(61d00a474) v0.9.7.1

2020-03-04 13:04:10 +01:00
parent 3c50efa5c9
commit 3c09ebe02f
5086 changed files with 786063 additions and 295871 deletions
@@ -0,0 +1,130 @@
+/*
+ *  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.
+ */
+
+#ifndef VPX_VP8_DECODER_DBOOLHUFF_H_
+#define VPX_VP8_DECODER_DBOOLHUFF_H_
+
+#include <stddef.h>
+#include <limits.h>
+
+#include "./vpx_config.h"
+#include "vpx_ports/mem.h"
+#include "vpx/vp8dx.h"
+#include "vpx/vpx_integer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef size_t VP8_BD_VALUE;
+
+#define VP8_BD_VALUE_SIZE ((int)sizeof(VP8_BD_VALUE) * CHAR_BIT)
+
+/*This is meant to be a large, positive constant that can still be efficiently
+   loaded as an immediate (on platforms like ARM, for example).
+  Even relatively modest values like 100 would work fine.*/
+#define VP8_LOTS_OF_BITS (0x40000000)
+
+typedef struct {
+  const unsigned char *user_buffer_end;
+  const unsigned char *user_buffer;
+  VP8_BD_VALUE value;
+  int count;
+  unsigned int range;
+  vpx_decrypt_cb decrypt_cb;
+  void *decrypt_state;
+} BOOL_DECODER;
+
+DECLARE_ALIGNED(16, extern const unsigned char, vp8_norm[256]);
+
+int vp8dx_start_decode(BOOL_DECODER *br, const unsigned char *source,
+                       unsigned int source_sz, vpx_decrypt_cb decrypt_cb,
+                       void *decrypt_state);
+
+void vp8dx_bool_decoder_fill(BOOL_DECODER *br);
+
+static int vp8dx_decode_bool(BOOL_DECODER *br, int probability) {
+  unsigned int bit = 0;
+  VP8_BD_VALUE value;
+  unsigned int split;
+  VP8_BD_VALUE bigsplit;
+  int count;
+  unsigned int range;
+
+  split = 1 + (((br->range - 1) * probability) >> 8);
+
+  if (br->count < 0) vp8dx_bool_decoder_fill(br);
+
+  value = br->value;
+  count = br->count;
+
+  bigsplit = (VP8_BD_VALUE)split << (VP8_BD_VALUE_SIZE - 8);
+
+  range = split;
+
+  if (value >= bigsplit) {
+    range = br->range - split;
+    value = value - bigsplit;
+    bit = 1;
+  }
+
+  {
+    const unsigned char shift = vp8_norm[(unsigned char)range];
+    range <<= shift;
+    value <<= shift;
+    count -= shift;
+  }
+  br->value = value;
+  br->count = count;
+  br->range = range;
+
+  return bit;
+}
+
+static INLINE int vp8_decode_value(BOOL_DECODER *br, int bits) {
+  int z = 0;
+  int bit;
+
+  for (bit = bits - 1; bit >= 0; bit--) {
+    z |= (vp8dx_decode_bool(br, 0x80) << bit);
+  }
+
+  return z;
+}
+
+static INLINE int vp8dx_bool_error(BOOL_DECODER *br) {
+  /* Check if we have reached the end of the buffer.
+   *
+   * Variable 'count' stores the number of bits in the 'value' buffer, minus
+   * 8. The top byte is part of the algorithm, and the remainder is buffered
+   * to be shifted into it. So if count == 8, the top 16 bits of 'value' are
+   * occupied, 8 for the algorithm and 8 in the buffer.
+   *
+   * When reading a byte from the user's buffer, count is filled with 8 and
+   * one byte is filled into the value buffer. When we reach the end of the
+   * data, count is additionally filled with VP8_LOTS_OF_BITS. So when
+   * count == VP8_LOTS_OF_BITS - 1, the user's data has been exhausted.
+   */
+  if ((br->count > VP8_BD_VALUE_SIZE) && (br->count < VP8_LOTS_OF_BITS)) {
+    /* We have tried to decode bits after the end of
+     * stream was encountered.
+     */
+    return 1;
+  }
+
+  /* No error. */
+  return 0;
+}
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // VPX_VP8_DECODER_DBOOLHUFF_H_