Remove generic M4A parsing code from libalac and create a libm4a - so it can be used by other codecs

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7682 a1c6a512-1295-4272-9138-f99709370657

apps/codecs/libm4a/m4a.c

@@ -0,0 +1,225 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2005 Dave Chapman
+ *
+ * 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 <codecs.h>
+#include <inttypes.h>
+#include "m4a.h"
+
+/* Implementation of the stream.h functions used by libalac */
+
+#define _Swap32(v) do { \
+                   v = (((v) & 0x000000FF) << 0x18) | \
+                       (((v) & 0x0000FF00) << 0x08) | \
+                       (((v) & 0x00FF0000) >> 0x08) | \
+                       (((v) & 0xFF000000) >> 0x18); } while(0)
+
+#define _Swap16(v) do { \
+                   v = (((v) & 0x00FF) << 0x08) | \
+                       (((v) & 0xFF00) >> 0x08); } while (0)
+
+/* A normal read without any byte-swapping */
+void stream_read(stream_t *stream, size_t size, void *buf)
+{
+    stream->ci->read_filebuf(buf,size);
+    if (stream->ci->curpos >= stream->ci->filesize) { stream->eof=1; }
+}
+
+int32_t stream_read_int32(stream_t *stream)
+{
+    int32_t v;
+    stream_read(stream, 4, &v);
+#ifdef ROCKBOX_LITTLE_ENDIAN
+    _Swap32(v);
+#endif
+    return v;
+}
+
+int32_t stream_tell(stream_t *stream)
+{
+    return stream->ci->curpos;
+}
+
+uint32_t stream_read_uint32(stream_t *stream)
+{
+    uint32_t v;
+    stream_read(stream, 4, &v);
+#ifdef ROCKBOX_LITTLE_ENDIAN
+    _Swap32(v);
+#endif
+    return v;
+}
+
+int16_t stream_read_int16(stream_t *stream)
+{
+    int16_t v;
+    stream_read(stream, 2, &v);
+#ifdef ROCKBOX_LITTLE_ENDIAN
+    _Swap16(v);
+#endif
+    return v;
+}
+
+uint16_t stream_read_uint16(stream_t *stream)
+{
+    uint16_t v;
+    stream_read(stream, 2, &v);
+#ifdef ROCKBOX_LITTLE_ENDIAN
+    _Swap16(v);
+#endif
+    return v;
+}
+
+int8_t stream_read_int8(stream_t *stream)
+{
+    int8_t v;
+    stream_read(stream, 1, &v);
+    return v;
+}
+
+uint8_t stream_read_uint8(stream_t *stream)
+{
+    uint8_t v;
+    stream_read(stream, 1, &v);
+    return v;
+}
+
+void stream_skip(stream_t *stream, size_t skip)
+{
+  (void)stream;
+  stream->ci->advance_buffer(skip);
+}
+
+int stream_eof(stream_t *stream)
+{
+    return stream->eof;
+}
+
+void stream_create(stream_t *stream,struct codec_api* ci)
+{
+    stream->ci=ci;
+    stream->eof=0;
+}
+
+/* This function was part of the original alac decoder implementation */
+
+int get_sample_info(demux_res_t *demux_res, uint32_t samplenum,
+                           uint32_t *sample_duration,
+                           uint32_t *sample_byte_size)
+{
+    unsigned int duration_index_accum = 0;
+    unsigned int duration_cur_index = 0;
+
+    if (samplenum >= demux_res->num_sample_byte_sizes) { 
+        return 0;
+    }
+
+    if (!demux_res->num_time_to_samples) {
+        return 0;
+    }
+
+    while ((demux_res->time_to_sample[duration_cur_index].sample_count
+            + duration_index_accum) <= samplenum) {
+        duration_index_accum +=
+        demux_res->time_to_sample[duration_cur_index].sample_count;
+
+        duration_cur_index++;
+        if (duration_cur_index >= demux_res->num_time_to_samples) {
+            return 0;
+        }
+    }
+
+    *sample_duration =
+     demux_res->time_to_sample[duration_cur_index].sample_duration;
+    *sample_byte_size = demux_res->sample_byte_size[samplenum];
+
+    return 1;
+}
+
+/* Seek to sample_loc (or close to it).  Return 1 on success (and
+   modify samplesdone and currentblock), 0 if failed 
+
+   Seeking uses the following two arrays:
+
+     1) the sample_byte_size array contains the length in bytes of
+        each block ("sample" in Applespeak).
+
+     2) the time_to_sample array contains the duration (in samples) of
+        each block of data.
+
+     So we just find the block number we are going to seek to (using
+     time_to_sample) and then find the offset in the file (using
+     sample_byte_size).
+
+     Each ALAC block seems to be independent of all the others.
+ */
+
+unsigned int alac_seek (demux_res_t* demux_res, 
+                        stream_t* stream,
+                        unsigned int sample_loc, 
+                        uint32_t* samplesdone, int* currentblock)
+{
+  int flag;
+  unsigned int i,j;
+  unsigned int newblock;
+  unsigned int newsample;
+  unsigned int newpos;
+
+  /* First check we have the appropriate metadata - we should always
+     have it. */
+  if ((demux_res->num_time_to_samples==0) ||
+    (demux_res->num_sample_byte_sizes==0)) { return 0; }
+
+  /* Find the destination block from time_to_sample array */
+  i=0;
+  newblock=0;
+  newsample=0;
+  flag=0;
+
+  while ((i<demux_res->num_time_to_samples) && (flag==0) && 
+         (newsample < sample_loc)) {
+    j=(sample_loc-newsample) /
+      demux_res->time_to_sample[i].sample_duration;
+    
+    if (j <= demux_res->time_to_sample[i].sample_count) {
+      newblock+=j;
+      newsample+=j*demux_res->time_to_sample[i].sample_duration;
+      flag=1;
+    } else {
+      newsample+=(demux_res->time_to_sample[i].sample_duration
+                 * demux_res->time_to_sample[i].sample_count);
+      newblock+=demux_res->time_to_sample[i].sample_count;
+      i++;
+    }
+  }
+
+  /* We know the new block, now calculate the file position */
+  newpos=demux_res->mdat_offset;
+  for (i=0;i<newblock;i++) {
+    newpos+=demux_res->sample_byte_size[i];
+  }
+
+  /* We know the new file position, so let's try to seek to it */
+  if (stream->ci->seek_buffer(newpos)) {
+    *samplesdone=newsample;
+    *currentblock=newblock;
+    return 1;
+  } else {
+    return 0;
+  }
+}