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#include "heap.h"
#include "paging.h"
#define HEAP_MAGIC 0xBAD0BEEF
#define HEAP_MIN_SIZE 0x4000
/* ******************* HEADER ****************** */
static void heapIdx_insert(struct heap *heap, struct heap_header *e) {
if ((heap->idxused + sizeof(struct heap_header*) + (size_t)heap->idx) >= heap->start_addr) return;
uint32_t iterator = 0, pos;
while (iterator < heap->idxused && heap->idx[iterator]->size < e->size) {
if (heap->idx[iterator] == e) return;
iterator++;
}
if (iterator == heap->idxused) {
heap->idx[heap->idxused++] = e;
} else {
pos = iterator;
iterator = heap->idxused;
while (iterator > pos) {
heap->idx[iterator] = heap->idx[iterator - 1];
iterator--;
}
heap->idxused++;
heap->idx[pos] = e;
}
}
static void heapIdx_remove(struct heap *heap, struct heap_header *e) {
uint32_t iterator;
for (iterator = 0; iterator < heap->idxused; iterator++) {
if (heap->idx[iterator] == e) break;
}
if (iterator == heap->idxused) return;
heap->idxused--;
while (iterator < heap->idxused) {
heap->idx[iterator] = heap->idx[iterator + 1];
iterator++;
}
}
/* ******************** CONTENTS ********************* */
void heap_create(struct heap *heap, size_t start, size_t idxsize, size_t datasize, size_t maxdatasize) {
uint32_t i;
if (start & 0x0FFF) start = (start & 0xFFFFF000) + 0x1000;
heap->start_addr = start + idxsize;
heap->end_addr = start + idxsize + datasize;
heap->max_end = start + idxsize + maxdatasize;
for (i = start; i < heap->end_addr; i += 0x1000) {
page_map(pagedir_getPage(kernel_pagedir, i, 1), frame_alloc(), 0, 0);
}
heap->idx = (struct heap_header**)start;
heap->idxused = 0;
struct heap_header *hole = (struct heap_header*) heap->start_addr;
hole->size = (heap->end_addr - heap->start_addr);
hole->magic = HEAP_MAGIC;
hole->is_hole = 1;
struct heap_footer *hole_footer = (struct heap_footer*)(heap->end_addr - sizeof(struct heap_footer));
hole_footer->header = hole;
hole_footer->magic = HEAP_MAGIC;
heapIdx_insert(heap, hole);
}
static uint32_t heap_expand(struct heap *heap, size_t quantity) {
uint32_t i;
if (quantity & 0x0FFF) {
quantity = (quantity & 0xFFFFF000) + 0x1000;
}
if (heap->end_addr + quantity > heap->max_end) return 0;
size_t newEnd = heap->end_addr + quantity;
for (i = heap->end_addr; i < newEnd; i += 0x1000) {
page_map(pagedir_getPage(kernel_pagedir, i, 1), frame_alloc(), 0, 0);
}
struct heap_footer *last_footer = (struct heap_footer*)(heap->end_addr - sizeof(struct heap_footer));
struct heap_header *last_header = last_footer->header;
if (last_header->is_hole) {
heapIdx_remove(heap, last_header);
last_header->size += quantity;
last_footer = (struct heap_footer*)(newEnd - sizeof(struct heap_footer));
last_footer->magic = HEAP_MAGIC;
last_footer->header = last_header;
heapIdx_insert(heap, last_header);
} else {
last_header = (struct heap_header*)heap->end_addr;
last_footer = (struct heap_footer*)(newEnd - sizeof(struct heap_footer));
last_header->is_hole = 1;
last_header->magic = HEAP_MAGIC;
last_header->size = quantity;
last_footer->magic = HEAP_MAGIC;
last_footer->header = last_header;
heapIdx_insert(heap, last_header);
}
heap->end_addr = newEnd;
return 1;
}
static void heap_contract(struct heap *heap) {
struct heap_footer *last_footer = (struct heap_footer*)(heap->end_addr - sizeof(struct heap_footer));
struct heap_header *last_header = last_footer->header;
if (last_header->is_hole == 0) return;
size_t quantity = 0;
while ((heap->end_addr - heap->start_addr) - quantity > HEAP_MIN_SIZE &&
(last_header->size - quantity) > 0x1000)
quantity += 0x1000;
if (quantity == 0) return;
size_t newEnd = heap->end_addr - quantity;
heapIdx_remove(heap, last_header);
last_header->size -= quantity;
last_footer = (struct heap_footer*)((size_t)last_footer - quantity);
last_footer->magic = HEAP_MAGIC;
last_footer->header = last_header;
heapIdx_insert(heap, last_header);
for (heap->end_addr -= 0x1000; heap->end_addr >= newEnd; heap->end_addr -= 0x1000) {
page_unmapFree(pagedir_getPage(kernel_pagedir, heap->end_addr, 0));
}
}
void* heap_alloc(struct heap *heap, size_t sz) {
size_t newsize = sz + sizeof(struct heap_header) + sizeof(struct heap_footer);
uint32_t iterator = 0;
while (iterator < heap->idxused) {
if (heap->idx[iterator]->size >= newsize) break;
iterator++;
}
if (iterator == heap->idxused) { //No hole is big enough
if (heap_expand(heap, (sz & 0xFFFFF000) + 0x1000) == 0) return 0; //FAILED
return heap_alloc(heap, sz);
}
struct heap_header *loc = heap->idx[iterator];
struct heap_footer *footer = (struct heap_footer*)((size_t)loc + loc->size - sizeof(struct heap_footer));
loc->is_hole = 0;
heapIdx_remove(heap, loc);
//If we have enough space to create a USEFUL new hole next to the allocated block, do it.
//If we do not, we might return a block that is a few bytes bigger than neede.
if (loc->size > (newsize + sizeof(struct heap_header) + sizeof(struct heap_footer))) {
loc->size = newsize;
//Write footer for block we return
struct heap_footer *newfooter = (struct heap_footer*)((size_t)loc + newsize - sizeof(struct heap_footer));
newfooter->header = loc;
newfooter->magic = HEAP_MAGIC;
//Write header for new hole we create
struct heap_header *nextloc = (struct heap_header*)((size_t)loc + newsize);
nextloc->is_hole = 1;
nextloc->magic = HEAP_MAGIC;
nextloc->size = ((size_t)footer - (size_t)nextloc + sizeof(struct heap_footer));
footer->header = nextloc; //Update footer
footer->magic = HEAP_MAGIC;
heapIdx_insert(heap, nextloc);
}
return (void*)((size_t)loc + sizeof(struct heap_header));
}
void heap_free(struct heap *heap, void* ptr) {
if (ptr == 0) return;
if ((size_t)ptr < heap->start_addr || (size_t)ptr > heap->end_addr) return;
struct heap_header *header = (struct heap_header*)((size_t)ptr - sizeof(struct heap_header));
struct heap_footer *footer = (struct heap_footer*)((size_t)header + header->size - sizeof(struct heap_footer));
if (header->magic != HEAP_MAGIC || footer->magic != HEAP_MAGIC) return;
//Unify left
struct heap_footer *prev_footer = (struct heap_footer*)((size_t)header - sizeof(struct heap_footer));
if (prev_footer->magic == HEAP_MAGIC && prev_footer->header->is_hole) {
header = prev_footer->header;
heapIdx_remove(heap, header);
footer->header = header;
header->size = ((size_t)footer - (size_t)header + sizeof(struct heap_footer));
}
//Unify right
struct heap_header *next_header = (struct heap_header*)((size_t)footer + sizeof(struct heap_footer));
if (next_header->magic == HEAP_MAGIC && next_header->is_hole) {
heapIdx_remove(heap, next_header);
footer = (struct heap_footer*)((size_t)footer + next_header->size);
footer->header = header;
header->size = ((size_t)footer - (size_t)header + sizeof(struct heap_footer));
}
header->is_hole = 1;
heapIdx_insert(heap, header);
if ((size_t)footer == (heap->end_addr - sizeof(struct heap_footer)) &&
header->size >= 0x2000 && (heap->end_addr - heap->start_addr > HEAP_MIN_SIZE)) {
heap_contract(heap);
}
}
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