Bundled libwebp updated to version 0.6.0

This commit imports libwebp 0.6.0, including AUTHORS, COPYING, ChangeLog,
NEWS, PATENTS, README and src directories. In src, only includes header
and source files.

Upstream changes since 0.5.1 have been merged in.
Also updated version in qt_attribution.json.

Conflicts:
	src/3rdparty/libwebp.pri
	src/3rdparty/libwebp/qt_attribution.json
	src/3rdparty/libwebp/src/webp/config.h

Change-Id: I001aa7a3fabf0130b54f9005c23aa822bc1d0ec1
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

1 files changed, 417 insertions, 0 deletions

diff --git a/src/3rdparty/libwebp/src/utils/huffman_encode_utils.c b/src/3rdparty/libwebp/src/utils/huffman_encode_utils.c
new file mode 100644
index 0000000..f950465
--- /dev/null
+++ b/src/3rdparty/libwebp/src/utils/huffman_encode_utils.c
@@ -0,0 +1,417 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING 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.
+// -----------------------------------------------------------------------------
+//
+// Author: Jyrki Alakuijala (jyrki@google.com)
+//
+// Entropy encoding (Huffman) for webp lossless.
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include "./huffman_encode_utils.h"
+#include "./utils.h"
+#include "../webp/format_constants.h"
+
+// -----------------------------------------------------------------------------
+// Util function to optimize the symbol map for RLE coding
+
+// Heuristics for selecting the stride ranges to collapse.
+static int ValuesShouldBeCollapsedToStrideAverage(int a, int b) {
+  return abs(a - b) < 4;
+}
+
+// Change the population counts in a way that the consequent
+// Huffman tree compression, especially its RLE-part, give smaller output.
+static void OptimizeHuffmanForRle(int length, uint8_t* const good_for_rle,
+                                  uint32_t* const counts) {
+  // 1) Let's make the Huffman code more compatible with rle encoding.
+  int i;
+  for (; length >= 0; --length) {
+    if (length == 0) {
+      return;  // All zeros.
+    }
+    if (counts[length - 1] != 0) {
+      // Now counts[0..length - 1] does not have trailing zeros.
+      break;
+    }
+  }
+  // 2) Let's mark all population counts that already can be encoded
+  // with an rle code.
+  {
+    // Let's not spoil any of the existing good rle codes.
+    // Mark any seq of 0's that is longer as 5 as a good_for_rle.
+    // Mark any seq of non-0's that is longer as 7 as a good_for_rle.
+    uint32_t symbol = counts[0];
+    int stride = 0;
+    for (i = 0; i < length + 1; ++i) {
+      if (i == length || counts[i] != symbol) {
+        if ((symbol == 0 && stride >= 5) ||
+            (symbol != 0 && stride >= 7)) {
+          int k;
+          for (k = 0; k < stride; ++k) {
+            good_for_rle[i - k - 1] = 1;
+          }
+        }
+        stride = 1;
+        if (i != length) {
+          symbol = counts[i];
+        }
+      } else {
+        ++stride;
+      }
+    }
+  }
+  // 3) Let's replace those population counts that lead to more rle codes.
+  {
+    uint32_t stride = 0;
+    uint32_t limit = counts[0];
+    uint32_t sum = 0;
+    for (i = 0; i < length + 1; ++i) {
+      if (i == length || good_for_rle[i] ||
+          (i != 0 && good_for_rle[i - 1]) ||
+          !ValuesShouldBeCollapsedToStrideAverage(counts[i], limit)) {
+        if (stride >= 4 || (stride >= 3 && sum == 0)) {
+          uint32_t k;
+          // The stride must end, collapse what we have, if we have enough (4).
+          uint32_t count = (sum + stride / 2) / stride;
+          if (count < 1) {
+            count = 1;
+          }
+          if (sum == 0) {
+            // Don't make an all zeros stride to be upgraded to ones.
+            count = 0;
+          }
+          for (k = 0; k < stride; ++k) {
+            // We don't want to change value at counts[i],
+            // that is already belonging to the next stride. Thus - 1.
+            counts[i - k - 1] = count;
+          }
+        }
+        stride = 0;
+        sum = 0;
+        if (i < length - 3) {
+          // All interesting strides have a count of at least 4,
+          // at least when non-zeros.
+          limit = (counts[i] + counts[i + 1] +
+                   counts[i + 2] + counts[i + 3] + 2) / 4;
+        } else if (i < length) {
+          limit = counts[i];
+        } else {
+          limit = 0;
+        }
+      }
+      ++stride;
+      if (i != length) {
+        sum += counts[i];
+        if (stride >= 4) {
+          limit = (sum + stride / 2) / stride;
+        }
+      }
+    }
+  }
+}
+
+// A comparer function for two Huffman trees: sorts first by 'total count'
+// (more comes first), and then by 'value' (more comes first).
+static int CompareHuffmanTrees(const void* ptr1, const void* ptr2) {
+  const HuffmanTree* const t1 = (const HuffmanTree*)ptr1;
+  const HuffmanTree* const t2 = (const HuffmanTree*)ptr2;
+  if (t1->total_count_ > t2->total_count_) {
+    return -1;
+  } else if (t1->total_count_ < t2->total_count_) {
+    return 1;
+  } else {
+    assert(t1->value_ != t2->value_);
+    return (t1->value_ < t2->value_) ? -1 : 1;
+  }
+}
+
+static void SetBitDepths(const HuffmanTree* const tree,
+                         const HuffmanTree* const pool,
+                         uint8_t* const bit_depths, int level) {
+  if (tree->pool_index_left_ >= 0) {
+    SetBitDepths(&pool[tree->pool_index_left_], pool, bit_depths, level + 1);
+    SetBitDepths(&pool[tree->pool_index_right_], pool, bit_depths, level + 1);
+  } else {
+    bit_depths[tree->value_] = level;
+  }
+}
+
+// Create an optimal Huffman tree.
+//
+// (data,length): population counts.
+// tree_limit: maximum bit depth (inclusive) of the codes.
+// bit_depths[]: how many bits are used for the symbol.
+//
+// Returns 0 when an error has occurred.
+//
+// The catch here is that the tree cannot be arbitrarily deep
+//
+// count_limit is the value that is to be faked as the minimum value
+// and this minimum value is raised until the tree matches the
+// maximum length requirement.
+//
+// This algorithm is not of excellent performance for very long data blocks,
+// especially when population counts are longer than 2**tree_limit, but
+// we are not planning to use this with extremely long blocks.
+//
+// See http://en.wikipedia.org/wiki/Huffman_coding
+static void GenerateOptimalTree(const uint32_t* const histogram,
+                                int histogram_size,
+                                HuffmanTree* tree, int tree_depth_limit,
+                                uint8_t* const bit_depths) {
+  uint32_t count_min;
+  HuffmanTree* tree_pool;
+  int tree_size_orig = 0;
+  int i;
+
+  for (i = 0; i < histogram_size; ++i) {
+    if (histogram[i] != 0) {
+      ++tree_size_orig;
+    }
+  }
+
+  if (tree_size_orig == 0) {   // pretty optimal already!
+    return;
+  }
+
+  tree_pool = tree + tree_size_orig;
+
+  // For block sizes with less than 64k symbols we never need to do a
+  // second iteration of this loop.
+  // If we actually start running inside this loop a lot, we would perhaps
+  // be better off with the Katajainen algorithm.
+  assert(tree_size_orig <= (1 << (tree_depth_limit - 1)));
+  for (count_min = 1; ; count_min *= 2) {
+    int tree_size = tree_size_orig;
+    // We need to pack the Huffman tree in tree_depth_limit bits.
+    // So, we try by faking histogram entries to be at least 'count_min'.
+    int idx = 0;
+    int j;
+    for (j = 0; j < histogram_size; ++j) {
+      if (histogram[j] != 0) {
+        const uint32_t count =
+            (histogram[j] < count_min) ? count_min : histogram[j];
+        tree[idx].total_count_ = count;
+        tree[idx].value_ = j;
+        tree[idx].pool_index_left_ = -1;
+        tree[idx].pool_index_right_ = -1;
+        ++idx;
+      }
+    }
+
+    // Build the Huffman tree.
+    qsort(tree, tree_size, sizeof(*tree), CompareHuffmanTrees);
+
+    if (tree_size > 1) {  // Normal case.
+      int tree_pool_size = 0;
+      while (tree_size > 1) {  // Finish when we have only one root.
+        uint32_t count;
+        tree_pool[tree_pool_size++] = tree[tree_size - 1];
+        tree_pool[tree_pool_size++] = tree[tree_size - 2];
+        count = tree_pool[tree_pool_size - 1].total_count_ +
+                tree_pool[tree_pool_size - 2].total_count_;
+        tree_size -= 2;
+        {
+          // Search for the insertion point.
+          int k;
+          for (k = 0; k < tree_size; ++k) {
+            if (tree[k].total_count_ <= count) {
+              break;
+            }
+          }
+          memmove(tree + (k + 1), tree + k, (tree_size - k) * sizeof(*tree));
+          tree[k].total_count_ = count;
+          tree[k].value_ = -1;
+
+          tree[k].pool_index_left_ = tree_pool_size - 1;
+          tree[k].pool_index_right_ = tree_pool_size - 2;
+          tree_size = tree_size + 1;
+        }
+      }
+      SetBitDepths(&tree[0], tree_pool, bit_depths, 0);
+    } else if (tree_size == 1) {  // Trivial case: only one element.
+      bit_depths[tree[0].value_] = 1;
+    }
+
+    {
+      // Test if this Huffman tree satisfies our 'tree_depth_limit' criteria.
+      int max_depth = bit_depths[0];
+      for (j = 1; j < histogram_size; ++j) {
+        if (max_depth < bit_depths[j]) {
+          max_depth = bit_depths[j];
+        }
+      }
+      if (max_depth <= tree_depth_limit) {
+        break;
+      }
+    }
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Coding of the Huffman tree values
+
+static HuffmanTreeToken* CodeRepeatedValues(int repetitions,
+                                            HuffmanTreeToken* tokens,
+                                            int value, int prev_value) {
+  assert(value <= MAX_ALLOWED_CODE_LENGTH);
+  if (value != prev_value) {
+    tokens->code = value;
+    tokens->extra_bits = 0;
+    ++tokens;
+    --repetitions;
+  }
+  while (repetitions >= 1) {
+    if (repetitions < 3) {
+      int i;
+      for (i = 0; i < repetitions; ++i) {
+        tokens->code = value;
+        tokens->extra_bits = 0;
+        ++tokens;
+      }
+      break;
+    } else if (repetitions < 7) {
+      tokens->code = 16;
+      tokens->extra_bits = repetitions - 3;
+      ++tokens;
+      break;
+    } else {
+      tokens->code = 16;
+      tokens->extra_bits = 3;
+      ++tokens;
+      repetitions -= 6;
+    }
+  }
+  return tokens;
+}
+
+static HuffmanTreeToken* CodeRepeatedZeros(int repetitions,
+                                           HuffmanTreeToken* tokens) {
+  while (repetitions >= 1) {
+    if (repetitions < 3) {
+      int i;
+      for (i = 0; i < repetitions; ++i) {
+        tokens->code = 0;   // 0-value
+        tokens->extra_bits = 0;
+        ++tokens;
+      }
+      break;
+    } else if (repetitions < 11) {
+      tokens->code = 17;
+      tokens->extra_bits = repetitions - 3;
+      ++tokens;
+      break;
+    } else if (repetitions < 139) {
+      tokens->code = 18;
+      tokens->extra_bits = repetitions - 11;
+      ++tokens;
+      break;
+    } else {
+      tokens->code = 18;
+      tokens->extra_bits = 0x7f;  // 138 repeated 0s
+      ++tokens;
+      repetitions -= 138;
+    }
+  }
+  return tokens;
+}
+
+int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
+                                    HuffmanTreeToken* tokens, int max_tokens) {
+  HuffmanTreeToken* const starting_token = tokens;
+  HuffmanTreeToken* const ending_token = tokens + max_tokens;
+  const int depth_size = tree->num_symbols;
+  int prev_value = 8;  // 8 is the initial value for rle.
+  int i = 0;
+  assert(tokens != NULL);
+  while (i < depth_size) {
+    const int value = tree->code_lengths[i];
+    int k = i + 1;
+    int runs;
+    while (k < depth_size && tree->code_lengths[k] == value) ++k;
+    runs = k - i;
+    if (value == 0) {
+      tokens = CodeRepeatedZeros(runs, tokens);
+    } else {
+      tokens = CodeRepeatedValues(runs, tokens, value, prev_value);
+      prev_value = value;
+    }
+    i += runs;
+    assert(tokens <= ending_token);
+  }
+  (void)ending_token;    // suppress 'unused variable' warning
+  return (int)(tokens - starting_token);
+}
+
+// -----------------------------------------------------------------------------
+
+// Pre-reversed 4-bit values.
+static const uint8_t kReversedBits[16] = {
+  0x0, 0x8, 0x4, 0xc, 0x2, 0xa, 0x6, 0xe,
+  0x1, 0x9, 0x5, 0xd, 0x3, 0xb, 0x7, 0xf
+};
+
+static uint32_t ReverseBits(int num_bits, uint32_t bits) {
+  uint32_t retval = 0;
+  int i = 0;
+  while (i < num_bits) {
+    i += 4;
+    retval |= kReversedBits[bits & 0xf] << (MAX_ALLOWED_CODE_LENGTH + 1 - i);
+    bits >>= 4;
+  }
+  retval >>= (MAX_ALLOWED_CODE_LENGTH + 1 - num_bits);
+  return retval;
+}
+
+// Get the actual bit values for a tree of bit depths.
+static void ConvertBitDepthsToSymbols(HuffmanTreeCode* const tree) {
+  // 0 bit-depth means that the symbol does not exist.
+  int i;
+  int len;
+  uint32_t next_code[MAX_ALLOWED_CODE_LENGTH + 1];
+  int depth_count[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 };
+
+  assert(tree != NULL);
+  len = tree->num_symbols;
+  for (i = 0; i < len; ++i) {
+    const int code_length = tree->code_lengths[i];
+    assert(code_length <= MAX_ALLOWED_CODE_LENGTH);
+    ++depth_count[code_length];
+  }
+  depth_count[0] = 0;  // ignore unused symbol
+  next_code[0] = 0;
+  {
+    uint32_t code = 0;
+    for (i = 1; i <= MAX_ALLOWED_CODE_LENGTH; ++i) {
+      code = (code + depth_count[i - 1]) << 1;
+      next_code[i] = code;
+    }
+  }
+  for (i = 0; i < len; ++i) {
+    const int code_length = tree->code_lengths[i];
+    tree->codes[i] = ReverseBits(code_length, next_code[code_length]++);
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Main entry point
+
+void VP8LCreateHuffmanTree(uint32_t* const histogram, int tree_depth_limit,
+                           uint8_t* const buf_rle,
+                           HuffmanTree* const huff_tree,
+                           HuffmanTreeCode* const huff_code) {
+  const int num_symbols = huff_code->num_symbols;
+  memset(buf_rle, 0, num_symbols * sizeof(*buf_rle));
+  OptimizeHuffmanForRle(num_symbols, buf_rle, histogram);
+  GenerateOptimalTree(histogram, num_symbols, huff_tree, tree_depth_limit,
+                      huff_code->code_lengths);
+  // Create the actual bit codes for the bit lengths.
+  ConvertBitDepthsToSymbols(huff_code);
+}