From 7396fe90099dcd6150b08f7ae85bd022186cb0f7 Mon Sep 17 00:00:00 2001
From: koolkdev <koolkdev@gmail.com>
Date: Sun, 26 Mar 2017 22:03:01 +0300
Subject: [PATCH] fat writing optimization

---
 ios_fs/source/fat/fat_access.c | 1 +
 ios_fs/source/fat/fat_access.h | 1 +
 ios_fs/source/fat/fat_table.c  | 1 +
 ios_fs/source/fat/fat_write.c  | 6 +++---
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/ios_fs/source/fat/fat_access.c b/ios_fs/source/fat/fat_access.c
index 394fa64..1665a3d 100644
--- a/ios_fs/source/fat/fat_access.c
+++ b/ios_fs/source/fat/fat_access.c
@@ -131,6 +131,7 @@ int fatfs_init(struct fatfs *fs)
 
     // For FAT32 (which this may be)
     fs->rootdir_first_cluster = GET_32BIT_WORD(fs->currentsector.sector, BPB_FAT32_ROOTCLUS);
+    fs->last_free_cluster = fs->rootdir_first_cluster + 1;
     fs->fs_info_sector = GET_16BIT_WORD(fs->currentsector.sector, BPB_FAT32_FSINFO);
 
     // For FAT16 (which this may be), rootdir_first_cluster is actuall rootdir_first_sector
diff --git a/ios_fs/source/fat/fat_access.h b/ios_fs/source/fat/fat_access.h
index 1752387..de23475 100644
--- a/ios_fs/source/fat/fat_access.h
+++ b/ios_fs/source/fat/fat_access.h
@@ -60,6 +60,7 @@ struct fatfs
     uint8                   sectors_per_cluster;
     uint32                  cluster_begin_lba;
     uint32                  rootdir_first_cluster;
+    uint32                  last_free_cluster;
     uint32                  rootdir_first_sector;
     uint32                  rootdir_sectors;
     uint32                  fat_begin_lba;
diff --git a/ios_fs/source/fat/fat_table.c b/ios_fs/source/fat/fat_table.c
index 6a01adf..c05dd9a 100644
--- a/ios_fs/source/fat/fat_table.c
+++ b/ios_fs/source/fat/fat_table.c
@@ -337,6 +337,7 @@ int fatfs_find_blank_cluster(struct fatfs *fs, uint32 start_cluster, uint32 *fre
     while (nextcluster != 0x0);
 
     // Found blank entry
+	fs->last_free_cluster = current_cluster + 1;
     *free_cluster = current_cluster;
     return 1;
 }
diff --git a/ios_fs/source/fat/fat_write.c b/ios_fs/source/fat/fat_write.c
index 620010e..cfe14d6 100644
--- a/ios_fs/source/fat/fat_write.c
+++ b/ios_fs/source/fat/fat_write.c
@@ -55,7 +55,7 @@ int fatfs_add_free_space(struct fatfs *fs, uint32 *startCluster, uint32 clusters
     for (i=0;i<clusters;i++)
     {
         // Start looking for free clusters from the beginning
-        if (fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &nextcluster))
+        if (fatfs_find_blank_cluster(fs, fs->last_free_cluster, &nextcluster))
         {
             // Point last to this
             fatfs_fat_set_cluster(fs, start, nextcluster);
@@ -103,7 +103,7 @@ int fatfs_allocate_free_space(struct fatfs *fs, int newFile, uint32 *startCluste
     // Allocated first link in the chain if a new file
     if (newFile)
     {
-        if (!fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &nextcluster))
+        if (!fatfs_find_blank_cluster(fs, fs->last_free_cluster, &nextcluster))
             return 0;
 
         // If this is all that is needed then all done
@@ -230,7 +230,7 @@ static int fatfs_find_free_dir_offset(struct fatfs *fs, uint32 dirCluster, int e
             uint32 newCluster;
 
             // Get a new cluster for directory
-            if (!fatfs_find_blank_cluster(fs, fs->rootdir_first_cluster, &newCluster))
+            if (!fatfs_find_blank_cluster(fs, fs->last_free_cluster, &newCluster))
                 return 0;
 
             // Add cluster to end of directory tree