protected override (MetaBlock, BrotliGlobalState) Transform(MetaBlock.Compressed original, BrotliGlobalState state, BrotliCompressionParameters parameters)
{
if (original.Data.InsertCopyCommands.Count <= 1 || original.Data.BlockSwitchCommands[Category.InsertCopy].Count > 0)
{
return(original, state);
}
var builder = new CompressedMetaBlockBuilder(original, state);
var icBlocks = builder.BlockTypes[Category.InsertCopy];
var icCommands = builder.GetTotalBlockLength(Category.InsertCopy);
icBlocks.SetInitialLength(icCommands / 2)
.AddFinalBlock(1);
return(builder.Build(parameters));
}
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));
}