src/memory/frame.c

@@ -6,24 +6,13 @@
 #include "memory.h"
 #include "utils.h"
 
-#define MAX_FRAMES (0xC0000000 / PAGE_SIZE)
+#define MAX_FRAMES 1048319
+
+static uint32_t end_kernel; // WIP but it's useless now
 
 static uint8_t frame_table[MAX_FRAMES];
 static uint32_t remaining_frames = MAX_FRAMES;
 
-static int32_t find_next_block(size_t nb_frames)
-{
-	for (uint32_t i = 1; i < MAX_FRAMES; i++) {
-		uint32_t j;
-		for (j = 0; frame_table[i + j] == 0 && j < nb_frames; j++)
-			;
-		if (j == nb_frames)
-			return i;
-		i += j;
-	}
-	return -1;
-}
-
 void *alloc_frames(size_t size)
 {
 	const uint32_t nb_frames = CEIL(size, PAGE_SIZE);
@@ -31,24 +20,35 @@ void *alloc_frames(size_t size)
 		kprintf(KERN_CRIT "Not enough frames (max: %d)\n", MAX_FRAMES);
 		return NULL;
 	}
-	size_t i = find_next_block(nb_frames);
-	if (i == -1) {
-		kprintf(KERN_WARNING "Not enough frames available\n",
-		        MAX_FRAMES);
-		return NULL;
+
+	size_t i = 0;
+	while (i < MAX_FRAMES) {
+		size_t free_frames = 1;
+		while (!frame_table[i + free_frames] && free_frames < nb_frames)
+			free_frames++;
+		if (free_frames == nb_frames)
+			goto end;
+		if (!free_frames)
+			i++;
+		i += free_frames;
 	}
-	for (size_t j = 0; j < nb_frames; j++)
-		frame_table[j + i] = 1;
-	remaining_frames -= nb_frames;
-	return (void*)(i * PAGE_SIZE);
+end:
+	if (i != MAX_FRAMES) {
+		for (size_t j = 0; j < nb_frames; j++)
+			frame_table[j + i] = 1;
+		remaining_frames -= nb_frames;
+		return &end_kernel + i * PAGE_SIZE;
+	}
+	kprintf(KERN_WARNING "Not enough frames available\n", MAX_FRAMES);
+	return NULL;
 }
 
 int free_frames(void *frame_ptr, size_t size)
 {
 	const uint32_t nb_frames = CEIL(size, PAGE_SIZE);
-	const uint32_t start = (uint32_t)frame_ptr / PAGE_SIZE;
+	const uint32_t start = (frame_ptr - (void *)&end_kernel) / PAGE_SIZE;
 
-	if (start > MAX_FRAMES) {
+	if (start > MAX_FRAMES || frame_ptr < (void *)&end_kernel) {
 		kprintf(KERN_WARNING "Address out of range\n");
 		return -1;
 	} else if ((uint32_t)frame_ptr % PAGE_SIZE) {

src/memory/page.c

@@ -13,7 +13,7 @@ extern uint32_t page_table_entries[PT_SIZE] __attribute__((aligned(4096)));
 
 static int16_t find_next_block(size_t nb_pages)
 {
-	for (uint16_t i = 1; i < PT_SIZE; i++) {
+	for (uint16_t i = 0; i < PT_SIZE; i++) {
 		uint16_t j;
 		for (j = 0;
 		     page_table_entries[i + j] >> 12 == i + j && j < nb_pages;
@@ -46,7 +46,7 @@ void *alloc_pages(size_t size)
 		}
 		page_table_entries[i] = (uint32_t)frame << 12 | INIT_FLAGS;
 	}
-	return (void *)(index * PAGE_SIZE);
+	return (void *)(page_table_entries[index] >> 12);
 }
 
 int free_pages(void *page_ptr, size_t size)