// Creates a new heap
void heap_create(heap* h, int initial_size, int (*comp_func)(void*,void*)) {
// Check if we need to setup our globals
if (PAGE_SIZE == 0) {
// Get the page size
PAGE_SIZE = getpagesize();
// Calculate the max entries
ENTRIES_PER_PAGE = PAGE_SIZE / sizeof(heap_entry);
}
// Check that initial size is greater than 0, else set it to ENTRIES_PER_PAGE
if (initial_size <= 0)
initial_size = ENTRIES_PER_PAGE;
// If the comp_func is null, treat the keys as signed ints
if (comp_func == NULL)
comp_func = compare_int_keys;
// Store the compare function
h->compare_func = comp_func;
// Set active entries to 0
h->active_entries = 0;
// Determine how many pages of entries we need
h->minimum_pages = initial_size / ENTRIES_PER_PAGE + ((initial_size % ENTRIES_PER_PAGE > 0) ? 1 : 0);
// Determine how big the map table should be
h->map_pages = sizeof(void*) * h->minimum_pages / PAGE_SIZE + 1;
// Allocate the map table
h->mapping_table = (void**)map_in_pages(h->map_pages);
assert(h->mapping_table != NULL);
// Allocate the entry pages
void* addr = map_in_pages(h->minimum_pages);
assert(addr != NULL);
// Add these to the map table
for (int i=0;i<h->minimum_pages;i++) {
*(h->mapping_table+i) = addr+(i*PAGE_SIZE);
}
// Set the allocated pages
h->allocated_pages = h->minimum_pages;
}
// Creates a new heap
void heap_create(heap* h, int initial_size, int (*comp_func)(void*,void*)) {
// Check if we need to setup our globals
if (PAGE_SIZE == 0) {
// Get the page size
PAGE_SIZE = getpagesize();
// Calculate the max entries
ENTRIES_PER_PAGE = PAGE_SIZE / sizeof(heap_entry);
}
// Check that initial size is greater than 0, else set it to ENTRIES_PER_PAGE
if (initial_size <= 0)
initial_size = ENTRIES_PER_PAGE;
// If the comp_func is null, treat the keys as signed ints
if (comp_func == NULL)
comp_func = compare_int_keys;
// Store the compare function
h->compare_func = comp_func;
// Set active entries to 0
h->active_entries = 0;
// Determine how many pages of entries we need
h->allocated_pages = initial_size / ENTRIES_PER_PAGE + ((initial_size % ENTRIES_PER_PAGE > 0) ? 1 : 0);
h->minimum_pages = h->allocated_pages;
// Allocate the table
h->table = (void*)map_in_pages(h->allocated_pages);
}
// Deletes the minimum entry in the heap
int heap_delmin(heap* h, void** key, void** value) {
// Check there is a minimum
if (h->active_entries == 0)
return 0;
// Load in the map table
heap_entry* table = h->table;
// Get the root element
int current_index = 0;
heap_entry* current = GET_ENTRY(current_index, table);
// Store the outputs
if (key) *key = current->key;
if (value) *value = current->value;
// Reduce the number of active entries
h->active_entries--;
// Get the active entries
int entries = h->active_entries;
// If there are any other nodes, we may need to move them up
if (h->active_entries > 0) {
// Move the last element to the root
heap_entry* last = GET_ENTRY(entries,table);
current->key = last->key;
current->value = last->value;
// Loop variables
heap_entry* left_child;
heap_entry* right_child;
// Load the comparison function
int (*cmp_func)(void*,void*) = h->compare_func;
// Store the left index
int left_child_index;
while (left_child_index = LEFT_CHILD(current_index), left_child_index < entries) {
// Load the left child
left_child = GET_ENTRY(left_child_index, table);
// We have a left + right child
if (left_child_index+1 < entries) {
// Load the right child
right_child = GET_ENTRY((left_child_index+1), table);
// Find the smaller child
if (cmp_func(left_child->key, right_child->key) <= 0) {
// Swap with the left if it is smaller
if (cmp_func(current->key, left_child->key) == 1) {
SWAP_ENTRIES(current,left_child);
current_index = left_child_index;
current = left_child;
// Otherwise, the current is smaller
} else
break;
// Right child is smaller
} else {
// Swap with the right if it is smaller
if (cmp_func(current->key, right_child->key) == 1) {
SWAP_ENTRIES(current,right_child);
current_index = left_child_index+1;
current = right_child;
// Current is smaller
} else
break;
}
// We only have a left child, only do something if the left is smaller
} else if (cmp_func(current->key, left_child->key) == 1) {
SWAP_ENTRIES(current,left_child);
current_index = left_child_index;
current = left_child;
// Done otherwise
} else
break;
}
}
// Check if we should release a page of memory
int used_pages = entries / ENTRIES_PER_PAGE + ((entries % ENTRIES_PER_PAGE > 0) ? 1 : 0);
// Allow one empty page, but not two
if (h->allocated_pages / 2 > used_pages + 1 && h->allocated_pages / 2 >= h->minimum_pages) {
// Get the new number of entries we need
int new_size = h->allocated_pages / 2;
// Map in a new table
heap_entry* new_table = map_in_pages(new_size);
// Copy the old entries, copy the entire pages
memcpy(new_table, h->table, used_pages*PAGE_SIZE);
// Cleanup the old table
map_out_pages(h->table, h->allocated_pages);
// Switch to the new table
h->table = new_table;
h->allocated_pages = new_size;
}
// Success
return 1;
}
// Insert a new element
void heap_insert(heap *h, void* key, void* value) {
// Check if this heap is not destoyed
assert(h->table != NULL);
// Check if we have room
int max_entries = h->allocated_pages * ENTRIES_PER_PAGE;
if (h->active_entries + 1 > max_entries) {
// Get the new number of entries we need
int new_size = h->allocated_pages * 2;
// Map in a new table
heap_entry* new_table = map_in_pages(new_size);
// Copy the old entries, copy the entire pages
memcpy(new_table, h->table, h->allocated_pages*PAGE_SIZE);
// Cleanup the old table
map_out_pages(h->table, h->allocated_pages);
// Switch to the new table
h->table = new_table;
h->allocated_pages = new_size;
}
// Store the comparison function
int (*cmp_func)(void*,void*) = h->compare_func;
// Store the table address
heap_entry* table = h->table;
// Get the current index
int current_index = h->active_entries;
heap_entry* current = GET_ENTRY(current_index, table);
// Loop variables
int parent_index;
heap_entry *parent;
// While we can, keep swapping with our parent
while (current_index > 0) {
// Get the parent index
parent_index = PARENT_ENTRY(current_index);
// Get the parent entry
parent = GET_ENTRY(parent_index, table);
// Compare the keys, and swap if we need to
if (cmp_func(key, parent->key) < 0) {
// Move the parent down
current->key = parent->key;
current->value = parent->value;
// Move our reference
current_index = parent_index;
current = parent;
// We are done swapping
} else
break;
}
// Insert at the current index
current->key = key;
current->value = value;
// Increase the number of active entries
h->active_entries++;
}
// Insert a new element
void heap_insert(heap *h, void* key, void* value) {
// Check if this heap is not destoyed
assert(h->mapping_table != NULL);
// Check if we have room
int max_entries = h->allocated_pages * ENTRIES_PER_PAGE;
if (h->active_entries + 1 > max_entries) {
// Get the number of map pages
int map_pages = h->map_pages;
// We need a new page, do we have room?
int mapable_pages = map_pages * PAGE_SIZE / sizeof(void*);
// Check if we need to grow the map table
if (h->allocated_pages + 1 > mapable_pages) {
// Allocate a new table, slightly bigger
void *new_table = map_in_pages(map_pages + 1);
// Get the old table
void *old_table = (void*)h->mapping_table;
// Copy the old entries to the new table
memcpy(new_table, old_table, map_pages * PAGE_SIZE);
// Delete the old table
map_out_pages(old_table, map_pages);
// Swap to the new table
h->mapping_table = (void**)new_table;
// Update the number of map pages
h->map_pages = map_pages + 1;
}
// Allocate a new page
void* addr = map_in_pages(1);
// Add this to the map
*(h->mapping_table+h->allocated_pages) = addr;
// Update the number of allocated pages
h->allocated_pages++;
}
// Store the comparison function
int (*cmp_func)(void*,void*) = h->compare_func;
// Store the map table address
void** map_table = h->mapping_table;
// Get the current index
int current_index = h->active_entries;
heap_entry* current = GET_ENTRY(current_index, map_table);
// Loop variables
int parent_index;
heap_entry *parent;
// While we can, keep swapping with our parent
while (current_index > 0) {
// Get the parent index
parent_index = PARENT_ENTRY(current_index);
// Get the parent entry
parent = GET_ENTRY(parent_index, map_table);
// Compare the keys, and swap if we need to
if (cmp_func(key, parent->key) < 0) {
// Move the parent down
current->key = parent->key;
current->value = parent->value;
// Move our reference
current_index = parent_index;
current = parent;
// We are done swapping
} else
break;
}
// Insert at the current index
current->key = key;
current->value = value;
// Increase the number of active entries
h->active_entries++;
}
