// SPDX-FileCopyrightText: 2016 The University of North Carolina at Chapel Hill
// SPDX-License-Identifier: Apache-2.0
// Please send all BUG REPORTS to <pavel@cs.unc.edu>.
// <http://gamma.cs.unc.edu/FasTC/>
#include <algorithm>
#include <bit>
#include <cassert>
#include <cstring>
#include <span>
#include <vector>
#include <boost/container/static_vector.hpp>
#include "common/common_types.h"
#include "video_core/textures/astc.h"
class InputBitStream {
public:
constexpr explicit InputBitStream(std::span<const u8> data, size_t start_offset = 0)
: cur_byte{data.data()}, total_bits{data.size()}, next_bit{start_offset % 8} {}
constexpr size_t GetBitsRead() const {
return bits_read;
}
constexpr bool ReadBit() {
if (bits_read >= total_bits * 8) {
return 0;
}
const bool bit = ((*cur_byte >> next_bit) & 1) != 0;
++next_bit;
while (next_bit >= 8) {
next_bit -= 8;
++cur_byte;
}
++bits_read;
return bit;
}
constexpr u32 ReadBits(std::size_t nBits) {
u32 ret = 0;
for (std::size_t i = 0; i < nBits; ++i) {
ret |= (ReadBit() & 1) << i;
}
return ret;
}
template <std::size_t nBits>
constexpr u32 ReadBits() {
u32 ret = 0;
for (std::size_t i = 0; i < nBits; ++i) {
ret |= (ReadBit() & 1) << i;
}
return ret;
}
private:
const u8* cur_byte;
size_t total_bits = 0;
size_t next_bit = 0;
size_t bits_read = 0;
};
class OutputBitStream {
public:
constexpr explicit OutputBitStream(u8* ptr, std::size_t bits = 0, std::size_t start_offset = 0)
: cur_byte{ptr}, num_bits{bits}, next_bit{start_offset % 8} {}
constexpr std::size_t GetBitsWritten() const {
return bits_written;
}
constexpr void WriteBitsR(u32 val, u32 nBits) {
for (u32 i = 0; i < nBits; i++) {
WriteBit((val >> (nBits - i - 1)) & 1);
}
}
constexpr void WriteBits(u32 val, u32 nBits) {
for (u32 i = 0; i < nBits; i++) {
WriteBit((val >> i) & 1);
}
}
private:
constexpr void WriteBit(bool b) {
if (bits_written >= num_bits) {
return;
}
const u32 mask = 1 << next_bit++;
// clear the bit
*cur_byte &= static_cast<u8>(~mask);
// Write the bit, if necessary
if (b)
*cur_byte |= static_cast<u8>(mask);
// Next byte?
if (next_bit >= 8) {
cur_byte += 1;
next_bit = 0;
}
}
u8* cur_byte;
std::size_t num_bits;
std::size_t bits_written = 0;
std::size_t next_bit = 0;
};
template <typename IntType>
class Bits {
public:
explicit Bits(const IntType& v) : m_Bits(v) {}
Bits(const Bits&) = delete;
Bits& operator=(const Bits&) = delete;
u8 operator[](u32 bitPos) const {
return static_cast<u8>((m_Bits >> bitPos) & 1);
}
IntType operator()(u32 start, u32 end) const {
if (start == end) {
return (*this)[start];
} else if (start > end) {
u32 t = start;
start = end;
end = t;
}
u64 mask = (1 << (end - start + 1)) - 1;
return (m_Bits >> start) & static_cast<IntType>(mask);
}
private:
const IntType& m_Bits;
};
enum class IntegerEncoding { JustBits, Quint, Trit };
struct IntegerEncodedValue {
constexpr IntegerEncodedValue() = default;
constexpr IntegerEncodedValue(IntegerEncoding encoding_, u32 num_bits_)
: encoding{encoding_}, num_bits{num_bits_} {}
constexpr bool MatchesEncoding(const IntegerEncodedValue& other) const {
return encoding == other.encoding && num_bits == other.num_bits;
}
// Returns the number of bits required to encode num_vals values.
u32 GetBitLength(u32 num_vals) const {
u32 total_bits = num_bits * num_vals;
if (encoding == IntegerEncoding::Trit) {
total_bits += (num_vals * 8 + 4) / 5;
} else if (encoding == IntegerEncoding::Quint) {
total_bits += (num_vals * 7 + 2) / 3;
}
return total_bits;
}
IntegerEncoding encoding{};
u32 num_bits = 0;
u32 bit_value = 0;
union {
u32 quint_value = 0;
u32 trit_value;
};
};
// Returns a new instance of this struct that corresponds to the
// can take no more than mav_value values
static constexpr IntegerEncodedValue CreateEncoding(u32 mav_value) {
while (mav_value > 0) {
u32 check = mav_value + 1;
// Is mav_value a power of two?
if (!(check & (check - 1))) {
return IntegerEncodedValue(IntegerEncoding::JustBits, std::popcount(mav_value));
}
// Is mav_value of the type 3*2^n - 1?
if ((check % 3 == 0) && !((check / 3) & ((check / 3) - 1))) {
return IntegerEncodedValue(IntegerEncoding::Trit, std::popcount(check / 3 - 1));
}
// Is mav_value of the type 5*2^n - 1?
if ((check % 5 == 0) && !((check / 5) & ((check / 5) - 1))) {
return IntegerEncodedValue(IntegerEncoding::Quint, std::popcount(check / 5 - 1));
}
// Apparently it can't be represented with a bounded integer sequence...
// just iterate.
mav_value--;
}
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<IntegerEncodedValue, 256> ASTC_ENCODINGS_VALUES = MakeEncodedValues();
namespace Tegra::Texture::ASTC {
using IntegerEncodedVector = boost::container::static_vector<
IntegerEncodedValue, 256,
boost::container::static_vector_options<
boost::container::inplace_alignment<alignof(IntegerEncodedValue)>,
boost::container::throw_on_overflow<false>>::type>;
static void DecodeTritBlock(InputBitStream& bits, IntegerEncodedVector& result, u32 nBitsPerValue) {
// Implement the algorithm in section C.2.12
std::array<u32, 5> m;
std::array<u32, 5> t;
u32 T;
// Read the trit encoded block according to
// table C.2.14
m[0] = bits.ReadBits(nBitsPerValue);
T = bits.ReadBits<2>();
m[1] = bits.ReadBits(nBitsPerValue);
T |= bits.ReadBits<2>() << 2;
m[2] = bits.ReadBits(nBitsPerValue);
T |= bits.ReadBit() << 4;
m[3] = bits.ReadBits(nBitsPerValue);
T |= bits.ReadBits<2>() << 5;
m[4] = bits.ReadBits(nBitsPerValue);
T |= bits.ReadBit() << 7;
u32 C = 0;
Bits<u32> Tb(T);
if (Tb(2, 4) == 7) {
C = (Tb(5, 7) << 2) | Tb(0, 1);
t[4] = t[3] = 2;
} else {
C = Tb(0, 4);
if (Tb(5, 6) == 3) {
t[4] = 2;
t[3] = Tb[7];
} else {
t[4] = Tb[7];
t[3] = Tb(5, 6);
}
}
Bits<u32> Cb(C);
if (Cb(0, 1) == 3) {
t[2] = 2;
t[1] = Cb[4];
t[0] = (Cb[3] << 1) | (Cb[2] & ~Cb[3]);
} else if (Cb(2, 3) == 3) {
t[2] = 2;
t[1] = 2;
t[0] = Cb(0, 1);
} else {
t[2] = Cb[4];
t[1] = Cb(2, 3);
t[0] = (Cb[1] << 1) | (Cb[0] & ~Cb[1]);
}
for (std::size_t i = 0; i < 5; ++i) {
IntegerEncodedValue& val = result.emplace_back(IntegerEncoding::Trit, nBitsPerValue);
val.bit_value = m[i];
val.trit_value = t[i];
}
}
static void DecodeQuintBlock(InputBitStream& bits, IntegerEncodedVector& result,
u32 nBitsPerValue) {
// Implement the algorithm in section C.2.12
u32 m[3];
u32 q[3];
u32 Q;
// Read the trit encoded block according to
// table C.2.15
m[0] = bits.ReadBits(nBitsPerValue);
Q = bits.ReadBits<3>();
m[1] = bits.ReadBits(nBitsPerValue);
Q |= bits.ReadBits<2>() << 3;
m[2] = bits.ReadBits(nBitsPerValue);
Q |= bits.ReadBits<2>() << 5;
Bits<u32> Qb(Q);
if (Qb(1, 2) == 3 && Qb(5, 6) == 0) {
q[0] = q[1] = 4;
q[2] = (Qb[0] << 2) | ((Qb[4] & ~Qb[0]) << 1) | (Qb[3] & ~Qb[0]);
} else {
u32 C = 0;
if (Qb(1, 2) == 3) {
q[2] = 4;
C = (Qb(3, 4) << 3) | ((~Qb(5, 6) & 3) << 1) | Qb[0];
} else {
q[2] = Qb(5, 6);
C = Qb(0, 4);
}
Bits<u32> Cb(C);
if (Cb(0, 2) == 5) {
q[1] = 4;
q[0] = Cb(3, 4);
} else {
q[1] = Cb(3, 4);
q[0] = Cb(0, 2);
}
}
for (std::size_t i = 0; i < 3; ++i) {
IntegerEncodedValue& val = result.emplace_back(IntegerEncoding::Quint, nBitsPerValue);
val.bit_value = m[i];
val.quint_value = q[i];
}
}
// Fills result with the values that are encoded in the given
// bitstream. We must know beforehand what the maximum possible
// value is, and how many values we're decoding.
static void DecodeIntegerSequence(IntegerEncodedVector& result, InputBitStream& bits, u32 maxRange,
u32 nValues) {
// Determine encoding parameters
IntegerEncodedValue val = ASTC_ENCODINGS_VALUES[maxRange];
// Start decoding
u32 nValsDecoded = 0;
while (nValsDecoded < nValues) {
switch (val.encoding) {
case IntegerEncoding::Quint:
DecodeQuintBlock(bits, result, val.num_bits);
nValsDecoded += 3;
break;
case IntegerEncoding::Trit:
DecodeTritBlock(bits, result, val.num_bits);
nValsDecoded += 5;
break;
case IntegerEncoding::JustBits:
val.bit_value = bits.ReadBits(val.num_bits);
result.push_back(val);
nValsDecoded++;
break;
}
}
}
struct TexelWeightParams {
u32 m_Width = 0;
u32 m_Height = 0;
bool m_bDualPlane = false;
u32 m_MaxWeight = 0;
bool m_bError = false;
bool m_bVoidExtentLDR = false;
bool m_bVoidExtentHDR = false;
u32 GetPackedBitSize() const {
// How many indices do we have?
u32 nIdxs = m_Height * m_Width;
if (m_bDualPlane) {
nIdxs *= 2;
}
return ASTC_ENCODINGS_VALUES[m_MaxWeight].GetBitLength(nIdxs);
}
u32 GetNumWeightValues() const {
u32 ret = m_Width * m_Height;
if (m_bDualPlane) {
ret *= 2;
}
return ret;
}
};
static TexelWeightParams DecodeBlockInfo(InputBitStream& strm) {
TexelWeightParams params;
// Read the entire block mode all at once
u16 modeBits = static_cast<u16>(strm.ReadBits<11>());
// Does this match the void extent block mode?
if ((modeBits & 0x01FF) == 0x1FC) {
if (modeBits & 0x200) {
params.m_bVoidExtentHDR = true;
} else {
params.m_bVoidExtentLDR = true;
}
// Next two bits must be one.
if (!(modeBits & 0x400) || !strm.ReadBit()) {
params.m_bError = true;
}
return params;
}
// First check if the last four bits are zero
if ((modeBits & 0xF) == 0) {
params.m_bError = true;
return params;
}
// If the last two bits are zero, then if bits
// [6-8] are all ones, this is also reserved.
if ((modeBits & 0x3) == 0 && (modeBits & 0x1C0) == 0x1C0) {
params.m_bError = true;
return params;
}
// Otherwise, there is no error... Figure out the layout
// of the block mode. Layout is determined by a number
// between 0 and 9 corresponding to table C.2.8 of the
// ASTC spec.
u32 layout = 0;
if ((modeBits & 0x1) || (modeBits & 0x2)) {
// layout is in [0-4]
if (modeBits & 0x8) {
// layout is in [2-4]
if (modeBits & 0x4) {
// layout is in [3-4]
if (modeBits & 0x100) {
layout = 4;
} else {
layout = 3;
}
} else {
layout = 2;
}
} else {
// layout is in [0-1]
if (modeBits & 0x4) {
layout = 1;
} else {
layout = 0;
}
}
} else {
// layout is in [5-9]
if (modeBits & 0x100) {
// layout is in [7-9]
if (modeBits & 0x80) {
// layout is in [7-8]
assert((modeBits & 0x40) == 0U);
if (modeBits & 0x20) {
layout = 8;
} else {
layout = 7;
}
} else {
layout = 9;
}
} else {
// layout is in [5-6]
if (modeBits & 0x80) {
layout = 6;
} else {
layout = 5;
}
}
}
assert(layout < 10);
// Determine R
u32 R = !!(modeBits & 0x10);
if (layout < 5) {
R |= (modeBits & 0x3) << 1;
} else {
R |= (modeBits & 0xC) >> 1;
}
assert(2 <= R && R <= 7);
// Determine width & height
switch (layout) {
case 0: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 7) & 0x3;
params.m_Width = B + 4;
params.m_Height = A + 2;
break;
}
case 1: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 7) & 0x3;
params.m_Width = B + 8;
params.m_Height = A + 2;
break;
}
case 2: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 7) & 0x3;
params.m_Width = A + 2;
params.m_Height = B + 8;
break;
}
case 3: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 7) & 0x1;
params.m_Width = A + 2;
params.m_Height = B + 6;
break;
}
case 4: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 7) & 0x1;
params.m_Width = B + 2;
params.m_Height = A + 2;
break;
}
case 5: {
u32 A = (modeBits >> 5) & 0x3;
params.m_Width = 12;
params.m_Height = A + 2;
break;
}
case 6: {
u32 A = (modeBits >> 5) & 0x3;
params.m_Width = A + 2;
params.m_Height = 12;
break;
}
case 7: {
params.m_Width = 6;
params.m_Height = 10;
break;
}
case 8: {
params.m_Width = 10;
params.m_Height = 6;
break;
}
case 9: {
u32 A = (modeBits >> 5) & 0x3;
u32 B = (modeBits >> 9) & 0x3;
params.m_Width = A + 6;
params.m_Height = B + 6;
break;
}
default:
assert(false && "Don't know this layout...");
params.m_bError = true;
break;
}
// Determine whether or not we're using dual planes
// and/or high precision layouts.
bool D = (layout != 9) && (modeBits & 0x400);
bool H = (layout != 9) && (modeBits & 0x200);
if (H) {
const u32 maxWeights[6] = {9, 11, 15, 19, 23, 31};
params.m_MaxWeight = maxWeights[R - 2];
} else {
const u32 maxWeights[6] = {1, 2, 3, 4, 5, 7};
params.m_MaxWeight = maxWeights[R - 2];
}
params.m_bDualPlane = D;
return params;
}
// Replicates low num_bits such that [(to_bit - 1):(to_bit - 1 - from_bit)]
// is the same as [(num_bits - 1):0] and repeats all the way down.
template <typename IntType>
static constexpr IntType Replicate(IntType val, u32 num_bits, u32 to_bit) {
if (num_bits == 0 || to_bit == 0) {
return 0;
}
const IntType v = val & static_cast<IntType>((1 << num_bits) - 1);
IntType res = v;
u32 reslen = num_bits;
while (reslen < to_bit) {
u32 comp = 0;
if (num_bits > to_bit - reslen) {
u32 newshift = to_bit - reslen;
comp = num_bits - newshift;
num_bits = newshift;
}
res = static_cast<IntType>(res << num_bits);
res = static_cast<IntType>(res | (v >> comp));
reslen += num_bits;
}
return res;
}
static constexpr std::size_t NumReplicateEntries(u32 num_bits) {
return std::size_t(1) << num_bits;
}
template <typename IntType, u32 num_bits, u32 to_bit>
static constexpr auto MakeReplicateTable() {
std::array<IntType, NumReplicateEntries(num_bits)> table{};
for (IntType value = 0; value < static_cast<IntType>(std::size(table)); ++value) {
table[value] = Replicate(value, num_bits, to_bit);
}
return table;
}
static constexpr auto REPLICATE_BYTE_TO_16_TABLE = MakeReplicateTable<u32, 8, 16>();
static constexpr u32 ReplicateByteTo16(std::size_t value) {
return REPLICATE_BYTE_TO_16_TABLE[value];
}
static constexpr auto REPLICATE_BIT_TO_7_TABLE = MakeReplicateTable<u32, 1, 7>();
static constexpr u32 ReplicateBitTo7(std::size_t value) {
return REPLICATE_BIT_TO_7_TABLE[value];
}
static constexpr auto REPLICATE_BIT_TO_9_TABLE = MakeReplicateTable<u32, 1, 9>();
static constexpr u32 ReplicateBitTo9(std::size_t value) {
return REPLICATE_BIT_TO_9_TABLE[value];
}
static constexpr auto REPLICATE_1_BIT_TO_8_TABLE = MakeReplicateTable<u32, 1, 8>();
static constexpr auto REPLICATE_2_BIT_TO_8_TABLE = MakeReplicateTable<u32, 2, 8>();
static constexpr auto REPLICATE_3_BIT_TO_8_TABLE = MakeReplicateTable<u32, 3, 8>();
static constexpr auto REPLICATE_4_BIT_TO_8_TABLE = MakeReplicateTable<u32, 4, 8>();
static constexpr auto REPLICATE_5_BIT_TO_8_TABLE = MakeReplicateTable<u32, 5, 8>();
static constexpr auto REPLICATE_6_BIT_TO_8_TABLE = MakeReplicateTable<u32, 6, 8>();
static constexpr auto REPLICATE_7_BIT_TO_8_TABLE = MakeReplicateTable<u32, 7, 8>();
static constexpr auto REPLICATE_8_BIT_TO_8_TABLE = MakeReplicateTable<u32, 8, 8>();
/// Use a precompiled table with the most common usages, if it's not in the expected range, fallback
/// to the runtime implementation
static constexpr u32 FastReplicateTo8(u32 value, u32 num_bits) {
switch (num_bits) {
case 1:
return REPLICATE_1_BIT_TO_8_TABLE[value];
case 2:
return REPLICATE_2_BIT_TO_8_TABLE[value];
case 3:
return REPLICATE_3_BIT_TO_8_TABLE[value];
case 4:
return REPLICATE_4_BIT_TO_8_TABLE[value];
case 5:
return REPLICATE_5_BIT_TO_8_TABLE[value];
case 6:
return REPLICATE_6_BIT_TO_8_TABLE[value];
case 7:
return REPLICATE_7_BIT_TO_8_TABLE[value];
case 8:
return REPLICATE_8_BIT_TO_8_TABLE[value];
default:
return Replicate(value, num_bits, 8);
}
}
static constexpr auto REPLICATE_1_BIT_TO_6_TABLE = MakeReplicateTable<u32, 1, 6>();
static constexpr auto REPLICATE_2_BIT_TO_6_TABLE = MakeReplicateTable<u32, 2, 6>();
static constexpr auto REPLICATE_3_BIT_TO_6_TABLE = MakeReplicateTable<u32, 3, 6>();
static constexpr auto REPLICATE_4_BIT_TO_6_TABLE = MakeReplicateTable<u32, 4, 6>();
static constexpr auto REPLICATE_5_BIT_TO_6_TABLE = MakeReplicateTable<u32, 5, 6>();
static constexpr u32 FastReplicateTo6(u32 value, u32 num_bits) {
switch (num_bits) {
case 1:
return REPLICATE_1_BIT_TO_6_TABLE[value];
case 2:
return REPLICATE_2_BIT_TO_6_TABLE[value];
case 3:
return REPLICATE_3_BIT_TO_6_TABLE[value];
case 4:
return REPLICATE_4_BIT_TO_6_TABLE[value];
case 5:
return REPLICATE_5_BIT_TO_6_TABLE[value];
default:
return Replicate(value, num_bits, 6);
}
}
class Pixel {
protected:
using ChannelType = s16;
u8 m_BitDepth[4] = {8, 8, 8, 8};
s16 color[4] = {};
public:
Pixel() = default;
Pixel(u32 a, u32 r, u32 g, u32 b, u32 bitDepth = 8)
: m_BitDepth{u8(bitDepth), u8(bitDepth), u8(bitDepth), u8(bitDepth)},
color{static_cast<ChannelType>(a), static_cast<ChannelType>(r),
static_cast<ChannelType>(g), static_cast<ChannelType>(b)} {}
// Changes the depth of each pixel. This scales the values to
// the appropriate bit depth by either truncating the least
// significant bits when going from larger to smaller bit depth
// or by repeating the most significant bits when going from
// smaller to larger bit depths.
void ChangeBitDepth() {
for (u32 i = 0; i < 4; i++) {
Component(i) = ChangeBitDepth(Component(i), m_BitDepth[i]);
m_BitDepth[i] = 8;
}
}
template <typename IntType>
static float ConvertChannelToFloat(IntType channel, u8 bitDepth) {
float denominator = static_cast<float>((1 << bitDepth) - 1);
return static_cast<float>(channel) / denominator;
}
// Changes the bit depth of a single component. See the comment
// above for how we do this.
static ChannelType ChangeBitDepth(Pixel::ChannelType val, u8 oldDepth) {
assert(oldDepth <= 8);
if (oldDepth == 8) {
// Do nothing
return val;
} else if (oldDepth == 0) {
return static_cast<ChannelType>((1 << 8) - 1);
} else if (8 > oldDepth) {
return static_cast<ChannelType>(FastReplicateTo8(static_cast<u32>(val), oldDepth));
} else {
// oldDepth > newDepth
const u8 bitsWasted = static_cast<u8>(oldDepth - 8);
u16 v = static_cast<u16>(val);
v = static_cast<u16>((v + (1 << (bitsWasted - 1))) >> bitsWasted);
v = ::std::min<u16>(::std::max<u16>(0, v), static_cast<u16>((1 << 8) - 1));
return static_cast<u8>(v);
}
assert(false && "We shouldn't get here.");
return 0;
}
const ChannelType& A() const {
return color[0];
}
ChannelType& A() {
return color[0];
}
const ChannelType& R() const {
return color[1];
}
ChannelType& R() {
return color[1];
}
const ChannelType& G() const {
return color[2];
}
ChannelType& G() {
return color[2];
}
const ChannelType& B() const {
return color[3];
}
ChannelType& B() {
return color[3];
}
const ChannelType& Component(u32 idx) const {
return color[idx];
}
ChannelType& Component(u32 idx) {
return color[idx];
}
void GetBitDepth(u8 (&outDepth)[4]) const {
for (s32 i = 0; i < 4; i++) {
outDepth[i] = m_BitDepth[i];
}
}
// Take all of the components, transform them to their 8-bit variants,
// and then pack each channel into an R8G8B8A8 32-bit integer. We assume
// that the architecture is little-endian, so the alpha channel will end
// up in the most-significant byte.
u32 Pack() const {
Pixel eightBit(*this);
eightBit.ChangeBitDepth();
u32 r = 0;
r |= eightBit.A();
r <<= 8;
r |= eightBit.B();
r <<= 8;
r |= eightBit.G();
r <<= 8;
r |= eightBit.R();
return r;
}
// Clamps the pixel to the range [0,255]
void ClampByte() {
for (u32 i = 0; i < 4; i++) {
color[i] = (color[i] < 0) ? 0 : ((color[i] > 255) ? 255 : color[i]);
}
}
void MakeOpaque() {
A() = 255;
}
};
static void DecodeColorValues(u32* out, std::span<u8> data, const u32* modes, const u32 nPartitions,
const u32 nBitsForColorData) {
// First figure out how many color values we have
u32 nValues = 0;
for (u32 i = 0; i < nPartitions; i++) {
nValues += ((modes[i] >> 2) + 1) << 1;
}
// Then based on the number of values and the remaining number of bits,
// figure out the max value for each of them...
u32 range = 256;
while (--range > 0) {
IntegerEncodedValue val = ASTC_ENCODINGS_VALUES[range];
u32 bitLength = val.GetBitLength(nValues);
if (bitLength <= nBitsForColorData) {
// Find the smallest possible range that matches the given encoding
while (--range > 0) {
IntegerEncodedValue newval = ASTC_ENCODINGS_VALUES[range];
if (!newval.MatchesEncoding(val)) {
break;
}
}
// Return to last matching range.
range++;
break;
}
}
// We now have enough to decode our integer sequence.
IntegerEncodedVector decodedColorValues;
InputBitStream colorStream(data, 0);
DecodeIntegerSequence(decodedColorValues, colorStream, range, nValues);
// Once we have the decoded values, we need to dequantize them to the 0-255 range
// This procedure is outlined in ASTC spec C.2.13
u32 outIdx = 0;
for (auto itr = decodedColorValues.begin(); itr != decodedColorValues.end(); ++itr) {
// Have we already decoded all that we need?
if (outIdx >= nValues) {
break;
}
const IntegerEncodedValue& val = *itr;
u32 bitlen = val.num_bits;
u32 bitval = val.bit_value;
assert(bitlen >= 1);
u32 A = 0, B = 0, C = 0, D = 0;
// A is just the lsb replicated 9 times.
A = ReplicateBitTo9(bitval & 1);
switch (val.encoding) {
// Replicate bits
case IntegerEncoding::JustBits:
out[outIdx++] = FastReplicateTo8(bitval, bitlen);
break;
// Use algorithm in C.2.13
case IntegerEncoding::Trit: {
D = val.trit_value;
switch (bitlen) {
case 1: {
C = 204;
} break;
case 2: {
C = 93;
// B = b000b0bb0
u32 b = (bitval >> 1) & 1;
B = (b << 8) | (b << 4) | (b << 2) | (b << 1);
} break;
case 3: {
C = 44;
// B = cb000cbcb
u32 cb = (bitval >> 1) & 3;
B = (cb << 7) | (cb << 2) | cb;
} break;
case 4: {
C = 22;
// B = dcb000dcb
u32 dcb = (bitval >> 1) & 7;
B = (dcb << 6) | dcb;
} break;
case 5: {
C = 11;
// B = edcb000ed
u32 edcb = (bitval >> 1) & 0xF;
B = (edcb << 5) | (edcb >> 2);
} break;
case 6: {
C = 5;
// B = fedcb000f
u32 fedcb = (bitval >> 1) & 0x1F;
B = (fedcb << 4) | (fedcb >> 4);
} break;
default:
assert(false && "Unsupported trit encoding for color values!");
break;
} // switch(bitlen)
} // case IntegerEncoding::Trit
break;
case IntegerEncoding::Quint: {
D = val.quint_value;
switch (bitlen) {
case 1: {
C = 113;
} break;
case 2: {
C = 54;
// B = b0000bb00
u32 b = (bitval >> 1) & 1;
B = (b << 8) | (b << 3) | (b << 2);
} break;
case 3: {
C = 26;
// B = cb0000cbc
u32 cb = (bitval >> 1) & 3;
B = (cb << 7) | (cb << 1) | (cb >> 1);
} break;
case 4: {
C = 13;
// B = dcb0000dc
u32 dcb = (bitval >> 1) & 7;
B = (dcb << 6) | (dcb >> 1);
} break;
case 5: {
C = 6;
// B = edcb0000e
u32 edcb = (bitval >> 1) & 0xF;
B = (edcb << 5) | (edcb >> 3);
} break;
default:
assert(false && "Unsupported quint encoding for color values!");
break;
} // switch(bitlen)
} // case IntegerEncoding::Quint
break;
} // switch(val.encoding)
if (val.encoding != IntegerEncoding::JustBits) {
u32 T = D * C + B;
T ^= A;
T = (A & 0x80) | (T >> 2);
out[outIdx++] = T;
}
}
// Make sure that each of our values is in the proper range...
for (u32 i = 0; i < nValues; i++) {
assert(out[i] <= 255);
}
}
static u32 UnquantizeTexelWeight(const IntegerEncodedValue& val) {
u32 bitval = val.bit_value;
u32 bitlen = val.num_bits;
u32 A = ReplicateBitTo7(bitval & 1);
u32 B = 0, C = 0, D = 0;
u32 result = 0;
switch (val.encoding) {
case IntegerEncoding::JustBits:
result = FastReplicateTo6(bitval, bitlen);
break;
case IntegerEncoding::Trit: {
D = val.trit_value;
assert(D < 3);
switch (bitlen) {
case 0: {
u32 results[3] = {0, 32, 63};
result = results[D];
} break;
case 1: {
C = 50;
} break;
case 2: {
C = 23;
u32 b = (bitval >> 1) & 1;
B = (b << 6) | (b << 2) | b;
} break;
case 3: {
C = 11;
u32 cb = (bitval >> 1) & 3;
B = (cb << 5) | cb;
} break;
default:
assert(false && "Invalid trit encoding for texel weight");
break;
}
} break;
case IntegerEncoding::Quint: {
D = val.quint_value;
assert(D < 5);
switch (bitlen) {
case 0: {
u32 results[5] = {0, 16, 32, 47, 63};
result = results[D];
} break;
case 1: {
C = 28;
} break;
case 2: {
C = 13;
u32 b = (bitval >> 1) & 1;
B = (b << 6) | (b << 1);
} break;
default:
assert(false && "Invalid quint encoding for texel weight");
break;
}
} break;
}
if (val.encoding != IntegerEncoding::JustBits && bitlen > 0) {
// Decode the value...
result = D * C + B;
result ^= A;
result = (A & 0x20) | (result >> 2);
}
assert(result < 64);
// Change from [0,63] to [0,64]
if (result > 32) {
result += 1;
}
return result;
}
static void UnquantizeTexelWeights(u32 out[2][144], const IntegerEncodedVector& weights,
const TexelWeightParams& params, const u32 blockWidth,
const u32 blockHeight) {
u32 weightIdx = 0;
u32 unquantized[2][144];
for (auto itr = weights.begin(); itr != weights.end(); ++itr) {
unquantized[0][weightIdx] = UnquantizeTexelWeight(*itr);
if (params.m_bDualPlane) {
++itr;
unquantized[1][weightIdx] = UnquantizeTexelWeight(*itr);
if (itr == weights.end()) {
break;
}
}
if (++weightIdx >= (params.m_Width * params.m_Height))
break;
}
// Do infill if necessary (Section C.2.18) ...
u32 Ds = (1024 + (blockWidth / 2)) / (blockWidth - 1);
u32 Dt = (1024 + (blockHeight / 2)) / (blockHeight - 1);
const u32 kPlaneScale = params.m_bDualPlane ? 2U : 1U;
for (u32 plane = 0; plane < kPlaneScale; plane++)
for (u32 t = 0; t < blockHeight; t++)
for (u32 s = 0; s < blockWidth; s++) {
u32 cs = Ds * s;
u32 ct = Dt * t;
u32 gs = (cs * (params.m_Width - 1) + 32) >> 6;
u32 gt = (ct * (params.m_Height - 1) + 32) >> 6;
u32 js = gs >> 4;
u32 fs = gs & 0xF;
u32 jt = gt >> 4;
u32 ft = gt & 0x0F;
u32 w11 = (fs * ft + 8) >> 4;
u32 w10 = ft - w11;
u32 w01 = fs - w11;
u32 w00 = 16 - fs - ft + w11;
u32 v0 = js + jt * params.m_Width;
#define FIND_TEXEL(tidx, bidx) \
u32 p##bidx = 0; \
do { \
if ((tidx) < (params.m_Width * params.m_Height)) { \
p##bidx = unquantized[plane][(tidx)]; \
} \
} while (0)
FIND_TEXEL(v0, 00);
FIND_TEXEL(v0 + 1, 01);
FIND_TEXEL(v0 + params.m_Width, 10);
FIND_TEXEL(v0 + params.m_Width + 1, 11);
#undef FIND_TEXEL
out[plane][t * blockWidth + s] =
(p00 * w00 + p01 * w01 + p10 * w10 + p11 * w11 + 8) >> 4;
}
}
// Transfers a bit as described in C.2.14
static inline void BitTransferSigned(int& a, int& b) {
b >>= 1;
b |= a & 0x80;
a >>= 1;
a &= 0x3F;
if (a & 0x20)
a -= 0x40;
}
// Adds more precision to the blue channel as described
// in C.2.14
static inline Pixel BlueContract(s32 a, s32 r, s32 g, s32 b) {
return Pixel(static_cast<s16>(a), static_cast<s16>((r + b) >> 1),
static_cast<s16>((g + b) >> 1), static_cast<s16>(b));
}
// Partition selection functions as specified in
// C.2.21
static inline u32 hash52(u32 p) {
p ^= p >> 15;
p -= p << 17;
p += p << 7;
p += p << 4;
p ^= p >> 5;
p += p << 16;
p ^= p >> 7;
p ^= p >> 3;
p ^= p << 6;
p ^= p >> 17;
return p;
}
static u32 SelectPartition(s32 seed, s32 x, s32 y, s32 z, s32 partitionCount, s32 smallBlock) {
if (1 == partitionCount)
return 0;
if (smallBlock) {
x <<= 1;
y <<= 1;
z <<= 1;
}
seed += (partitionCount - 1) * 1024;
u32 rnum = hash52(static_cast<u32>(seed));
u8 seed1 = static_cast<u8>(rnum & 0xF);
u8 seed2 = static_cast<u8>((rnum >> 4) & 0xF);
u8 seed3 = static_cast<u8>((rnum >> 8) & 0xF);
u8 seed4 = static_cast<u8>((rnum >> 12) & 0xF);
u8 seed5 = static_cast<u8>((rnum >> 16) & 0xF);
u8 seed6 = static_cast<u8>((rnum >> 20) & 0xF);
u8 seed7 = static_cast<u8>((rnum >> 24) & 0xF);
u8 seed8 = static_cast<u8>((rnum >> 28) & 0xF);
u8 seed9 = static_cast<u8>((rnum >> 18) & 0xF);
u8 seed10 = static_cast<u8>((rnum >> 22) & 0xF);
u8 seed11 = static_cast<u8>((rnum >> 26) & 0xF);
u8 seed12 = static_cast<u8>(((rnum >> 30) | (rnum << 2)) & 0xF);
seed1 = static_cast<u8>(seed1 * seed1);
seed2 = static_cast<u8>(seed2 * seed2);
seed3 = static_cast<u8>(seed3 * seed3);
seed4 = static_cast<u8>(seed4 * seed4);
seed5 = static_cast<u8>(seed5 * seed5);
seed6 = static_cast<u8>(seed6 * seed6);
seed7 = static_cast<u8>(seed7 * seed7);
seed8 = static_cast<u8>(seed8 * seed8);
seed9 = static_cast<u8>(seed9 * seed9);
seed10 = static_cast<u8>(seed10 * seed10);
seed11 = static_cast<u8>(seed11 * seed11);
seed12 = static_cast<u8>(seed12 * seed12);
s32 sh1, sh2, sh3;
if (seed & 1) {
sh1 = (seed & 2) ? 4 : 5;
sh2 = (partitionCount == 3) ? 6 : 5;
} else {
sh1 = (partitionCount == 3) ? 6 : 5;
sh2 = (seed & 2) ? 4 : 5;
}
sh3 = (seed & 0x10) ? sh1 : sh2;
seed1 = static_cast<u8>(seed1 >> sh1);
seed2 = static_cast<u8>(seed2 >> sh2);
seed3 = static_cast<u8>(seed3 >> sh1);
seed4 = static_cast<u8>(seed4 >> sh2);
seed5 = static_cast<u8>(seed5 >> sh1);
seed6 = static_cast<u8>(seed6 >> sh2);
seed7 = static_cast<u8>(seed7 >> sh1);
seed8 = static_cast<u8>(seed8 >> sh2);
seed9 = static_cast<u8>(seed9 >> sh3);
seed10 = static_cast<u8>(seed10 >> sh3);
seed11 = static_cast<u8>(seed11 >> sh3);
seed12 = static_cast<u8>(seed12 >> sh3);
s32 a = seed1 * x + seed2 * y + seed11 * z + (rnum >> 14);
s32 b = seed3 * x + seed4 * y + seed12 * z + (rnum >> 10);
s32 c = seed5 * x + seed6 * y + seed9 * z + (rnum >> 6);
s32 d = seed7 * x + seed8 * y + seed10 * z + (rnum >> 2);
a &= 0x3F;
b &= 0x3F;
c &= 0x3F;
d &= 0x3F;
if (partitionCount < 4)
d = 0;
if (partitionCount < 3)
c = 0;
if (a >= b && a >= c && a >= d)
return 0;
else if (b >= c && b >= d)
return 1;
else if (c >= d)
return 2;
return 3;
}
static inline u32 Select2DPartition(s32 seed, s32 x, s32 y, s32 partitionCount, s32 smallBlock) {
return SelectPartition(seed, x, y, 0, partitionCount, smallBlock);
}
// Section C.2.14
static void ComputeEndpoints(Pixel& ep1, Pixel& ep2, const u32*& colorValues,
u32 colorEndpointMode) {
#define READ_UINT_VALUES(N) \
u32 v[N]; \
for (u32 i = 0; i < N; i++) { \
v[i] = *(colorValues++); \
}
#define READ_INT_VALUES(N) \
s32 v[N]; \
for (u32 i = 0; i < N; i++) { \
v[i] = static_cast<int>(*(colorValues++)); \
}
switch (colorEndpointMode) {
case 0: {
READ_UINT_VALUES(2)
ep1 = Pixel(0xFF, v[0], v[0], v[0]);
ep2 = Pixel(0xFF, v[1], v[1], v[1]);
} break;
case 1: {
READ_UINT_VALUES(2)
u32 L0 = (v[0] >> 2) | (v[1] & 0xC0);
u32 L1 = std::min(L0 + (v[1] & 0x3F), 0xFFU);
ep1 = Pixel(0xFF, L0, L0, L0);
ep2 = Pixel(0xFF, L1, L1, L1);
} break;
case 4: {
READ_UINT_VALUES(4)
ep1 = Pixel(v[2], v[0], v[0], v[0]);
ep2 = Pixel(v[3], v[1], v[1], v[1]);
} break;
case 5: {
READ_INT_VALUES(4)
BitTransferSigned(v[1], v[0]);
BitTransferSigned(v[3], v[2]);
ep1 = Pixel(v[2], v[0], v[0], v[0]);
ep2 = Pixel(v[2] + v[3], v[0] + v[1], v[0] + v[1], v[0] + v[1]);
ep1.ClampByte();
ep2.ClampByte();
} break;
case 6: {
READ_UINT_VALUES(4)
ep1 = Pixel(0xFF, v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8);
ep2 = Pixel(0xFF, v[0], v[1], v[2]);
} break;
case 8: {
READ_UINT_VALUES(6)
if (v[1] + v[3] + v[5] >= v[0] + v[2] + v[4]) {
ep1 = Pixel(0xFF, v[0], v[2], v[4]);
ep2 = Pixel(0xFF, v[1], v[3], v[5]);
} else {
ep1 = BlueContract(0xFF, v[1], v[3], v[5]);
ep2 = BlueContract(0xFF, v[0], v[2], v[4]);
}
} break;
case 9: {
READ_INT_VALUES(6)
BitTransferSigned(v[1], v[0]);
BitTransferSigned(v[3], v[2]);
BitTransferSigned(v[5], v[4]);
if (v[1] + v[3] + v[5] >= 0) {
ep1 = Pixel(0xFF, v[0], v[2], v[4]);
ep2 = Pixel(0xFF, v[0] + v[1], v[2] + v[3], v[4] + v[5]);
} else {
ep1 = BlueContract(0xFF, v[0] + v[1], v[2] + v[3], v[4] + v[5]);
ep2 = BlueContract(0xFF, v[0], v[2], v[4]);
}
ep1.ClampByte();
ep2.ClampByte();
} break;
case 10: {
READ_UINT_VALUES(6)
ep1 = Pixel(v[4], v[0] * v[3] >> 8, v[1] * v[3] >> 8, v[2] * v[3] >> 8);
ep2 = Pixel(v[5], v[0], v[1], v[2]);
} break;
case 12: {
READ_UINT_VALUES(8)
if (v[1] + v[3] + v[5] >= v[0] + v[2] + v[4]) {
ep1 = Pixel(v[6], v[0], v[2], v[4]);
ep2 = Pixel(v[7], v[1], v[3], v[5]);
} else {
ep1 = BlueContract(v[7], v[1], v[3], v[5]);
ep2 = BlueContract(v[6], v[0], v[2], v[4]);
}
} break;
case 13: {
READ_INT_VALUES(8)
BitTransferSigned(v[1], v[0]);
BitTransferSigned(v[3], v[2]);
BitTransferSigned(v[5], v[4]);
BitTransferSigned(v[7], v[6]);
if (v[1] + v[3] + v[5] >= 0) {
ep1 = Pixel(v[6], v[0], v[2], v[4]);
ep2 = Pixel(v[7] + v[6], v[0] + v[1], v[2] + v[3], v[4] + v[5]);
} else {
ep1 = BlueContract(v[6] + v[7], v[0] + v[1], v[2] + v[3], v[4] + v[5]);
ep2 = BlueContract(v[6], v[0], v[2], v[4]);
}
ep1.ClampByte();
ep2.ClampByte();
} break;
default:
assert(false && "Unsupported color endpoint mode (is it HDR?)");
break;
}
#undef READ_UINT_VALUES
#undef READ_INT_VALUES
}
static void FillVoidExtentLDR(InputBitStream& strm, std::span<u32> outBuf, u32 blockWidth,
u32 blockHeight) {
// Don't actually care about the void extent, just read the bits...
for (s32 i = 0; i < 4; ++i) {
strm.ReadBits<13>();
}
// Decode the RGBA components and renormalize them to the range [0, 255]
u16 r = static_cast<u16>(strm.ReadBits<16>());
u16 g = static_cast<u16>(strm.ReadBits<16>());
u16 b = static_cast<u16>(strm.ReadBits<16>());
u16 a = static_cast<u16>(strm.ReadBits<16>());
u32 rgba = (r >> 8) | (g & 0xFF00) | (static_cast<u32>(b) & 0xFF00) << 8 |
(static_cast<u32>(a) & 0xFF00) << 16;
for (u32 j = 0; j < blockHeight; j++) {
for (u32 i = 0; i < blockWidth; i++) {
outBuf[j * blockWidth + i] = rgba;
}
}
}
static void FillError(std::span<u32> outBuf, u32 blockWidth, u32 blockHeight) {
for (u32 j = 0; j < blockHeight; j++) {
for (u32 i = 0; i < blockWidth; i++) {
outBuf[j * blockWidth + i] = 0xFFFF00FF;
}
}
}
static void DecompressBlock(std::span<const u8, 16> inBuf, const u32 blockWidth,
const u32 blockHeight, std::span<u32, 12 * 12> outBuf) {
InputBitStream strm(inBuf);
TexelWeightParams weightParams = DecodeBlockInfo(strm);
// Was there an error?
if (weightParams.m_bError) {
assert(false && "Invalid block mode");
FillError(outBuf, blockWidth, blockHeight);
return;
}
if (weightParams.m_bVoidExtentLDR) {
FillVoidExtentLDR(strm, outBuf, blockWidth, blockHeight);
return;
}
if (weightParams.m_bVoidExtentHDR) {
assert(false && "HDR void extent blocks are unsupported!");
FillError(outBuf, blockWidth, blockHeight);
return;
}
if (weightParams.m_Width > blockWidth) {
assert(false && "Texel weight grid width should be smaller than block width");
FillError(outBuf, blockWidth, blockHeight);
return;
}
if (weightParams.m_Height > blockHeight) {
assert(false && "Texel weight grid height should be smaller than block height");
FillError(outBuf, blockWidth, blockHeight);
return;
}
// Read num partitions
u32 nPartitions = strm.ReadBits<2>() + 1;
assert(nPartitions <= 4);
if (nPartitions == 4 && weightParams.m_bDualPlane) {
assert(false && "Dual plane mode is incompatible with four partition blocks");
FillError(outBuf, blockWidth, blockHeight);
return;
}
// Based on the number of partitions, read the color endpoint mode for
// each partition.
// Determine partitions, partition index, and color endpoint modes
u32 planeIdx{UINT32_MAX};
u32 partitionIndex{};
u32 colorEndpointMode[4] = {0, 0, 0, 0};
// Define color data.
u8 colorEndpointData[16];
memset(colorEndpointData, 0, sizeof(colorEndpointData));
OutputBitStream colorEndpointStream(colorEndpointData, 16 * 8, 0);
// Read extra config data...
u32 baseCEM = 0;
if (nPartitions == 1) {
colorEndpointMode[0] = strm.ReadBits<4>();
partitionIndex = 0;
} else {
partitionIndex = strm.ReadBits<10>();
baseCEM = strm.ReadBits<6>();
}
u32 baseMode = (baseCEM & 3);
// Remaining bits are color endpoint data...
u32 nWeightBits = weightParams.GetPackedBitSize();
s32 remainingBits = 128 - nWeightBits - static_cast<int>(strm.GetBitsRead());
// Consider extra bits prior to texel data...
u32 extraCEMbits = 0;
if (baseMode) {
switch (nPartitions) {
case 2:
extraCEMbits += 2;
break;
case 3:
extraCEMbits += 5;
break;
case 4:
extraCEMbits += 8;
break;
default:
assert(false);
break;
}
}
remainingBits -= extraCEMbits;
// Do we have a dual plane situation?
u32 planeSelectorBits = 0;
if (weightParams.m_bDualPlane) {
planeSelectorBits = 2;
}
remainingBits -= planeSelectorBits;
// Read color data...
u32 colorDataBits = remainingBits;
while (remainingBits > 0) {
u32 nb = std::min(remainingBits, 8);
u32 b = strm.ReadBits(nb);
colorEndpointStream.WriteBits(b, nb);
remainingBits -= 8;
}
// Read the plane selection bits
planeIdx = strm.ReadBits(planeSelectorBits);
// Read the rest of the CEM
if (baseMode) {
u32 extraCEM = strm.ReadBits(extraCEMbits);
u32 CEM = (extraCEM << 6) | baseCEM;
CEM >>= 2;
bool C[4] = {0};
for (u32 i = 0; i < nPartitions; i++) {
C[i] = CEM & 1;
CEM >>= 1;
}
u8 M[4] = {0};
for (u32 i = 0; i < nPartitions; i++) {
M[i] = CEM & 3;
CEM >>= 2;
assert(M[i] <= 3);
}
for (u32 i = 0; i < nPartitions; i++) {
colorEndpointMode[i] = baseMode;
if (!(C[i]))
colorEndpointMode[i] -= 1;
colorEndpointMode[i] <<= 2;
colorEndpointMode[i] |= M[i];
}
} else if (nPartitions > 1) {
u32 CEM = baseCEM >> 2;
for (u32 i = 0; i < nPartitions; i++) {
colorEndpointMode[i] = CEM;
}
}
// Make sure everything up till here is sane.
for (u32 i = 0; i < nPartitions; i++) {
assert(colorEndpointMode[i] < 16);
}
assert(strm.GetBitsRead() + weightParams.GetPackedBitSize() == 128);
// Decode both color data and texel weight data
u32 colorValues[32]; // Four values, two endpoints, four maximum paritions
DecodeColorValues(colorValues, colorEndpointData, colorEndpointMode, nPartitions,
colorDataBits);
Pixel endpoints[4][2];
const u32* colorValuesPtr = colorValues;
for (u32 i = 0; i < nPartitions; i++) {
ComputeEndpoints(endpoints[i][0], endpoints[i][1], colorValuesPtr, colorEndpointMode[i]);
}
// Read the texel weight data..
std::array<u8, 16> texelWeightData;
std::ranges::copy(inBuf, texelWeightData.begin());
// Reverse everything
for (u32 i = 0; i < 8; i++) {
// Taken from http://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith64Bits
#define REVERSE_BYTE(b) (((b)*0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32
u8 a = static_cast<u8>(REVERSE_BYTE(texelWeightData[i]));
u8 b = static_cast<u8>(REVERSE_BYTE(texelWeightData[15 - i]));
#undef REVERSE_BYTE
texelWeightData[i] = b;
texelWeightData[15 - i] = a;
}
// Make sure that higher non-texel bits are set to zero
const u32 clearByteStart = (weightParams.GetPackedBitSize() >> 3) + 1;
if (clearByteStart > 0 && clearByteStart <= texelWeightData.size()) {
texelWeightData[clearByteStart - 1] &=
static_cast<u8>((1 << (weightParams.GetPackedBitSize() % 8)) - 1);
std::memset(texelWeightData.data() + clearByteStart, 0,
std::min(16U - clearByteStart, 16U));
}
IntegerEncodedVector texelWeightValues;
InputBitStream weightStream(texelWeightData);
DecodeIntegerSequence(texelWeightValues, weightStream, weightParams.m_MaxWeight,
weightParams.GetNumWeightValues());
// Blocks can be at most 12x12, so we can have as many as 144 weights
u32 weights[2][144];
UnquantizeTexelWeights(weights, texelWeightValues, weightParams, blockWidth, blockHeight);
// Now that we have endpoints and weights, we can interpolate and generate
// the proper decoding...
for (u32 j = 0; j < blockHeight; j++)
for (u32 i = 0; i < blockWidth; i++) {
u32 partition = Select2DPartition(partitionIndex, i, j, nPartitions,
(blockHeight * blockWidth) < 32);
assert(partition < nPartitions);
Pixel p;
for (u32 c = 0; c < 4; c++) {
u32 C0 = endpoints[partition][0].Component(c);
C0 = ReplicateByteTo16(C0);
u32 C1 = endpoints[partition][1].Component(c);
C1 = ReplicateByteTo16(C1);
u32 plane = 0;
if (weightParams.m_bDualPlane && (((planeIdx + 1) & 3) == c)) {
plane = 1;
}
u32 weight = weights[plane][j * blockWidth + i];
u32 C = (C0 * (64 - weight) + C1 * weight + 32) / 64;
if (C == 65535) {
p.Component(c) = 255;
} else {
double Cf = static_cast<double>(C);
p.Component(c) = static_cast<u16>(255.0 * (Cf / 65536.0) + 0.5);
}
}
outBuf[j * blockWidth + i] = p.Pack();
}
}
void Decompress(std::span<const uint8_t> data, uint32_t width, uint32_t height, uint32_t depth,
uint32_t block_width, uint32_t block_height, std::span<uint8_t> output) {
u32 block_index = 0;
std::size_t depth_offset = 0;
for (u32 z = 0; z < depth; z++) {
for (u32 y = 0; y < height; y += block_height) {
for (u32 x = 0; x < width; x += block_width) {
const std::span<const u8, 16> blockPtr{data.subspan(block_index * 16, 16)};
// Blocks can be at most 12x12
std::array<u32, 12 * 12> uncompData;
DecompressBlock(blockPtr, block_width, block_height, uncompData);
u32 decompWidth = std::min(block_width, width - x);
u32 decompHeight = std::min(block_height, height - y);
const std::span<u8> outRow = output.subspan(depth_offset + (y * width + x) * 4);
for (u32 jj = 0; jj < decompHeight; jj++) {
std::memcpy(outRow.data() + jj * width * 4,
uncompData.data() + jj * block_width, decompWidth * 4);
}
++block_index;
}
}
depth_offset += height * width * 4;
}
}
} // namespace Tegra::Texture::ASTC
