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#include <types.h>
#include <mem.h>
#include <dtb.h>
#include <common.h>
static struct page *free_list;
static void merge_freelist() {
struct page *list = free_list;
while (list && list->next) {
if ((void*)list + list->size == list->next) {
list->size += list->next->size;
list->next = list->next->next;
continue;
}
list = list->next;
}
}
void* kmalloc(size_t size) {
struct page *page = free_list;
struct page *last = NULL;
size_t combined_size = size + sizeof(struct page);
while (page && page->size < combined_size) {
last = page;
page = page->next;
}
if (page == NULL)
return NULL;
if (page->size - combined_size < sizeof(struct page)) {
// Return the entire page
if (last)
last->next = page->next;
else
free_list = page->next;
} else {
// break page and create a new one
struct page *broken = (void *)page + combined_size;
broken->size = page->size - combined_size;
broken->next = page->next;
broken->status = MEMPAGE_FREE;
page->size = combined_size;
page->next = broken;
if (last)
last->next = broken;
else
free_list = broken;
}
page->status = MEMPAGE_USED;
return (void *)page + sizeof(struct page);
}
void kfree(void *ptr) {
if (!ptr)
return;
struct page *page_info = (struct page *)(ptr - sizeof(struct page));
struct page *iter = free_list;
page_info->status = MEMPAGE_FREE;
if (!iter) {
free_list = page_info;
page_info->next = NULL;
goto merge;
}
if (page_info < free_list) {
page_info->next = iter;
free_list = page_info;
goto merge;
}
while (iter->next && iter->next < page_info) {
iter = iter->next;
}
page_info->next = iter->next;
iter->next = page_info;
merge:
merge_freelist();
}
void* memcpy(void *to, const void *from, size_t size) {
char *dest = (char *)to;
const char *src = (const char *)from;
while (size--) {
*dest++ = *src++;
}
return dest;
}
void km_init(struct mem_info *info) {
struct page *base = (struct page *)info->start;
base->next = NULL;
base->size = info->size - sizeof(struct page);
base->status = MEMPAGE_FREE;
free_list = base;
}
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