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authorLinus Nielsen Feltzing <linus@haxx.se>2004-07-23 14:54:04 +0000
committerLinus Nielsen Feltzing <linus@haxx.se>2004-07-23 14:54:04 +0000
commita17df38de7370cf73041a45a2847657719f3f4a4 (patch)
tree8c32860ca12b095fe481fe968549c0c0bc7564e0 /apps/plugins/sort.c
parent80c31c9ea0c4beb52e223141a1b2fb5e2e2e64b4 (diff)
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New viewer plugin, sorts a text (or playlist) file
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4924 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'apps/plugins/sort.c')
-rw-r--r--apps/plugins/sort.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/apps/plugins/sort.c b/apps/plugins/sort.c
new file mode 100644
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--- /dev/null
+++ b/apps/plugins/sort.c
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+/***************************************************************************
+ * __________ __ ___.
+ * Open \______ \ ____ ____ | | _\_ |__ _______ ___
+ * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
+ * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
+ * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
+ * \/ \/ \/ \/ \/
+ * $Id$
+ *
+ * Copyright (C) 2002 Linus Nielsen Feltzing
+ *
+ * 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 "plugin.h"
+
+/****************************************************************************
+ * Buffer handling:
+ *
+ * We allocate the MP3 buffer for storing the text to be sorted, and then
+ * search the buffer for newlines and store an array of character pointers
+ * to the strings.
+ *
+ * The pointer array grows from the top of the buffer and downwards:
+ *
+ * |-------------|
+ * | pointers[2] |--------|
+ * | pointers[1] |------| |
+ * | pointers[0] |----| | |
+ * |-------------| | | |
+ * | | | | |
+ * | | | | |
+ * | free space | | | |
+ * | | | | |
+ * | | | | |
+ * |-------------| | | |
+ * | | | | |
+ * | line 3\0 |<---| | |
+ * | line 2\0 |<-----| |
+ * | line 1\0 |<-------|
+ * |-------------|
+ *
+ * The advantage of this method is that we optimize the buffer usage.
+ *
+ * The disadvantage is that the string pointers will be loaded in reverse
+ * order. We therefore sort the strings in reverse order as well, so we
+ * don't have to sort an already sorted buffer.
+ ****************************************************************************/
+
+/***************************************************************************
+ * TODO: Implement a merge sort for files larger than the buffer
+ ****************************************************************************/
+
+static struct plugin_api* rb;
+
+int buf_size;
+static char *filename;
+static int num_entries;
+static char **pointers;
+static char *stringbuffer;
+static char crlf[2] = "\r\n";
+
+/* Compare function for sorting backwards */
+static int compare(const void* p1, const void* p2)
+{
+ char *s1 = *(char **)p1;
+ char *s2 = *(char **)p2;
+
+ return rb->strcmp(s2, s1);
+}
+
+static void sort_buffer(void)
+{
+ rb->qsort(pointers, num_entries, sizeof(char *), compare);
+}
+
+int read_buffer(int offset)
+{
+ int fd;
+ char *buf_ptr;
+ char *tmp_ptr;
+ int readsize;
+
+ fd = rb->open(filename, O_RDONLY);
+ if(fd < 0)
+ return 10 * fd - 1;
+
+ /* Fill the buffer from the file */
+ rb->lseek(fd, offset, SEEK_SET);
+ readsize = rb->read(fd, stringbuffer, buf_size);
+ rb->close(fd);
+
+ if(readsize < 0)
+ return readsize * 10 - 2;
+
+ /* Temporary fix until we can do merged sorting */
+ if(readsize == buf_size)
+ return buf_size; /* File too big */
+
+ buf_ptr = stringbuffer;
+ num_entries = 0;
+
+ do {
+ tmp_ptr = buf_ptr;
+ while(*buf_ptr != '\n' && buf_ptr < (char *)pointers) {
+ /* Terminate the string with CR... */
+ if(*buf_ptr == '\r')
+ *buf_ptr = 0;
+ buf_ptr++;
+ }
+ /* ...and with LF */
+ if(*buf_ptr == '\n')
+ *buf_ptr = 0;
+ else {
+ return tmp_ptr - stringbuffer; /* Buffer is full, return
+ the point to resume at */
+ }
+
+ pointers--;
+ *pointers = tmp_ptr;
+ num_entries++;
+ buf_ptr++;
+ } while(buf_ptr < stringbuffer + readsize);
+
+ return 0;
+}
+
+static int write_file(void)
+{
+ char tmpfilename[MAX_PATH+1];
+ int fd;
+ int i;
+ int rc;
+
+ /* Create a temporary file */
+ rb->snprintf(tmpfilename, MAX_PATH+1, "%s.tmp", filename);
+ fd = rb->creat(tmpfilename, 0);
+ if(fd < 0)
+ return 10 * fd - 1;
+
+ /* Write the sorted strings, with appended CR/LF, to the temp file,
+ in reverse order */
+ for(i = num_entries-1;i >= 0;i--) {
+ rc = rb->write(fd, pointers[i], rb->strlen(pointers[i]));
+ if(rc < 0) {
+ rb->close(fd);
+ return 10 * rc - 2;
+ }
+
+ rc = rb->write(fd, crlf, 2);
+ if(rc < 0) {
+ rb->close(fd);
+ return 10 * rc - 3;
+ }
+ }
+
+ rb->close(fd);
+
+ /* Remove the original file */
+ rc = rb->remove(filename);
+ if(rc < 0) {
+ return 10 * rc - 4;
+ }
+
+ /* Replace the old file with the new */
+ rc = rb->rename(tmpfilename, filename);
+ if(rc < 0) {
+ return 10 * rc - 5;
+ }
+ return 0;
+}
+
+enum plugin_status plugin_start(struct plugin_api* api, void* parameter)
+{
+ char *buf;
+ int rc;
+ TEST_PLUGIN_API(api);
+
+ filename = (char *)parameter;
+
+ rb = api;
+
+ buf = rb->plugin_get_mp3_buffer(&buf_size); /* start munching memory */
+
+ stringbuffer = buf;
+ pointers = (char **)(buf + buf_size - sizeof(int));
+
+ rc = read_buffer(0);
+ if(rc == 0) {
+ sort_buffer();
+ rc = write_file();
+ if(rc < 0) {
+ rb->splash(HZ, true, "Can't write file: %d", rc);
+ }
+ } else {
+ if(rc < 0)
+ rb->splash(HZ, true, "Can't read file: %d", rc);
+ else
+ rb->splash(HZ, true, "The file is too big");
+ }
+
+ return PLUGIN_OK;
+}