KR100390486B1 - File name recording method for digital data player - Google Patents

Abstract

The present invention relates to a technique for setting the first byte containing information of a file in a root directory to a specific value in order to notify that an arbitrary file has been erased in the apparatus for reproducing digital data to which the MS-DOS operating system is applied. In the present invention, a value that satisfies both the condition that it is not used for the first name of the file and the condition that the value of the first byte is not a value of 01 to 20 to solve all problems caused by using 0xE5 or 0x05 as a specific value. Set to use.

Description

FILE NAME RECORDING METHOD FOR DIGITAL DATA PLAYER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for storing the name of a file system used in a digital data reproducing apparatus. In particular, the present invention relates to a root directory of a reproducing apparatus in which a specific operating system (e.g., MS-DOS) file system is widely used, such as an MP3 player. The present invention relates to a method of storing a file name of a digital data reproducing apparatus that properly sets a character indicating that file information is deleted so that MS-DOS format information can be read correctly without causing problems in Windows and Macintosh operating systems.

Recently, portable devices (eg, MP3 players) capable of playing MP3 files are widely used, and various types of storage devices are used for such portable devices. These storage devices require a file system for storing / managing data. In general, MS-DOS compatible file systems are widely used.

Typically, file names have the format "8.3" for MS-DOS. That is, the file name is set to 8 characters before the punctuation mark and 3 characters after the punctuation mark. However, this "8.3" format has been insufficient to adequately cope with the increase in the capacity of the hard disk and satisfy the desire of users who want to store more files in one directory.

To solve this problem, 32 bytes were used to store a single file information by introducing a relatively long name format. To support such long names, the file information storage space is increased by 32 bytes. However, long names are limited to 256 characters. If you delete a file in MS-DOS before allowing a long name, instead of clearing the contents of the actual file, you replace the first byte with file information with 0xE5 (hex E5) in the root directory where the file's information is written. .

Occasionally, you can recover a file after erasing it, because you can find out where the file is actually written by looking for an area that has changed to 0xE5 in the root directory that contains the file information.

When 0xE5 is used to indicate that the file information is deleted, a problem occurs that the file is recognized as deleted if the initial value of the actual file name is 0xE5. To solve this problem, if the initial value of the actual file name is 0xE5, 0x05 is stored and 0x05 is recognized as 0xE5 when reading the root directory information.

The 0x05 value had no problem in use before the long name value was used, but the 0x05 value is not appropriate.

That is, in the case of MS-DOS, when the file information is deleted, 0xE5 is written in the first byte indicating the file information of the root directory, indicating that the file is deleted. Then, when necessary, it searches for an entry whose first byte is 0xE5 value, recognizes that the information on this file is erased, and cleans up the root directory information. At this time, since the value "0xE5" is used, if the first character of the file name is 0xE5, it is recognized that the information on the file is deleted. For reference, in the case of Hangul, characters having a value of 0xE5 include "W" (女) and "Z" (子) characters.

To solve this problem, MS-DOS recognizes that when the initial value of the file name is 0xE5, it is changed to 0x05 and stored, and then changed to 0xE5 when reading from the root directory. However, in the case of using 0x05 in this way, when supporting long names, it may collide with the first byte indicating the number of entries.

As described above, in the file name storage method of the conventional digital data reproducing apparatus, when 0xE5 is used to indicate that the file information has been deleted, a problem occurs that the file is recognized as an erased file if the initial value of the actual file name is 0xE5. It became. To prevent this, if the initial value of the actual file name is 0xE5, 0x05 is recognized as 0xE5 when the root directory information is read, and when the long name is supported, the new byte that conflicts with the first byte indicating the number of entries is supported. A problem has occurred.

Accordingly, an object of the present invention is to provide a digital data player suitable for accurately reading MS-DOS format information without causing problems in Windows and Macintosh operating systems when storing file system names used in digital data player such as MP3 players. Provides a way to save file names.

1 is a format diagram of logical volume and directory information of MS-DOS.

2 is a data format diagram for supporting long names in MS-DOS.

3 is a signal flow diagram for a process for storing a long name of a file in the present invention.

*** Description of the symbols for the main parts of the drawings ***

1: logical volume

In the method of storing a file name of a digital data reproducing apparatus according to the present invention, in a storage device of a portable device for reproducing digital data, a first value containing information of a corresponding file in a root directory is specified to indicate that an arbitrary file has been deleted. In the first step of selecting a value that is not used in the first name of the file in any case; The first byte is a second process of selecting a value other than the value of 01 to 20, and will be described in detail with reference to FIGS. 1 to 3 attached to the operation of the present invention.

The first condition of the character that replaces 0xE5 must be a value that is never used in the first name of the file, because if it is a character that can be used in the first name of the file, it replaces 0xE5 (hex E5) or the original character. It is indistinguishable. The second condition is that you cannot use values from 01 to 20 for the first byte used to represent long names. The character that satisfies the above two conditions is a colon (:), and the ASCII code value is 58 in decimal and 3A in hexadecimal.

If a character with 0xE5 value is stored, instead of 0xE5 value, 0x3A is stored. If 0x3A is read from the first byte of the root directory entry, it is recognized as 0xE5. In addition, there is no risk of confusion with 0xE5, which indicates deleted files.

The logical volume 1 of MS-DOS is composed of a boot sector, a file allocation table, a copy of the file allocation table, root directory information, and the actual contents of a file as in the left part of FIG. However, when looking at the contents of the root directory information in more detail, as shown in the right part of FIG. 1, a file name, an extension name, a file attribute, a spare area, a time at which the file is created or modified, a date at which the file is created, or a modified date , The starting cluster, and the file size information. In this case, it can be seen that 32 bytes are required to represent one file information.

Looking at the portion of the root directory information indicating the name of the file, it can be seen that 8 bytes are allocated to indicate the file name, and 3 bytes are allocated to indicate the extension name. In the case of the English alphabet, one byte is allocated for one letter of the alphabet, so only a file name of "8.3" format can be stored. In contrast, Hangul allocates 2 bytes for one character, so the length of the file name becomes smaller. Thus, more space is needed to store longer file names.

A data format format for indicating a relatively long name is described with reference to FIG.

First, if the file name is determined to be a long name or a short name and is identified as a long name, more area is used to store one file information. Record the long name at the beginning of the file information. In order to support long names, MS-DOS has a format as shown in FIG. 2.

That is, 32 bytes are used to store one file. If the long name is used, an additional area of 32 bytes is used. In the case of storing a long name in the format as shown in FIG. 2, a thirteen character name can be stored in 32 bytes. If the file name is 15 characters long, two 32 bytes are required. In FIG. 2, the number of entries is recorded in the first byte, and the number of entries means the number of 32 bytes additionally required to record the long name.

Windows allows up to 256 file names, which requires 20 entries. Because 13 characters can be recorded in one entry, when writing 256 characters, 20 entries are required. In this case, the numbers 1 through 20 are recorded in the first byte representing the number of entries.

In this case, however, data conflicting with data in MS-DOS format is generated. That is, as mentioned in the related art, MS-DOS recognizes that when the initial value of the file name is 0xE5, it is changed to 0x05 and stored, and then it is recognized as 0xE5 when read from the root directory. When you support long names, you might collide with the first byte that represents the number of entries.

Meanwhile, referring to FIG. 3, a process for storing a long name of a file is described as follows.

First, if the length of the file name is divided by 13 and there is no remaining value, the number of entries is the quotient of the file name length divided by 13, and if there are remaining values, the number of entries is the quotient of the file name divided by 13 This is 1 plus (S1-S5).

The above process is repeated as many as the number of entries, and the file name is assigned in accordance with the format of FIG. 2.

If it is determined that the current entry (i) is not the preset number of entries, it indicates the number of entries and records the first five letters of the file name. 2 bytes are allocated per character (S6, S7).

However, if the current entry is found to be a preset number of entries, the value of "0x40 ?? entries" is input as it is. The reason for miscalculating 0x40 is to indicate that the file information from now on is a long name. (S8)

Subsequently, the attributes of the file are recorded. In this case, 0x0F is always recorded to indicate the long name (S9).

Thereafter, 0x00 is recorded as the spare area, and checksum information is recorded to determine whether the character information is correct (S10, S11).

Subsequently, the next six letters of the file name are recorded, followed by cluster information containing the actual file contents, where the long name information is always filled with 0x00 (S12, S13).

Recording the next two letters of the file name ends the file name storing process (S14).

On the other hand, the two skip conditions of the character to substitute for the 0xE5, that is, first, the value must never be used for the first name of the file, second, the value of 01 to 20 as the value of the first byte used to represent the long name Looking at characters that are not suitable for Windows OS file names as candidates for all of the characters that can't be met, ??, /,:, *,?, ”, <,>, ?? There are a total of nine characters. On Mac OSs other than the Windows OS, the invalid character for the file name is a colon (:). The ASCII code value of the colon is 58 in decimal and 3A in hexadecimal. Thus, 58 does not fall between 01 and 20.

In conclusion, the character that can support long names in place of the 0xE5 file name in MS-DOS is a colon (:). If the file is named "F", instead of 0x05 instead of 0xE5, use 0x3A to solve the problem of 0x05, which indicates that the file has been erased, and the 0x05 used if the long name is supported. Will be.

As described in detail above, the present invention causes problems in Windows and Macintosh OS by using 0x3A value instead of using 0xE5 or 0x05 to indicate that file information is erased in all storage devices using the MS-DOS file format. The effect is that the MS-DOS format information can be read correctly without doing so.

Claims (4)

A method of setting the first byte of a file's information in the root directory to a specific value to indicate that an arbitrary file has been erased from a digital data playback device with the MS-DOS operating system. And setting the value of the first byte to a value other than the value of 01 to 20. The method of claim 1, wherein the value satisfying both conditions is a value corresponding to a colon (:). The method of claim 1, wherein the value satisfying both conditions is 3A in hexadecimal. The method of claim 1, wherein the file has a file information storage space of a multiple of 32 bytes.