memory changes

1 files changed, 250 insertions, 0 deletions

diff --git a/src/memory/physalloc.c b/src/memory/physalloc.c
new file mode 100644
index 0000000..b8eada6
--- /dev/null
+++ b/src/memory/physalloc.c
@@ -0,0 +1,250 @@
+#include <memory.h>
+#include <stdint.h>
+#include <lib.h>
+#include <stddef.h>
+
+#define MEMORY_INTERNAL
+#include <memory/physalloc.h>
+#include <memory/virtalloc.h>
+
+extern uintptr_t kernel_start;
+extern uintptr_t kernel_end;
+
+// between memory_start and kernel_start will be the bitmap
+static uintptr_t memory_start = 0;
+
+typedef unsigned char page[4096];
+
+struct memory_area {
+	uint64_t len;
+	uintptr_t addr;
+};
+
+static uint64_t *bitmap;
+static uint64_t total_memory;
+static uint64_t free_memory;
+static uint64_t page_count;
+static uint64_t page_free_start;
+static struct memory_area *page_start;
+
+static int n_pages(const struct memory_area *m) {
+	return m->len / PAGE_SIZE;
+}
+
+static void *page_at(int i) {
+	int cur_page = 0;
+	for (struct memory_area *m = page_start; m != NULL; m++) {
+		int pages = n_pages(m);
+		if (i - cur_page < pages) {
+			return (void *) (m->addr + (PAGE_SIZE * (i - cur_page)));
+		}
+		cur_page += pages;
+	}
+	return NULL;
+}
+
+static long page_idx(page p) {
+	uintptr_t addr = (uintptr_t) p;
+	int cur_page = 0;
+	for (struct memory_area *m = page_start; m != NULL; m++) {
+		if ((uintptr_t) m + m->len > addr) {
+			return cur_page + ((addr - m->addr) / PAGE_SIZE);
+		}
+		cur_page += n_pages(m);
+	}
+	return -1;
+}
+
+static inline bool bitmap_get(int i) {
+	return (bitmap[i / 64] >> i % 64) & 1;
+}
+
+static inline void bitmap_set(int i, bool v) {
+	int idx = i / 64;
+	bitmap[idx] &= ~(1 << i % 64);
+	bitmap[idx] |=  (v << i % 64);
+}
+
+void *alloc_phys_page(void) {
+	return alloc_phys_pages(1);
+}
+
+void *alloc_phys_pages(int pages) {
+	if (pages < 1) return NULL;
+
+	int n_contiguous = 0;
+	int free_region_start = 0;
+	bool first = true;
+	for (uint64_t i = page_free_start; i < page_count; i++) {
+		bool free = !bitmap_get(i);
+
+		if (first) {
+			first = false;
+			page_free_start = i;
+		}
+
+		if (free) {
+			if (n_contiguous == 0) free_region_start = i;
+			n_contiguous++;
+			if (n_contiguous == pages) {
+				for (int j = 0; j < pages; j++)
+					bitmap_set(free_region_start + j, true);
+				return page_at(free_region_start);
+			}
+		} else n_contiguous = 0;
+	}
+
+	return NULL;
+}
+
+void free_phys_page(void *ptr) {
+	free_phys_pages(ptr, 1);
+}
+
+void free_phys_pages(void *ptr, int pages) {
+	long idx = page_idx(ptr);
+	if (idx == -1) return;
+
+	if ((unsigned) idx < page_free_start) page_free_start = idx;
+
+	for (int i = 0; i < pages; i++)
+		bitmap_set(idx + pages, false);
+}
+
+static bool segment_invalid(const struct memory_segment *segment) {
+	if (segment->type != 1) return false;
+	if (segment->addr < kernel_start) return false;
+	if (segment->addr + segment->len < memory_start) return false;
+	if (segment->addr + segment->len < kernel_start) return false;
+	return true;
+}
+
+static struct memory_area segment_to_area(const struct memory_segment *segment) {
+	uint64_t length = segment->len;
+	uintptr_t addr = segment->addr;
+
+	uintptr_t start;
+	if (memory_start)
+		start = memory_start;
+	else
+		start = kernel_end;
+
+	if (segment->addr < start) {
+		addr = start;
+		length -= addr - segment->addr;
+	} else {
+		addr = segment->addr;
+	}
+
+	struct memory_area temp;
+	temp.len = length;
+	temp.addr = addr;
+
+	return temp;
+}
+
+static uintptr_t page_align(uintptr_t ptr) {
+	return ptr + PAGE_SIZE - 1 / PAGE_SIZE;
+}
+
+void memory_init(struct memory_map *map) {
+
+	memory_lock();
+
+	virtaddr_init();
+
+	bitmap = NULL;
+	total_memory = 0;
+	free_memory = 0;
+	page_count = 0;
+	page_free_start = 0;
+	page_start = NULL;
+
+	uintptr_t end = (uintptr_t) map;
+	end += map->size;
+
+	struct memory_segment *segment = &map->entries[0];
+	int segment_count = 0;
+
+	for(; (uintptr_t) segment < end; segment++) {
+		if (segment_invalid(segment))
+			continue;
+
+		struct memory_area temp = segment_to_area(segment);
+		page_count += n_pages(&temp);
+		segment_count++;
+	}
+
+	long bitmap_pages = page_count / 64 / PAGE_SIZE + 1;
+	free_memory = page_count * PAGE_SIZE;
+
+	//HACK: terrible hack bad bad bad bad
+	long bitmap_size = bitmap_pages * PAGE_SIZE;
+	bitmap = (uint64_t *) page_at(page_count - bitmap_pages);
+
+	long page_area_size = segment_count * sizeof(struct memory_area);
+	char *page_area_addr = (char *)bitmap + bitmap_size;
+	
+	bitmap = mmap(bitmap, bitmap_size);
+	memset(bitmap, 0, bitmap_size);
+	
+	memory_start = page_align(kernel_end + bitmap_size + page_area_size);
+
+	page_area_addr = mmap(page_area_addr, page_area_size);
+	page_start = (struct memory_area *) page_area_addr;
+	
+	struct memory_area *area = page_start;
+	segment = &map->entries[0];
+	
+	for(; (uintptr_t) segment < end; segment++) {
+		if (segment_invalid(segment))
+			continue;
+
+		struct memory_area temp = segment_to_area(segment);
+		*area = temp;
+		area++;
+	}
+	
+	page_count -= bitmap_pages;
+
+	memory_unlock();
+
+}
+
+void *alloc_page(void) {
+	return alloc_pages(1);
+}
+
+uint64_t memory_total(void) {
+	return total_memory;
+}
+
+uint64_t memory_free(void) {
+	return free_memory;
+}
+
+uint64_t memory_used(void) {
+	return total_memory - free_memory;
+}
+
+// stubs
+// simon do these ik you want to
+// :3
+
+void *malloc(size_t size) {
+	//TODO: implement
+	(void)size;
+	return NULL;
+}
+
+void *realloc(void *ptr, size_t size) {
+	//TODO: implement
+	(void)ptr;
+	(void)size;
+	return NULL;
+}
+
+void free(void *ptr) {
+	//TODO: implement
+	(void)ptr;
+}