1 files changed, 72 insertions, 0 deletions
diff --git a/media/libvpx/libvpx/vp8/decoder/dboolhuff.c b/media/libvpx/libvpx/vp8/decoder/dboolhuff.c
new file mode 100644
index 0000000000..11099c453c
--- /dev/null
+++ b/media/libvpx/libvpx/vp8/decoder/dboolhuff.c
@@ -0,0 +1,72 @@
+/*
+ *  Copyright (c) 2010 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.
+ */
+
+#include "dboolhuff.h"
+#include "vp8/common/common.h"
+#include "vpx_dsp/vpx_dsp_common.h"
+
+int vp8dx_start_decode(BOOL_DECODER *br, const unsigned char *source,
+                       unsigned int source_sz, vpx_decrypt_cb decrypt_cb,
+                       void *decrypt_state) {
+  if (source_sz && !source) return 1;
+
+  // To simplify calling code this fuction can be called with |source| == null
+  // and |source_sz| == 0. This and vp8dx_bool_decoder_fill() are essentially
+  // no-ops in this case.
+  // Work around a ubsan warning with a ternary to avoid adding 0 to null.
+  br->user_buffer_end = source ? source + source_sz : source;
+  br->user_buffer = source;
+  br->value = 0;
+  br->count = -8;
+  br->range = 255;
+  br->decrypt_cb = decrypt_cb;
+  br->decrypt_state = decrypt_state;
+
+  /* Populate the buffer */
+  vp8dx_bool_decoder_fill(br);
+
+  return 0;
+}
+
+void vp8dx_bool_decoder_fill(BOOL_DECODER *br) {
+  const unsigned char *bufptr = br->user_buffer;
+  VP8_BD_VALUE value = br->value;
+  int count = br->count;
+  int shift = VP8_BD_VALUE_SIZE - CHAR_BIT - (count + CHAR_BIT);
+  size_t bytes_left = br->user_buffer_end - bufptr;
+  size_t bits_left = bytes_left * CHAR_BIT;
+  int x = shift + CHAR_BIT - (int)bits_left;
+  int loop_end = 0;
+  unsigned char decrypted[sizeof(VP8_BD_VALUE) + 1];
+
+  if (br->decrypt_cb) {
+    size_t n = VPXMIN(sizeof(decrypted), bytes_left);
+    br->decrypt_cb(br->decrypt_state, bufptr, decrypted, (int)n);
+    bufptr = decrypted;
+  }
+
+  if (x >= 0) {
+    count += VP8_LOTS_OF_BITS;
+    loop_end = x;
+  }
+
+  if (x < 0 || bits_left) {
+    while (shift >= loop_end) {
+      count += CHAR_BIT;
+      value |= (VP8_BD_VALUE)*bufptr << shift;
+      ++bufptr;
+      ++br->user_buffer;
+      shift -= CHAR_BIT;
+    }
+  }
+
+  br->value = value;
+  br->count = count;
+}