public static Int32[] Decode(UInt32[] codeTextWords, Int32ProbabilityContexts int32ProbabilityContexts, Int32[] outOfBandValues, Int32 valueCount)
{
var bytes = new Byte[codeTextWords.Length * 4];
Buffer.BlockCopy(codeTextWords, 0, bytes, 0, bytes.Length);
var decodedSymbols = new List <Int32>(valueCount);
var accumulatedProbabilityCounts = new AccumulatedProbabilityCounts(int32ProbabilityContexts);
var code = 0x0000;
var low = 0x0000;
var high = 0xffff;
var bitBuffer = 0;
var bits = 0;
var symbolCount = valueCount;
var currentContext = 0;
var newSymbolRange = new Int32[3];
var outOfBandDataCounter = 0;
using (var memoryStream = new MemoryStream(bytes))
{
var bitStream = new BitStream(memoryStream);
GetNextCodeText(bitStream, out bitBuffer, out bits);
code = (bitBuffer >> 16) & 0xffff;
bitBuffer <<= 16;
bits = 16;
for (int i = 0; i < symbolCount; ++i)
{
var rescaledCode = (((code - low) + 1) * accumulatedProbabilityCounts.SymbolCounts[currentContext] - 1) / ((high - low) + 1);
var int32ProbabilityContextTableEntry = GetEntryAndSymbolRangeByRescaledCode(accumulatedProbabilityCounts, int32ProbabilityContexts, currentContext, rescaledCode, ref newSymbolRange);
var range = high - low + 1;
high = low + ((range * newSymbolRange[1]) / newSymbolRange[2] - 1);
low += ((range * newSymbolRange[0]) / newSymbolRange[2]);
while (true)
{
if (((~(high ^ low)) & 0x8000) > 0)
{
//Shift both out if most sign.
}
else if (((low & 0x4000) > 0) && ((high & 0x4000) == 0))
{
code ^= 0x4000;
code &= 0xffff;
low &= 0x3fff;
low &= 0xffff;
high |= 0x4000;
high &= 0xffff;
}
else
{
// Nothing to shift out any more
break;
}
low = (low << 1) & 0xffff;
high = (high << 1) & 0xffff;
high = (high | 1) & 0xffff;
code = (code << 1) & 0xffff;
if (bits == 0)
{
GetNextCodeText(bitStream, out bitBuffer, out bits);
}
code |= ((bitBuffer >> 31) & 0x00000001);
bitBuffer <<= 1;
bits--;
}
var symbol = int32ProbabilityContextTableEntry.Symbol;
if (symbol != -2 || currentContext <= 0)
{
if (symbol == -2 && outOfBandDataCounter >= outOfBandValues.Length)
{
throw new Exception("'Out-Of-Band' data missing! Read values: " + i + " / " + symbolCount);
}
decodedSymbols.Add(symbol == -2 && outOfBandDataCounter < outOfBandValues.Length ? outOfBandValues[outOfBandDataCounter++] : int32ProbabilityContextTableEntry.AssociatedValue);
}
currentContext = int32ProbabilityContextTableEntry.NextContext;
}
}
return(decodedSymbols.ToArray());
}
private static Int32ProbabilityContextTableEntry GetEntryAndSymbolRangeByRescaledCode(AccumulatedProbabilityCounts accumulatedProbabilityCounts, Int32ProbabilityContexts int32ProbabilityContexts, Int32 contextIndex, Int32 rescaledCode, ref Int32[] newSymbolRange)
{
var entryByAccumulatedCountPerContext = accumulatedProbabilityCounts.EntriesByAccumulatedCountPerContext[contextIndex];
var key = entryByAccumulatedCountPerContext.Keys.DefaultIfEmpty(-1).First(k => k > rescaledCode - 1);
var value = entryByAccumulatedCountPerContext[key];
var int32ProbabilityContextTableEntry = int32ProbabilityContexts.ProbabilityContextTableEntries[contextIndex][value];
newSymbolRange[0] = key + 1 - int32ProbabilityContextTableEntry.OccurrenceCount;
newSymbolRange[1] = key + 1;
newSymbolRange[2] = accumulatedProbabilityCounts.SymbolCounts[contextIndex];
return(int32ProbabilityContextTableEntry);
}
