private static unsafe void BrotliBuildMetaBlock(ref MemoryManager m,
byte *ringbuffer,
size_t pos,
size_t mask,
BrotliEncoderParams *params_,
byte prev_byte,
byte prev_byte2,
Command *cmds,
size_t num_commands,
ContextType literal_context_mode,
MetaBlockSplit *mb)
{
/* Histogram ids need to fit in one byte. */
size_t kMaxNumberOfHistograms = 256;
HistogramDistance *distance_histograms;
HistogramLiteral * literal_histograms;
ContextType * literal_context_modes = null;
size_t literal_histograms_size;
size_t distance_histograms_size;
size_t i;
size_t literal_context_multiplier = 1;
BrotliSplitBlock(ref m, cmds, num_commands,
ringbuffer, pos, mask, params_,
&mb->literal_split,
&mb->command_split,
&mb->distance_split);
if (!params_->disable_literal_context_modeling)
{
literal_context_multiplier = 1 << BROTLI_LITERAL_CONTEXT_BITS;
literal_context_modes =
(ContextType *)BrotliAllocate(ref m, mb->literal_split.num_types * sizeof(ContextType));
for (i = 0; i < mb->literal_split.num_types; ++i)
{
literal_context_modes[i] = literal_context_mode;
}
}
literal_histograms_size =
mb->literal_split.num_types * literal_context_multiplier;
literal_histograms =
(HistogramLiteral *)BrotliAllocate(ref m, literal_histograms_size * sizeof(HistogramLiteral));
HistogramLiteral.ClearHistograms(literal_histograms, literal_histograms_size);
distance_histograms_size =
mb->distance_split.num_types << BROTLI_DISTANCE_CONTEXT_BITS;
distance_histograms =
(HistogramDistance *)BrotliAllocate(ref m, distance_histograms_size * sizeof(HistogramDistance));
HistogramDistance.ClearHistograms(distance_histograms, distance_histograms_size);
mb->command_histograms_size = mb->command_split.num_types;
mb->command_histograms =
(HistogramCommand *)BrotliAllocate(ref m, mb->command_histograms_size * sizeof(HistogramCommand));
HistogramCommand.ClearHistograms(mb->command_histograms, mb->command_histograms_size);
BrotliBuildHistogramsWithContext(cmds, num_commands,
&mb->literal_split, &mb->command_split, &mb->distance_split,
ringbuffer, pos, mask, prev_byte, prev_byte2, literal_context_modes,
literal_histograms, mb->command_histograms, distance_histograms);
BrotliFree(ref m, literal_context_modes);
mb->literal_context_map_size =
mb->literal_split.num_types << BROTLI_LITERAL_CONTEXT_BITS;
mb->literal_context_map =
(uint *)BrotliAllocate(ref m, mb->literal_context_map_size * sizeof(uint));
mb->literal_histograms_size = mb->literal_context_map_size;
mb->literal_histograms =
(HistogramLiteral *)BrotliAllocate(ref m, mb->literal_histograms_size * sizeof(HistogramLiteral));
ClusterLiteral.BrotliClusterHistograms(ref m, literal_histograms, literal_histograms_size,
kMaxNumberOfHistograms, mb->literal_histograms,
&mb->literal_histograms_size, mb->literal_context_map);
BrotliFree(ref m, literal_histograms);
if (params_->disable_literal_context_modeling)
{
/* Distribute assignment to all contexts. */
for (i = mb->literal_split.num_types; i != 0;)
{
size_t j = 0;
i--;
for (; j < (1 << BROTLI_LITERAL_CONTEXT_BITS); j++)
{
mb->literal_context_map[(i << BROTLI_LITERAL_CONTEXT_BITS) + j] =
mb->literal_context_map[i];
}
}
}
mb->distance_context_map_size =
mb->distance_split.num_types << BROTLI_DISTANCE_CONTEXT_BITS;
mb->distance_context_map =
(uint *)BrotliAllocate(ref m, mb->distance_context_map_size * sizeof(uint));
mb->distance_histograms_size = mb->distance_context_map_size;
mb->distance_histograms =
(HistogramDistance *)BrotliAllocate(ref m, mb->distance_histograms_size * sizeof(HistogramDistance));
ClusterDistance.BrotliClusterHistograms(ref m, distance_histograms,
mb->distance_context_map_size,
kMaxNumberOfHistograms,
mb->distance_histograms,
&mb->distance_histograms_size,
mb->distance_context_map);
BrotliFree(ref m, distance_histograms);
}
