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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Björn Stenberg
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <string.h>
#include "file.h"
#include "fat.h"
#include "types.h"
#include "dir.h"
#include "debug.h"
#define MAX_OPEN_FILES 4
struct filedesc {
unsigned char sector[SECTOR_SIZE];
int offset;
struct fat_file fatfile;
bool busy;
};
static struct filedesc openfiles[MAX_OPEN_FILES];
int open(char* pathname, int flags)
{
DIR* dir;
struct dirent* entry;
int fd;
char* name;
int namelen;
if ( pathname[0] != '/' ) {
DEBUGF("'%s' is not an absolute path.\n",pathname);
DEBUGF("Only absolute pathnames supported at the moment\n");
return -1;
}
/* find a free file descriptor */
for ( fd=0; fd<MAX_OPEN_FILES; fd++ )
if ( !openfiles[fd].busy )
break;
if ( fd == MAX_OPEN_FILES ) {
DEBUGF("Too many files open\n");
return -1;
}
/* locate filename */
name=strrchr(pathname+1,'/');
if ( name ) {
*name = 0;
dir = opendir(pathname);
*name = '/';
name++;
}
else {
dir = opendir("/");
name = pathname+1;
}
if (!dir) {
DEBUGF("Failed opening dir\n");
return -1;
}
/* scan dir for name */
namelen = strlen(name);
while ((entry = readdir(dir))) {
if ( !strncmp(name, entry->d_name, namelen) ) {
fat_open(entry->startcluster, &(openfiles[fd].fatfile));
break;
}
else {
DEBUGF("entry: %s\n",entry->d_name);
}
}
closedir(dir);
if ( !entry ) {
DEBUGF("Couldn't find %s in %s\n",name,pathname);
/* fixme: we need to use proper error codes */
return -1;
}
openfiles[fd].offset = 0;
openfiles[fd].busy = TRUE;
return fd;
}
int close(int fd)
{
openfiles[fd].busy = FALSE;
return 0;
}
int read(int fd, void* buf, int count)
{
int sectors;
int nread=0;
/* are we in the middle of a cached sector? */
if ( openfiles[fd].offset ) {
if ( count > (SECTOR_SIZE - openfiles[fd].offset) ) {
memcpy( buf, openfiles[fd].sector,
SECTOR_SIZE - openfiles[fd].offset );
openfiles[fd].offset = 0;
nread = SECTOR_SIZE - openfiles[fd].offset;
count -= nread;
}
else {
memcpy( buf, openfiles[fd].sector, count );
openfiles[fd].offset += count;
nread = count;
count = 0;
}
}
/* read whole sectors right into the supplied buffer */
sectors = count / SECTOR_SIZE;
if ( sectors ) {
if ( fat_read(&(openfiles[fd].fatfile), sectors, buf+nread ) < 0 ) {
DEBUGF("Failed reading %d sectors\n",sectors);
return -1;
}
nread += sectors * SECTOR_SIZE;
count -= sectors * SECTOR_SIZE;
openfiles[fd].offset = 0;
}
/* trailing odd bytes? */
if ( count ) {
/* do we already have the sector cached? */
if ( count < (SECTOR_SIZE - openfiles[fd].offset) ) {
memcpy( buf + nread, openfiles[fd].sector, count );
openfiles[fd].offset += count;
nread += count;
count = 0;
}
else {
/* cache one sector and copy the trailing bytes */
if ( fat_read(&(openfiles[fd].fatfile), 1,
&(openfiles[fd].sector)) < 0 ) {
DEBUGF("Failed reading odd sector\n");
return -1;
}
memcpy( buf + nread, openfiles[fd].sector, count );
openfiles[fd].offset = nread;
nread += count;
}
}
return nread;
}
/*
* local variables:
* eval: (load-file "../rockbox-mode.el")
* end:
*/
|
