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GLAST/LAT > DAQ and FSW > FSW > Doxygen Index > FILE / V3-8-1

Constituent: file_hdr     Tag: mv2304

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FILE_hdr.h File Reference

File object header library. More...

#include "FILE/FILE_hdr_msg.h"

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Defines
#define	FILE_HDR_NAME_SIZE   8
Typedefs
typedef enum _FILE_Hdr_Version	FILE_Hdr_Version
typedef enum _FILE_Hdr_Compression_Flag	FILE_Hdr_Compression_Flag
Enumerations
enum	_FILE_Hdr_Version {   FILE_HDR_VERSION_1 = 0x2000,   FILE_HDR_VERSION_2 = 0x4000 }
enum	_FILE_Hdr_Compression_Flag {   FILE_HDR_UNCOMPRESSED = 0x0000,   FILE_HDR_COMPRESSED = 0x1000 }
Functions
unsigned int	FILE_hdrSizeof (void)
	Get the size of a file header.
unsigned int	FILE_hdrCreate (void *buf, unsigned int length, unsigned int time, unsigned int chksum, unsigned short type, unsigned int key, FILE_Hdr_Compression_Flag compress, const char *name)
	Create a new file header.
unsigned int	FILE_hdrGetLength (const void *buf, unsigned int *length)
	Get the file data size.
unsigned int	FILE_hdrGetChksum (const void *buf, unsigned int *chksum)
	Get the file checksum.
unsigned int	FILE_hdrGetTime (const void *buf, unsigned int *time)
	Get the file timestamp.
unsigned int	FILE_hdrGetType (const void *buf, unsigned short *type)
	Get the file type.
unsigned int	FILE_hdrGetKey (const void *buf, unsigned int *key)
	Get the file key.
unsigned int	FILE_hdrGetCompression (const void *buf, unsigned short *compress)
	Get the file compression flag.
unsigned int	FILE_hdrGetName (const void *buf, char *name)
	Get the file name string.
unsigned int	FILE_hdrVerify (const void *buf)
	Verify the integrety of a file header.

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Detailed Description

File object header library.

Author:

D.L. Wood

The functions in this library manuipulate the members of a standard LAT file object header. All of the functions work on a memory buffer; users are responsible for reading in the header from a file before queries and for writing the header to a file after modifications.

There is a function FILE_hdrCreate(), which will create a new file header in user memory from scratch. All header member values must be specified. For each of the header members, the functions FILE_hdrGetXXX() will selectively retrive values from an existing file header in user memory.

The LAT file headers contain two checksums: one for the header contents and one for the file data contents. It is up to the user to calculate and verify the checksums for the actual file data. The library functions simply treat the file data checksum as an opaque value. The library functions, however, will calculate and verify the header checksum value when appropriate. The header checksum is not exposed by any functions in this library. It is calculated using the ZLIB adler32() function. The value is set in FILE_hdrCreate() and verified in FILE_hdrVerify().

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Define Documentation

#define FILE_HDR_NAME_SIZE   8

The size in bytes of the file name contained in a file header.

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Typedef Documentation

FILE_Hdr_Compression_Flag

The typedef for _FILE_Hdr_Compression_Flag.

FILE_Hdr_Version

The typedef for _FILE_Hdr_Version.

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Enumeration Type Documentation

enum _FILE_Hdr_Compression_Flag

The file header compression flag values. Enumerator: FILE_HDR_UNCOMPRESSED  File data is not ZLIB compressed. FILE_HDR_COMPRESSED  File data is ZLIB compressed.

enum _FILE_Hdr_Version

The file header version values. Tracks the binary external format changes. Enumerator: FILE_HDR_VERSION_1  Original format. Obsolete FILE_HDR_VERSION_2  Current format.

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Function Documentation

unsigned int FILE_hdrCreate (  void *  buf, unsigned int  length, unsigned int  time, unsigned int  chksum, unsigned short  type, unsigned int  key, FILE_Hdr_Compression_Flag  compress, const char *  name )

Create a new file header. Creates a file header in the buffer specified by buf. The user is resposible for actually writing the new header into file storage. This library only supports buffers whose total size is aligned on a 16-bit boundary. The function will fail with error #FILE_EHDRPARM if the length parameter is not correctly aligned. Parameters: buf  A pointer to the file header buffer. length  The size in bytes of file data to follow the file header. time  The file timestamp, in seconds. chksum  The checksum of the remainder of the file header and file data. type  The file type code. key  The file key value. compress  #FILE_HDR_UNCOMPRESSED - The file data following the header is uncompressed. #FILE_HDR_COMPRESSED The file data following the header is compressed. name  The ASCII file name. This parameter should point to a buffer containing #FILE_HDR_NAME_SIZE characters. Returns: A FHDR MSG value.

unsigned int FILE_hdrGetChksum (  const void *  buf, unsigned int *  chksum )

Get the file checksum. Returns the checksum of the remainder of the file header and file data. Parameters: buf  A pointer to the start of the file header buffer. chksum  Stores the checksum value. Returns: A FILE MSG value.

unsigned int FILE_hdrGetCompression (  const void *  buf, unsigned short *  compress )

Get the file compression flag. Returns the file compression flag value. Parameters: buf  A pointer to the start of the file header buffer. compress  Stores the compression flag value. Returns: A FILE MSG value.

unsigned int FILE_hdrGetKey (  const void *  buf, unsigned int *  key )

Get the file key. Returns the file key value. Parameters: buf  A pointer to the start of the file header buffer. key  Stores the key value. Returns: A FILE MSG value.

unsigned int FILE_hdrGetLength (  const void *  buf, unsigned int *  length )

Get the file data size. Returns the size in bytes of file data following the file header. Parameters: buf  A pointer to the start of the file header buffer. length  Stores the length value. Returns: A FILE MSG value.

unsigned int FILE_hdrGetName (  const void *  buf, char *  name )

Get the file name string. Returns the file name string. The ASCII characters are copied to the user buffer indicated by name. The string is not NULL terminated after return. Parameters: buf  A pointer to the start of the file header buffer. name  Stores the name string. Should be at least FILE_HDR_NAME_SIZE bytes in size. Returns: A FILE MSG value.

unsigned int FILE_hdrGetTime (  const void *  buf, unsigned int *  time )

Get the file timestamp. Returns the file timestamp. Parameters: buf  A pointer to the start of the file header buffer. time  Stores the timestamp value. Returns: A FILE MSG value.

unsigned int FILE_hdrGetType (  const void *  buf, unsigned short *  type )

Get the file type. Returns the file type code. Parameters: buf  A pointer to the start of the file header buffer. type  Stores the type value. Returns: A FILE MSG value.

unsigned int FILE_hdrSizeof (  void   )

Get the size of a file header. Returns the size in bytes of a LAT file header. Returns: The header size.

unsigned int FILE_hdrVerify (  const void *  buf  )

Verify the integrety of a file header. Verifies the format of a file header in buf. Calculates header checksum and compares it to value stored in header. Parameters: buf  A pointer to the start of the file header buffer. Returns: A FILE MSG value.

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