mufs: add code to lookup, allocate and free pages in file trees

Makefile

@@ -25,6 +25,7 @@ obj-y += source/core/flash.o
 
 obj-y += source/fs/mufs/block.o
 obj-y += source/fs/mufs/super.o
+obj-y += source/fs/mufs/tree.o
 
 obj-y += source/ftl/dev.o
 obj-y += source/ftl/ftl.o

source/fs/mufs/tree.c

@@ -0,0 +1,97 @@
+#include <stdint.h>
+
+#include <bitops.h>
+#include <flash.h>
+
+#include <fs/mufs.h>
+
+#include "block.h"
+#include "tree.h"
+
+static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
+	uint32_t base, uint8_t depth, uint32_t va, unsigned alloc)
+{
+	char data[1 << fs->dev->log2_block_size];
+	uint32_t *table = (uint32_t *)data;
+	size_t index;
+	uint8_t log2_nentries = fs->dev->log2_block_size - ilog2(sizeof(uint32_t));
+
+	if (!base)
+		return -1;
+
+	if (!depth) {
+		*page = base;
+		return 0;
+	}
+
+	if (flash_read(fs->dev, base << fs->dev->log2_block_size, data,
+		sizeof data) == 0)
+		return -1;
+
+	index = va & ((1 << (log2_nentries * (depth - 1))) - 1);
+
+	if (!table[index]) {
+		if (!alloc || mufs_alloc_block(fs, &table[index]) < 0)
+			return -1;
+	}
+
+	return mufs_do_lookup(fs, page, table[index], depth - 1, va, alloc);
+}
+
+int mufs_lookup_page(struct mufs *fs, struct mufs_tree *tree, uint32_t *page,
+	uint32_t va)
+{
+	return mufs_do_lookup(fs, page, tree->base, tree->depth, va, 0);
+}
+
+int mufs_alloc_page(struct mufs *fs, struct mufs_tree *tree, uint32_t *page,
+	uint32_t va)
+{
+	return mufs_do_lookup(fs, page, tree->base, tree->depth, va, 1);
+}
+
+static int mufs_do_free_page(struct mufs *fs, uint32_t base,
+	uint8_t depth, uint32_t va)
+{
+	char data[1 << fs->dev->log2_block_size];
+	uint32_t *table = (uint32_t *)data;
+	size_t index;
+	uint8_t log2_nentries = fs->dev->log2_block_size - ilog2(sizeof(uint32_t));
+
+	if (!base)
+		return -1;
+
+	if (!depth) {
+		mufs_free_block(fs, base);
+		return 0;
+	}
+
+	if (flash_read(fs->dev, base << fs->dev->log2_block_size, data,
+		sizeof data) == 0)
+		return -1;
+
+	index = va & ((1 << (log2_nentries * (depth - 1))) - 1);
+
+	if (mufs_do_free_page(fs, table[index], depth - 1, va) < 0)
+		return -1;
+
+	table[index] = 0;
+
+	for (index = 0; index < (UINT32_C(1) << log2_nentries); ++index) {
+		if (!table[index])
+			continue;
+
+		if (flash_write(fs->dev, base << fs->dev->log2_block_size, data,
+			sizeof data) == 0)
+			return -1;
+
+		return 0;
+	}
+
+	return mufs_free_block(fs, base);
+}
+
+void mufs_free_page(struct mufs *fs, struct mufs_tree *tree, uint32_t va)
+{
+	mufs_do_free_page(fs, tree->base, tree->depth, va);
+}

source/fs/mufs/tree.h

@@ -0,0 +1,12 @@
+#pragma once
+
+struct mufs_tree {
+	uint32_t base;
+	uint8_t depth;
+};
+
+int mufs_lookup_page(struct mufs *fs, struct mufs_tree *tree, uint32_t *page,
+	uint32_t va);
+int mufs_alloc_page(struct mufs *fs, struct mufs_tree *tree, uint32_t *page,
+	uint32_t va);
+void mufs_free_page(struct mufs *fs, struct mufs_tree *tree, uint32_t va);