Revert of Initial ASTC decoder -- currently only supports 2D LDR decomrpession modes.

src/utils/SkTextureCompressor_ASTC.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTextureCompressor_ASTC.h"
 #include "SkTextureCompressor_Blitter.h"
 
 #include "SkBlitter.h"
 #include "SkEndian.h"
-#include "SkMath.h"
 
 // This table contains the weight values for each texel. This is used in determining
 // how to convert a 12x12 grid of alpha values into a 6x5 grid of index values. Since
 // we have a 6x5 grid, that gives 30 values that we have to compute. For each index,
 // we store up to 20 different triplets of values. In order the triplets are:
 // weight, texel-x, texel-y
 // The weight value corresponds to the amount that this index contributes to the final
 // index value of the given texel. Hence, we need to reconstruct the 6x5 index grid
 // from their relative contribution to the 12x12 texel grid.
 //
@@ skipping 231 matching lines @@
     top = top ^ t ^ (t << 2);
 
     send_packing(dst, SkEndian_SwapLE64(top), SkEndian_SwapLE64(bottom));
 }
 
 inline void CompressA8ASTCBlockVertical(uint8_t* dst, const uint8_t* src) {
     compress_a8_astc_block<GetAlphaTranspose>(&dst, src, 12);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-//
-// ASTC Decoder
-//
-// Full details available in the spec:
-// http://www.khronos.org/registry/gles/extensions/OES/OES_texture_compression_astc.txt
-//
-////////////////////////////////////////////////////////////////////////////////
-
-// Enable this to assert whenever a decoded block has invalid ASTC values. Otherwise, 
-// each invalid block will result in a disgusting magenta color.
-#define ASSERT_ASTC_DECODE_ERROR 0
-
-// Reverse 64-bit integer taken from TAOCP 4a, although it's better
-// documented at this site:
-// http://matthewarcus.wordpress.com/2012/11/18/reversing-a-64-bit-word/
-
-template <typename T, T m, int k>
-static inline T swap_bits(T p) {
-    T q = ((p>>k)^p) & m;
-    return p^q^(q<<k);
-}
-
-static inline uint64_t reverse64(uint64_t n) {
-    static const uint64_t m0 = 0x5555555555555555LLU;
-    static const uint64_t m1 = 0x0300c0303030c303LLU;
-    static const uint64_t m2 = 0x00c0300c03f0003fLLU;
-    static const uint64_t m3 = 0x00000ffc00003fffLLU;
-    n = ((n>>1)&m0) | (n&m0)<<1;
-    n = swap_bits<uint64_t, m1, 4>(n);
-    n = swap_bits<uint64_t, m2, 8>(n);
-    n = swap_bits<uint64_t, m3, 20>(n);
-    n = (n >> 34) | (n << 30);
-    return n;
-}
-
-// An ASTC block is 128 bits. We represent it as two 64-bit integers in order
-// to efficiently operate on the block using bitwise operations.
-struct ASTCBlock {
-    uint64_t fLow;
-    uint64_t fHigh;
-
-    // Reverses the bits of an ASTC block, making the LSB of the
-    // 128 bit block the MSB.
-    inline void reverse() {
-        const uint64_t newLow = reverse64(this->fHigh);
-        this->fHigh = reverse64(this->fLow);
-        this->fLow = newLow;
-    }
-};
-
-// Writes the given color to every pixel in the block. This is used by void-extent
-// blocks (a special constant-color encoding of a block) and by the error function.
-static inline void write_constant_color(uint8_t* dst, int blockDimX, int blockDimY,
-                                        int dstRowBytes, SkColor color) {
-    for (int y = 0; y < blockDimY; ++y) {
-        SkColor *dstColors = reinterpret_cast<SkColor*>(dst);
-        for (int x = 0; x < blockDimX; ++x) {
-            dstColors[x] = color;
-        }
-        dst += dstRowBytes;
-    }
-}
-
-// Sets the entire block to the ASTC "error" color, a disgusting magenta
-// that's not supposed to appear in natural images.
-static inline void write_error_color(uint8_t* dst, int blockDimX, int blockDimY,
-                                     int dstRowBytes) {
-    static const SkColor kASTCErrorColor = SkColorSetRGB(0xFF, 0, 0xFF);
-
-#if ASSERT_ASTC_DECODE_ERROR
-    SkDEBUGFAIL("ASTC decoding error!\n");
-#endif
-
-    write_constant_color(dst, blockDimX, blockDimY, dstRowBytes, kASTCErrorColor);
-}
-
-// Reads up to 64 bits of the ASTC block starting from bit
-// 'from' and going up to but not including bit 'to'. 'from' starts
-// counting from the LSB, counting up to the MSB. Returns -1 on
-// error.
-static uint64_t read_astc_bits(const ASTCBlock &block, int from, int to) {
-    SkASSERT(0 <= from && from <= 128);
-    SkASSERT(0 <= to && to <= 128);
-
-    const int nBits = to - from;
-    if (0 == nBits) {
-        return 0;
-    }
-
-    if (nBits < 0 || 64 <= nBits) {
-        SkDEBUGFAIL("ASTC -- shouldn't read more than 64 bits");
-        return -1;
-    }
-
-    // Remember, the 'to' bit isn't read.
-    uint64_t result = 0;
-    if (to <= 64) {
-        // All desired bits are in the low 64-bits.
-        result = (block.fLow >> from) & ((1ULL << nBits) - 1);
-    } else if (from >= 64) {
-        // All desired bits are in the high 64-bits.
-        result = (block.fHigh >> (from - 64)) & ((1ULL << nBits) - 1);
-    } else {
-        // from < 64 && to > 64
-        SkASSERT(nBits > (64 - from));
-        const int nLow = 64 - from;
-        const int nHigh = nBits - nLow;
-        result = 
-            ((block.fLow >> from) & ((1ULL << nLow) - 1)) |
-            ((block.fHigh & ((1ULL << nHigh) - 1)) << nLow);
-    }
-
-    return result;
-}
-
-// Returns the number of bits needed to represent a number
-// in the given power-of-two range (excluding the power of two itself).
-static inline int bits_for_range(int x) {
-    SkASSERT(SkIsPow2(x));
-    SkASSERT(0 != x);
-    // Since we know it's a power of two, there should only be one bit set,
-    // meaning the number of trailing zeros is 31 minus the number of leading
-    // zeros.
-    return 31 - SkCLZ(x);
-}
-
-// Clamps an integer to the range [0, 255]
-static inline int clamp_byte(int x) {
-    return SkClampMax(x, 255);
-}
-
-// Helper function defined in the ASTC spec, section C.2.14
-// It transfers a few bits of precision from one value to another.
-static inline void bit_transfer_signed(int *a, int *b) {
-    *b >>= 1;
-    *b |= *a & 0x80;
-    *a >>= 1;
-    *a &= 0x3F;
-    if ( (*a & 0x20) != 0 ) {
-        *a -= 0x40;
-    }
-}
-
-// Helper function defined in the ASTC spec, section C.2.14
-// It uses the value in the blue channel to tint the red and green
-static inline SkColor blue_contract(int a, int r, int g, int b) {
-    return SkColorSetARGB(a, (r + b) >> 1, (g + b) >> 1, b);
-}
-
-// Helper function that decodes two colors from eight values. If isRGB is true,
-// then the pointer 'v' contains six values and the last two are considered to be
-// 0xFF. If isRGB is false, then all eight values come from the pointer 'v'. This
-// corresponds to the decode procedure for the following endpoint modes:
-//   kLDR_RGB_Direct_ColorEndpointMode
-//   kLDR_RGBA_Direct_ColorEndpointMode
-static inline void decode_rgba_direct(const int *v, SkColor *endpoints, bool isRGB) {
-
-    int v6 = 0xFF;
-    int v7 = 0xFF;
-    if (!isRGB) {
-        v6 = v[6];
-        v7 = v[7];
-    }
-
-    const int s0 = v[0] + v[2] + v[4];
-    const int s1 = v[1] + v[3] + v[5];
-
-    if (s1 >= s0) {
-        endpoints[0] = SkColorSetARGB(v6, v[0], v[2], v[4]);
-        endpoints[1] = SkColorSetARGB(v7, v[1], v[3], v[5]);
-    } else {
-        endpoints[0] = blue_contract(v7, v[1], v[3], v[5]);
-        endpoints[1] = blue_contract(v6, v[0], v[2], v[4]);
-    }
-}
-
-// Helper function that decodes two colors from six values. If isRGB is true,
-// then the pointer 'v' contains four values and the last two are considered to be
-// 0xFF. If isRGB is false, then all six values come from the pointer 'v'. This
-// corresponds to the decode procedure for the following endpoint modes:
-//   kLDR_RGB_BaseScale_ColorEndpointMode
-//   kLDR_RGB_BaseScaleWithAlpha_ColorEndpointMode
-static inline void decode_rgba_basescale(const int *v, SkColor *endpoints, bool isRGB) {
-
-    int v4 = 0xFF;
-    int v5 = 0xFF;
-    if (!isRGB) {
-        v4 = v[4];
-        v5 = v[5];
-    }
-                  
-    endpoints[0] = SkColorSetARGB(v4,
-                                  (v[0]*v[3]) >> 8,
-                                  (v[1]*v[3]) >> 8,
-                                  (v[2]*v[3]) >> 8);
-    endpoints[1] = SkColorSetARGB(v5, v[0], v[1], v[2]);
-}
-
-// Helper function that decodes two colors from eight values. If isRGB is true,
-// then the pointer 'v' contains six values and the last two are considered to be
-// 0xFF. If isRGB is false, then all eight values come from the pointer 'v'. This
-// corresponds to the decode procedure for the following endpoint modes:
-//   kLDR_RGB_BaseOffset_ColorEndpointMode
-//   kLDR_RGBA_BaseOffset_ColorEndpointMode
-//
-// If isRGB is true, then treat this as if v6 and v7 are meant to encode full alpha values.
-static inline void decode_rgba_baseoffset(const int *v, SkColor *endpoints, bool isRGB) {
-    int v0 = v[0];
-    int v1 = v[1];
-    int v2 = v[2];
-    int v3 = v[3];
-    int v4 = v[4];
-    int v5 = v[5];
-    int v6 = isRGB ? 0xFF : v[6];
-    // The 0 is here because this is an offset, not a direct value
-    int v7 = isRGB ? 0 : v[7];
-
-    bit_transfer_signed(&v1, &v0);
-    bit_transfer_signed(&v3, &v2);
-    bit_transfer_signed(&v5, &v4);
-    if (!isRGB) {
-        bit_transfer_signed(&v7, &v6);
-    }
-
-    int c[2][4];
-    if ((v1 + v3 + v5) >= 0) {
-        c[0][0] = v6;
-        c[0][1] = v0;
-        c[0][2] = v2;
-        c[0][3] = v4;
-
-        c[1][0] = v6 + v7;
-        c[1][1] = v0 + v1;
-        c[1][2] = v2 + v3;
-        c[1][3] = v4 + v5;
-    } else {
-        c[0][0] = v6 + v7;
-        c[0][1] = (v0 + v1 + v4 + v5) >> 1;
-        c[0][2] = (v2 + v3 + v4 + v5) >> 1;
-        c[0][3] = v4 + v5;
-
-        c[1][0] = v6;
-        c[1][1] = (v0 + v4) >> 1;
-        c[1][2] = (v2 + v4) >> 1;
-        c[1][3] = v4;
-    }
-
-    endpoints[0] = SkColorSetARGB(clamp_byte(c[0][0]),
-                                  clamp_byte(c[0][1]),
-                                  clamp_byte(c[0][2]),
-                                  clamp_byte(c[0][3]));
-
-    endpoints[1] = SkColorSetARGB(clamp_byte(c[1][0]),
-                                  clamp_byte(c[1][1]),
-                                  clamp_byte(c[1][2]),
-                                  clamp_byte(c[1][3]));
-}
-
-
-// A helper class used to decode bit values from standard integer values.
-// We can't use this class with ASTCBlock because then it would need to
-// handle multi-value ranges, and it's non-trivial to lookup a range of bits
-// that splits across two different ints.
-template <typename T>
-class SkTBits {
-public:
-    SkTBits(const T val) : fVal(val) { }
-
-    // Returns the bit at the given position
-    T operator [](const int idx) const {
-        return (fVal >> idx) & 1;
-    }
-
-    // Returns the bits in the given range, inclusive
-    T operator ()(const int end, const int start) const {
-        SkASSERT(end >= start);
-        return (fVal >> start) & ((1ULL << ((end - start) + 1)) - 1);
-    }
-
-private:
-    const T fVal;
-};
-
-// This algorithm matches the trit block decoding in the spec (Table C.2.14)
-static void decode_trit_block(int* dst, int nBits, const uint64_t &block) {
-
-    SkTBits<uint64_t> blockBits(block);
-
-    // According to the spec, a trit block, which contains five values,
-    // has the following layout:
-    //
-    // 27  26  25  24  23  22  21  20  19  18  17  16
-    //  -----------------------------------------------
-    // |T7 |     m4        |T6  T5 |     m3        |T4 |
-    //  -----------------------------------------------
-    //
-    // 15  14  13  12  11  10  9   8   7   6   5   4   3   2   1   0
-    //  --------------------------------------------------------------
-    // |    m2        |T3  T2 |      m1       |T1  T0 |      m0       |
-    //  --------------------------------------------------------------
-    //
-    // Where the m's are variable width depending on the number of bits used
-    // to encode the values (anywhere from 0 to 6). Since 3^5 = 243, the extra
-    // byte labeled T (whose bits are interleaved where 0 is the LSB and 7 is
-    // the MSB), contains five trit values. To decode the trit values, the spec
-    // says that we need to follow the following algorithm:
-    //
-    // if T[4:2] = 111
-    //     C = { T[7:5], T[1:0] }; t4 = t3 = 2
-    // else
-    //     C = T[4:0]
-    //
-    // if T[6:5] = 11
-    //     t4 = 2; t3 = T[7]
-    // else
-    //     t4 = T[7]; t3 = T[6:5]
-    //
-    // if C[1:0] = 11
-    //     t2 = 2; t1 = C[4]; t0 = { C[3], C[2]&~C[3] }
-    // else if C[3:2] = 11
-    //     t2 = 2; t1 = 2; t0 = C[1:0]
-    // else
-    //     t2 = C[4]; t1 = C[3:2]; t0 = { C[1], C[0]&~C[1] }
-    //
-    // The following C++ code is meant to mirror this layout and algorithm as
-    // closely as possible.
-
-    int m[5];
-    if (0 == nBits) {
-        memset(m, 0, sizeof(m));
-    } else {
-        SkASSERT(nBits < 8);
-        m[0] = static_cast<int>(blockBits(nBits - 1, 0));
-        m[1] = static_cast<int>(blockBits(2*nBits - 1 + 2, nBits + 2));
-        m[2] = static_cast<int>(blockBits(3*nBits - 1 + 4, 2*nBits + 4));
-        m[3] = static_cast<int>(blockBits(4*nBits - 1 + 5, 3*nBits + 5));
-        m[4] = static_cast<int>(blockBits(5*nBits - 1 + 7, 4*nBits + 7));
-    }
-
-    int T =
-        static_cast<int>(blockBits(nBits + 1, nBits)) |
-        (static_cast<int>(blockBits(2*nBits + 2 + 1, 2*nBits + 2)) << 2) |
-        (static_cast<int>(blockBits[3*nBits + 4] << 4)) |
-        (static_cast<int>(blockBits(4*nBits + 5 + 1, 4*nBits + 5)) << 5) |
-        (static_cast<int>(blockBits[5*nBits + 7] << 7));
-
-    int t[5];
-
-    int C;
-    SkTBits<int> Tbits(T);
-    if (0x7 == Tbits(4, 2)) {
-        C = (Tbits(7, 5) << 2) | Tbits(1, 0);
-        t[3] = t[4] = 2;
-    } else {
-        C = Tbits(4, 0);
-        if (Tbits(6, 5) == 0x3) {
-            t[4] = 2; t[3] = Tbits[7];
-        } else {
-            t[4] = Tbits[7]; t[3] = Tbits(6, 5);
-        }
-    }
-
-    SkTBits<int> Cbits(C);
-    if (Cbits(1, 0) == 0x3) {
-        t[2] = 2;
-        t[1] = Cbits[4];
-        t[0] = (Cbits[3] << 1) | (Cbits[2] & (0x1 & ~(Cbits[3])));
-    } else if (Cbits(3, 2) == 0x3) {
-        t[2] = 2;
-        t[1] = 2;
-        t[0] = Cbits(1, 0);
-    } else {
-        t[2] = Cbits[4];
-        t[1] = Cbits(3, 2);
-        t[0] = (Cbits[1] << 1) | (Cbits[0] & (0x1 & ~(Cbits[1])));
-    }
-
-#if SK_DEBUG
-    // Make sure all of the decoded values have a trit less than three
-    // and a bit value within the range of the allocated bits.
-    for (int i = 0; i < 5; ++i) {
-        SkASSERT(t[i] < 3);
-        SkASSERT(m[i] < (1 << nBits));
-    }
-#endif
-
-    for (int i = 0; i < 5; ++i) {
-        *dst = (t[i] << nBits) + m[i];
-        ++dst;
-    }
-}
-
-// This algorithm matches the quint block decoding in the spec (Table C.2.15)
-static void decode_quint_block(int* dst, int nBits, const uint64_t &block) {
-    SkTBits<uint64_t> blockBits(block);
-
-    // According to the spec, a quint block, which contains three values,
-    // has the following layout:
-    //
-    //
-    // 18  17  16  15  14  13  12  11  10  9   8   7   6   5   4   3   2   1   0
-    //  --------------------------------------------------------------------------
-    // |Q6  Q5 |     m2       |Q4  Q3 |     m1        |Q2  Q1  Q0 |      m0       |
-    //  --------------------------------------------------------------------------
-    //
-    // Where the m's are variable width depending on the number of bits used
-    // to encode the values (anywhere from 0 to 4). Since 5^3 = 125, the extra
-    // 7-bit value labeled Q (whose bits are interleaved where 0 is the LSB and 6 is
-    // the MSB), contains three quint values. To decode the quint values, the spec
-    // says that we need to follow the following algorithm:
-    //
-    // if Q[2:1] = 11 and Q[6:5] = 00
-    //     q2 = { Q[0], Q[4]&~Q[0], Q[3]&~Q[0] }; q1 = q0 = 4
-    // else
-    //     if Q[2:1] = 11
-    //         q2 = 4; C = { Q[4:3], ~Q[6:5], Q[0] }
-    //     else
-    //         q2 = T[6:5]; C = Q[4:0]
-    //
-    //     if C[2:0] = 101
-    //         q1 = 4; q0 = C[4:3]
-    //     else
-    //         q1 = C[4:3]; q0 = C[2:0]
-    //
-    // The following C++ code is meant to mirror this layout and algorithm as
-    // closely as possible.
-
-    int m[3];
-    if (0 == nBits) {
-        memset(m, 0, sizeof(m));
-    } else {
-        SkASSERT(nBits < 8);
-        m[0] = static_cast<int>(blockBits(nBits - 1, 0));
-        m[1] = static_cast<int>(blockBits(2*nBits - 1 + 3, nBits + 3));
-        m[2] = static_cast<int>(blockBits(3*nBits - 1 + 5, 2*nBits + 5));
-    }
-
-    int Q =
-        static_cast<int>(blockBits(nBits + 2, nBits)) |
-        (static_cast<int>(blockBits(2*nBits + 3 + 1, 2*nBits + 3)) << 3) |
-        (static_cast<int>(blockBits(3*nBits + 5 + 1, 3*nBits + 5)) << 5);
-
-    int q[3];
-    SkTBits<int> Qbits(Q); // quantum?
-
-    if (Qbits(2, 1) == 0x3 && Qbits(6, 5) == 0) {
-        const int notBitZero = (0x1 & ~(Qbits[0]));
-        q[2] = (Qbits[0] << 2) | ((Qbits[4] & notBitZero) << 1) | (Qbits[3] & notBitZero);
-        q[1] = 4;
-        q[0] = 4;
-    } else {
-        int C;
-        if (Qbits(2, 1) == 0x3) {
-            q[2] = 4;
-            C = (Qbits(4, 3) << 3) | ((0x3 & ~(Qbits(6, 5))) << 1) | Qbits[0];
-        } else {
-            q[2] = Qbits(6, 5);
-            C = Qbits(4, 0);
-        }
-
-        SkTBits<int> Cbits(C);
-        if (Cbits(2, 0) == 0x5) {
-            q[1] = 4;
-            q[0] = Cbits(4, 3);
-        } else {
-            q[1] = Cbits(4, 3);
-            q[0] = Cbits(2, 0);
-        }
-    }
-
-#if SK_DEBUG
-    for (int i = 0; i < 3; ++i) {
-        SkASSERT(q[i] < 5);
-        SkASSERT(m[i] < (1 << nBits));
-    }
-#endif
-
-    for (int i = 0; i < 3; ++i) {
-        *dst = (q[i] << nBits) + m[i];
-        ++dst;
-    }
-}
-
-// Function that decodes a sequence of integers stored as an ISE (Integer
-// Sequence Encoding) bit stream. The full details of this function are outlined
-// in section C.2.12 of the ASTC spec. A brief overview is as follows:
-//
-// - Each integer in the sequence is bounded by a specific range r.
-// - The range of each value determines the way the bit stream is interpreted,
-// - If the range is a power of two, then the sequence is a sequence of bits
-// - If the range is of the form 3*2^n, then the sequence is stored as a
-//   sequence of blocks, each block contains 5 trits and 5 bit sequences, which
-//   decodes into 5 values.
-// - Similarly, if the range is of the form 5*2^n, then the sequence is stored as a
-//   sequence of blocks, each block contains 3 quints and 3 bit sequences, which
-//   decodes into 3 values.
-static bool decode_integer_sequence(
-    int* dst,                 // The array holding the destination bits
-    int dstSize,              // The maximum size of the array
-    int nVals,                // The number of values that we'd like to decode
-    const ASTCBlock &block,   // The block that we're decoding from
-    int startBit,             // The bit from which we're going to do the reading
-    int endBit,               // The bit at which we stop reading (not inclusive)
-    bool bReadForward,        // If true, then read LSB -> MSB, else read MSB -> LSB
-    int nBits,                // The number of bits representing this encoding
-    int nTrits,               // The number of trits representing this encoding
-    int nQuints               // The number of quints representing this encoding
-) {
-    // If we want more values than we have, then fail.
-    if (nVals > dstSize) {
-        return false;
-    }
-
-    ASTCBlock src = block;
-
-    if (!bReadForward) {
-        src.reverse();
-        startBit = 128 - startBit;
-        endBit = 128 - endBit;
-    }
-
-    while (nVals > 0) {
-
-        if (nTrits > 0) {
-            SkASSERT(0 == nQuints);
-
-            int endBlockBit = startBit + 8 + 5*nBits;
-            if (endBlockBit > endBit) {
-                endBlockBit = endBit;
-            }
-
-            decode_trit_block(dst, nBits, read_astc_bits(src, startBit, endBlockBit));
-            dst += 5;
-            nVals -= 5;
-            startBit = endBlockBit;
-
-        } else if (nQuints > 0) {
-            SkASSERT(0 == nTrits);
-
-            int endBlockBit = startBit + 7 + 3*nBits;
-            if (endBlockBit > endBit) {
-                endBlockBit = endBit;
-            }
-
-            decode_quint_block(dst, nBits, read_astc_bits(src, startBit, endBlockBit));
-            dst += 3;
-            nVals -= 3;
-            startBit = endBlockBit;
-
-        } else {
-            // Just read the bits, but don't read more than we have...
-            int endValBit = startBit + nBits;
-            if (endValBit > endBit) {
-                endValBit = endBit;
-            }
-
-            SkASSERT(endValBit - startBit < 31);
-            *dst = static_cast<int>(read_astc_bits(src, startBit, endValBit));
-            ++dst;
-            --nVals;
-            startBit = endValBit;
-        }
-    }
-
-    return true;
-}
-
-// Helper function that unquantizes some (seemingly random) generated
-// numbers... meant to match the ASTC hardware. This function is used
-// to unquantize both colors (Table C.2.16) and weights (Table C.2.26)
-static inline int unquantize_value(unsigned mask, int A, int B, int C, int D) {
-    int T = D * C + B;
-    T = T ^ A;
-    T = (A & mask) | (T >> 2);
-    SkASSERT(T < 256);
-    return T;
-}
-
-// Helper function to replicate the bits in x that represents an oldPrec
-// precision integer into a prec precision integer. For example:
-//   255 == replicate_bits(7, 3, 8);
-static inline int replicate_bits(int x, int oldPrec, int prec) {
-    while (oldPrec < prec) {
-        const int toShift = SkMin32(prec-oldPrec, oldPrec);
-        x = (x << toShift) | (x >> (oldPrec - toShift));
-        oldPrec += toShift;
-    }
-
-    // Make sure that no bits are set outside the desired precision.
-    SkASSERT((-(1 << prec) & x) == 0);
-    return x;
-}
-
-// Returns the unquantized value of a color that's represented only as
-// a set of bits.
-static inline int unquantize_bits_color(int val, int nBits) {
-    return replicate_bits(val, nBits, 8);
-}
-
-// Returns the unquantized value of a color that's represented as a
-// trit followed by nBits bits. This algorithm follows the sequence
-// defined in section C.2.13 of the ASTC spec.
-static inline int unquantize_trit_color(int val, int nBits) {
-    SkASSERT(nBits > 0);
-    SkASSERT(nBits < 7);
-
-    const int D = (val >> nBits) & 0x3;
-    SkASSERT(D < 3);
-
-    const int A = -(val & 0x1) & 0x1FF;
-
-    static const int Cvals[6] = { 204, 93, 44, 22, 11, 5 };
-    const int C = Cvals[nBits - 1];
-
-    int B = 0;
-    const SkTBits<int> valBits(val);
-    switch (nBits) {
-        case 1:
-            B = 0;
-            break;
-
-        case 2: {
-            const int b = valBits[1];
-            B = (b << 1) | (b << 2) | (b << 4) | (b << 8);
-        }
-        break;
-
-        case 3: {
-            const int cb = valBits(2, 1);
-            B = cb | (cb << 2) | (cb << 7);
-        }
-        break;
-
-        case 4: {
-            const int dcb = valBits(3, 1);
-            B = dcb | (dcb << 6);
-        }
-        break;
-
-        case 5: {
-            const int edcb = valBits(4, 1);
-            B = (edcb << 5) | (edcb >> 2);
-        }
-        break;
-
-        case 6: {
-            const int fedcb = valBits(5, 1);
-            B = (fedcb << 4) | (fedcb >> 4);
-        }
-        break;
-    }
-
-    return unquantize_value(0x80, A, B, C, D);
-}
-
-// Returns the unquantized value of a color that's represented as a
-// quint followed by nBits bits. This algorithm follows the sequence
-// defined in section C.2.13 of the ASTC spec.
-static inline int unquantize_quint_color(int val, int nBits) {
-    const int D = (val >> nBits) & 0x7;
-    SkASSERT(D < 5);
-
-    const int A = -(val & 0x1) & 0x1FF;
-
-    static const int Cvals[5] = { 113, 54, 26, 13, 6 };
-    SkASSERT(nBits > 0);
-    SkASSERT(nBits < 6);
-
-    const int C = Cvals[nBits - 1];
-
-    int B = 0;
-    const SkTBits<int> valBits(val);
-    switch (nBits) {
-        case 1:
-            B = 0;
-            break;
-
-        case 2: {
-            const int b = valBits[1];
-            B = (b << 2) | (b << 3) | (b << 8);
-        }
-        break;
-
-        case 3: {
-            const int cb = valBits(2, 1);
-            B = (cb >> 1) | (cb << 1) | (cb << 7);
-        }
-        break;
-
-        case 4: {
-            const int dcb = valBits(3, 1);
-            B = (dcb >> 1) | (dcb << 6);
-        }
-        break;
-
-        case 5: {
-            const int edcb = valBits(4, 1);
-            B = (edcb << 5) | (edcb >> 3);
-        }
-        break;
-    }
-
-    return unquantize_value(0x80, A, B, C, D);
-}
-
-// This algorithm takes a list of integers, stored in vals, and unquantizes them
-// in place. This follows the algorithm laid out in section C.2.13 of the ASTC spec.
-static void unquantize_colors(int *vals, int nVals, int nBits, int nTrits, int nQuints) {
-    for (int i = 0; i < nVals; ++i) {
-        if (nTrits > 0) {
-            SkASSERT(nQuints == 0);
-            vals[i] = unquantize_trit_color(vals[i], nBits);
-        } else if (nQuints > 0) {
-            SkASSERT(nTrits == 0);
-            vals[i] = unquantize_quint_color(vals[i], nBits);
-        } else {
-            SkASSERT(nQuints == 0 && nTrits == 0);
-            vals[i] = unquantize_bits_color(vals[i], nBits);
-        }
-    }
-}
-
-// Returns an interpolated value between c0 and c1 based on the weight. This
-// follows the algorithm laid out in section C.2.19 of the ASTC spec.
-static int interpolate_channel(int c0, int c1, int weight) {
-    SkASSERT(0 <= c0 && c0 < 256);
-    SkASSERT(0 <= c1 && c1 < 256);
-
-    c0 = (c0 << 8) | c0;
-    c1 = (c1 << 8) | c1;
-
-    const int result = ((c0*(64 - weight) + c1*weight + 32) / 64) >> 8;
-
-    if (result > 255) {
-        return 255;
-    }
-
-    SkASSERT(result >= 0);
-    return result;
-}
-
-// Returns an interpolated color between the two endpoints based on the weight.
-static SkColor interpolate_endpoints(const SkColor endpoints[2], int weight) {
-    return SkColorSetARGB(
-        interpolate_channel(SkColorGetA(endpoints[0]), SkColorGetA(endpoints[1]), weight),
-        interpolate_channel(SkColorGetR(endpoints[0]), SkColorGetR(endpoints[1]), weight),
-        interpolate_channel(SkColorGetG(endpoints[0]), SkColorGetG(endpoints[1]), weight),
-        interpolate_channel(SkColorGetB(endpoints[0]), SkColorGetB(endpoints[1]), weight));
-}
-
-// Returns an interpolated color between the two endpoints based on the weight.
-// It uses separate weights for the channel depending on the value of the 'plane'
-// variable. By default, all channels will use weight 0, and the value of plane
-// means that weight1 will be used for:
-// 0: red
-// 1: green
-// 2: blue
-// 3: alpha
-static SkColor interpolate_dual_endpoints(
-    const SkColor endpoints[2], int weight0, int weight1, int plane) {
-    int a = interpolate_channel(SkColorGetA(endpoints[0]), SkColorGetA(endpoints[1]), weight0);
-    int r = interpolate_channel(SkColorGetR(endpoints[0]), SkColorGetR(endpoints[1]), weight0);
-    int g = interpolate_channel(SkColorGetG(endpoints[0]), SkColorGetG(endpoints[1]), weight0);
-    int b = interpolate_channel(SkColorGetB(endpoints[0]), SkColorGetB(endpoints[1]), weight0);
-
-    switch (plane) {
-
-        case 0:
-            r = interpolate_channel(
-                SkColorGetR(endpoints[0]), SkColorGetR(endpoints[1]), weight1);
-            break;
-
-        case 1:
-            g = interpolate_channel(
-                SkColorGetG(endpoints[0]), SkColorGetG(endpoints[1]), weight1);
-            break;
-
-        case 2:
-            b = interpolate_channel(
-                SkColorGetB(endpoints[0]), SkColorGetB(endpoints[1]), weight1);
-            break;
-
-        case 3:
-            a = interpolate_channel(
-                SkColorGetA(endpoints[0]), SkColorGetA(endpoints[1]), weight1);
-            break;
-
-        default:
-            SkDEBUGFAIL("Plane should be 0-3");
-            break;
-    }
-
-    return SkColorSetARGB(a, r, g, b);
-}
-
-// A struct of decoded values that we use to carry around information
-// about the block. dimX and dimY are the dimension in texels of the block,
-// for which there is only a limited subset of valid values:
-//
-// 4x4, 5x4, 5x5, 6x5, 6x6, 8x5, 8x6, 8x8, 10x5, 10x6, 10x8, 10x10, 12x10, 12x12
-
-struct ASTCDecompressionData {
-    ASTCDecompressionData(int dimX, int dimY) : fDimX(dimX), fDimY(dimY) { }
-    const int   fDimX;      // the X dimension of the decompressed block
-    const int   fDimY;      // the Y dimension of the decompressed block
-    ASTCBlock   fBlock;     // the block data
-    int         fBlockMode; // the block header that contains the block mode.
-
-    bool fDualPlaneEnabled; // is this block compressing dual weight planes?
-    int  fDualPlane;        // the independent plane in dual plane mode.
-
-    bool fVoidExtent;       // is this block a single color?
-    bool fError;            // does this block have an error encoding?
-
-    int  fWeightDimX;       // the x dimension of the weight grid
-    int  fWeightDimY;       // the y dimension of the weight grid
-
-    int  fWeightBits;       // the number of bits used for each weight value
-    int  fWeightTrits;      // the number of trits used for each weight value
-    int  fWeightQuints;     // the number of quints used for each weight value
-
-    int  fPartCount;        // the number of partitions in this block
-    int  fPartIndex;        // the partition index: only relevant if fPartCount > 0
-
-    // CEM values can be anything in the range 0-15, and each corresponds to a different
-    // mode that represents the color data. We only support LDR modes.
-    enum ColorEndpointMode {
-        kLDR_Luminance_Direct_ColorEndpointMode          = 0,
-        kLDR_Luminance_BaseOffset_ColorEndpointMode      = 1,
-        kHDR_Luminance_LargeRange_ColorEndpointMode      = 2,
-        kHDR_Luminance_SmallRange_ColorEndpointMode      = 3,
-        kLDR_LuminanceAlpha_Direct_ColorEndpointMode     = 4,
-        kLDR_LuminanceAlpha_BaseOffset_ColorEndpointMode = 5,
-        kLDR_RGB_BaseScale_ColorEndpointMode             = 6,
-        kHDR_RGB_BaseScale_ColorEndpointMode             = 7,
-        kLDR_RGB_Direct_ColorEndpointMode                = 8,
-        kLDR_RGB_BaseOffset_ColorEndpointMode            = 9,
-        kLDR_RGB_BaseScaleWithAlpha_ColorEndpointMode    = 10,
-        kHDR_RGB_ColorEndpointMode                       = 11,
-        kLDR_RGBA_Direct_ColorEndpointMode               = 12,
-        kLDR_RGBA_BaseOffset_ColorEndpointMode           = 13,
-        kHDR_RGB_LDRAlpha_ColorEndpointMode              = 14,
-        kHDR_RGB_HDRAlpha_ColorEndpointMode              = 15
-    };
-    static const int kMaxColorEndpointModes = 16;
-
-    // the color endpoint modes for this block.
-    static const int kMaxPartitions = 4;
-    ColorEndpointMode fCEM[kMaxPartitions];
-
-    int  fColorStartBit;    // The bit position of the first bit of the color data
-    int  fColorEndBit;      // The bit position of the last *possible* bit of the color data
-
-    // Returns the number of partitions for this block.
-    int numPartitions() const {
-        return fPartCount;
-    }
-
-    // Returns the total number of weight values that are stored in this block
-    int numWeights() const {
-        return fWeightDimX * fWeightDimY * (fDualPlaneEnabled ? 2 : 1);
-    }
-
-#ifdef SK_DEBUG
-    // Returns the maximum value that any weight can take. We really only use
-    // this function for debugging.
-    int maxWeightValue() const {
-        int maxVal = (1 << fWeightBits);
-        if (fWeightTrits > 0) {
-            SkASSERT(0 == fWeightQuints);
-            maxVal *= 3;
-        } else if (fWeightQuints > 0) {
-            SkASSERT(0 == fWeightTrits);
-            maxVal *= 5;
-        }
-        return maxVal - 1;
-    }
-#endif
-
-    // The number of bits needed to represent the texel weight data. This
-    // comes from the 'data size determination' section of the ASTC spec (C.2.22)
-    int numWeightBits() const {
-        const int nWeights = this->numWeights();
-        return
-            ((nWeights*8*fWeightTrits + 4) / 5) +
-            ((nWeights*7*fWeightQuints + 2) / 3) +
-            (nWeights*fWeightBits);
-    }
-
-    // Returns the number of color values stored in this block. The number of
-    // values stored is directly a function of the color endpoint modes.
-    int numColorValues() const {
-        int numValues = 0;
-        for (int i = 0; i < this->numPartitions(); ++i) {
-            int cemInt = static_cast<int>(fCEM[i]);
-            numValues += ((cemInt >> 2) + 1) * 2;
-        }
-
-        return numValues;
-    }
-
-    // Figures out the number of bits available for color values, and fills
-    // in the maximum encoding that will fit the number of color values that
-    // we need. Returns false on error. (See section C.2.22 of the spec)
-    bool getColorValueEncoding(int *nBits, int *nTrits, int *nQuints) const {
-        if (NULL == nBits || NULL == nTrits || NULL == nQuints) {
-            return false;
-        }
-
-        const int nColorVals = this->numColorValues();
-        if (nColorVals <= 0) {
-            return false;
-        }
-
-        const int colorBits = fColorEndBit - fColorStartBit;
-        SkASSERT(colorBits > 0);
-
-        // This is the minimum amount of accuracy required by the spec.
-        if (colorBits < ((13 * nColorVals + 4) / 5)) {
-            return false;
-        }
-
-        // Values can be represented as at most 8-bit values.
-        // !SPEED! place this in a lookup table based on colorBits and nColorVals
-        for (int i = 255; i > 0; --i) {
-            int range = i + 1;
-            int bits = 0, trits = 0, quints = 0;
-            bool valid = false;
-            if (SkIsPow2(range)) {
-                bits = bits_for_range(range);
-                valid = true;
-            } else if ((range % 3) == 0 && SkIsPow2(range/3)) {
-                trits = 1;
-                bits = bits_for_range(range/3);
-                valid = true;
-            } else if ((range % 5) == 0 && SkIsPow2(range/5)) {
-                quints = 1;
-                bits = bits_for_range(range/5);
-                valid = true;
-            }
-
-            if (valid) {
-                const int actualColorBits =
-                    ((nColorVals*8*trits + 4) / 5) +
-                    ((nColorVals*7*quints + 2) / 3) +
-                    (nColorVals*bits);
-                if (actualColorBits <= colorBits) {
-                    *nTrits = trits;
-                    *nQuints = quints;
-                    *nBits = bits;
-                    return true;
-                }
-            }
-        }
-
-        return false;
-    }
-
-    // Converts the sequence of color values into endpoints. The algorithm here
-    // corresponds to the values determined by section C.2.14 of the ASTC spec
-    void colorEndpoints(SkColor endpoints[4][2], const int* colorValues) const {
-        for (int i = 0; i < this->numPartitions(); ++i) {
-            switch (fCEM[i]) {
-                case kLDR_Luminance_Direct_ColorEndpointMode: {
-                    const int* v = colorValues;
-                    endpoints[i][0] = SkColorSetARGB(0xFF, v[0], v[0], v[0]);
-                    endpoints[i][1] = SkColorSetARGB(0xFF, v[1], v[1], v[1]);
-
-                    colorValues += 2;
-                }
-                break;
-
-                case kLDR_Luminance_BaseOffset_ColorEndpointMode: {
-                    const int* v = colorValues;
-                    const int L0 = (v[0] >> 2) | (v[1] & 0xC0);
-                    const int L1 = clamp_byte(L0 + (v[1] & 0x3F));
-
-                    endpoints[i][0] = SkColorSetARGB(0xFF, L0, L0, L0);
-                    endpoints[i][1] = SkColorSetARGB(0xFF, L1, L1, L1);
-
-                    colorValues += 2;
-                }
-                break;
-
-                case kLDR_LuminanceAlpha_Direct_ColorEndpointMode: {
-                    const int* v = colorValues;
-                    
-                    endpoints[i][0] = SkColorSetARGB(v[2], v[0], v[0], v[0]);
-                    endpoints[i][1] = SkColorSetARGB(v[3], v[1], v[1], v[1]);
-
-                    colorValues += 4;
-                }
-                break;
-
-                case kLDR_LuminanceAlpha_BaseOffset_ColorEndpointMode: {
-                    int v0 = colorValues[0];
-                    int v1 = colorValues[1];
-                    int v2 = colorValues[2];
-                    int v3 = colorValues[3];
-
-                    bit_transfer_signed(&v1, &v0);
-                    bit_transfer_signed(&v3, &v2);
-                    
-                    endpoints[i][0] = SkColorSetARGB(v2, v0, v0, v0);
-                    endpoints[i][1] = SkColorSetARGB(
-                        clamp_byte(v3+v2),
-                        clamp_byte(v1+v0),
-                        clamp_byte(v1+v0),
-                        clamp_byte(v1+v0));
-
-                    colorValues += 4;
-                }
-                break;
-
-                case kLDR_RGB_BaseScale_ColorEndpointMode: {
-                    decode_rgba_basescale(colorValues, endpoints[i], true);
-                    colorValues += 4;
-                }
-                break;
-
-                case kLDR_RGB_Direct_ColorEndpointMode: {
-                    decode_rgba_direct(colorValues, endpoints[i], true);
-                    colorValues += 6;
-                }
-                break;
-
-                case kLDR_RGB_BaseOffset_ColorEndpointMode: {
-                    decode_rgba_baseoffset(colorValues, endpoints[i], true);
-                    colorValues += 6;
-                }
-                break;
-
-                case kLDR_RGB_BaseScaleWithAlpha_ColorEndpointMode: {
-                    decode_rgba_basescale(colorValues, endpoints[i], false);
-                    colorValues += 6;
-                }
-                break;
-
-                case kLDR_RGBA_Direct_ColorEndpointMode: {
-                    decode_rgba_direct(colorValues, endpoints[i], false);
-                    colorValues += 8;
-                }
-                break;
-
-                case kLDR_RGBA_BaseOffset_ColorEndpointMode: {
-                    decode_rgba_baseoffset(colorValues, endpoints[i], false);
-                    colorValues += 8;
-                }
-                break;
-
-                default:
-                    SkDEBUGFAIL("HDR mode unsupported! This should be caught sooner.");
-                    break;
-            }
-        }
-    }
-
-    // Follows the procedure from section C.2.17 of the ASTC specification
-    int unquantizeWeight(int x) const {
-        SkASSERT(x <= this->maxWeightValue());
-
-        const int D = (x >> fWeightBits) & 0x7;
-        const int A = -(x & 0x1) & 0x7F;
-
-        SkTBits<int> xbits(x);
-
-        int T = 0;
-        if (fWeightTrits > 0) {
-            SkASSERT(0 == fWeightQuints);
-            switch (fWeightBits) {
-                case 0: {
-                    // x is a single trit
-                    SkASSERT(x < 3);
-
-                    static const int kUnquantizationTable[3] = { 0, 32, 63 };
-                    T = kUnquantizationTable[x];
-                }
-                break;
-
-                case 1: {
-                    const int B = 0;
-                    const int C = 50;
-                    T = unquantize_value(0x20, A, B, C, D);
-                }
-                break;
-
-                case 2: {
-                    const int b = xbits[1];
-                    const int B = b | (b << 2) | (b << 6);
-                    const int C = 23;
-                    T = unquantize_value(0x20, A, B, C, D);
-                }
-                break;
-
-                case 3: {
-                    const int cb = xbits(2, 1);
-                    const int B = cb | (cb << 5);
-                    const int C = 11;
-                    T = unquantize_value(0x20, A, B, C, D);
-                }
-                break;
-
-                default:
-                    SkDEBUGFAIL("Too many bits for trit encoding");
-                    break;
-            }
-
-        } else if (fWeightQuints > 0) {
-            SkASSERT(0 == fWeightTrits);
-            switch (fWeightBits) {
-                case 0: {
-                    // x is a single quint
-                    SkASSERT(x < 5);
-
-                    static const int kUnquantizationTable[5] = { 0, 16, 32, 47, 63 };
-                    T = kUnquantizationTable[x];
-                }
-                break;
-
-                case 1: {
-                    const int B = 0;
-                    const int C = 28;
-                    T = unquantize_value(0x20, A, B, C, D);
-                }
-                break;
-
-                case 2: {
-                    const int b = xbits[1];
-                    const int B = (b << 1) | (b << 6);
-                    const int C = 13;
-                    T = unquantize_value(0x20, A, B, C, D);
-                }
-                break;
-
-                default:
-                    SkDEBUGFAIL("Too many bits for quint encoding");
-                    break;
-            }
-        } else {
-            SkASSERT(0 == fWeightTrits);
-            SkASSERT(0 == fWeightQuints);
-
-            T = replicate_bits(x, fWeightBits, 6);
-        }
-
-        // This should bring the value within [0, 63]..
-        SkASSERT(T <= 63);
-
-        if (T > 32) {
-            T += 1;
-        }
-
-        SkASSERT(T <= 64);
-
-        return T;
-    }
-
-    // Returns the weight at the associated index. If the index is out of bounds, it
-    // returns zero. It also chooses the weight appropriately based on the given dual
-    // plane.
-    int getWeight(const int* unquantizedWeights, int idx, bool dualPlane) const {
-        const int maxIdx = (fDualPlaneEnabled ? 2 : 1) * fWeightDimX * fWeightDimY - 1;
-        if (fDualPlaneEnabled) {
-            const int effectiveIdx = 2*idx + (dualPlane ? 1 : 0);
-            if (effectiveIdx > maxIdx) {
-                return 0;
-            }
-            return unquantizedWeights[effectiveIdx];
-        }
-
-        SkASSERT(!dualPlane);
-
-        if (idx > maxIdx) {
-            return 0;
-        } else {
-            return unquantizedWeights[idx];
-        }
-    }
-
-    // This computes the effective weight at location (s, t) of the block. This
-    // weight is computed by sampling the texel weight grid (it's usually not 1-1), and
-    // then applying a bilerp. The algorithm outlined here follows the algorithm
-    // defined in section C.2.18 of the ASTC spec.
-    int infillWeight(const int* unquantizedValues, int s, int t, bool dualPlane) const {
-        const int Ds = (1024 + fDimX/2) / (fDimX - 1);
-        const int Dt = (1024 + fDimY/2) / (fDimY - 1);
-
-        const int cs = Ds * s;
-        const int ct = Dt * t;
-
-        const int gs = (cs*(fWeightDimX - 1) + 32) >> 6;
-        const int gt = (ct*(fWeightDimY - 1) + 32) >> 6;
-
-        const int js = gs >> 4;
-        const int jt = gt >> 4;
-
-        const int fs = gs & 0xF;
-        const int ft = gt & 0xF;
-
-        const int idx = js + jt*fWeightDimX;
-        const int p00 = this->getWeight(unquantizedValues, idx, dualPlane);
-        const int p01 = this->getWeight(unquantizedValues, idx + 1, dualPlane);
-        const int p10 = this->getWeight(unquantizedValues, idx + fWeightDimX, dualPlane);
-        const int p11 = this->getWeight(unquantizedValues, idx + fWeightDimX + 1, dualPlane);
-
-        const int w11 = (fs*ft + 8) >> 4;
-        const int w10 = ft - w11;
-        const int w01 = fs - w11;
-        const int w00 = 16 - fs - ft + w11;
-
-        const int weight = (p00*w00 + p01*w01 + p10*w10 + p11*w11 + 8) >> 4;
-        SkASSERT(weight <= 64);
-        return weight;
-    }
-
-    // Unquantizes the decoded texel weights as described in section C.2.17 of
-    // the ASTC specification. Additionally, it populates texelWeights with
-    // the expanded weight grid, which is computed according to section C.2.18
-    void texelWeights(int texelWeights[2][12][12], const int* texelValues) const {
-        // Unquantized texel weights...
-        int unquantizedValues[144*2]; // 12x12 blocks with dual plane decoding...
-        SkASSERT(this->numWeights() <= 144*2);
-
-        // Unquantize the weights and cache them
-        for (int j = 0; j < this->numWeights(); ++j) {
-            unquantizedValues[j] = this->unquantizeWeight(texelValues[j]);
-        }
-
-        // Do weight infill...
-        for (int y = 0; y < fDimY; ++y) {
-            for (int x = 0; x < fDimX; ++x) {
-                texelWeights[0][x][y] = this->infillWeight(unquantizedValues, x, y, false);
-                if (fDualPlaneEnabled) {
-                    texelWeights[1][x][y] = this->infillWeight(unquantizedValues, x, y, true);
-                }
-            }
-        }
-    }
-
-    // Returns the partition for the texel located at position (x, y).
-    // Adapted from C.2.21 of the ASTC specification
-    int getPartition(int x, int y) const {
-        const int partitionCount = this->numPartitions();
-        int seed = fPartIndex;
-        if ((fDimX * fDimY) < 31) {
-            x <<= 1;
-            y <<= 1;
-        }
-
-        seed += (partitionCount - 1) * 1024;
-
-        uint32_t p = seed;
-        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;
-
-        uint32_t rnum = p;
-        uint8_t seed1  =  rnum        & 0xF;
-        uint8_t seed2  = (rnum >>  4) & 0xF;
-        uint8_t seed3  = (rnum >>  8) & 0xF;
-        uint8_t seed4  = (rnum >> 12) & 0xF;
-        uint8_t seed5  = (rnum >> 16) & 0xF;
-        uint8_t seed6  = (rnum >> 20) & 0xF;
-        uint8_t seed7  = (rnum >> 24) & 0xF;
-        uint8_t seed8  = (rnum >> 28) & 0xF;
-        uint8_t seed9  = (rnum >> 18) & 0xF;
-        uint8_t seed10 = (rnum >> 22) & 0xF;
-        uint8_t seed11 = (rnum >> 26) & 0xF;
-        uint8_t seed12 = ((rnum >> 30) | (rnum << 2)) & 0xF;
-
-        seed1 *= seed1;     seed2 *= seed2;
-        seed3 *= seed3;     seed4 *= seed4;
-        seed5 *= seed5;     seed6 *= seed6;
-        seed7 *= seed7;     seed8 *= seed8;
-        seed9 *= seed9;     seed10 *= seed10;
-        seed11 *= seed11;   seed12 *= seed12;
-
-        int sh1, sh2, sh3;
-        if (0 != (seed & 1)) {
-            sh1 = (0 != (seed & 2))? 4 : 5;
-            sh2 = (partitionCount == 3)? 6 : 5;
-        } else {
-            sh1 = (partitionCount==3)? 6 : 5;
-            sh2 = (0 != (seed & 2))? 4 : 5;
-        }
-        sh3 = (0 != (seed & 0x10))? sh1 : sh2;
-
-        seed1 >>= sh1; seed2  >>= sh2; seed3  >>= sh1; seed4  >>= sh2;
-        seed5 >>= sh1; seed6  >>= sh2; seed7  >>= sh1; seed8  >>= sh2;
-        seed9 >>= sh3; seed10 >>= sh3; seed11 >>= sh3; seed12 >>= sh3;
-
-        const int z = 0;
-        int a = seed1*x + seed2*y + seed11*z + (rnum >> 14);
-        int b = seed3*x + seed4*y + seed12*z + (rnum >> 10);
-        int c = seed5*x + seed6*y + seed9 *z + (rnum >>  6);
-        int 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;
-        } else {
-            return 3;
-        }
-    }
-
-    // Performs the proper interpolation of the texel based on the
-    // endpoints and weights.
-    SkColor getTexel(const SkColor endpoints[4][2],
-                     const int weights[2][12][12],
-                     int x, int y) const {
-        int part = 0;
-        if (this->numPartitions() > 1) {
-            part = this->getPartition(x, y);
-        }
-
-        SkColor result;
-        if (fDualPlaneEnabled) {
-            result = interpolate_dual_endpoints(
-                endpoints[part], weights[0][x][y], weights[1][x][y], fDualPlane);
-        } else {
-            result = interpolate_endpoints(endpoints[part], weights[0][x][y]);
-        }
-
-#if 1
-        // !FIXME! if we're writing directly to a bitmap, then we don't need
-        // to swap the red and blue channels, but since we're usually being used
-        // by the SkImageDecoder_astc module, the results are expected to be in RGBA.
-        result = SkColorSetARGB(
-            SkColorGetA(result), SkColorGetB(result), SkColorGetG(result), SkColorGetR(result));
-#endif
-
-        return result;
-    }
-
-    void decode() {
-        // First decode the block mode.
-        this->decodeBlockMode();
-
-        // Now we can decode the partition information.
-        fPartIndex = static_cast<int>(read_astc_bits(fBlock, 11, 23));
-        fPartCount = (fPartIndex & 0x3) + 1;
-        fPartIndex >>= 2;
-
-        // This is illegal
-        if (fDualPlaneEnabled && this->numPartitions() == 4) {
-            fError = true;
-            return;
-        }
-
-        // Based on the partition info, we can decode the color information.
-        this->decodeColorData();
-    }
-
-    // Decodes the dual plane based on the given bit location. The final
-    // location, if the dual plane is enabled, is also the end of our color data.
-    // This function is only meant to be used from this->decodeColorData()
-    void decodeDualPlane(int bitLoc) {
-        if (fDualPlaneEnabled) {
-            fDualPlane = static_cast<int>(read_astc_bits(fBlock, bitLoc - 2, bitLoc));
-            fColorEndBit = bitLoc - 2;
-        } else {
-            fColorEndBit = bitLoc;
-        }
-    }
-
-    // Decodes the color information based on the ASTC spec.
-    void decodeColorData() {
-
-        // By default, the last color bit is at the end of the texel weights
-        const int lastWeight = 128 - this->numWeightBits();
-
-        // If we have a dual plane then it will be at this location, too.
-        int dualPlaneBitLoc = lastWeight;
-
-        // If there's only one partition, then our job is (relatively) easy.
-        if (this->numPartitions() == 1) {
-            fCEM[0] = static_cast<ColorEndpointMode>(read_astc_bits(fBlock, 13, 17));
-            fColorStartBit = 17;
-
-            // Handle dual plane mode...
-            this->decodeDualPlane(dualPlaneBitLoc);
-
-            return;
-        } 
-
-        // If we have more than one partition, then we need to make
-        // room for the partition index.
-        fColorStartBit = 29;
-
-        // Read the base CEM. If it's zero, then we have no additional
-        // CEM data and the endpoints for each partition share the same CEM.
-        const int baseCEM = static_cast<int>(read_astc_bits(fBlock, 23, 25));
-        if (0 == baseCEM) {
-
-            const ColorEndpointMode sameCEM =
-                static_cast<ColorEndpointMode>(read_astc_bits(fBlock, 25, 29));
-
-            for (int i = 0; i < kMaxPartitions; ++i) {
-                fCEM[i] = sameCEM;
-            }
-
-            // Handle dual plane mode...
-            this->decodeDualPlane(dualPlaneBitLoc);
-
-            return;
-        } 
-
-        // Move the dual plane selector bits down based on how many
-        // partitions the block contains.
-        switch (this->numPartitions()) {
-            case 2:
-                dualPlaneBitLoc -= 2;
-                break;
-
-            case 3:
-                dualPlaneBitLoc -= 5;
-                break;
-
-            case 4:
-                dualPlaneBitLoc -= 8;
-                break;
-
-            default:
-                SkDEBUGFAIL("Internal ASTC decoding error.");
-                break;
-        }
-
-        // The rest of the CEM config will be between the dual plane bit selector
-        // and the texel weight grid.
-        const int lowCEM = static_cast<int>(read_astc_bits(fBlock, 23, 29));
-        SkASSERT(lastWeight - dualPlaneBitLoc > 31);
-        int fullCEM = static_cast<int>(read_astc_bits(fBlock, dualPlaneBitLoc, lastWeight));
-
-        // Attach the config at the end of the weight grid to the CEM values
-        // in the beginning of the block.
-        fullCEM = (fullCEM << 6) | lowCEM;
-
-        // Ignore the two least significant bits, since those are our baseCEM above.
-        fullCEM = fullCEM >> 2;
-
-        int C[kMaxPartitions]; // Next, decode C and M from the spec (Table C.2.12)
-        for (int i = 0; i < this->numPartitions(); ++i) {
-            C[i] = fullCEM & 1;
-            fullCEM = fullCEM >> 1;
-        }
-
-        int M[kMaxPartitions];
-        for (int i = 0; i < this->numPartitions(); ++i) {
-            M[i] = fullCEM & 0x3;
-            fullCEM = fullCEM >> 2;
-        }
-
-        // Construct our CEMs..
-        SkASSERT(baseCEM > 0);
-        for (int i = 0; i < this->numPartitions(); ++i) {
-            int cem = (baseCEM - 1) * 4;
-            cem += (0 == C[i])? 0 : 4;
-            cem += M[i];
-
-            SkASSERT(cem < 16);
-            fCEM[i] = static_cast<ColorEndpointMode>(cem);
-        }
-
-        // Finally, if we have dual plane mode, then read the plane selector.
-        this->decodeDualPlane(dualPlaneBitLoc);
-    }
-
-    // Decodes the block mode. This function determines whether or not we use
-    // dual plane encoding, the size of the texel weight grid, and the number of
-    // bits, trits and quints that are used to encode it. For more information, 
-    // see section C.2.10 of the ASTC spec.
-    //
-    // For 2D blocks, the Block Mode field is laid out as follows:
-    //
-    // -------------------------------------------------------------------------
-    // 10  9   8   7   6   5   4   3   2   1   0   Width Height Notes
-    // -------------------------------------------------------------------------
-    // D   H     B       A     R0  0   0   R2  R1  B+4   A+2
-    // D   H     B       A     R0  0   1   R2  R1  B+8   A+2
-    // D   H     B       A     R0  1   0   R2  R1  A+2   B+8
-    // D   H   0   B     A     R0  1   1   R2  R1  A+2   B+6
-    // D   H   1   B     A     R0  1   1   R2  R1  B+2   A+2
-    // D   H   0   0     A     R0  R2  R1  0   0   12    A+2
-    // D   H   0   1     A     R0  R2  R1  0   0   A+2   12
-    // D   H   1   1   0   0   R0  R2  R1  0   0   6     10
-    // D   H   1   1   0   1   R0  R2  R1  0   0   10    6
-    //   B     1   0     A     R0  R2  R1  0   0   A+6   B+6   D=0, H=0
-    // x   x   1   1   1   1   1   1   1   0   0   -     -     Void-extent
-    // x   x   1   1   1   x   x   x   x   0   0   -     -     Reserved*
-    // x   x   x   x   x   x   x   0   0   0   0   -     -     Reserved
-    // -------------------------------------------------------------------------
-    //
-    // D - dual plane enabled
-    // H, R - used to determine the number of bits/trits/quints in texel weight encoding
-    //        R is a three bit value whose LSB is R0 and MSB is R1
-    // Width, Height - dimensions of the texel weight grid (determined by A and B)
-
-    void decodeBlockMode() {
-        const int blockMode = static_cast<int>(read_astc_bits(fBlock, 0, 11));
-
-        // Check for special void extent encoding
-        fVoidExtent = (blockMode & 0x1FF) == 0x1FC;
-
-        // Check for reserved block modes
-        fError = ((blockMode & 0x1C3) == 0x1C0) || ((blockMode & 0xF) == 0);
-
-        // Neither reserved nor void-extent, decode as usual
-        // This code corresponds to table C.2.8 of the ASTC spec
-        bool highPrecision = false;
-        int R = 0;
-        if ((blockMode & 0x3) == 0) {
-            R = ((0xC & blockMode) >> 1) | ((0x10 & blockMode) >> 4);
-            const int bitsSevenAndEight = (blockMode & 0x180) >> 7;
-            SkASSERT(0 <= bitsSevenAndEight && bitsSevenAndEight < 4);
-
-            const int A = (blockMode >> 5) & 0x3;
-            const int B = (blockMode >> 9) & 0x3;
-
-            fDualPlaneEnabled = (blockMode >> 10) & 0x1;
-            highPrecision = (blockMode >> 9) & 0x1;
-
-            switch (bitsSevenAndEight) {
-                default:
-                case 0:
-                    fWeightDimX = 12;
-                    fWeightDimY = A + 2;
-                    break;
-
-                case 1:
-                    fWeightDimX = A + 2;
-                    fWeightDimY = 12;
-                    break;
-
-                case 2:
-                    fWeightDimX = A + 6;
-                    fWeightDimY = B + 6;
-                    fDualPlaneEnabled = false;
-                    highPrecision = false;
-                    break;
-
-                case 3:
-                    if (0 == A) {
-                        fWeightDimX = 6;
-                        fWeightDimY = 10;
-                    } else {
-                        fWeightDimX = 10;
-                        fWeightDimY = 6;
-                    }
-                    break;
-            }
-        } else { // (blockMode & 0x3) != 0
-            R = ((blockMode & 0x3) << 1) | ((blockMode & 0x10) >> 4);
-
-            const int bitsTwoAndThree = (blockMode >> 2) & 0x3;
-            SkASSERT(0 <= bitsTwoAndThree && bitsTwoAndThree < 4);
-
-            const int A = (blockMode >> 5) & 0x3;
-            const int B = (blockMode >> 7) & 0x3;
-
-            fDualPlaneEnabled = (blockMode >> 10) & 0x1;
-            highPrecision = (blockMode >> 9) & 0x1;
-
-            switch (bitsTwoAndThree) {
-                case 0:
-                    fWeightDimX = B + 4;
-                    fWeightDimY = A + 2;
-                    break;
-                case 1:
-                    fWeightDimX = B + 8;
-                    fWeightDimY = A + 2;
-                    break;
-                case 2:
-                    fWeightDimX = A + 2;
-                    fWeightDimY = B + 8;
-                    break;
-                case 3:
-                    if ((B & 0x2) == 0) {
-                        fWeightDimX = A + 2;
-                        fWeightDimY = (B & 1) + 6;
-                    } else {
-                        fWeightDimX = (B & 1) + 2;
-                        fWeightDimY = A + 2;
-                    }
-                    break;
-            }
-        }
-
-        // We should have set the values of R and highPrecision
-        // from decoding the block mode, these are used to determine
-        // the proper dimensions of our weight grid.
-        if ((R & 0x6) == 0) {
-            fError = true;
-        } else {
-            static const int kBitAllocationTable[2][6][3] = {
-                {
-                    {  1, 0, 0 },
-                    {  0, 1, 0 },
-                    {  2, 0, 0 },
-                    {  0, 0, 1 },
-                    {  1, 1, 0 },
-                    {  3, 0, 0 }
-                },
-                {
-                    {  1, 0, 1 },
-                    {  2, 1, 0 },
-                    {  4, 0, 0 },
-                    {  2, 0, 1 },
-                    {  3, 1, 0 },
-                    {  5, 0, 0 }
-                }
-            };
-
-            fWeightBits = kBitAllocationTable[highPrecision][R - 2][0];
-            fWeightTrits = kBitAllocationTable[highPrecision][R - 2][1];
-            fWeightQuints = kBitAllocationTable[highPrecision][R - 2][2];
-        }
-    }
-};
-
-// Reads an ASTC block from the given pointer.
-static inline void read_astc_block(ASTCDecompressionData *dst, const uint8_t* src) {
-    const uint64_t* qword = reinterpret_cast<const uint64_t*>(src);
-    dst->fBlock.fLow = SkEndian_SwapLE64(qword[0]);
-    dst->fBlock.fHigh = SkEndian_SwapLE64(qword[1]);
-    dst->decode();
-}
-
-// Take a known void-extent block, and write out the values as a constant color.
-static void decompress_void_extent(uint8_t* dst, int dstRowBytes,
-                                   const ASTCDecompressionData &data) {
-    // The top 64 bits contain 4 16-bit RGBA values.
-    int a = (static_cast<int>(read_astc_bits(data.fBlock, 112, 128)) + 255) >> 8;
-    int b = (static_cast<int>(read_astc_bits(data.fBlock, 96, 112)) + 255) >> 8;
-    int g = (static_cast<int>(read_astc_bits(data.fBlock, 80, 96)) + 255) >> 8;
-    int r = (static_cast<int>(read_astc_bits(data.fBlock, 64, 80)) + 255) >> 8;
-
-    write_constant_color(dst, data.fDimX, data.fDimY, dstRowBytes, SkColorSetARGB(a, r, g, b));
-}
-
-// Decompresses a single ASTC block. It's assumed that data.fDimX and data.fDimY are
-// set and that the block has already been decoded (i.e. data.decode() has been called)
-static void decompress_astc_block(uint8_t* dst, int dstRowBytes,
-                                  const ASTCDecompressionData &data) {
-    if (data.fError) {
-        write_error_color(dst, data.fDimX, data.fDimY, dstRowBytes);
-        return;
-    }
-
-    if (data.fVoidExtent) {
-        decompress_void_extent(dst, dstRowBytes, data);
-        return;
-    }
-
-    // According to the spec, any more than 64 values is illegal. (C.2.24)
-    static const int kMaxTexelValues = 64;
-
-    // Decode the texel weights.
-    int texelValues[kMaxTexelValues];
-    bool success = decode_integer_sequence(
-        texelValues, kMaxTexelValues, data.numWeights(),
-        // texel data goes to the end of the 128 bit block.
-        data.fBlock, 128, 128 - data.numWeightBits(), false,
-        data.fWeightBits, data.fWeightTrits, data.fWeightQuints);
-
-    if (!success) {
-        write_error_color(dst, data.fDimX, data.fDimY, dstRowBytes);
-        return;
-    }
-
-    // Decode the color endpoints
-    int colorBits, colorTrits, colorQuints;
-    if (!data.getColorValueEncoding(&colorBits, &colorTrits, &colorQuints)) {
-        write_error_color(dst, data.fDimX, data.fDimY, dstRowBytes);
-        return;
-    }
-
-    // According to the spec, any more than 18 color values is illegal. (C.2.24)
-    static const int kMaxColorValues = 18;
-
-    int colorValues[kMaxColorValues];
-    success = decode_integer_sequence(
-        colorValues, kMaxColorValues, data.numColorValues(),
-        data.fBlock, data.fColorStartBit, data.fColorEndBit, true,
-        colorBits, colorTrits, colorQuints);
-
-    if (!success) {
-        write_error_color(dst, data.fDimX, data.fDimY, dstRowBytes);
-        return;
-    }
-
-    // Unquantize the color values after they've been decoded.
-    unquantize_colors(colorValues, data.numColorValues(), colorBits, colorTrits, colorQuints);
-
-    // Decode the colors into the appropriate endpoints.
-    SkColor endpoints[4][2];
-    data.colorEndpoints(endpoints, colorValues);
-
-    // Do texel infill and decode the texel values.
-    int texelWeights[2][12][12];
-    data.texelWeights(texelWeights, texelValues);
-
-    // Write the texels by interpolating them based on the information
-    // stored in the block.
-    dst += data.fDimY * dstRowBytes;
-    for (int y = 0; y < data.fDimY; ++y) {
-        dst -= dstRowBytes;
-        SkColor* colorPtr = reinterpret_cast<SkColor*>(dst);
-        for (int x = 0; x < data.fDimX; ++x) {
-            colorPtr[x] = data.getTexel(endpoints, texelWeights, x, y);
-        }
-    }
-}
-
-////////////////////////////////////////////////////////////////////////////////
 
 namespace SkTextureCompressor {
 
-bool CompressA8To12x12ASTC(uint8_t* dst, const uint8_t* src,
-                           int width, int height, int rowBytes) {
+bool CompressA8To12x12ASTC(uint8_t* dst, const uint8_t* src, int width, int height, int rowBytes) {
     if (width < 0 || ((width % 12) != 0) || height < 0 || ((height % 12) != 0)) {
         return false;
     }
 
     uint8_t** dstPtr = &dst;
     for (int y = 0; y < height; y += 12) {
         for (int x = 0; x < width; x += 12) {
             compress_a8_astc_block<GetAlpha>(dstPtr, src + y*rowBytes + x, rowBytes);
         }
     }
 
     return true;
 }
 
 SkBlitter* CreateASTCBlitter(int width, int height, void* outputBuffer) {
     return new
         SkTCompressedAlphaBlitter<12, 16, CompressA8ASTCBlockVertical>
         (width, height, outputBuffer);
 }
 
-void DecompressASTC(uint8_t* dst, int dstRowBytes, const uint8_t* src,
-                    int width, int height, int blockDimX, int blockDimY) {
-    // ASTC is encoded in what they call "raster order", so that the first
-    // block is the bottom-left block in the image, and the first pixel
-    // is the bottom-left pixel of the image
-    dst += height * dstRowBytes;
-
-    ASTCDecompressionData data(blockDimX, blockDimY);
-    for (int y = 0; y < height; y += blockDimY) {
-        dst -= blockDimY * dstRowBytes;
-        SkColor *colorPtr = reinterpret_cast<SkColor*>(dst);
-        for (int x = 0; x < width; x += blockDimX) {
-            read_astc_block(&data, src);
-            decompress_astc_block(reinterpret_cast<uint8_t*>(colorPtr + x), dstRowBytes, data);
-
-            // ASTC encoded blocks are 16 bytes (128 bits) large.
-            src += 16;
-        }
-    }
-}
-
 }  // SkTextureCompressor