Added open/close/read. read() only works on whole sectors right now.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@498 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 170 insertions, 0 deletions

diff --git a/firmware/common/file.c b/firmware/common/file.c
new file mode 100644
index 0000000000..86e1099918
--- /dev/null
+++ b/firmware/common/file.c
@@ -0,0 +1,170 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   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:
+ */