protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters)
{
var builder = new CompressedMetaBlockBuilder(original, state)
{
LiteralCtxMap = ContextMapBuilder.Literals.Simple,
DistanceCtxMap = ContextMapBuilder.Distances.Simple
};
foreach (var category in Categories.LID)
{
builder.BlockTypes[category].Reset();
}
builder.UseSameLiteralContextMode(LiteralContextMode.UTF8);
var tracker = new MetaBlockSizeTracker(state);
tracker.Test(builder, parameters);
foreach (var category in Categories.LID)
{
TestBlockSplits(builder, parameters, tracker, category);
}
tracker.Test(original);
return(tracker.Smallest ?? throw new InvalidOperationException("Transformation did not generate any meta-blocks."));
}
protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters)
{
var builder = new CompressedMetaBlockBuilder(original, state)
{
LiteralCtxMap = ContextMapBuilder.Literals.Simple,
DistanceCtxMap = ContextMapBuilder.Distances.Simple
};
foreach (var category in Categories.LID)
{
builder.BlockTypes[category].Reset();
}
return(builder.UseSameLiteralContextMode(LiteralContextMode.LSB6).Build(parameters));
}
private void PrepareContextMap(CompressedMetaBlockBuilder builder, Category category, int lengthSplits)
{
int blockTypes = Math.Min(lengthSplits, 256);
if (category == Category.Literal)
{
if (builder.LiteralCtxMap.BlockTypes != blockTypes)
{
builder.UseSameLiteralContextMode(LiteralContextMode.UTF8);
builder.LiteralCtxMap = new ContextMapBuilder.Literals(blockTypes).RepeatFirstBlockType(lengthSplits <= blockTypes).Build();
}
}
else if (category == Category.Distance)
{
if (builder.DistanceCtxMap.BlockTypes != blockTypes)
{
builder.DistanceCtxMap = new ContextMapBuilder.Distances(blockTypes).RepeatFirstBlockType(lengthSplits <= blockTypes).Build();
}
}
}
protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters)
{
var builder = new CompressedMetaBlockBuilder(original, state);
var literals = new List <Literal>(builder.GetTotalBlockLength(Category.Literal));
var lengthCodes = new List <InsertCopyLengthCode>(builder.GetTotalBlockLength(Category.InsertCopy));
var distanceCodes = new List <DistanceCode>(builder.GetTotalBlockLength(Category.Distance));
var distanceFreq = new FrequencyList <DistanceCode>();
var validDistanceCodes = new List <DistanceCode>(5);
foreach (var command in original.Data.InsertCopyCommands)
{
literals.AddRange(command.Literals);
state.OutputLiterals(command.Literals);
if (command.CopyDistance == DistanceInfo.EndsAfterLiterals)
{
lengthCodes.Add(command.Lengths.MakeCode(ImplicitDistanceCodeZero.PreferEnabled));
break;
}
if (!command.CopyDistance.FindCodes(original.Header.DistanceParameters, state, validDistanceCodes))
{
lengthCodes.Add(command.Lengths.MakeCode(ImplicitDistanceCodeZero.ForceEnabled));
}
else
{
DistanceCode distanceCode;
if (command.CopyDistance == DistanceInfo.ExplicitCodeZero)
{
distanceCode = DistanceCode.Zero;
}
else
{
distanceCode = validDistanceCodes.Count > 1 ? parameters.DistanceCodePicker(validDistanceCodes, distanceFreq) : validDistanceCodes[0];
}
distanceFreq.Add(distanceCode);
distanceCodes.Add(distanceCode);
lengthCodes.Add(command.Lengths.MakeCode(ImplicitDistanceCodeZero.Disable));
}
}
var origLitCtxMap = builder.LiteralCtxMap;
if (origLitCtxMap.TreeCount == 1)
{
Split(builder, Category.Literal, literals, 512, 400.0);
builder.UseSameLiteralContextMode(LiteralContextMode.UTF8);
builder.LiteralCtxMap = new ContextMapBuilder.Literals(builder).RepeatFirstBlockType(true).Build();
}
else
{
var literalContextMap = Enumerable.Range(0, origLitCtxMap.ContextsPerBlockType).Select(index => origLitCtxMap.DetermineTreeID(0, index)).ToArray();
var literalContextMode = builder.LiteralContextModes[0];
var literalBuffer = RingBufferFast <byte> .From(0, 0);
Split(builder, Category.Literal, literals, 512, 400.0, new BlockSplitter <Literal> .ContextInfo(literalContextMap, literal => {
literalBuffer.Push(literal.Value);
return(literalContextMode.DetermineContextID(literalBuffer.Front, literalBuffer.Back));
}));
builder.UseSameLiteralContextMode(literalContextMode);
builder.LiteralCtxMap = new ContextMapBuilder.Literals(builder).Set(0, literalContextMap).RepeatFirstBlockType(true).Build();
}
Split(builder, Category.InsertCopy, lengthCodes, 1024, 500.0);
Split(builder, Category.Distance, distanceCodes, 512, 100.0);
builder.DistanceCtxMap = new ContextMapBuilder.Distances(builder).RepeatFirstBlockType(true).Build();
return(builder.Build(parameters));
}