",
		    (i / 256 % 4 == 0 ? "\t    " : " "),
		    state->holes256[i >> 8],
		    (i / 256 % 4 == 3 ? "\n" : ""));
	fprintf(nbperf->output, "%s\t};\n", (i / 256 % 4 ? "\n" : ""));

	fprintf(nbperf->output,
	    "\tstatic const uint8_t holes256_64[%" PRId32 "] = {\n",
	    (state->graph.v + 255) / 256);
	for (i = 64; i < state->graph.v; i += 256)
		fprintf(nbperf->output, "%s0x%02" PRIx32 ",%s",
		    (i / 256 % 4 == 0 ? "\t    " : " "),
		    state->holes256_64[i >> 8],
		    (i / 256 % 4 == 3 ? "\n" : ""));
	fprintf(nbperf->output, "%s\t};\n", (i / 256 % 4 ? "\n" : ""));

	fprintf(nbperf->output,
	    "\tstatic const uint8_t holes256_128[%" PRId32 "] = {\n",
	    (state->graph.v + 255) / 256);
	for (i = 128; i < state->graph.v; i += 256)
		fprintf(nbperf->output, "%s0x%02" PRIx32 ",%s",
		    (i / 256 % 4 == 0 ? "\t    " : " "),
		    state->holes256_128[i >> 8],
		    (i / 256 % 4 == 3 ? "\n" : ""));
	fprintf(nbperf->output, "%s\t};\n", (i / 256 % 4 ? "\n" : ""));

	fprintf(nbperf->output,
	    "\tstatic const uint8_t holes256_192[%" PRId32 "] = {\n",
	    (state->graph.v + 255) / 256);
	for (i = 192; i < state->graph.v; i += 256)
		fprintf(nbperf->output, "%s0x%02" PRIx32 ",%s",
		    (i / 256 % 4 == 0 ? "\t    " : " "),
		    state->holes256_192[i >> 8],
		    (i / 256 % 4 == 3 ? "\n" : ""));
	fprintf(nbperf->output, "%s\t};\n", (i / 256 % 4 ? "\n" : ""));

	fprintf(nbperf->output, "\tuint32_t h[%zu];\n\n", nbperf->hash_size);
	fprintf(nbperf->output, "\tuint32_t m;\n");
	fprintf(nbperf->output, "\tuint32_t a1, a2, b1, b2, c1, c2, idx, idx2;\n\n");

	(*nbperf->print_hash)(nbperf, "\t", "key", "keylen", "h");

	fprintf(nbperf->output, "\n\th[0] = h[0] %% %" PRIu32 ";\n", state->graph.v);
	fprintf(nbperf->output, "\th[1] = h[1] %% %" PRIu32 ";\n", state->graph.v);
	fprintf(nbperf->output, "\th[2] = h[2] %% %" PRIu32 ";\n", state->graph.v);

	fprintf(nbperf->output, "\n\ta1 = h[0] >> 4;\n");
	fprintf(nbperf->output, "\ta2 = 2 * (h[0] & 15);\n");
	fprintf(nbperf->output, "\tb1 = h[1] >> 4;\n");
	fprintf(nbperf->output, "\tb2 = 2 * (h[1] & 15);\n");
	fprintf(nbperf->output, "\tc1 = h[2] >> 4;\n");
	fprintf(nbperf->output, "\tc2 = 2 * (h[2] & 15);\n");

	fprintf(nbperf->output,
	    "\tidx = h[(((g[a1] >> a2) & 3) + ((g[b1] >> b2) & 3) +\n"
	    "\t    ((g[c1] >> c2) & 3)) %% 3];\n\n");

	fprintf(nbperf->output,
	    "\tswitch ((idx >> 5) & 7) {\n"
	    "\tcase 0:\n"
	    "\t\tidx2 = idx - holes64k[idx >> 16] - holes256[idx >> 8];\n"
	    "\t\tbreak;\n"
	    "\tcase 1: case 2:\n"
	    "\t\tidx2 = idx - holes64k[idx >> 16] - holes256[idx >> 8]\n"
	    "\t\t    - holes256_64[idx >> 8];\n"
	    "\t\tbreak;\n"
	    "\tcase 3: case 4:\n"
	    "\t\tidx2 = idx - holes64k[idx >> 16] - holes256[idx >> 8]\n"
	    "\t\t    - holes256_128[idx >> 8];\n"
	    "\t\tbreak;\n"
	    "\tcase 5: case 6:\n"
	    "\t\tidx2 = idx - holes64k[idx >> 16] - holes256[idx >> 8]\n"
	    "\t\t    - holes256_192[idx >> 8];\n"
	    "\t\tbreak;\n"
	    "\tcase 7:\n"
	    "\t\tidx2 = idx - holes64k[(idx + 32) >> 16] -\n"
	    "\t\t    holes256[(idx + 32) >> 8];\n"
	    "\t\tbreak;\n"
	    "\tdefault:\n"
	    "\t\tabort();\n"
	    "\t}\n"
	    "\tswitch ((idx >> 4) & 3) {\n"
	    "\tcase 1:\n"
	    "\t\tm = (g[(idx >> 4) - 1] & (g[(idx >> 4) - 1] >> 1) & 0x55555555U);\n"
	    "\t\tidx2 -= popcount32(m);\n"
	    "\tcase 0:\n"
	    "\t\tm = (g[idx >> 4] & (g[idx >> 4] >> 1) & 0x55555555U);\n"
	    "\t\tm &= ((2U << (2 * (idx & 15))) - 1);\n"
	    "\t\tidx2 -= popcount32(m);\n"
	    "\t\tbreak;\n"
	    "\tcase 2:\n"
	    "\t\tm = (g[(idx >> 4) + 1] & (g[(idx >> 4) + 1] >> 1) & 0x55555555U);\n"
	    "\t\tidx2 += popcount32(m);\n"
	    "\tcase 3:\n"
	    "\t\tm = (g[idx >> 4] & (g[idx >> 4] >> 1) & 0x55555555U);\n"
	    "\t\tm &= ~((2U << (2 * (idx & 15))) - 1);\n"
	    "\t\tidx2 += popcount32(m);\n"
	    "\t\tbreak;\n"
	    "\t}\n\n");

	fprintf(nbperf->output,
	    "\treturn idx2;\n");
	fprintf(nbperf->output, "}\n");

	if (nbperf->map_output != NULL) {
		for (i = 0; i < state->graph.e; ++i)
			fprintf(nbperf->map_output, "%" PRIu32 "\n",
			    state->result_map[i]);
	}
}

int
bdz_compute(struct nbperf *nbperf)
{
	struct state state;
	int retval = -1;
	uint32_t v, e;

	if (nbperf->c == 0)
		nbperf->c = 1.24;
	if (nbperf->c < 1.24)
		errx(1, "The argument for option -c must be at least 1.24");
	if (nbperf->hash_size < 3)
		errx(1, "The hash function must generate at least 3 values");

	(*nbperf->seed_hash)(nbperf);
	e = nbperf->n;
	v = nbperf->c * nbperf->n;
	if (1.24 * nbperf->n > v)
		++v;
	if (v < 10)
		v = 10;

	graph3_setup(&state.graph, v, e);

	state.holes64k = calloc(sizeof(uint32_t), (v + 65535) / 65536 + 1);
	state.holes256 = calloc(sizeof(uint16_t), (v + 255) / 256 + 1);
	state.holes256_64 = calloc(sizeof(uint8_t), (v + 255) / 256 + 1);
	state.holes256_128 = calloc(sizeof(uint8_t), (v + 255) / 256 + 1);
	state.holes256_192 = calloc(sizeof(uint8_t), (v + 255) / 256 + 1);
	state.g = calloc(sizeof(uint32_t), v);
	state.visited = calloc(sizeof(uint32_t), v);
	state.result_map = calloc(sizeof(uint32_t), e);

	if (state.holes64k == NULL || state.holes256 == NULL ||
	    state.holes256_64 == NULL || state.holes256_128 == NULL ||
	    state.holes256_192 == NULL || state.g == NULL ||
	    state.visited == NULL || state.result_map == NULL)
		err(1, "malloc failed");

	if (graph3_hash(nbperf, &state.graph))
		goto failed;
	if (graph3_output_order(&state.graph))
		goto failed;
	assign_nodes(&state);
	print_hash(nbperf, &state);

	retval = 0;

failed:
	graph3_free(&state.graph);
	free(state.visited);
	free(state.g);
	free(state.holes64k);
	free(state.holes256);
	free(state.holes256_64);
	free(state.holes256_128);
	free(state.holes256_192);
	free(state.result_map);
	return retval;
}