text: #ifndef SPIFFS_CONFIG_H_
  #define SPIFFS_CONFIG_H_
  
  #include "user_config.h"
  #include "c_stdio.h"
  #include "c_stdint.h"
  
  #include "user_interface.h"
  
  // #define SPIFFS_DBG c_printf
  // compile time switches
  
  // Set generic spiffs debug output call.
  #ifdef SPIFFS_DEBUG
  #define SPIFFS_DBG c_printf
  #else
  #define SPIFFS_DBG
  #endif
  
  // Set spiffs debug output call for garbage collecting.
  #ifndef SPIFFS_GC_DBG
  #define SPIFFS_GC_DBG
  #endif
  // #define SPIFFS_GC_DBG(...) c_printf( __VA_ARGS__ )
  
  // Set spiffs debug output call for caching.
  #ifndef SPIFFS_CACHE_DBG
  #define SPIFFS_CACHE_DBG
  #endif
  // #define SPIFFS_CACHE_DBG(...) c_printf( __VA_ARGS__ )
  
  // Set spiffs debug output call for system consistency checks.
  #ifndef SPIFFS_CHECK_DBG
  #define SPIFFS_CHECK_DBG
  #endif
  
  // Enable/disable API functions to determine exact number of bytes
  // for filedescriptor and cache buffers. Once decided for a configuration,
  // this can be disabled to reduce flash.
  #ifndef SPIFFS_BUFFER_HELP
  #define SPIFFS_BUFFER_HELP              0
  #endif
  
  // Enables/disable memory read caching of nucleus file system operations.
  // If enabled, memory area must be provided for cache in SPIFFS_mount.
  #ifndef  SPIFFS_CACHE
  #define SPIFFS_CACHE                    0
  #endif
  
  #ifndef  DYNFS_CACHE
  #define DYNFS_CACHE                    1
  #endif
  
  #if SPIFFS_CACHE
  // Enables memory write caching for file descriptors in hydrogen
  #ifndef  SPIFFS_CACHE_WR
  #define SPIFFS_CACHE_WR                 1
  #endif
  
  // Enable/disable statistics on caching. Debug/test purpose only.
  #ifndef  SPIFFS_CACHE_STATS
  #define SPIFFS_CACHE_STATS              0
  #endif
  #else
  #ifndef  SPIFFS_CACHE_WR
  #define SPIFFS_CACHE_WR                 0
  #endif
  #endif
  
  // Always check header of each accessed page to ensure consistent state.
  // If enabled it will increase number of reads, will increase flash.
  #ifndef SPIFFS_PAGE_CHECK
  #define SPIFFS_PAGE_CHECK               1
  #endif
  
  // Define maximum number of gc runs to perform to reach desired free pages.
  #ifndef SPIFFS_GC_MAX_RUNS
  #define SPIFFS_GC_MAX_RUNS              5
  #endif
  
  // Enable/disable statistics on gc. Debug/test purpose only.
  #ifndef SPIFFS_GC_STATS
  #define SPIFFS_GC_STATS                 0
  #endif
  
  // Garbage collecting examines all pages in a block which and sums up
  // to a block score. Deleted pages normally gives positive score and
  // used pages normally gives a negative score (as these must be moved).
  // To have a fair wear-leveling, the erase age is also included in score,
  // whose factor normally is the most positive.
  // The larger the score, the more likely it is that the block will
  // picked for garbage collection.
  
  // Garbage collecting heuristics - weight used for deleted pages.
  #ifndef SPIFFS_GC_HEUR_W_DELET
  #define SPIFFS_GC_HEUR_W_DELET          (5)
  #endif
  // Garbage collecting heuristics - weight used for used pages.
  #ifndef SPIFFS_GC_HEUR_W_USED
  #define SPIFFS_GC_HEUR_W_USED           (-1)
  #endif
  // Garbage collecting heuristics - weight used for time between
  // last erased and erase of this block.
  #ifndef SPIFFS_GC_HEUR_W_ERASE_AGE
  #define SPIFFS_GC_HEUR_W_ERASE_AGE      (50)
  #endif
  
  // Object name maximum length
  #ifndef SPIFFS_OBJ_NAME_LEN
  #define SPIFFS_OBJ_NAME_LEN             (32)
  #endif
  
  // Size of buffer allocated on stack used when copying data.
  // Lower value generates more read/writes. No meaning having it bigger
  // than logical page size.
  #ifndef SPIFFS_COPY_BUFFER_STACK
  #define SPIFFS_COPY_BUFFER_STACK        (256)
  #endif
  
  // Enable this to have an identifiable spiffs filesystem. This will look for
  // a magic in all sectors to determine if this is a valid spiffs system or
  // not on mount point. If not, SPIFFS_format must be called prior to mounting
  // again.
  #ifndef SPIFFS_USE_MAGIC
  #define SPIFFS_USE_MAGIC                (0)
  #endif
  
  #if SPIFFS_USE_MAGIC
  // Only valid when SPIFFS_USE_MAGIC is enabled. If SPIFFS_USE_MAGIC_LENGTH is
  // enabled, the magic will also be dependent on the length of the filesystem.
  // For example, a filesystem configured and formatted for 4 megabytes will not
  // be accepted for mounting with a configuration defining the filesystem as 2
  // megabytes.
  #ifndef SPIFFS_USE_MAGIC_LENGTH
  #define SPIFFS_USE_MAGIC_LENGTH         (0)
  #endif
  #endif
  
  // SPIFFS_LOCK and SPIFFS_UNLOCK protects spiffs from reentrancy on api level
  // These should be defined on a multithreaded system
  
  // define this to enter a mutex if you're running on a multithreaded system
  #ifndef SPIFFS_LOCK
  #define SPIFFS_LOCK(fs)
  #endif
  // define this to exit a mutex if you're running on a multithreaded system
  #ifndef SPIFFS_UNLOCK
  #define SPIFFS_UNLOCK(fs)
  #endif
  
  
  // Enable if only one spiffs instance with constant configuration will exist
  // on the target. This will reduce calculations, flash and memory accesses.
  // Parts of configuration must be defined below instead of at time of mount.
  #ifndef SPIFFS_SINGLETON
  #define SPIFFS_SINGLETON                  0
  #endif
  
  /* Singleton Config */
  #if SPIFFS_SINGLETON
  #ifndef SPIFFS_CFG_PHYS_SZ
  #define SPIFFS_CFG_PHYS_SZ(ignore)        (512*1024)
  #endif
  #ifndef SPIFFS_CFG_PHYS_ERASE_SZ
  #define SPIFFS_CFG_PHYS_ERASE_SZ(ignore)  (4*1024) //(4096)
  #endif
  #ifndef SPIFFS_CFG_PHYS_ADDR
  #define SPIFFS_CFG_PHYS_ADDR(ignore)      0x58000
  #endif
  #ifndef SPIFFS_CFG_LOG_PAGE_SZ
  #define SPIFFS_CFG_LOG_PAGE_SZ(ignore)    (256)
  #endif
  #ifndef SPIFFS_CFG_LOG_BLOCK_SZ
  #define SPIFFS_CFG_LOG_BLOCK_SZ(ignore)   (64*1024)
  #endif
  
  /* NOT Singleton */
  #else
  
  #ifndef MY_SPIFFS_ERASE_BLK_SZ
  #define MY_SPIFFS_ERASE_BLK_SZ            (4*1024)
  #endif
  #ifndef MY_SPIFFS_LOG_BLK_SZ
  #define MY_SPIFFS_LOG_BLK_SZ              (8*1024)
  #endif
  #ifndef MY_SPIFFS_PHYS_SZ
  #define MY_SPIFFS_PHYS_SZ                 0x10000
  #endif
  #ifndef MY_SPIFFS_FIXED_LOCATION
  #define MY_SPIFFS_FIXED_LOCATION          SPIFFS_ADDR
  #define SPIFFS_FIXED_LOCATION             MY_SPIFFS_FIXED_LOCATION
  #endif
  
  #ifndef DYNFS_ERASE_BLK_SZ
  #define DYNFS_ERASE_BLK_SZ                (32*1024)
  #endif
  #ifndef DYNFS_LOG_BLK_SZ
  #define DYNFS_LOG_BLK_SZ                  (64*1024)
  #endif
  #ifndef DYNFS_PHYS_SZ
  #define DYNFS_PHYS_SZ                     0x14C000 //(1328 x 1024)
  // #define DYNFS_PHYS_SZ                     0x148000
  #endif
  #ifndef DYNFS_FIXED_LOCATION
  #define DYNFS_FIXED_LOCATION              0x90000 //SPIFFS_ADDR
  #define DYNFS_LOCATION                    DYNFS_FIXED_LOCATION
  #endif
  
  #endif /* end singleton ifdef */
  
  
  
  
  // Enable this if your target needs aligned data for index tables
  #ifndef SPIFFS_ALIGNED_OBJECT_INDEX_TABLES
  #define SPIFFS_ALIGNED_OBJECT_INDEX_TABLES      1
  #endif
  
  // Enable this if you want the HAL callbacks to be called with the spiffs struct
  #ifndef SPIFFS_HAL_CALLBACK_EXTRA
  #define SPIFFS_HAL_CALLBACK_EXTRA               0
  #endif
  
  // Enable this if you want to add an integer offset to all file handles
  // (spiffs_file). This is useful if running multiple instances of spiffs on
  // same target, in order to recognise to what spiffs instance a file handle
  // belongs.
  // NB: This adds config field fh_ix_offset in the configuration struct when
  // mounting, which must be defined.
  #ifndef SPIFFS_FILEHDL_OFFSET
  #define SPIFFS_FILEHDL_OFFSET                 0
  #endif
  
  #ifndef SPIFFS_READ_ONLY
  #define SPIFFS_READ_ONLY                      0
  #endif
  
  // Set SPIFFS_TEST_VISUALISATION to non-zero to enable SPIFFS_vis function
  // in the api. This function will visualize all filesystem using given printf
  // function.
  #ifndef SPIFFS_TEST_VISUALISATION
  #define SPIFFS_TEST_VISUALISATION         0
  #endif
  #if SPIFFS_TEST_VISUALISATION
  #ifndef spiffs_printf
  #define spiffs_printf(...)                c_printf(__VA_ARGS__)
  #endif
  // spiffs_printf argument for a free page
  #ifndef SPIFFS_TEST_VIS_FREE_STR
  #define SPIFFS_TEST_VIS_FREE_STR          "_"
  #endif
  // spiffs_printf argument for a deleted page
  #ifndef SPIFFS_TEST_VIS_DELE_STR
  #define SPIFFS_TEST_VIS_DELE_STR          "/"
  #endif
  // spiffs_printf argument for an index page for given object id
  #ifndef SPIFFS_TEST_VIS_INDX_STR
  #define SPIFFS_TEST_VIS_INDX_STR(id)      "i"
  #endif
  // spiffs_printf argument for a data page for given object id
  #ifndef SPIFFS_TEST_VIS_DATA_STR
  #define SPIFFS_TEST_VIS_DATA_STR(id)      "d"
  #endif
  #endif
  
  // Types depending on configuration such as the amount of flash bytes
  // given to spiffs file system in total (spiffs_file_system_size),
  // the logical block size (log_block_size), and the logical page size
  // (log_page_size)
  
  // Block index type. Make sure the size of this type can hold
  // the highest number of all blocks - i.e. spiffs_file_system_size / log_block_size
  typedef u16_t spiffs_block_ix;
  // Page index type. Make sure the size of this type can hold
  // the highest page number of all pages - i.e. spiffs_file_system_size / log_page_size
  typedef u16_t spiffs_page_ix;
  // Object id type - most significant bit is reserved for index flag. Make sure the
  // size of this type can hold the highest object id on a full system,
  // i.e. 2 + (spiffs_file_system_size / (2*log_page_size))*2
  typedef u16_t spiffs_obj_id;
  // Object span index type. Make sure the size of this type can
  // hold the largest possible span index on the system -
  // i.e. (spiffs_file_system_size / log_page_size) - 1
  typedef u16_t spiffs_span_ix;
  
  #endif /* SPIFFS_CONFIG_H_ */
  