/*
* Copyright (C) 2014 Tobias Brunner
* Copyright (C) 2014 Andreas Steffen
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "bliss_param_set.h"
#include <library.h>
#include <stdio.h>
#include <math.h>
typedef struct tuple_t tuple_t;
struct tuple_t {
int8_t z1;
int8_t z2;
uint16_t index;
uint16_t bits;
uint32_t code;
};
typedef struct node_t node_t;
struct node_t {
node_t *next;
node_t *l;
node_t *r;
tuple_t *tuple;
double p;
uint16_t depth;
uint16_t index;
};
static void print_node(node_t *node)
{
if (node->tuple)
{
fprintf(stderr, "(%1d,%2d)", node->tuple->z1, node->tuple->z2);
}
else
{
fprintf(stderr, " ");
}
fprintf(stderr, " %18.16f\n", node->p);
}
static double code_node(node_t *node, int *index, uint8_t bits, uint32_t code)
{
double code_length = 0;
node->index = (*index)++;
if (node->tuple)
{
node->tuple->code = code;
node->tuple->bits = bits;
code_length += node->p * bits;
}
if (node->l)
{
code_length += code_node(node->l, index, bits + 1, (code << 1));
}
if (node->r)
{
code_length += code_node(node->r, index, bits + 1, (code << 1) + 1);
}
return code_length;
}
static void write_node(node_t *node)
{
int16_t node_0, node_1, tuple;
node_0 = node->l ? node->l->index : BLISS_HUFFMAN_CODE_NO_NODE;
node_1 = node->r ? node->r->index : BLISS_HUFFMAN_CODE_NO_NODE;
tuple = node->tuple ? node->tuple->index : BLISS_HUFFMAN_CODE_NO_TUPLE;
printf("\t{ %3d, %3d, %3d }, /* %3d: ", node_0, node_1, tuple, node->index);
if (node->tuple)
{
printf("(%d,%2d) %2u bit%s ", node->tuple->z1, node->tuple->z2,
node->tuple->bits, (node->tuple->bits == 1) ? " " : "s");
}
printf("*/\n");
if (node->l)
{
write_node(node->l);
}
if (node->r)
{
write_node(node->r);
}
}
static void write_header(void)
{
printf("/*\n");
printf(" * Copyright (C) 2014 Andreas Steffen\n");
printf(" * HSR Hochschule fuer Technik Rapperswil\n");
printf(" *\n");
printf(" * Optimum Huffman code for BLISS-X signatures\n");
printf(" *\n");
printf(" * This file has been automatically generated by the"
" bliss_huffman utility\n");
printf(" * Do not edit manually!\n");
printf(" */\n\n");
};
static void write_code_tables(int bliss_type, int n_z1, int n_z2, node_t *nodes,
tuple_t **tuples)
{
int index, i, k;
uint32_t bit;
double code_length;
printf("#include \"bliss_huffman_code.h\"\n\n");
printf("static bliss_huffman_code_node_t nodes[] = {\n");
index = 0;
code_length = code_node(nodes, &index, 0, 0);
write_node(nodes);
printf("};\n\n");
printf("static bliss_huffman_code_tuple_t tuples[] = {\n");
index = 0;
for (i = 0; i < n_z1; i++)
{
if (i > 0)
{
printf("\n");
}
for (k = 1 - n_z2; k < n_z2; k++)
{
printf("\t{ %5u, %2u }, /* %3d: (%1d,%2d) ",
tuples[index]->code, tuples[index]->bits, index, i, k);
bit = 1 << (tuples[index]->bits - 1);
while (bit)
{
printf("%s", (tuples[index]->code & bit) ? "1" : "0");
bit >>= 1;
}
printf(" */\n");
index++;
}
}
printf("};\n\n");
printf("/* code_length = %6.4f bits/tuple (%d bits) */\n\n",
code_length, (int)(512 * code_length + 1));
printf("bliss_huffman_code_t bliss_huffman_code_%d = {\n", bliss_type);
printf("\t.n_z1 = %d,\n", n_z1);
printf("\t.n_z2 = %d,\n", n_z2);
printf("\t.tuples = tuples,\n");
printf("\t.nodes = nodes\n");
printf("};\n");
}
static void destroy_node(node_t *node)
{
if (node->l)
{
destroy_node(node->l);
}
if (node->r)
{
destroy_node(node->r);
}
free(node->tuple);
free(node);
}
static void remove_node(node_t *list, node_t **last, node_t *node)
{
node_t *current, *prev;
for (current = list->next, prev = list; current;
prev = current, current = current->next)
{
if (current == node)
{
prev->next = current->next;
if (*last == current)
{
*last = prev->next ?: prev;
}
break;
}
}
}
/**
* Generate a Huffman code for the optimum encoding of BLISS signatures
*/
int main(int argc, char *argv[])
{
const bliss_param_set_t *set;
int dx, bliss_type, depth = 1, groups, groups_left, pairs = 1;
int i_max = 9, k_max = 8, index_max = (2*k_max - 1) * i_max;
int i, i_top, k, k_top;
uint16_t index;
double p, p_z1[i_max], p_z2[k_max], x_z1[i_max], x_z2[k_max];
double t, x, x0, p_sum, entropy = 0, erf_i, erf_k, erf_0 = 0;
tuple_t *tuple, *tuples[index_max];
node_t *node, *node_l, *node_r, *nodes = NULL;
node_t *node_list, *node_last;
if (argc < 2)
{
fprintf(stderr, "usage: bliss_huffman <bliss type> [<pairs>]\n");
exit(1);
}
if (argc > 2)
{
pairs = atoi(argv[2]);
}
fprintf(stderr, "%d code pairs with constant length\n\n", pairs);
groups_left = groups = pairs >> 1;
bliss_type = atoi(argv[1]);
set = bliss_param_set_get_by_id(bliss_type);
if (!set)
{
fprintf(stderr, "bliss type %d unsupported\n", bliss_type);
exit(1);
}
write_header();
printf("/*\n");
printf(" * Design: sigma = %u\n", set->sigma);
printf(" *\n");
t = 1/(sqrt(2) * set->sigma);
/* Probability distribution for z1 */
i_top = (set->B_inf + 255) / 256;
p_sum = 0;
x = 0;
for (i = 0; i < i_top; i++)
{
x = min(x + 256, set->B_inf);
erf_i = erf(t*x);
p_z1[i] = erf_i - erf_0;
p_sum += p_z1[i];
erf_0 = erf_i;
x_z1[i] = x;
}
/* Normalize and print the probability distribution for z1 */
printf(" * i p_z1[i]\n");
x0 = 0;
for (i = 0; i < i_top; i++)
{
p_z1[i] /= p_sum;
printf(" * %2d %18.16f %4.0f .. %4.0f\n", i, p_z1[i], x0, x_z1[i]);
x0 = x_z1[i];
}
printf(" *\n");
/* Probability distribution for z2 */
dx = 1 << set->d;
k_top = 1 + set->B_inf / dx;
x = (dx >> 1) - 0.5;
p_sum = 0;
for (k = 0; k < k_top; k++)
{
erf_k = erf(t*x) / 2;
p_z2[k] = (k == 0) ? 2*erf_k : erf_k - erf_0;
p_sum += (k == 0) ? p_z2[k] : 2*p_z2[k];
erf_0 = erf_k;
x_z2[k] = x;
x += dx;
}
/* Normalize the probability distribution for z2 */
for (k = 0; k < k_top; k++)
{
p_z2[k] /= p_sum;
}
/* Print the probability distribution for z2 */
printf(" * k p_z2[k] dx = %d\n", dx);
for (k = 1 - k_top; k < k_top; k++)
{
printf(" * %2d %18.16f ",k, p_z2[abs(k)]);
if (k < 0)
{
printf(" %7.1f ..%7.1f\n", -x_z2[-k], -x_z2[-k-1]);
}
else if (k == 0)
{
printf(" %7.1f ..%7.1f\n", -x_z2[k], x_z2[k]);
}
else
{
printf(" %7.1f ..%7.1f\n", x_z2[k-1], x_z2[k]);
}
}
printf(" *\n");
/* Compute probabilities of tuples (z1, z2) */
INIT(node_list);
node_last = node_list;
printf(" * (i, k) p\n");
p_sum =0;
index = 0;
for (i = 0; i < i_top; i++)
{
for (k = 1 - k_top; k < k_top; k++)
{
p = p_z1[i] * p_z2[abs(k)];
printf(" * (%1d,%2d) %18.16f\n", i, k, p);
p_sum += p;
entropy += -log(p) * p;
INIT(tuple,
.z1 = i,
.z2 = k,
.index = index,
);
tuples[index++] = tuple;
INIT(node,
.p = p,
.tuple = tuple,
);
node_last->next = node;
node_last = node;
}
printf(" *\n");
}
entropy /= log(2);
printf(" * p_sum %18.16f\n", p_sum);
printf(" *\n");
printf(" * entropy = %6.4f bits/tuple (%d bits)\n",
entropy, (int)(512 * entropy));
printf(" */\n\n");
/* Build Huffman tree */
while (node_list->next != node_last)
{
node_r = node_l = NULL;
for (node = node_list->next; node; node = node->next)
{
if (pairs > 0)
{
if (!node->tuple)
{
continue;
}
}
else if (groups_left > 0)
{
if (node->tuple || node->depth != depth)
{
continue;
}
}
if (node_r == NULL || node->p < node_r->p)
{
node_l = node_r;
node_r = node;
}
else if (node_l == NULL || node->p < node_l->p)
{
node_l = node;
}
}
INIT(node,
.l = node_l,
.r = node_r,
.p = node_l->p + node_r->p,
.depth = 1 + max(node_l->depth, node_r->depth),
.tuple = NULL,
);
print_node(node_r);
print_node(node_l);
fprintf(stderr, " %18.16f", node->p);
remove_node(node_list, &node_last, node_l);
remove_node(node_list, &node_last, node_r);
node_last->next = node;
node_last = node;
if (pairs > 0)
{
pairs--;
}
else if (groups > 0)
{
if (--groups_left == 0)
{
groups >>= 1;
groups_left = groups;
depth++;
}
}
fprintf(stderr, "\n\n");
}
nodes = node_list->next;
write_code_tables(bliss_type, i_top, k_top, nodes, tuples);
destroy_node(nodes);
destroy_node(node_list);
exit(0);
}
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