From 7d5c8eb943f92a94b420568778d61e0bd6f7df43 Mon Sep 17 00:00:00 2001
From: claude-bot <claude@ancap.in.ua>
Date: Mon, 13 Jul 2026 12:40:01 +0000
Subject: Import xiph/opus @ 034c1b61a250457649d788bbf983b3f0fb63f02e

Snapshot for re3/reVC vendoring, per @lzcnt.
Source: https://github.com/xiph/opus (034c1b61a250457649d788bbf983b3f0fb63f02e).
---
 src/opus_multistream.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 src/opus_multistream.c

(limited to 'src/opus_multistream.c')

diff --git a/src/opus_multistream.c b/src/opus_multistream.c
new file mode 100644
index 0000000..09c3639
--- /dev/null
+++ b/src/opus_multistream.c
@@ -0,0 +1,92 @@
+/* Copyright (c) 2011 Xiph.Org Foundation
+   Written by Jean-Marc Valin */
+/*
+   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.
+
+   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 COPYRIGHT OWNER
+   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.
+*/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "opus_multistream.h"
+#include "opus.h"
+#include "opus_private.h"
+#include "stack_alloc.h"
+#include <stdarg.h>
+#include "float_cast.h"
+#include "os_support.h"
+
+
+int validate_layout(const ChannelLayout *layout)
+{
+   int i, max_channel;
+
+   max_channel = layout->nb_streams+layout->nb_coupled_streams;
+   if (max_channel>255)
+      return 0;
+   for (i=0;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i] >= max_channel && layout->mapping[i] != 255)
+         return 0;
+   }
+   return 1;
+}
+
+
+int get_left_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==stream_id*2)
+         return i;
+   }
+   return -1;
+}
+
+int get_right_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==stream_id*2+1)
+         return i;
+   }
+   return -1;
+}
+
+int get_mono_channel(const ChannelLayout *layout, int stream_id, int prev)
+{
+   int i;
+   i = (prev<0) ? 0 : prev+1;
+   for (;i<layout->nb_channels;i++)
+   {
+      if (layout->mapping[i]==stream_id+layout->nb_coupled_streams)
+         return i;
+   }
+   return -1;
+}
+
-- 
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