sync with upstream

1 files changed, 96 insertions, 0 deletions

diff --git a/xbmc/utils/BitstreamReader.cpp b/xbmc/utils/BitstreamReader.cpp
new file mode 100644
index 0000000..6f2a7ff
--- /dev/null
+++ b/xbmc/utils/BitstreamReader.cpp
@@ -0,0 +1,96 @@
+/*
+ *  Copyright (C) 2017-2018 Team Kodi
+ *  This file is part of Kodi - https://kodi.tv
+ *
+ *  SPDX-License-Identifier: GPL-2.0-or-later
+ *  See LICENSES/README.md for more information.
+ */
+
+#include "BitstreamReader.h"
+
+CBitstreamReader::CBitstreamReader(const uint8_t *buf, int len)
+  : buffer(buf)
+  , start(buf)
+  , offbits(0)
+  , length(len)
+  , oflow(0)
+{
+}
+
+uint32_t CBitstreamReader::ReadBits(int nbits)
+{
+  uint32_t ret = GetBits(nbits);
+
+  offbits += nbits;
+  buffer += offbits / 8;
+  offbits %= 8;
+
+  return ret;
+}
+
+void CBitstreamReader::SkipBits(int nbits)
+{
+  offbits += nbits;
+  buffer += offbits / 8;
+  offbits %= 8;
+
+  if (buffer > (start + length))
+    oflow = 1;
+}
+
+uint32_t CBitstreamReader::GetBits(int nbits)
+{
+  int i, nbytes;
+  uint32_t ret = 0;
+  const uint8_t *buf;
+
+  buf = buffer;
+  nbytes = (offbits + nbits) / 8;
+
+  if (((offbits + nbits) % 8) > 0)
+    nbytes++;
+
+  if ((buf + nbytes) > (start + length))
+  {
+    oflow = 1;
+    return 0;
+  }
+  for (i = 0; i<nbytes; i++)
+    ret += buf[i] << ((nbytes - i - 1) * 8);
+
+  i = (4 - nbytes) * 8 + offbits;
+
+  ret = ((ret << i) >> i) >> ((nbytes * 8) - nbits - offbits);
+
+  return ret;
+}
+
+const uint8_t* find_start_code(const uint8_t *p, const uint8_t *end, uint32_t *state)
+{
+  if (p >= end)
+    return end;
+
+  for (int i = 0; i < 3; i++)
+  {
+    uint32_t tmp = *state << 8;
+    *state = tmp + *(p++);
+    if (tmp == 0x100 || p == end)
+      return p;
+  }
+
+  while (p < end)
+  {
+    if (p[-1] > 1) p += 3;
+    else if (p[-2]) p += 2;
+    else if (p[-3] | (p[-1] - 1)) p++;
+    else {
+      p++;
+      break;
+    }
+  }
+
+  p = (p < end)? p - 4 : end - 4;
+  *state = BS_RB32(p);
+
+  return p + 4;
+}