/**
* mds — A micro-display server
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* 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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "linked-list.h"
#include <string.h>
#include <errno.h>
/**
* The default initial capacity
*/
#ifndef LINKED_LIST_DEFAULT_INITIAL_CAPACITY
#define LINKED_LIST_DEFAULT_INITIAL_CAPACITY 128
#endif
/**
* Computes the nearest, but higher, power of two,
* but only if the current value is not a power of two
*
* @param value The value to be rounded up to a power of two
* @return The nearest, but not smaller, power of two
*/
static size_t to_power_of_two(size_t value)
{
value -= 1;
value |= value >> 1;
value |= value >> 2;
value |= value >> 4;
value |= value >> 8;
value |= value >> 16;
#if __WORDSIZE == 64
value |= value >> 32;
#endif
return value + 1;
}
/**
* Create a linked list
*
* @param this Memory slot in which to store the new linked list
* @param capacity The minimum initial capacity of the linked list, 0 for default
* @return Non-zero on error, `errno` will have been set accordingly
*/
int linked_list_create(linked_list_t* restrict this, size_t capacity)
{
/* Use default capacity of zero is specified. */
if (capacity == 0)
capacity = LINKED_LIST_DEFAULT_INITIAL_CAPACITY;
/* Initialise the linked list. */
capacity = to_power_of_two(capacity);
this->capacity = capacity;
this->edge = 0;
this->end = 1;
this->reuse_head = 0;
this->reusable = NULL;
this->values = NULL;
this->next = NULL;
this->previous = NULL;
if ((this->reusable = malloc(capacity * sizeof(ssize_t))) == NULL)
return -1;
if ((this->values = malloc(capacity * sizeof(size_t))) == NULL)
return -1;
if ((this->next = malloc(capacity * sizeof(ssize_t))) == NULL)
return -1;
if ((this->previous = malloc(capacity * sizeof(ssize_t))) == NULL)
return -1;
this->values[this->edge] = 0;
this->next[this->edge] = this->edge;
this->previous[this->edge] = this->edge;
return 0;
}
/**
* Release all resources in a linked list, should
* be done even if `linked_list_create` fails
*
* @param this The linked list
*/
void linked_list_destroy(linked_list_t* restrict this)
{
if (this->reusable != NULL) free(this->reusable);
if (this->values != NULL) free(this->values);
if (this->next != NULL) free(this->next);
if (this->previous != NULL) free(this->previous);
this->reusable = NULL;
this->values = NULL;
this->next = NULL;
this->previous = NULL;
}
/**
* Clone a linked list
*
* @param this The linked list to clone
* @param out Memory slot in which to store the new linked list
* @return Non-zero on error, `errno` will have been set accordingly
*/
int linked_list_clone(const linked_list_t* restrict this, linked_list_t* restrict out)
{
size_t n = this->capacity * sizeof(ssize_t);
size_t* restrict new_values;
ssize_t* restrict new_next;
ssize_t* restrict new_previous;
ssize_t* restrict new_reusable;
out->values = NULL;
out->next = NULL;
out->previous = NULL;
out->reusable = NULL;
if ((new_values = malloc(n)) == NULL)
return -1;
if ((new_next = malloc(n)) == NULL)
{
free(new_values);
return -1;
}
if ((new_previous = malloc(n)) == NULL)
{
free(new_values);
free(new_previous);
return -1;
}
if ((new_reusable = malloc(n)) == NULL)
{
free(new_values);
free(new_previous);
free(new_reusable);
return -1;
}
out->values = new_values;
out->next = new_next;
out->previous = new_previous;
out->reusable = new_reusable;
out->capacity = this->capacity;
out->end = this->end;
out->reuse_head = this->reuse_head;
out->edge = this->edge;
memcpy(out->values, this->values, n);
memcpy(out->next, this->next, n);
memcpy(out->previous, this->previous, n);
memcpy(out->reusable, this->reusable, n);
return 0;
}
/**
* Pack the list so that there are no reusable
* positions, and reduce the capacity to the
* smallest capacity that can be used. Not that
* values (nodes) returned by the list's methods
* will become invalid. Additionally (to reduce
* the complexity) the list will be defragment
* so that the nodes' indices are continuous.
* This method has linear time complexity and
* linear memory complexity.
*
* @param this The list
* @return Non-zero on error, `errno` will have been set accordingly
*/
int linked_list_pack(linked_list_t* restrict this)
{
size_t size = this->end - this->reuse_head;
size_t cap = to_power_of_two(size);
ssize_t head = 0;
size_t i = 0;
ssize_t node;
size_t* restrict vals;
vals = malloc(cap * sizeof(size_t));
if (vals == NULL)
return -1;
while (((size_t)head != this->end) && (this->next[head] == LINKED_LIST_UNUSED))
head++;
if ((size_t)head != this->end)
for (node = head; (node != head) || (i == 0); i++)
{
vals[i] = this->values[node];
node = this->next[node];
}
if (cap != this->capacity)
{
ssize_t* restrict new_next;
ssize_t* restrict new_previous;
ssize_t* restrict new_reusable;
new_next = malloc(cap * sizeof(ssize_t));
if (new_next == NULL)
{
free(vals);
return -1;
}
new_previous = malloc(cap * sizeof(ssize_t));
if (new_previous == NULL)
{
free(vals);
free(new_next);
return -1;
}
new_reusable = malloc(cap * sizeof(ssize_t));
if (new_reusable == NULL)
{
free(vals);
free(new_next);
free(new_previous);
return -1;
}
free(this->next);
free(this->previous);
free(this->reusable);
this->next = new_next;
this->previous = new_previous;
this->reusable = new_reusable;
}
for (i = 0; i < size; i++)
this->next[i] = (ssize_t)(i + 1);
this->next[size - 1] = 0;
for (i = 1; i < size; i++)
this->previous[i] = (ssize_t)(i - 1);
this->previous[0] = (ssize_t)(size - 1);
this->values = vals;
this->end = size;
this->reuse_head = 0;
return 0;
}
/**
* Gets the next free position, and grow the
* arrays if necessary. This methods has constant
* amortised time complexity.
*
* @param this The list
* @return The next free position,
* `LINKED_LIST_UNUSED` on error, `errno` will be set accordingly
*/
static ssize_t linked_list_get_next(linked_list_t* restrict this)
{
if (this->reuse_head > 0)
return this->reusable[--(this->reuse_head)];
if (this->end == this->capacity)
{
size_t* old_values;
ssize_t* old;
if ((ssize_t)(this->end) < 0)
{
errno = ENOMEM;
return LINKED_LIST_UNUSED;
}
this->capacity <<= 1;
this->values = realloc(old_values = this->values, this->capacity * sizeof(size_t));
if (this->values == NULL)
{
this->values = old_values;
return LINKED_LIST_UNUSED;
}
this->next = realloc(old = this->next, this->capacity * sizeof(ssize_t));
if (this->next == NULL)
{
this->next = old;
return LINKED_LIST_UNUSED;
}
this->previous = realloc(old = this->previous, this->capacity * sizeof(ssize_t));
if (this->previous == NULL)
{
this->previous = old;
return LINKED_LIST_UNUSED;
}
this->reusable = realloc(old = this->reusable, this->capacity * sizeof(ssize_t));
if (this->reusable == NULL)
{
this->reusable = old;
return LINKED_LIST_UNUSED;
}
}
return (ssize_t)(this->end++);
}
/**
* Mark a position as unused
*
* @param this The list
* @param node The position
* @return The position
*/
static ssize_t linked_list_unuse(linked_list_t* restrict this, ssize_t node)
{
if (node < 0)
return node;
this->reusable[this->reuse_head++] = node;
this->next[node] = LINKED_LIST_UNUSED;
this->previous[node] = LINKED_LIST_UNUSED;
return node;
}
/**
* Insert a value after a specified, reference, node
*
* @param this The list
* @param value The value to insert
* @param predecessor The reference node
* @return The node that has been created and inserted,
* `LINKED_LIST_UNUSED` on error, `errno` will be set accordingly
*/
ssize_t linked_list_insert_after(linked_list_t* this, size_t value, ssize_t predecessor)
{
ssize_t node = linked_list_get_next(this);
if (node == LINKED_LIST_UNUSED)
return LINKED_LIST_UNUSED;
this->values[node] = value;
this->next[node] = this->next[predecessor];
this->next[predecessor] = node;
this->previous[node] = predecessor;
this->previous[this->next[node]] = node;
return node;
}
/**
* Remove the node after a specified, reference, node
*
* @param this The list
* @param predecessor The reference node
* @return The node that has been removed
*/
ssize_t linked_list_remove_after(linked_list_t* restrict this, ssize_t predecessor)
{
ssize_t node = this->next[predecessor];
this->next[predecessor] = this->next[node];
this->previous[this->next[node]] = predecessor;
return linked_list_unuse(this, node);
}
/**
* Insert a value before a specified, reference, node
*
* @param this The list
* @param value The value to insert
* @param successor The reference node
* @return The node that has been created and inserted,
* `LINKED_LIST_UNUSED` on error, `errno` will be set accordingly
*/
ssize_t linked_list_insert_before(linked_list_t* restrict this, size_t value, ssize_t successor)
{
ssize_t node = linked_list_get_next(this);
if (node == LINKED_LIST_UNUSED)
return LINKED_LIST_UNUSED;
this->values[node] = value;
this->previous[node] = this->next[successor];
this->previous[successor] = node;
this->next[node] = successor;
this->next[this->previous[node]] = node;
return node;
}
/**
* Remove the node before a specified, reference, node
*
* @param this The list
* @param successor The reference node
* @return The node that has been removed
*/
ssize_t linked_list_remove_before(linked_list_t* restrict this, ssize_t successor)
{
ssize_t node = this->previous[successor];
this->previous[successor] = this->previous[node];
this->next[this->previous[node]] = successor;
return linked_list_unuse(this, node);
}
/**
* Remove the node from the list
*
* @param this The list
* @param node The node to remove
*/
void linked_list_remove(linked_list_t* restrict this, ssize_t node)
{
this->next[this->previous[node]] = this->next[node];
this->previous[this->next[node]] = this->previous[node];
linked_list_unuse(this, node);
}
/**
* Calculate the buffer size need to marshal a linked list
*
* @param this The list
* @return The number of bytes to allocate to the output buffer
*/
size_t linked_list_marshal_size(const linked_list_t* restrict this)
{
return sizeof(size_t) * (4 + this->reuse_head + 3 * this->end);
}
/**
* Marshals a linked list
*
* @param this The list
* @param data Output buffer for the marshalled data
*/
void linked_list_marshal(const linked_list_t* restrict this, char* restrict data)
{
((size_t*)data)[0] = this->capacity;
((size_t*)data)[1] = this->end;
((size_t*)data)[2] = this->reuse_head;
((ssize_t*)data)[3] = this->edge;
data += 4 * sizeof(size_t) / sizeof(char);
memcpy(data, this->reusable, this->reuse_head * sizeof(ssize_t));
data += this->reuse_head * sizeof(ssize_t) / sizeof(char);
memcpy(data, this->values, this->end * sizeof(size_t));
data += this->end * sizeof(size_t) / sizeof(char);
memcpy(data, this->next, this->end * sizeof(ssize_t));
data += this->end * sizeof(ssize_t) / sizeof(char);
memcpy(data, this->previous, this->end * sizeof(ssize_t));
}
/**
* Unmarshals a linked list
*
* @param this Memory slot in which to store the new linked list
* @param data In buffer with the marshalled data
* @return Non-zero one error, errno will be set accordingly.
* Destroy the list on error.
*/
int linked_list_unmarshal(linked_list_t* restrict this, char* restrict data)
{
size_t n;
this->reusable = NULL;
this->values = NULL;
this->next = NULL;
this->previous = NULL;
this->capacity = ((size_t*)data)[0];
this->end = ((size_t*)data)[1];
this->reuse_head = ((size_t*)data)[2];
this->edge = ((ssize_t*)data)[3];
data += 4 * sizeof(size_t) / sizeof(char);
n = this->capacity * sizeof(size_t);
if ((this->reusable = malloc(n)) == NULL) return -1;
if ((this->values = malloc(n)) == NULL) return -1;
if ((this->next = malloc(n)) == NULL) return -1;
if ((this->previous = malloc(n)) == NULL) return -1;
memcpy(this->reusable, data, this->reuse_head * sizeof(ssize_t));
data += this->reuse_head * sizeof(ssize_t) / sizeof(char);
memcpy(this->values, data, this->end * sizeof(size_t));
data += this->end * sizeof(size_t) / sizeof(char);
memcpy(this->next, data, this->end * sizeof(ssize_t));
data += this->end * sizeof(ssize_t) / sizeof(char);
memcpy(this->previous, data, this->end * sizeof(ssize_t));
return 0;
}
