//*************************************************************************
// Function: CETYPE FS_Flush(FSFILE* filePtr)
// Summary: Update file information and FAT entry for the file
// Input:
// filePtr - Pointer to the file to flush to disk
// Return Values:
// CE_GOOD - File flushed successfully
// Other code - Error closing the file
// Description:
// This function will update the directory entry for the
// file pointed to by 'fo' with the information contained
// in 'fo,' including the new file size and attributes.
// Timestamp information will also be updated. The file
// entry will then be written to the device. Finally,
// the memory used for the specified file object will be
// freed from the array of FSFILE objects.
// Remarks:
// A function to flush data to the device without closing
// the file can be created by removing the portion of this
// function that frees the memory and the line that clears
// the write flag.
//*************************************************************************
CETYPE FS_Flush(FSFILE *filePtr)
{
//----------------------------------------------------------------
// Validate conditions and parameters
//----------------------------------------------------------------
if (!SDFS_InitStatus)
return CE_NOT_INIT; // FS is not initialized!
if (NULL == filePtr)
return CE_INVALID_ARGUMENT;
//----------------------------------------------------------------
CETYPE RC;
//----------------------------------------------------------------
if ( !FS_IsReadOnly(filePtr) )
{
// Save directory entry for the file
RC = SDFS_DataCacheWrite( filePtr->dirLBA, &filePtr->dirFileEntry,
filePtr->dirOffset, sizeof(DIRENTRY) );
if (CE_GOOD != RC)
return RC;
// Flush data
if ( (RC = SDFS_DataCacheFlush()) != CE_GOOD)
return RC;
}
//----------------------------------------------------------------
return CE_GOOD;
}
//*********************************************************************************
// Function: CETYPE FS_Write(FSFILE* filePtr, const void* origin, WORD length)
// Summary: Write data to a file
// Conditions: File opened in FS_CREATE_NEW, FS_APPEND, or FS_OPEN_EXISTING mode
// Input:
// filePtr - Pointer to file structure
// origin - Pointer to source buffer
// length - Length of the source buffer (data to write)
// Return:
// CETYPE - Error code (expected: CE_GOOD)
// Description:
// The FS_Write function will write data to a file. First, the sector
// that corresponds to the current position in the file will be loaded
// (if it hasn't already been cached in the global data buffer). Data
// will then be written to the device from the specified buffer until
// the specified amount has been written.
// If the end of a cluster is reached, the next cluster will be
// loaded, unless the end-of-file flag for the specified file has been
// set. If it has, a new cluster will be allocated to the file. Finally,
// the new position and filesize will be stored in the FSFILE object.
//*********************************************************************************
CETYPE FS_Write(FSFILE* filePtr, const void* origin, WORD length )
{
//----------------------------------------------------------------
// Validate conditions and parameters
//----------------------------------------------------------------
if (!SDFS_InitStatus)
return CE_NOT_INIT; // FS is not initialized!
if (NULL == filePtr)
return CE_INVALID_ARGUMENT;
//----------------------------------------------------------------
// Check if the file attributes allow write
if( (filePtr->dirFileEntry.DIR_Attr & ATTR_READONLY) == ATTR_READONLY )
return CE_READONLY;
// Check if pointer is valid
if (origin == NULL)
return CE_INVALID_ARGUMENT;
// Check if length is valid
if (length == 0)
return CE_INVALID_ARGUMENT;
//-----------------------------------------------------------------
DWORD LBA;
BYTE* ptrFrom = (BYTE*)origin;
WORD ChunkSize;
CETYPE RC;
// Write data to the file
//{
//------------------------------------------------------------
// Loop while writing bytes, exit loop if:
// * All bytes are written
// * Error encountered
//------------------------------------------------------------
while (length > 0)
{
//----------------------------------------------------
// Make sure we have defined a place to write to
//----------------------------------------------------
//{
if (filePtr->fileCrntSecPos == SDFS_VolumeInfo.sectorSize)
{
//----------------------------------------------------
// Current sector is filled in...
//----------------------------------------------------
// NOTE: fileCrntSec is a 0-based counter (index)
//----------------------------------------------------
if (filePtr->fileCrntSec == SDFS_VolumeInfo.SecPerClus - 1)
{
//----------------------------------------------------
// Current cluster is exhausted - move to the next one
//----------------------------------------------------
RC = SDFS_ClusterGetNext(filePtr);
if ( CE_EOF == RC )
// Oops! Reached end-of-file - try to add another cluster
RC = SDFS_ClusterAllocateNew(filePtr);
//----------------------------------------------------
if ( CE_GOOD != RC )
// Bad luck - no cluster to advance to!
return RC;
}
else
{
// It is safe to move to the next sector in the current cluster
filePtr->fileCrntSec++; // move to the next sector
filePtr->fileCrntSecPos = 0; // reset position
}
//----------------------------------------------------
}
//}
//-----------------------------------------------------------------
LBA = SDFS_FATClusterToLBA( filePtr->fileCrntCls)
+ filePtr->fileCrntSec; // add the sector number to it
ChunkSize = length <= SDFS_VolumeInfo.sectorSize - filePtr->fileCrntSecPos ?
length
: SDFS_VolumeInfo.sectorSize - filePtr->fileCrntSecPos;
//-----------------------------------------------------------------
if (CE_GOOD != (RC = SDFS_DataCacheWrite (LBA, ptrFrom, filePtr->fileCrntSecPos, ChunkSize )))
return RC;
//-----------------------------------------------------------------
length -= ChunkSize;
ptrFrom += ChunkSize;
//----------------------
filePtr->fileCrntSecPos += ChunkSize;
filePtr->fileSeek += ChunkSize;
if (filePtr->dirFileEntry.DIR_FileSize < filePtr->fileSeek)
filePtr->dirFileEntry.DIR_FileSize = filePtr->fileSeek;
}
//-----------------------------------
return CE_GOOD;
} // write
