feature: both physical and virtual allocators should be done

src/memory/page.c

@@ -0,0 +1,73 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "kprintf.h"
+#include "memory.h"
+#include "utils.h"
+
+#define PT_SIZE         1024
+#define MAX_TLB_ENTRIES 32
+
+extern uint32_t page_table_entries[PT_SIZE] __attribute__((aligned(4096)));
+
+static int16_t find_next_block(size_t nb_pages)
+{
+	for (size_t i = 0; i < PT_SIZE; i++) {
+		if (page_table_entries[i] >> 12 == i) {
+			size_t j = i + 1;
+			for (; j - i < nb_pages && j < PT_SIZE; j++)
+				if (page_table_entries[j] >> 12 != j)
+					break;
+			if (j - i == nb_pages)
+				return i;
+			i = j - 1;
+		}
+	}
+	return -1;
+}
+
+void *alloc_pages(size_t size)
+{
+	const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
+	const int16_t index = find_next_block(nb_pages);
+
+	if (index < 0) {
+		kprintf(KERN_CRIT "Not enough pages (max: %d)\n", PT_SIZE);
+		return NULL;
+	}
+	for (size_t i = index; i - (size_t)index < nb_pages; i++) {
+		void *frame = alloc_frames(PAGE_SIZE);
+		if (!frame) {
+			for (size_t j = index; j < i; j++)
+				free_frames(
+				    (void *)(page_table_entries[j] >> 12),
+				    PAGE_SIZE);
+			return NULL;
+		}
+		page_table_entries[i] = (uint32_t)frame << 12;
+	}
+	return (void *)(page_table_entries[index] >> 12);
+}
+
+int free_pages(void *page_ptr, size_t size)
+{
+	const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
+	const uint32_t page_index = (uint32_t)page_ptr / PAGE_SIZE;
+
+	if ((uint32_t)page_ptr > PT_SIZE * PAGE_SIZE) {
+		kprintf(KERN_WARNING "Address out of range\n");
+		return -1;
+	} else if ((uint32_t)page_ptr % PAGE_SIZE) {
+		kprintf(KERN_WARNING "Invalid address\n");
+		return -1;
+	} else if (page_index + nb_pages > PT_SIZE) {
+		kprintf(KERN_WARNING "Invalid number of frames\n");
+		return -1;
+	}
+	for (size_t i = page_index; i < page_index + nb_pages; i++) {
+		free_frames((void *)(page_table_entries[i] >> 12), PAGE_SIZE);
+		page_table_entries[i] = (i >> 12) | INIT_FLAGS;
+	}
+	return 0;
+}