astc: Create a LUT at compile time for encoding values

This commit is contained in:
ReinUsesLisp 2020-03-13 23:40:02 -03:00
parent e183820956
commit 801fd04f75

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@ -161,6 +161,8 @@ private:
enum class IntegerEncoding { JustBits, Qus32, Trit }; enum class IntegerEncoding { JustBits, Qus32, Trit };
struct IntegerEncodedValue { struct IntegerEncodedValue {
constexpr IntegerEncodedValue() = default;
constexpr IntegerEncodedValue(IntegerEncoding encoding_, u32 num_bits_) constexpr IntegerEncodedValue(IntegerEncoding encoding_, u32 num_bits_)
: encoding{encoding_}, num_bits{num_bits_} {} : encoding{encoding_}, num_bits{num_bits_} {}
@ -179,8 +181,8 @@ struct IntegerEncodedValue {
return totalBits; return totalBits;
} }
IntegerEncoding encoding; IntegerEncoding encoding{};
u32 num_bits; u32 num_bits = 0;
u32 bit_value = 0; u32 bit_value = 0;
union { union {
u32 qus32_value = 0; u32 qus32_value = 0;
@ -296,7 +298,7 @@ static void DecodeQus32Block(InputBitStream& bits, std::vector<IntegerEncodedVal
// Returns a new instance of this struct that corresponds to the // Returns a new instance of this struct that corresponds to the
// can take no more than maxval values // can take no more than maxval values
static IntegerEncodedValue CreateEncoding(u32 maxVal) { static constexpr IntegerEncodedValue CreateEncoding(u32 maxVal) {
while (maxVal > 0) { while (maxVal > 0) {
u32 check = maxVal + 1; u32 check = maxVal + 1;
@ -322,13 +324,23 @@ static IntegerEncodedValue CreateEncoding(u32 maxVal) {
return IntegerEncodedValue(IntegerEncoding::JustBits, 0); return IntegerEncodedValue(IntegerEncoding::JustBits, 0);
} }
static constexpr std::array<IntegerEncodedValue, 256> MakeEncodedValues() {
std::array<IntegerEncodedValue, 256> encodings{};
for (std::size_t i = 0; i < encodings.size(); ++i) {
encodings[i] = CreateEncoding(static_cast<u32>(i));
}
return encodings;
}
static constexpr std::array EncodingsValues = MakeEncodedValues();
// Fills result with the values that are encoded in the given // Fills result with the values that are encoded in the given
// bitstream. We must know beforehand what the maximum possible // bitstream. We must know beforehand what the maximum possible
// value is, and how many values we're decoding. // value is, and how many values we're decoding.
static void DecodeIntegerSequence(std::vector<IntegerEncodedValue>& result, InputBitStream& bits, static void DecodeIntegerSequence(std::vector<IntegerEncodedValue>& result, InputBitStream& bits,
u32 maxRange, u32 nValues) { u32 maxRange, u32 nValues) {
// Determine encoding parameters // Determine encoding parameters
IntegerEncodedValue val = CreateEncoding(maxRange); IntegerEncodedValue val = EncodingsValues[maxRange];
// Start decoding // Start decoding
u32 nValsDecoded = 0; u32 nValsDecoded = 0;
@ -371,7 +383,7 @@ struct TexelWeightParams {
nIdxs *= 2; nIdxs *= 2;
} }
return CreateEncoding(m_MaxWeight).GetBitLength(nIdxs); return EncodingsValues[m_MaxWeight].GetBitLength(nIdxs);
} }
u32 GetNumWeightValues() const { u32 GetNumWeightValues() const {
@ -780,12 +792,12 @@ static void DecodeColorValues(u32* out, u8* data, const u32* modes, const u32 nP
// figure out the max value for each of them... // figure out the max value for each of them...
u32 range = 256; u32 range = 256;
while (--range > 0) { while (--range > 0) {
IntegerEncodedValue val = CreateEncoding(range); IntegerEncodedValue val = EncodingsValues[range];
u32 bitLength = val.GetBitLength(nValues); u32 bitLength = val.GetBitLength(nValues);
if (bitLength <= nBitsForColorData) { if (bitLength <= nBitsForColorData) {
// Find the smallest possible range that matches the given encoding // Find the smallest possible range that matches the given encoding
while (--range > 0) { while (--range > 0) {
IntegerEncodedValue newval = CreateEncoding(range); IntegerEncodedValue newval = EncodingsValues[range];
if (!newval.MatchesEncoding(val)) { if (!newval.MatchesEncoding(val)) {
break; break;
} }