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/* Copyright (C) 2023 Aryadev Chavali
* You may distribute and modify this code under the terms of the
* GPLv2 license. You should have received a copy of the GPLv2
* license with this file. If not, please write to:
* aryadev@aryadevchavali.com.
* Created: 2023-11-01
* Author: Aryadev Chavali
* Description: Arena allocator
*/
#include "./heap.h"
#include <stdio.h>
page_t *page_create(size_t max, page_t *next)
{
page_t *page = calloc(1, sizeof(*page) + max);
page->available = max;
page->next = next;
return page;
}
void page_delete(page_t *page)
{
free(page);
}
void heap_create(heap_t *heap)
{
heap->beg = heap->end = NULL;
heap->pages = 0;
}
bool heap_free_page(heap_t *heap, page_t *page)
{
if (!page || !heap)
return false;
if (page == heap->beg)
{
heap->beg = heap->beg->next;
page_delete(page);
--heap->pages;
if (heap->pages == 0)
heap->end = NULL;
return true;
}
page_t *prev = NULL, *next = NULL, *cur = NULL;
for (cur = heap->beg; cur; cur = cur->next)
{
next = cur->next;
if (cur == page)
break;
prev = cur;
}
if (!cur)
// Couldn't find the page
return false;
// Page was found
prev->next = next;
if (!next)
// This means page == heap->end
heap->end = prev;
page_delete(page);
--heap->pages;
if (heap->pages == 0)
heap->beg = NULL;
return true;
}
page_t *heap_allocate(heap_t *heap, size_t requested)
{
page_t *cur = page_create(requested, NULL);
if (heap->end)
heap->end->next = cur;
else
heap->beg = cur;
heap->end = cur;
heap->pages++;
return cur;
}
void heap_stop(heap_t *heap)
{
page_t *ptr = heap->beg;
for (size_t i = 0; i < heap->pages; ++i)
{
page_t *cur = ptr;
page_t *next = ptr->next;
page_delete(cur);
ptr = next;
}
heap->beg = NULL;
heap->end = NULL;
heap->pages = 0;
}
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