Initial code for parsing/packing/unpacking packets

Warning: untested, may not even compile

src/framepack.c

+/* Copyright (c) 2010 Xiph.Org Foundation, Skype Limited
+   Written by Jean-Marc Valin and Koen Vos */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   - Neither the name of the Xiph.org Foundation nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+static int decode_length(unsigned char *c, int len)
+{
+    int tmp;
+    tmp = c[0];
+    if (len < 1)
+        return -1;
+    if (tmp >= 252)
+    {
+        if (len >= 2)
+            return 4*c[1] + (tmp&0x3) + 252;
+        else
+            return -1;
+    } else {
+        return tmp;
+    }
+}
+
+int count_frames(unsigned char *packet, int len)
+{
+    int sz = packet[0]&0x7;
+
+    if (sz == 0)
+        return 1;
+    else if (sz == 1 || sz == 4)
+        return 2;
+    else if (sz == 2 || sz == 5)
+        return 3;
+    else if (sz == 3)
+    {
+        /* Many packets, same size */
+        int count, payload;
+        int flen = decode_length(packet+1, len-1);
+        if (flen<=0)
+            return -1;
+        payload = len - 2;
+        if (flen>=252)
+            payload--;
+        count = payload/flen;
+        if (count*flen==payload)
+            return count;
+        else
+            return -1;
+    } else if (sz == 6)
+    {
+        /* Many packets, different sizes */
+        int count = 0;
+        int pos = 1;
+        int bytes = 1;
+        while (bytes < len)
+        {
+            int tmp=1;
+            int flen = decode_length(packet+pos, len-bytes);
+            if (flen==-1)
+                return -1;
+            if (flen >= 252)
+                tmp = 2;
+            pos += tmp;
+            bytes += tmp+flen;
+            count++;
+        }
+        if (bytes != len)
+            return -1;
+        else
+            return count;
+    } else {
+
+    }
+}
+
+#define MAX_FRAMES 256
+int hybrid_merge_packets(unsigned char **packets, int *len, unsigned *output, int maxlen)
+{
+    unsigned char cfg[MAX_FRAMES];
+    unsigned char len[MAX_FRAMES];
+    int nb_frames=0;
+
+}