Move AMR-NB frame unpacking code to a common file so it can be reused in

the AMR-WB decoder.

Patch by Marcelo Galvăo Póvoa.

Originally committed as revision 25100 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/amr.h

+/*
+ * Shared functions between AMR codecs
+ *
+ * Copyright (c) 2010 Marcelo Galvao Povoa
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_AMR_H
+#define AVCODEC_AMR_H
+
+#ifdef AMR_USE_16BIT_TABLES
+#define R_TABLE_TYPE uint16_t
+#else
+#define R_TABLE_TYPE uint8_t
+#endif
+
+/**
+ * Fill the frame structure variables from bitstream by parsing the
+ * given reordering table that uses the following format:
+ *
+ * Each field (16 bits) in the AMR Frame is stored as:
+ * - one byte for the number of bits in the field
+ * - one byte for the field index
+ * - then, one byte for each bit of the field (from most-significant to least)
+ *         of the position of that bit in the AMR frame.
+ *
+ * @param out pointer to the frame struct
+ * @param size the size in bytes of the frame struct
+ * @param data input bitstream after the frame header
+ * @param ord_table the reordering table as above
+ */
+static inline void ff_amr_bit_reorder(uint16_t *out, int size,
+                                      const uint8_t *data,
+                                      const R_TABLE_TYPE *ord_table)
+{
+    int field_size;
+
+    memset(out, 0, size);
+    while ((field_size = *ord_table++)) {
+        int field = 0;
+        int field_offset = *ord_table++;
+        while (field_size--) {
+           int bit = *ord_table++;
+           field <<= 1;
+           field |= data[bit >> 3] >> (bit & 7) & 1;
+        }
+        out[field_offset] = field;
+    }
+}
+
+#endif /* AVCODEC_AMR_H */

libavcodec/amrnbdec.c

@@ -52,6 +52,7 @@
 #include "acelp_vectors.h"
 #include "acelp_pitch_delay.h"
 #include "lsp.h"
+#include "amr.h"
 
 #include "amrnbdata.h"
 
@@ -195,24 +196,9 @@ static enum Mode unpack_bitstream(AMRContext *p, const uint8_t *buf,
     p->bad_frame_indicator = !get_bits1(&gb); // quality bit
     skip_bits(&gb, 2);                        // two padding bits
 
-    if (mode < MODE_DTX) {
-        uint16_t *data = (uint16_t *)&p->frame;
-        const uint8_t *order = amr_unpacking_bitmaps_per_mode[mode];
-        int field_size;
-
-        memset(&p->frame, 0, sizeof(AMRNBFrame));
-        buf++;
-        while ((field_size = *order++)) {
-            int field = 0;
-            int field_offset = *order++;
-            while (field_size--) {
-               int bit = *order++;
-               field <<= 1;
-               field |= buf[bit >> 3] >> (bit & 7) & 1;
-            }
-            data[field_offset] = field;
-        }
-    }
+    if (mode < MODE_DTX)
+        ff_amr_bit_reorder((uint16_t *) &p->frame, sizeof(AMRNBFrame), buf + 1,
+                           amr_unpacking_bitmaps_per_mode[mode]);
 
     return mode;
 }