Merge "Adding API to read/write uncompressed frame header bits." into experimental

1 files changed, 35 insertions, 0 deletions

diff --git a/vp9/decoder/vp9_read_bit_buffer.h b/vp9/decoder/vp9_read_bit_buffer.h
new file mode 100644
index 000000000..7141722f3
--- /dev/null
+++ b/vp9/decoder/vp9_read_bit_buffer.h
@@ -0,0 +1,35 @@
+/*
+ *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef VP9_READ_BIT_BUFFER_
+#define VP9_READ_BIT_BUFFER_
+
+struct vp9_read_bit_buffer {
+  const uint8_t *const bit_buffer;
+  size_t bit_offset;
+};
+
+static int vp9_rb_read_bit(struct vp9_read_bit_buffer *rb) {
+  const int off = rb->bit_offset;
+  const int p = off / CHAR_BIT;
+  const int q = /*CHAR_BIT - 1 -*/ off % CHAR_BIT;
+  const int bit = (rb->bit_buffer[p] & (1 << q)) >> q;
+  rb->bit_offset = off + 1;
+  return bit;
+}
+
+static int vp9_rb_read_literal(struct vp9_read_bit_buffer *rb, int bits) {
+  int value = 0, bit;
+  for (bit = bits - 1; bit >= 0; bit--)
+    value |= vp9_rb_read_bit(rb) << bit;
+  return value;
+}
+
+#endif  // VP9_READ_BIT_BUFFER_