Exemplo n.º 1
0
/* ****************************************************************************  
 * euint32 file_fread(File *file,euint32 offset, euint32 size,euint8 *buf)
 * Description: This function reads 'size' bytes from 'file' starting at
 * 'offset' and puts the result in '*buf'.
 * Return value: amount of bytes actually read (can differ from the given
 * size when the file was smaller
*/
euint32 file_fread(File *file,euint32 offset, euint32 size,euint8 *buf)
{
    //OSTaskSuspend(1);
    
	euint32 bytes_read=0,size_left=size,coffset=offset;
	euint32 cclus,csec,cbyte;
	euint32 rclus,rsec;
	euint32 btr;
	euint8 *tbuf;
    
	if(!file_getAttr(file,FILE_STATUS_OPEN))return(0);
	
	if(offset>=file->FileSize)
		size_left=0; /* Offset check */
	
	if( (offset+size > file->FileSize) && size_left!=0)
		size_left=file->FileSize-offset;
	
	while(size_left>0){
        //printf("size_left = %d\n", size_left);
	
		cclus = coffset/(512*file->fs->volumeId.SectorsPerCluster);
		csec = (coffset/(512))%file->fs->volumeId.SectorsPerCluster;
		cbyte = coffset%512;
		
		if(cbyte!=0 || size_left<512){
			btr = 512-(coffset%512)>=size_left?size_left:512-(coffset%512);
		}else{
			btr = 512;
		}

		if((fat_LogicToDiscCluster(file->fs,&(file->Cache),cclus))!=0){
			return(0);
		}
		rclus=file->Cache.DiscCluster;
		rsec=fs_clusterToSector(file->fs,rclus);
		
		
		if(btr==512){
			/*part_readBuf(file->fs->part,rsec+csec,buf+bytes_read);*/
			part_directSectorRead(file->fs->part,rsec+csec,buf+bytes_read);
		}else{
			/*part_readBuf(file->fs->part,rsec+csec,tbuf);*/
			tbuf = part_getSect(file->fs->part,rsec+csec,IOM_MODE_READONLY);
			memCpy(tbuf+(coffset%512),buf+bytes_read,btr);
			part_relSect(file->fs->part,tbuf);
		}
		
		coffset+=btr;
		bytes_read+=btr;
		size_left-=btr;
	}
    
    //OSTaskResume(1);
	return(bytes_read);
}
Exemplo n.º 2
0
/* ****************************************************************************  
 * unsigned long file_fread(File *file,unsigned long offset, unsigned long size,unsigned char *buf)
 * Description: This function reads 'size' bytes from 'file' starting at
 * 'offset' and puts the result in '*buf'.
 * Return value: amount of bytes actually read (can differ from the given
 * size when the file was smaller
*/
unsigned long file_fread(File *file,unsigned long offset, unsigned long size,unsigned char *buf)
{
	unsigned long bytes_read=0,size_left=size,coffset=offset;
	unsigned long cclus,csec,cbyte;
	unsigned long rclus,rsec;
	unsigned long btr;
	unsigned char *tbuf;
		
	if(!file_getAttr(file,FILE_STATUS_OPEN))return(0);
	
	if(offset>=file->FileSize)
		size_left=0; /* Offset check */
	
	if( (offset+size > file->FileSize) && size_left!=0)
		size_left=file->FileSize-offset;
	
	while(size_left>0){
	
		cclus = coffset/(512*file->fs->volumeId.SectorsPerCluster);
		csec = (coffset/(512))%file->fs->volumeId.SectorsPerCluster;
		cbyte = coffset%512;
		
		if(cbyte!=0 || size_left<512){
			btr = 512-(coffset%512)>=size_left?size_left:512-(coffset%512);
		}else{
			btr = 512;
		}

		if((fat_LogicToDiscCluster(file->fs,&(file->Cache),cclus))!=0){
			return(0);
		}
		rclus=file->Cache.DiscCluster;
		rsec=fs_clusterToSector(file->fs,rclus);
		
		
		if(btr==512){
			/*part_readBuf(file->fs->part,rsec+csec,buf+bytes_read);*/
			part_directSectorRead(file->fs->part,rsec+csec,buf+bytes_read);
		}else{
			/*part_readBuf(file->fs->part,rsec+csec,tbuf);*/
			tbuf = part_getSect(file->fs->part,rsec+csec,IOM_MODE_READONLY);
			memCpy(tbuf+(coffset%512),buf+bytes_read,btr);
			part_relSect(file->fs->part,tbuf);
		}
		
		coffset+=btr;
		bytes_read+=btr;
		size_left-=btr;
	}
		
	return(bytes_read);
}