Merged in paimonen/nuttx/pullreq_FAT_improvements (pull request #755)

Pullreq FAT improvements

* NuttX: Add CONFIG_FAT_LFN_ALIAS_HASH to speed up creating long filenames.

    Long filenames on FAT filesystems have associated 8.3 character alias
    short filenames. The traditional form of these is FILENA~1.EXT with
    a running count of the number of similar names. However creating this
    unique count can take several seconds if there are many similarly named
    files in the directory. Enabling FAT_LFN_ALIAS_HASH uses an alternative
    format of FI0123~1.TXT where the four digits are a hash of the original
    filename. This method is similar to what is used by Windows 2000 and
    later.

* NuttX: Add CONFIG_FAT_LFN_ALIAS_TRAILCHARS alternative format for 8.3 filenames.

    Traditional format for long filename 8.3 aliases takes first 6
    characters of long filename. If this option is set to N > 0,
    NuttX will instead take first 6-N and last N characters to form
    the short name. This is useful for filenames like "datafile12.txt"
    where the first characters would always remain the same.

* NuttX: FAT32: Fix file date corruption in fat_truncate().

* NuttX: if SD card wait seems to be a long one, give time for other threads to run.

Approved-by: GregoryN <gnutt@nuttx.org>

drivers/mmcsd/mmcsd_spi.c

@@ -50,6 +50,7 @@
 #include <time.h>
 #include <errno.h>
 #include <debug.h>
+#include <unistd.h>
 
 #include <nuttx/arch.h>
 #include <nuttx/clock.h>
@@ -441,6 +442,12 @@ static int mmcsd_waitready(FAR struct mmcsd_slot_s *slot)
         }
 
       elapsed = ELAPSED_TIME(start);
+
+      if (elapsed > MMCSD_DELAY_10MS)
+      {
+        // Give other threads time to run
+        usleep(10000);
+      }
     }
   while (elapsed < MMCSD_DELAY_500MS);
 

fs/fat/Kconfig

@@ -46,6 +46,31 @@ config FAT_MAXFNAME
 		This setting may not exceed NAME_MAX.  That will be verified at compile
 		time.  The minimum values is 12 due to assumptions in internal logic.
 
+config FAT_LFN_ALIAS_HASH
+    bool "Use faster method for forming long filename 8.3 alias"
+    depends on FAT_LFN
+    default n
+    ---help---
+       Long filenames on FAT filesystems have associated 8.3 character alias
+       short filenames. The traditional form of these is FILENA~1.EXT with
+       a running count of the number of similar names. However creating this
+       unique count can take several seconds if there are many similarly named
+       files in the directory. Enabling FAT_LFN_ALIAS_HASH uses an alternative
+       format of FI0123~1.TXT where the four digits are a hash of the original
+       filename. This method is similar to what is used by Windows 2000 and
+       later.
+
+config FAT_LFN_ALIAS_TRAILCHARS
+    int "Number of trailing characters to use for 8.3 alias"
+    depends on FAT_LFN
+    default 0
+    ---help---
+       Traditional format for long filename 8.3 aliases takes first 6
+       characters of long filename. If this option is set to N > 0,
+       NuttX will instead take first 6-N and last N characters to form
+       the short name. This is useful for filenames like "datafile12.txt"
+       where the first characters would always remain the same.
+
 config FS_FATTIME
 	bool "FAT timestamps"
 	default n

fs/fat/fs_fat32dirent.c

@@ -754,6 +754,17 @@ static inline int fat_createalias(struct fat_dirinfo_s *dirinfo)
               return OK;
             }
         }
+
+#if defined(CONFIG_FAT_LFN_ALIAS_TRAILCHARS) && CONFIG_FAT_LFN_ALIAS_TRAILCHARS > 0
+      /* Take first 6-N characters from beginning of filename and last N
+       * characters from end of the filename. Useful for filenames like
+       * "datafile123.txt". */
+      if (ndx == 6 - CONFIG_FAT_LFN_ALIAS_TRAILCHARS
+          && namechars > CONFIG_FAT_LFN_ALIAS_TRAILCHARS)
+        {
+          src += namechars - CONFIG_FAT_LFN_ALIAS_TRAILCHARS;
+        }
+#endif
     }
 }
 #endif
@@ -837,6 +848,33 @@ static inline int fat_uniquealias(struct fat_mountpt_s *fs,
   lsdigit = tilde + 1;
   DEBUGASSERT(dirinfo->fd_name[lsdigit] == '1');
 
+#ifdef CONFIG_FAT_LFN_ALIAS_HASH
+  /* Add a hash of the long filename to the short filename, to reduce collisions. */
+  if ((ret = fat_findalias(fs, dirinfo)) == OK)
+    {
+      uint16_t hash = dirinfo->fd_seq.ds_offset;
+      for (i = 0; dirinfo->fd_lfname[i] != '\0'; i++)
+        {
+          hash = ((hash << 5) + hash) ^ dirinfo->fd_lfname[i];
+        }
+
+      for (i = 0; i < tilde - 2; i++)
+        {
+          uint8_t nibble = (hash >> (i * 4)) & 0x0F;
+          const char *digits = "0123456789ABCDEF";
+          dirinfo->fd_name[tilde - 1 - i] = digits[nibble];
+        }
+    }
+  else if (ret == -ENOENT)
+    {
+      return OK; /* Alias was unique already */
+    }
+  else
+    {
+      return ret; /* Other error */
+    }
+#endif
+
   /* Search for the single short file name directory entry in this directory */
 
   while ((ret = fat_findalias(fs, dirinfo)) == OK)

fs/fat/fs_fat32util.c

@@ -1465,7 +1465,7 @@ int fat_dirtruncate(struct fat_mountpt_s *fs, FAR uint8_t *direntry)
 
   writetime = fat_systime2fattime();
   DIR_PUTWRTTIME(direntry, writetime & 0xffff);
-  DIR_PUTWRTDATE(direntry, writetime > 16);
+  DIR_PUTWRTDATE(direntry, writetime >> 16);
 
   /* This sector needs to be written back to disk eventually */
 
@@ -1526,7 +1526,7 @@ int fat_dirshrink(struct fat_mountpt_s *fs, FAR uint8_t *direntry,
 
   writetime = fat_systime2fattime();
   DIR_PUTWRTTIME(direntry, writetime & 0xffff);
-  DIR_PUTWRTDATE(direntry, writetime > 16);
+  DIR_PUTWRTDATE(direntry, writetime >> 16);
 
   /* This sector needs to be written back to disk eventually */