From 84abec80a89879aeebd5fbc5fdb5c74b4f05ccd4 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Wed, 5 Oct 2022 18:11:00 +0700
Subject: [PATCH] support filesystem with only 1 fat

---
 src/FatLib/FatPartition.cpp |  5 +++--
 src/FatLib/FatPartition.h   | 11 ++++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/FatLib/FatPartition.cpp b/src/FatLib/FatPartition.cpp
index d8716a6..b62278b 100644
--- a/src/FatLib/FatPartition.cpp
+++ b/src/FatLib/FatPartition.cpp
@@ -431,10 +431,11 @@ bool FatPartition::init(FsBlockDevice* dev, uint8_t part, uint32_t volStart) {
     goto fail;
   }
   bpb = reinterpret_cast<BpbFat32_t*>(pbs->bpb);
-  if (bpb->fatCount != 2 || getLe16(bpb->bytesPerSector) != m_bytesPerSector) {
+  if ( !(bpb->fatCount == 1 || bpb->fatCount == 2) || getLe16(bpb->bytesPerSector) != m_bytesPerSector) {
     DBG_FAIL_MACRO;
     goto fail;
   }
+  m_fatCount = bpb->fatCount;
   m_sectorsPerCluster = bpb->sectorsPerCluster;
   m_clusterSectorMask = m_sectorsPerCluster - 1;
   // determine shift that is same as multiply by m_sectorsPerCluster
@@ -456,7 +457,7 @@ bool FatPartition::init(FsBlockDevice* dev, uint8_t part, uint32_t volStart) {
   m_rootDirEntryCount = getLe16(bpb->rootDirEntryCount);
 
   // directory start for FAT16 dataStart for FAT32
-  m_rootDirStart = m_fatStartSector + 2 * m_sectorsPerFat;
+  m_rootDirStart = m_fatStartSector + m_fatCount * m_sectorsPerFat;
   // data start for FAT16 and FAT32
   m_dataStartSector = m_rootDirStart +
     ((FS_DIR_SIZE*m_rootDirEntryCount + m_bytesPerSector - 1)/m_bytesPerSector);
diff --git a/src/FatLib/FatPartition.h b/src/FatLib/FatPartition.h
index cb7b03f..6cb6d79 100644
--- a/src/FatLib/FatPartition.h
+++ b/src/FatLib/FatPartition.h
@@ -184,11 +184,12 @@ class FatPartition {
   static const uint16_t m_bytesPerSector = 1 << m_bytesPerSectorShift;
   static const uint16_t m_sectorMask = m_bytesPerSector - 1;
   //----------------------------------------------------------------------------
-  FsBlockDevice* m_blockDev;            // sector device
+  FsBlockDevice* m_blockDev;          // sector device
   uint8_t  m_sectorsPerCluster;       // Cluster size in sectors.
   uint8_t  m_clusterSectorMask;       // Mask to extract sector of cluster.
   uint8_t  m_sectorsPerClusterShift;  // Cluster count to sector count shift.
   uint8_t  m_fatType = 0;             // Volume type (12, 16, OR 32).
+  uint8_t  m_fatCount;                // Number of FAT (1 or 2)
   uint16_t m_rootDirEntryCount;       // Number of entries in FAT16 root dir.
   uint32_t m_allocSearchStart;        // Start cluster for alloc search.
   uint32_t m_sectorsPerFat;           // FAT size in sectors
@@ -240,7 +241,9 @@ class FatPartition {
 #if USE_SEPARATE_FAT_CACHE
   FsCache m_fatCache;
   uint8_t* fatCachePrepare(uint32_t sector, uint8_t options) {
-    options |= FsCache::CACHE_STATUS_MIRROR_FAT;
+    if ( m_fatCount == 2) {
+      options |= FsCache::CACHE_STATUS_MIRROR_FAT;
+    }
     return m_fatCache.prepare(sector, options);
   }
   bool cacheSync() {
@@ -248,7 +251,9 @@ class FatPartition {
   }
 #else  // USE_SEPARATE_FAT_CACHE
   uint8_t* fatCachePrepare(uint32_t sector, uint8_t options) {
-    options |= FsCache::CACHE_STATUS_MIRROR_FAT;
+    if ( m_fatCount == 2) {
+      options |= FsCache::CACHE_STATUS_MIRROR_FAT;
+    }
     return dataCachePrepare(sector, options);
   }
   bool cacheSync() {