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/* catdvi - get text from DVI files
Copyright (C) 2001, 2002 Bjoern Brill <brill@fs.math.uni-frankfurt.de>
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.
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.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdlib.h>
#include "sparse.h"
#include "util.h"
/******************************* spar_t *******************************/
#define SPAR_NODES_PER_BLOCK (1 << SPAR_BITS_PER_STAGE)
#define SPAR_STAGE_MASK ((1 << SPAR_BITS_PER_STAGE) - 1)
/* Readability notes:
* - stage(node) := this->height - distance(root, node)
* = distance(node, nearest leaf)
*
* - invariant: this->max_shift = (this->height - 1) * SPAR_BITS_PER_STAGE
*/
/* Allocate a block of SPAR_NODES_PER_STAGE nodes and initialize them
* with fill_with.
*/
static spar_node_t * spar_new_block(spar_node_t fill_with);
/* Free block block of nodes at stage stage and recursively all of its
* children.
*/
static void spar_free_block(spar_node_t * block, int stage);
/* Create a new tree root and make the old one the 0-th child of the new,
* thus increasing the height of the tree by 1.
*/
static void spar_grow(spar_t * this);
/* the default non-leaf node */
static const spar_node_t default_branch = {NULL};
void spar_init(spar_t * this, spar_node_t default_entry)
{
this->height = 0;
this->max_shift = - SPAR_BITS_PER_STAGE;
this->max_index = 0;
this->default_leaf = default_entry;
/* we start with a single entry (index 0) with default value */
this->root = default_entry;
}
void spar_done(spar_t * this)
{
if(this->height > 0) {
spar_free_block(this->root.children, this->height - 1);
}
this->root.children = NULL;
/* block erroneous access to now freed memory */
}
const spar_node_t * spar_const_entry(const spar_t * this, spar_index_t i)
{
int shift;
const spar_node_t * p;
if(i > this->max_index) return &(this->default_leaf);
p = &(this->root);
for(shift = this->max_shift; shift >= 0; shift -= SPAR_BITS_PER_STAGE) {
if(p->children == NULL) return &(this->default_leaf);
p = p->children + ((i >> shift) & SPAR_STAGE_MASK);
}
return p;
}
spar_node_t * spar_assignable_entry(spar_t * this, spar_index_t i)
{
int shift;
spar_node_t * p;
while(i > this->max_index) spar_grow(this);
p = &(this->root);
for(shift = this->max_shift; shift >= 0; shift -= SPAR_BITS_PER_STAGE) {
if(p->children == NULL) {
/* The path from root to requested leaf exists only until here.
* Create the rest and return address of new leaf.
*/
for( ; shift > 0; shift -= SPAR_BITS_PER_STAGE) {
p->children = spar_new_block(default_branch);
p = p->children + ((i >> shift) & SPAR_STAGE_MASK);
}
/* shift == 0 is different because the new children are leaves */
p->children = spar_new_block(this->default_leaf);
p = p->children + (i & SPAR_STAGE_MASK);
return p;
}
p = p->children + ((i >> shift) & SPAR_STAGE_MASK);
}
return p;
}
static spar_node_t * spar_new_block(spar_node_t fill_with)
{
spar_node_t * p, * q;
p = xmalloc(SPAR_NODES_PER_BLOCK * sizeof(spar_node_t));
for(q = p; q < p + SPAR_NODES_PER_BLOCK; ++q) *q = fill_with;
return p;
}
static void spar_free_block(spar_node_t * block, int stage)
{
int i;
if(stage > 0) {
for(i = 0; i < SPAR_NODES_PER_BLOCK; ++i) {
if(block[i].children != NULL) {
spar_free_block(block[i].children, stage - 1);
}
}
}
free(block);
}
static void spar_grow(spar_t * this)
{
spar_node_t * p;
/* We grow at the root, i.e. we have a new root node, and the old one
* becomes the new roots zeroth child.
*/
if(this->height == 0) {
p = spar_new_block(this->default_leaf);
}
else {
p = spar_new_block(default_branch);
}
p[0] = this->root;
this->root.children = p;
/* tell the world */
this->height += 1;
this->max_shift += SPAR_BITS_PER_STAGE;
this->max_index = (this->max_index << SPAR_BITS_PER_STAGE)
| SPAR_STAGE_MASK;
}
/******************************* sparp_t *******************************/
void sparp_init(sparp_t * this) {
spar_node_t default_leaf;
default_leaf.p = NULL;
spar_init(&this->p_spar, default_leaf);
}
void sparp_done(sparp_t * this) {
spar_done(&this->p_spar);
}
/******************************* spars32_t *******************************/
void spars32_init(spars32_t * this, sint32 default_value) {
spar_node_t default_leaf;
default_leaf.s32 = default_value;
spar_init(&this->s32_spar, default_leaf);
}
void spars32_done(spars32_t * this) {
spar_done(&this->s32_spar);
}
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