mesa: add ASTC 2D LDR decoder

Tested-by: Mike Lothian <[email protected]>
Tested-By: Gert Wollny <[email protected]>
Tested-by: Dieter Nützel <[email protected]>

1 files changed, 1871 insertions, 0 deletions

diff --git a/src/mesa/main/texcompress_astc.cpp b/src/mesa/main/texcompress_astc.cpp
new file mode 100644
index 00000000000..996e8ea28d6
--- /dev/null
+++ b/src/mesa/main/texcompress_astc.cpp
@@ -0,0 +1,1871 @@
+/*
+ * Copyright 2015 Philip Taylor <[email protected]>
+ * Copyright 2018 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file texcompress_astc.c
+ *
+ * Decompression code for GL_KHR_texture_compression_astc_ldr, which is just
+ * ASTC 2D LDR.
+ *
+ * The ASTC 2D LDR decoder (without the sRGB part) was copied from the OASTC
+ * library written by Philip Taylor. I added sRGB support and adjusted it for
+ * Mesa. - Marek
+ */
+
+#include "texcompress_astc.h"
+#include "macros.h"
+#include "util/half_float.h"
+#include <stdio.h>
+
+static bool VERBOSE_DECODE = false;
+static bool VERBOSE_WRITE = false;
+
+static inline uint8_t
+uint16_div_64k_to_half_to_unorm8(uint16_t v)
+{
+   return _mesa_half_to_unorm8(_mesa_uint16_div_64k_to_half(v));
+}
+
+class decode_error
+{
+public:
+   enum type {
+      ok,
+      unsupported_hdr_void_extent,
+      reserved_block_mode_1,
+      reserved_block_mode_2,
+      dual_plane_and_too_many_partitions,
+      invalid_range_in_void_extent,
+      weight_grid_exceeds_block_size,
+      invalid_colour_endpoints_size,
+      invalid_colour_endpoints_count,
+      invalid_weight_bits,
+      invalid_num_weights,
+   };
+};
+
+
+struct cem_range {
+   uint8_t max;
+   uint8_t t, q, b;
+};
+
+/* Based on the Color Unquantization Parameters table,
+ * plus the bit-only representations, sorted by increasing size
+ */
+static cem_range cem_ranges[] = {
+   { 5, 1, 0, 1 },
+   { 7, 0, 0, 3 },
+   { 9, 0, 1, 1 },
+   { 11, 1, 0, 2 },
+   { 15, 0, 0, 4 },
+   { 19, 0, 1, 2 },
+   { 23, 1, 0, 3 },
+   { 31, 0, 0, 5 },
+   { 39, 0, 1, 3 },
+   { 47, 1, 0, 4 },
+   { 63, 0, 0, 6 },
+   { 79, 0, 1, 4 },
+   { 95, 1, 0, 5 },
+   { 127, 0, 0, 7 },
+   { 159, 0, 1, 5 },
+   { 191, 1, 0, 6 },
+   { 255, 0, 0, 8 },
+};
+
+#define CAT_BITS_2(a, b)          ( ((a) << 1) | (b) )
+#define CAT_BITS_3(a, b, c)       ( ((a) << 2) | ((b) << 1) | (c) )
+#define CAT_BITS_4(a, b, c, d)    ( ((a) << 3) | ((b) << 2) | ((c) << 1) | (d) )
+#define CAT_BITS_5(a, b, c, d, e) ( ((a) << 4) | ((b) << 3) | ((c) << 2) | ((d) << 1) | (e) )
+
+/**
+ * Unpack 5n+8 bits from 'in' into 5 output values.
+ * If n <= 4 then T should be uint32_t, else it must be uint64_t.
+ */
+template <typename T>
+static void unpack_trit_block(int n, T in, uint8_t *out)
+{
+   assert(n <= 6); /* else output will overflow uint8_t */
+
+   uint8_t T0 = (in >> (n)) & 0b1;
+   uint8_t T1 = (in >> (n+1)) & 0b1;
+   uint8_t T2 = (in >> (2*n+2)) & 0b1;
+   uint8_t T3 = (in >> (2*n+3)) & 0b1;
+   uint8_t T4 = (in >> (3*n+4)) & 0b1;
+   uint8_t T5 = (in >> (4*n+5)) & 0b1;
+   uint8_t T6 = (in >> (4*n+6)) & 0b1;
+   uint8_t T7 = (in >> (5*n+7)) & 0b1;
+   uint8_t mmask = (1 << n) - 1;
+   uint8_t m0 = (in >> (0)) & mmask;
+   uint8_t m1 = (in >> (n+2)) & mmask;
+   uint8_t m2 = (in >> (2*n+4)) & mmask;
+   uint8_t m3 = (in >> (3*n+5)) & mmask;
+   uint8_t m4 = (in >> (4*n+7)) & mmask;
+
+   uint8_t C;
+   uint8_t t4, t3, t2, t1, t0;
+   if (CAT_BITS_3(T4, T3, T2) == 0b111) {
+      C = CAT_BITS_5(T7, T6, T5, T1, T0);
+      t4 = t3 = 2;
+   } else {
+      C = CAT_BITS_5(T4, T3, T2, T1, T0);
+      if (CAT_BITS_2(T6, T5) == 0b11) {
+         t4 = 2;
+         t3 = T7;
+      } else {
+         t4 = T7;
+         t3 = CAT_BITS_2(T6, T5);
+      }
+   }
+
+   if ((C & 0b11) == 0b11) {
+      t2 = 2;
+      t1 = (C >> 4) & 0b1;
+      uint8_t C3 = (C >> 3) & 0b1;
+      uint8_t C2 = (C >> 2) & 0b1;
+      t0 = (C3 << 1) | (C2 & ~C3);
+   } else if (((C >> 2) & 0b11) == 0b11) {
+      t2 = 2;
+      t1 = 2;
+      t0 = C & 0b11;
+   } else {
+      t2 = (C >> 4) & 0b1;
+      t1 = (C >> 2) & 0b11;
+      uint8_t C1 = (C >> 1) & 0b1;
+      uint8_t C0 = (C >> 0) & 0b1;
+      t0 = (C1 << 1) | (C0 & ~C1);
+   }
+
+   out[0] = (t0 << n) | m0;
+   out[1] = (t1 << n) | m1;
+   out[2] = (t2 << n) | m2;
+   out[3] = (t3 << n) | m3;
+   out[4] = (t4 << n) | m4;
+}
+
+/**
+ * Unpack 3n+7 bits from 'in' into 3 output values
+ */
+static void unpack_quint_block(int n, uint32_t in, uint8_t *out)
+{
+   assert(n <= 5); /* else output will overflow uint8_t */
+
+   uint8_t Q0 = (in >> (n)) & 0b1;
+   uint8_t Q1 = (in >> (n+1)) & 0b1;
+   uint8_t Q2 = (in >> (n+2)) & 0b1;
+   uint8_t Q3 = (in >> (2*n+3)) & 0b1;
+   uint8_t Q4 = (in >> (2*n+4)) & 0b1;
+   uint8_t Q5 = (in >> (3*n+5)) & 0b1;
+   uint8_t Q6 = (in >> (3*n+6)) & 0b1;
+   uint8_t mmask = (1 << n) - 1;
+   uint8_t m0 = (in >> (0)) & mmask;
+   uint8_t m1 = (in >> (n+3)) & mmask;
+   uint8_t m2 = (in >> (2*n+5)) & mmask;
+
+   uint8_t C;
+   uint8_t q2, q1, q0;
+   if (CAT_BITS_4(Q6, Q5, Q2, Q1) == 0b0011) {
+      q2 = CAT_BITS_3(Q0, Q4 & ~Q0, Q3 & ~Q0);
+      q1 = 4;
+      q0 = 4;
+   } else {
+      if (CAT_BITS_2(Q2, Q1) == 0b11) {
+         q2 = 4;
+         C = CAT_BITS_5(Q4, Q3, 0b1 & ~Q6, 0b1 & ~Q5, Q0);
+      } else {
+         q2 = CAT_BITS_2(Q6, Q5);
+         C = CAT_BITS_5(Q4, Q3, Q2, Q1, Q0);
+      }
+      if ((C & 0b111) == 0b101) {
+         q1 = 4;
+         q0 = (C >> 3) & 0b11;
+      } else {
+         q1 = (C >> 3) & 0b11;
+         q0 = C & 0b111;
+      }
+   }
+   out[0] = (q0 << n) | m0;
+   out[1] = (q1 << n) | m1;
+   out[2] = (q2 << n) | m2;
+}
+
+
+struct uint8x4_t
+{
+   uint8_t v[4];
+
+   uint8x4_t() { }
+
+   uint8x4_t(int a, int b, int c, int d)
+   {
+      assert(0 <= a && a <= 255);
+      assert(0 <= b && b <= 255);
+      assert(0 <= c && c <= 255);
+      assert(0 <= d && d <= 255);
+      v[0] = a;
+      v[1] = b;
+      v[2] = c;
+      v[3] = d;
+   }
+
+   static uint8x4_t clamped(int a, int b, int c, int d)
+   {
+      uint8x4_t r;
+      r.v[0] = MAX2(0, MIN2(255, a));
+      r.v[1] = MAX2(0, MIN2(255, b));
+      r.v[2] = MAX2(0, MIN2(255, c));
+      r.v[3] = MAX2(0, MIN2(255, d));
+      return r;
+   }
+};
+
+static uint8x4_t blue_contract(int r, int g, int b, int a)
+{
+   return uint8x4_t((r+b) >> 1, (g+b) >> 1, b, a);
+}
+
+static uint8x4_t blue_contract_clamped(int r, int g, int b, int a)
+{
+   return uint8x4_t::clamped((r+b) >> 1, (g+b) >> 1, b, a);
+}
+
+static void bit_transfer_signed(int &a, int &b)
+{
+   b >>= 1;
+   b |= a & 0x80;
+   a >>= 1;
+   a &= 0x3f;
+   if (a & 0x20)
+      a -= 0x40;
+}
+
+static uint32_t hash52(uint32_t 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 int select_partition(int seed, int x, int y, int z, int partitioncount,
+                            int small_block)
+{
+   if (small_block) {
+      x <<= 1;
+      y <<= 1;
+      z <<= 1;
+   }
+   seed += (partitioncount - 1) * 1024;
+   uint32_t rnum = hash52(seed);
+   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 (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 >>= sh1;
+   seed2 >>= sh2;
+   seed3 >>= sh1;
+   seed4 >>= sh2;
+   seed5 >>= sh1;
+   seed6 >>= sh2;
+   seed7 >>= sh1;
+   seed8 >>= sh2;
+   seed9 >>= sh3;
+   seed10 >>= sh3;
+   seed11 >>= sh3;
+   seed12 >>= sh3;
+
+   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;
+}
+
+
+struct InputBitVector
+{
+   uint32_t data[4];
+
+   void printf_bits(int offset, int count, const char *fmt = "", ...)
+   {
+      char out[129];
+      memset(out, '.', 128);
+      out[128] = '\0';
+      int idx = offset;
+      for (int i = 0; i < count; ++i) {
+         out[127 - idx] = ((data[idx >> 5] >> (idx & 31)) & 1) ? '1' : '0';
+         ++idx;
+      }
+      printf("%s ", out);
+      va_list ap;
+      va_start(ap, fmt);
+      vprintf(fmt, ap);
+      va_end(ap);
+      printf("\n");
+   }
+
+   uint32_t get_bits(int offset, int count)
+   {
+      assert(count >= 0 && count < 32);
+
+      uint32_t out = 0;
+      if (offset < 32)
+         out |= data[0] >> offset;
+
+      if (0 < offset && offset <= 32)
+         out |= data[1] << (32 - offset);
+      if (32 < offset && offset < 64)
+         out |= data[1] >> (offset - 32);
+
+      if (32 < offset && offset <= 64)
+         out |= data[2] << (64 - offset);
+      if (64 < offset && offset < 96)
+         out |= data[2] >> (offset - 64);
+
+      if (64 < offset && offset <= 96)
+         out |= data[3] << (96 - offset);
+      if (96 < offset && offset < 128)
+         out |= data[3] >> (offset - 96);
+
+      out &= (1 << count) - 1;
+      return out;
+   }
+
+   uint64_t get_bits64(int offset, int count)
+   {
+      assert(count >= 0 && count < 64);
+
+      uint64_t out = 0;
+      if (offset < 32)
+         out |= data[0] >> offset;
+
+      if (offset <= 32)
+         out |= (uint64_t)data[1] << (32 - offset);
+      if (32 < offset && offset < 64)
+         out |= data[1] >> (offset - 32);
+
+      if (0 < offset && offset <= 64)
+         out |= (uint64_t)data[2] << (64 - offset);
+      if (64 < offset && offset < 96)
+         out |= data[2] >> (offset - 64);
+
+      if (32 < offset && offset <= 96)
+         out |= (uint64_t)data[3] << (96 - offset);
+      if (96 < offset && offset < 128)
+         out |= data[3] >> (offset - 96);
+
+      out &= ((uint64_t)1 << count) - 1;
+      return out;
+   }
+
+   uint32_t get_bits_rev(int offset, int count)
+   {
+      assert(offset >= count);
+      uint32_t tmp = get_bits(offset - count, count);
+      uint32_t out = 0;
+      for (int i = 0; i < count; ++i)
+         out |= ((tmp >> i) & 1) << (count - 1 - i);
+      return out;
+   }
+};
+
+struct OutputBitVector
+{
+   uint32_t data[4];
+   int offset;
+
+   OutputBitVector()
+      : offset(0)
+   {
+      memset(data, 0, sizeof(data));
+   }
+
+   void append(uint32_t value, int size)
+   {
+      if (VERBOSE_WRITE)
+         printf("append offset=%d size=%d values=0x%x\n", offset, size, value);
+
+      assert(offset + size <= 128);
+
+      assert(size <= 32);
+      if (size < 32)
+         assert((value >> size) == 0);
+
+      while (size) {
+         int c = MIN2(size, 32 - (offset & 31));
+         data[offset >> 5] |= (value << (offset & 31));
+         offset += c;
+         size -= c;
+         value >>= c;
+      }
+   }
+
+   void append64(uint64_t value, int size)
+   {
+      if (VERBOSE_WRITE)
+         printf("append offset=%d size=%d values=0x%llx\n", offset, size, (unsigned long long)value);
+
+      assert(offset + size <= 128);
+
+      assert(size <= 64);
+      if (size < 64)
+         assert((value >> size) == 0);
+
+      while (size) {
+         int c = MIN2(size, 32 - (offset & 31));
+         data[offset >> 5] |= (value << (offset & 31));
+         offset += c;
+         size -= c;
+         value >>= c;
+      }
+   }
+
+   void append(OutputBitVector &v, int size)
+   {
+      if (VERBOSE_WRITE)
+         printf("append vector offset=%d size=%d\n", offset, size);
+
+      assert(offset + size <= 128);
+      int i = 0;
+      while (size >= 32) {
+         append(v.data[i++], 32);
+         size -= 32;
+      }
+      if (size > 0)
+         append(v.data[i] & ((1 << size) - 1), size);
+   }
+
+   void append_end(OutputBitVector &v, int size)
+   {
+      for (int i = 0; i < size; ++i)
+         data[(127 - i) >> 5] |= ((v.data[i >> 5] >> (i & 31)) & 1) << ((127 - i) & 31);
+   }
+
+   /* Insert the given number of '1' bits. (We could use 0s instead, but 1s are
+    * more likely to flush out bugs where we accidentally read undefined bits.)
+    */
+   void skip(int size)
+   {
+      if (VERBOSE_WRITE)
+         printf("skip offset=%d size=%d\n", offset, size);
+
+      assert(offset + size <= 128);
+      while (size >= 32) {
+         append(0xffffffff, 32);
+         size -= 32;
+      }
+      if (size > 0)
+         append(0xffffffff >> (32 - size), size);
+   }
+};
+
+
+class Decoder
+{
+public:
+   Decoder(int block_w, int block_h, int block_d, bool srgb, bool output_unorm8)
+      : block_w(block_w), block_h(block_h), block_d(block_d), srgb(srgb),
+        output_unorm8(output_unorm8) {}
+
+   decode_error::type decode(const uint8_t *in, uint16_t *output) const;
+
+   int block_w, block_h, block_d;
+   bool srgb, output_unorm8;
+};
+
+struct Block
+{
+   bool is_error;
+   bool bogus_colour_endpoints;
+   bool bogus_weights;
+
+   int high_prec;
+   int dual_plane;
+   int colour_component_selector;
+   int wt_range;
+   int wt_w, wt_h, wt_d;
+   int num_parts;
+   int partition_index;
+
+   bool is_void_extent;
+   int void_extent_d;
+   int void_extent_min_s;
+   int void_extent_max_s;
+   int void_extent_min_t;
+   int void_extent_max_t;
+   uint16_t void_extent_colour_r;
+   uint16_t void_extent_colour_g;
+   uint16_t void_extent_colour_b;
+   uint16_t void_extent_colour_a;
+
+   bool is_multi_cem;
+   int num_extra_cem_bits;
+   int colour_endpoint_data_offset;
+   int extra_cem_bits;
+   int cem_base_class;
+   int cems[4];
+
+   int num_cem_values;
+
+   /* Calculated by unpack_weights(): */
+   uint8_t weights_quant[64 + 4]; /* max 64 values, plus padding for overflows in trit parsing */
+
+   /* Calculated by unquantise_weights(): */
+   uint8_t weights[64 + 18]; /* max 64 values, plus padding for the infill interpolation */
+
+   /* Calculated by unpack_colour_endpoints(): */
+   uint8_t colour_endpoints_quant[18 + 4]; /* max 18 values, plus padding for overflows in trit parsing */
+
+   /* Calculated by unquantise_colour_endpoints(): */
+   uint8_t colour_endpoints[18];
+
+   /* Calculated by calculate_from_weights(): */
+   int wt_trits;
+   int wt_quints;
+   int wt_bits;
+   int wt_max;
+   int num_weights;
+   int weight_bits;
+
+   /* Calculated by calculate_remaining_bits(): */
+   int remaining_bits;
+
+   /* Calculated by calculate_colour_endpoints_size(): */
+   int colour_endpoint_bits;
+   int ce_max;
+   int ce_trits;
+   int ce_quints;
+   int ce_bits;
+
+   /* Calculated by compute_infill_weights(); */
+   uint8_t infill_weights[2][216]; /* large enough for 6x6x6 */
+
+   /* Calculated by decode_colour_endpoints(); */
+   uint8x4_t endpoints_decoded[2][4];
+
+   void calculate_from_weights();
+   void calculate_remaining_bits();
+   decode_error::type calculate_colour_endpoints_size();
+
+   void unquantise_weights();
+   void unquantise_colour_endpoints();
+
+   decode_error::type decode(const Decoder &decoder, InputBitVector in);
+
+   decode_error::type decode_block_mode(InputBitVector in);
+   decode_error::type decode_void_extent(InputBitVector in);
+   void decode_cem(InputBitVector in);
+   void unpack_colour_endpoints(InputBitVector in);
+   void decode_colour_endpoints();
+   void unpack_weights(InputBitVector in);
+   void compute_infill_weights(int block_w, int block_h, int block_d);
+
+   void write_decoded(const Decoder &decoder, uint16_t *output);
+};
+
+
+decode_error::type Decoder::decode(const uint8_t *in, uint16_t *output) const
+{
+   Block blk;
+   InputBitVector in_vec;
+   memcpy(&in_vec.data, in, 16);
+   decode_error::type err = blk.decode(*this, in_vec);
+   if (err == decode_error::ok) {
+      blk.write_decoded(*this, output);
+   } else {
+      /* Fill output with the error colour */
+      for (int i = 0; i < block_w * block_h * block_d; ++i) {
+         if (output_unorm8) {
+            output[i*4+0] = 0xff;
+            output[i*4+1] = 0;
+            output[i*4+2] = 0xff;
+            output[i*4+3] = 0xff;
+         } else {
+            assert(!srgb); /* srgb must use unorm8 */
+
+            output[i*4+0] = FP16_ONE;
+            output[i*4+1] = FP16_ZERO;
+            output[i*4+2] = FP16_ONE;
+            output[i*4+3] = FP16_ONE;
+         }
+      }
+   }
+   return err;
+}
+
+
+decode_error::type Block::decode_void_extent(InputBitVector block)
+{
+   /* TODO: 3D */
+
+   is_void_extent = true;
+   void_extent_d = block.get_bits(9, 1);
+   void_extent_min_s = block.get_bits(12, 13);
+   void_extent_max_s = block.get_bits(25, 13);
+   void_extent_min_t = block.get_bits(38, 13);
+   void_extent_max_t = block.get_bits(51, 13);
+   void_extent_colour_r = block.get_bits(64, 16);
+   void_extent_colour_g = block.get_bits(80, 16);
+   void_extent_colour_b = block.get_bits(96, 16);
+   void_extent_colour_a = block.get_bits(112, 16);
+
+   /* TODO: maybe we should do something useful with the extent coordinates? */
+
+   if (void_extent_d) {
+      return decode_error::unsupported_hdr_void_extent;
+   }
+
+   if (void_extent_min_s == 0x1fff && void_extent_max_s == 0x1fff
+       && void_extent_min_t == 0x1fff && void_extent_max_t == 0x1fff) {
+
+      /* No extents */
+
+   } else {
+
+      /* Check for illegal encoding */
+      if (void_extent_min_s >= void_extent_max_s || void_extent_min_t >= void_extent_max_t) {
+         return decode_error::invalid_range_in_void_extent;
+      }
+   }
+
+   return decode_error::ok;
+}
+
+decode_error::type Block::decode_block_mode(InputBitVector in)
+{
+   dual_plane = in.get_bits(10, 1);
+   high_prec = in.get_bits(9, 1);
+
+   if (in.get_bits(0, 2) != 0x0) {
+      wt_range = (in.get_bits(0, 2) << 1) | in.get_bits(4, 1);
+      int a = in.get_bits(5, 2);
+      int b = in.get_bits(7, 2);
+      switch (in.get_bits(2, 2)) {
+      case 0x0:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "DHBBAAR00RR");
+         wt_w = b + 4;
+         wt_h = a + 2;
+         break;
+      case 0x1:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "DHBBAAR01RR");
+         wt_w = b + 8;
+         wt_h = a + 2;
+         break;
+      case 0x2:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "DHBBAAR10RR");
+         wt_w = a + 2;
+         wt_h = b + 8;
+         break;
+      case 0x3:
+         if ((b & 0x2) == 0) {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "DH0BAAR11RR");
+            wt_w = a + 2;
+            wt_h = b + 6;
+         } else {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "DH1BAAR11RR");
+            wt_w = (b & 0x1) + 2;
+            wt_h = a + 2;
+         }
+         break;
+      }
+   } else {
+      if (in.get_bits(6, 3) == 0x7) {
+         if (in.get_bits(0, 9) == 0x1fc) {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "xx111111100 (void extent)");
+            return decode_void_extent(in);
+         } else {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "xx111xxxx00");
+            return decode_error::reserved_block_mode_1;
+         }
+      }
+      if (in.get_bits(0, 4) == 0x0) {
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "xxxxxxx0000");
+         return decode_error::reserved_block_mode_2;
+      }
+
+      wt_range = in.get_bits(1, 3) | in.get_bits(4, 1);
+      int a = in.get_bits(5, 2);
+      int b;
+
+      switch (in.get_bits(7, 2)) {
+      case 0b00:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "DH00AARRR00");
+         wt_w = 12;
+         wt_h = a + 2;
+         break;
+      case 0b01:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "DH01AARRR00");
+         wt_w = a + 2;
+         wt_h = 12;
+         break;
+      case 0b11:
+         if (in.get_bits(5, 1) == 0) {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "DH1100RRR00");
+            wt_w = 6;
+            wt_h = 10;
+         } else {
+            if (VERBOSE_DECODE)
+               in.printf_bits(0, 11, "DH1101RRR00");
+            wt_w = 10;
+            wt_h = 6;
+         }
+         break;
+      case 0b10:
+         if (VERBOSE_DECODE)
+            in.printf_bits(0, 11, "BB10AARRR00");
+         b = in.get_bits(9, 2);
+         wt_w = a + 6;
+         wt_h = b + 6;
+         dual_plane = 0;
+         high_prec = 0;
+         break;
+      }
+   }
+   return decode_error::ok;
+}
+
+void Block::decode_cem(InputBitVector in)
+{
+   cems[0] = cems[1] = cems[2] = cems[3] = -1;
+
+   num_extra_cem_bits = 0;
+   extra_cem_bits = 0;
+
+   if (num_parts > 1) {
+
+      partition_index = in.get_bits(13, 10);
+      if (VERBOSE_DECODE)
+         in.printf_bits(13, 10, "partition ID (%d)", partition_index);
+
+      uint32_t cem = in.get_bits(23, 6);
+
+      if ((cem & 0b11) == 0b00) {
+         cem >>= 2;
+         cem_base_class = cem >> 2;
+         is_multi_cem = false;
+
+         for (int i = 0; i < num_parts; ++i)
+            cems[i] = cem;
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(23, 6, "CEM (single, %d)", cem);
+      } else {
+
+         cem_base_class = (cem & 0b11) - 1;
+         is_multi_cem = true;
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(23, 6, "CEM (multi, base class %d)", cem_base_class);
+
+         int offset = 128 - weight_bits;
+
+         if (num_parts == 2) {
+            if (VERBOSE_DECODE) {
+               in.printf_bits(25, 4, "M0M0 C1 C0");
+               in.printf_bits(offset - 2, 2, "M1M1");
+            }
+
+            uint32_t c0 = in.get_bits(25, 1);
+            uint32_t c1 = in.get_bits(26, 1);
+
+            extra_cem_bits = c0 + c1;
+
+            num_extra_cem_bits = 2;
+
+            uint32_t m0 = in.get_bits(27, 2);
+            uint32_t m1 = in.get_bits(offset - 2, 2);
+
+            cems[0] = ((cem_base_class + c0) << 2) | m0;
+            cems[1] = ((cem_base_class + c1) << 2) | m1;
+
+         } else if (num_parts == 3) {
+            if (VERBOSE_DECODE) {
+               in.printf_bits(25, 4, "M0 C2 C1 C0");
+               in.printf_bits(offset - 5, 5, "M2M2 M1M1 M0");
+            }
+
+            uint32_t c0 = in.get_bits(25, 1);
+            uint32_t c1 = in.get_bits(26, 1);
+            uint32_t c2 = in.get_bits(27, 1);
+
+            extra_cem_bits = c0 + c1 + c2;
+
+            num_extra_cem_bits = 5;
+
+            uint32_t m0 = in.get_bits(28, 1) | (in.get_bits(128 - weight_bits - 5, 1) << 1);
+            uint32_t m1 = in.get_bits(offset - 4, 2);
+            uint32_t m2 = in.get_bits(offset - 2, 2);
+
+            cems[0] = ((cem_base_class + c0) << 2) | m0;
+            cems[1] = ((cem_base_class + c1) << 2) | m1;
+            cems[2] = ((cem_base_class + c2) << 2) | m2;
+
+         } else if (num_parts == 4) {
+            if (VERBOSE_DECODE) {
+               in.printf_bits(25, 4, "C3 C2 C1 C0");
+               in.printf_bits(offset - 8, 8, "M3M3 M2M2 M1M1 M0M0");
+            }
+
+            uint32_t c0 = in.get_bits(25, 1);
+            uint32_t c1 = in.get_bits(26, 1);
+            uint32_t c2 = in.get_bits(27, 1);
+            uint32_t c3 = in.get_bits(28, 1);
+
+            extra_cem_bits = c0 + c1 + c2 + c3;
+
+            num_extra_cem_bits = 8;
+
+            uint32_t m0 = in.get_bits(offset - 8, 2);
+            uint32_t m1 = in.get_bits(offset - 6, 2);
+            uint32_t m2 = in.get_bits(offset - 4, 2);
+            uint32_t m3 = in.get_bits(offset - 2, 2);
+
+            cems[0] = ((cem_base_class + c0) << 2) | m0;
+            cems[1] = ((cem_base_class + c1) << 2) | m1;
+            cems[2] = ((cem_base_class + c2) << 2) | m2;
+            cems[3] = ((cem_base_class + c3) << 2) | m3;
+         } else {
+            unreachable("");
+         }
+      }
+
+      colour_endpoint_data_offset = 29;
+
+   } else {
+      uint32_t cem = in.get_bits(13, 4);
+
+      cem_base_class = cem >> 2;
+      is_multi_cem = false;
+
+      cems[0] = cem;
+
+      partition_index = -1;
+
+      if (VERBOSE_DECODE)
+         in.printf_bits(13, 4, "CEM = %d (class %d)", cem, cem_base_class);
+
+      colour_endpoint_data_offset = 17;
+   }
+}
+
+void Block::unpack_colour_endpoints(InputBitVector in)
+{
+   if (ce_trits) {
+      int offset = colour_endpoint_data_offset;
+      int bits_left = colour_endpoint_bits;
+      for (int i = 0; i < num_cem_values; i += 5) {
+         int bits_to_read = MIN2(bits_left, 8 + ce_bits * 5);
+         /* If ce_trits then ce_bits <= 6, so bits_to_read <= 38 and we have to use uint64_t */
+         uint64_t raw = in.get_bits64(offset, bits_to_read);
+         unpack_trit_block(ce_bits, raw, &colour_endpoints_quant[i]);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset, bits_to_read,
+                           "trits [%d,%d,%d,%d,%d]",
+                           colour_endpoints_quant[i+0], colour_endpoints_quant[i+1],
+                  colour_endpoints_quant[i+2], colour_endpoints_quant[i+3],
+                  colour_endpoints_quant[i+4]);
+
+         offset += 8 + ce_bits * 5;
+         bits_left -= 8 + ce_bits * 5;
+      }
+   } else if (ce_quints) {
+      int offset = colour_endpoint_data_offset;
+      int bits_left = colour_endpoint_bits;
+      for (int i = 0; i < num_cem_values; i += 3) {
+         int bits_to_read = MIN2(bits_left, 7 + ce_bits * 3);
+         /* If ce_quints then ce_bits <= 5, so bits_to_read <= 22 and we can use uint32_t */
+         uint32_t raw = in.get_bits(offset, bits_to_read);
+         unpack_quint_block(ce_bits, raw, &colour_endpoints_quant[i]);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset, bits_to_read,
+                           "quints [%d,%d,%d]",
+                           colour_endpoints_quant[i], colour_endpoints_quant[i+1], colour_endpoints_quant[i+2]);
+
+         offset += 7 + ce_bits * 3;
+         bits_left -= 7 + ce_bits * 3;
+      }
+   } else {
+      assert((colour_endpoint_bits % ce_bits) == 0);
+      int offset = colour_endpoint_data_offset;
+      for (int i = 0; i < num_cem_values; i++) {
+         colour_endpoints_quant[i] = in.get_bits(offset, ce_bits);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset, ce_bits, "bits [%d]", colour_endpoints_quant[i]);
+
+         offset += ce_bits;
+      }
+   }
+}
+
+void Block::decode_colour_endpoints()
+{
+   int cem_values_idx = 0;
+   for (int part = 0; part < num_parts; ++part) {
+      uint8_t *v = &colour_endpoints[cem_values_idx];
+      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 = v[6];
+      int v7 = v[7];
+      cem_values_idx += ((cems[part] >> 2) + 1) * 2;
+
+      uint8x4_t e0, e1;
+      int s0, s1, L0, L1;
+
+      switch (cems[part])
+      {
+      case 0:
+         e0 = uint8x4_t(v0, v0, v0, 0xff);
+         e1 = uint8x4_t(v1, v1, v1, 0xff);
+         break;
+      case 1:
+         L0 = (v0 >> 2) | (v1 & 0xc0);
+         L1 = L0 + (v1 & 0x3f);
+         if (L1 > 0xff)
+            L1 = 0xff;
+         e0 = uint8x4_t(L0, L0, L0, 0xff);
+         e1 = uint8x4_t(L1, L1, L1, 0xff);
+         break;
+      case 4:
+         e0 = uint8x4_t(v0, v0, v0, v2);
+         e1 = uint8x4_t(v1, v1, v1, v3);
+         break;
+      case 5:
+         bit_transfer_signed(v1, v0);
+         bit_transfer_signed(v3, v2);
+         e0 = uint8x4_t(v0, v0, v0, v2);
+         e1 = uint8x4_t::clamped(v0+v1, v0+v1, v0+v1, v2+v3);
+         break;
+      case 6:
+         e0 = uint8x4_t(v0*v3 >> 8, v1*v3 >> 8, v2*v3 >> 8, 0xff);
+         e1 = uint8x4_t(v0, v1, v2, 0xff);
+         break;
+      case 8:
+         s0 = v0 + v2 + v4;
+         s1 = v1 + v3 + v5;
+         if (s1 >= s0) {
+            e0 = uint8x4_t(v0, v2, v4, 0xff);
+            e1 = uint8x4_t(v1, v3, v5, 0xff);
+         } else {
+            e0 = blue_contract(v1, v3, v5, 0xff);
+            e1 = blue_contract(v0, v2, v4, 0xff);
+         }
+         break;
+      case 9:
+         bit_transfer_signed(v1, v0);
+         bit_transfer_signed(v3, v2);
+         bit_transfer_signed(v5, v4);
+         if (v1 + v3 + v5 >= 0) {
+            e0 = uint8x4_t(v0, v2, v4, 0xff);
+            e1 = uint8x4_t::clamped(v0+v1, v2+v3, v4+v5, 0xff);
+         } else {
+            e0 = blue_contract_clamped(v0+v1, v2+v3, v4+v5, 0xff);
+            e1 = blue_contract(v0, v2, v4, 0xff);
+         }
+         break;
+      case 10:
+         e0 = uint8x4_t(v0*v3 >> 8, v1*v3 >> 8, v2*v3 >> 8, v4);
+         e1 = uint8x4_t(v0, v1, v2, v5);
+         break;
+      case 12:
+         s0 = v0 + v2 + v4;
+         s1 = v1 + v3 + v5;
+         if (s1 >= s0) {
+            e0 = uint8x4_t(v0, v2, v4, v6);
+            e1 = uint8x4_t(v1, v3, v5, v7);
+         } else {
+            e0 = blue_contract(v1, v3, v5, v7);
+            e1 = blue_contract(v0, v2, v4, v6);
+         }
+         break;
+      case 13:
+         bit_transfer_signed(v1, v0);
+         bit_transfer_signed(v3, v2);
+         bit_transfer_signed(v5, v4);
+         bit_transfer_signed(v7, v6);
+         if (v1 + v3 + v5 >= 0) {
+            e0 = uint8x4_t(v0, v2, v4, v6);
+            e1 = uint8x4_t::clamped(v0+v1, v2+v3, v4+v5, v6+v7);
+         } else {
+            e0 = blue_contract_clamped(v0+v1, v2+v3, v4+v5, v6+v7);
+            e1 = blue_contract(v0, v2, v4, v6);
+         }
+         break;
+      default:
+         /* HDR endpoints not supported; return error colour */
+         e0 = uint8x4_t(255, 0, 255, 255);
+         e1 = uint8x4_t(255, 0, 255, 255);
+         break;
+      }
+
+      endpoints_decoded[0][part] = e0;
+      endpoints_decoded[1][part] = e1;
+
+      if (VERBOSE_DECODE) {
+         printf("cems[%d]=%d v=[", part, cems[part]);
+         for (int i = 0; i < (cems[part] >> 2) + 1; ++i) {
+            if (i)
+               printf(", ");
+            printf("%3d", v[i]);
+         }
+         printf("] e0=[%3d,%4d,%4d,%4d] e1=[%3d,%4d,%4d,%4d]\n",
+                e0.v[0], e0.v[1], e0.v[2], e0.v[3],
+               e1.v[0], e1.v[1], e1.v[2], e1.v[3]);
+      }
+   }
+}
+
+void Block::unpack_weights(InputBitVector in)
+{
+   if (wt_trits) {
+      int offset = 128;
+      int bits_left = weight_bits;
+      for (int i = 0; i < num_weights; i += 5) {
+         int bits_to_read = MIN2(bits_left, 8 + 5*wt_bits);
+         /* If wt_trits then wt_bits <= 3, so bits_to_read <= 23 and we can use uint32_t */
+         uint32_t raw = in.get_bits_rev(offset, bits_to_read);
+         unpack_trit_block(wt_bits, raw, &weights_quant[i]);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset - bits_to_read, bits_to_read, "weight trits [%d,%d,%d,%d,%d]",
+                           weights_quant[i+0], weights_quant[i+1],
+                  weights_quant[i+2], weights_quant[i+3],
+                  weights_quant[i+4]);
+
+         offset -= 8 + wt_bits * 5;
+         bits_left -= 8 + wt_bits * 5;
+      }
+
+   } else if (wt_quints) {
+
+      int offset = 128;
+      int bits_left = weight_bits;
+      for (int i = 0; i < num_weights; i += 3) {
+         int bits_to_read = MIN2(bits_left, 7 + 3*wt_bits);
+         /* If wt_quints then wt_bits <= 2, so bits_to_read <= 13 and we can use uint32_t */
+         uint32_t raw = in.get_bits_rev(offset, bits_to_read);
+         unpack_quint_block(wt_bits, raw, &weights_quant[i]);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset - bits_to_read, bits_to_read, "weight quints [%d,%d,%d]",
+                           weights_quant[i], weights_quant[i+1], weights_quant[i+2]);
+
+         offset -= 7 + wt_bits * 3;
+         bits_left -= 7 + wt_bits * 3;
+      }
+
+   } else {
+      int offset = 128;
+      assert((weight_bits % wt_bits) == 0);
+      for (int i = 0; i < num_weights; ++i) {
+         weights_quant[i] = in.get_bits_rev(offset, wt_bits);
+
+         if (VERBOSE_DECODE)
+            in.printf_bits(offset - wt_bits, wt_bits, "weight bits [%d]", weights_quant[i]);
+
+         offset -= wt_bits;
+      }
+   }
+}
+
+void Block::unquantise_weights()
+{
+   assert(num_weights <= (int)ARRAY_SIZE(weights_quant));
+   assert(num_weights <= (int)ARRAY_SIZE(weights));
+
+   memset(weights, 0, sizeof(weights));
+
+   for (int i = 0; i < num_weights; ++i) {
+
+      uint8_t v = weights_quant[i];
+      uint8_t w;
+
+      if (wt_trits) {
+
+         if (wt_bits == 0) {
+            w = v * 32;
+         } else {
+            uint8_t A, B, C, D;
+            A = (v & 0b1) ? 0b1111111 : 0b0000000;
+            switch (wt_bits) {
+            case 1:
+               B = 0;
+               C = 50;
+               D = v >> 1;
+               break;
+            case 2:
+               B = (v & 0b10) ? 0b1000101 : 0b0000000;
+               C = 23;
+               D = v >> 2;
+               break;
+            case 3:
+               B = ((v & 0b110) >> 1) | ((v & 0b110) << 4);
+               C = 11;
+               D = v >> 3;
+               break;
+            default:
+               unreachable("");
+            }
+            uint16_t T = D * C + B;
+            T = T ^ A;
+            T = (A & 0x20) | (T >> 2);
+            assert(T < 64);
+            if (T > 32)
+               T++;
+            w = T;
+         }
+
+      } else if (wt_quints) {
+
+         if (wt_bits == 0) {
+            w = v * 16;
+         } else {
+            uint8_t A, B, C, D;
+            A = (v & 0b1) ? 0b1111111 : 0b0000000;
+            switch (wt_bits) {
+            case 1:
+               B = 0;
+               C = 28;
+               D = v >> 1;
+               break;
+            case 2:
+               B = (v & 0b10) ? 0b1000010 : 0b0000000;
+               C = 13;
+               D = v >> 2;
+               break;
+            default:
+               unreachable("");
+            }
+            uint16_t T = D * C + B;
+            T = T ^ A;
+            T = (A & 0x20) | (T >> 2);
+            assert(T < 64);
+            if (T > 32)
+               T++;
+            w = T;
+         }
+         weights[i] = w;
+
+      } else {
+
+         switch (wt_bits) {
+         case 1: w = v ? 0b111111 : 0b000000; break;
+         case 2: w = v | (v << 2) | (v << 4); break;
+         case 3: w = v | (v << 3); break;
+         case 4: w = (v >> 2) | (v << 2); break;
+         case 5: w = (v >> 4) | (v << 1); break;
+         default: unreachable("");
+         }
+         assert(w < 64);
+         if (w > 32)
+            w++;
+      }
+      weights[i] = w;
+   }
+}
+
+void Block::compute_infill_weights(int block_w, int block_h, int block_d)
+{
+   int Ds = block_w <= 1 ? 0 : (1024 + block_w / 2) / (block_w - 1);
+   int Dt = block_h <= 1 ? 0 : (1024 + block_h / 2) / (block_h - 1);
+   int Dr = block_d <= 1 ? 0 : (1024 + block_d / 2) / (block_d - 1);
+   for (int r = 0; r < block_d; ++r) {
+      for (int t = 0; t < block_h; ++t) {
+         for (int s = 0; s < block_w; ++s) {
+            int cs = Ds * s;
+            int ct = Dt * t;
+            int cr = Dr * r;
+            int gs = (cs * (wt_w - 1) + 32) >> 6;
+            int gt = (ct * (wt_h - 1) + 32) >> 6;
+            int gr = (cr * (wt_d - 1) + 32) >> 6;
+            assert(gs >= 0 && gs <= 176);
+            assert(gt >= 0 && gt <= 176);
+            assert(gr >= 0 && gr <= 176);
+            int js = gs >> 4;
+            int fs = gs & 0xf;
+            int jt = gt >> 4;
+            int ft = gt & 0xf;
+            int jr = gr >> 4;
+            int fr = gr & 0xf;
+
+            /* TODO: 3D */
+            (void)jr;
+            (void)fr;
+
+            int w11 = (fs * ft + 8) >> 4;
+            int w10 = ft - w11;
+            int w01 = fs - w11;
+            int w00 = 16 - fs - ft + w11;
+
+            if (dual_plane) {
+               int p00, p01, p10, p11, i0, i1;
+               int v0 = js + jt * wt_w;
+               p00 = weights[(v0) * 2];
+               p01 = weights[(v0 + 1) * 2];
+               p10 = weights[(v0 + wt_w) * 2];
+               p11 = weights[(v0 + wt_w + 1) * 2];
+               i0 = (p00*w00 + p01*w01 + p10*w10 + p11*w11 + 8) >> 4;
+               p00 = weights[(v0) * 2 + 1];
+               p01 = weights[(v0 + 1) * 2 + 1];
+               p10 = weights[(v0 + wt_w) * 2 + 1];
+               p11 = weights[(v0 + wt_w + 1) * 2 + 1];
+               assert((v0 + wt_w + 1) * 2 + 1 < (int)ARRAY_SIZE(weights));
+               i1 = (p00*w00 + p01*w01 + p10*w10 + p11*w11 + 8) >> 4;
+               assert(0 <= i0 && i0 <= 64);
+               infill_weights[0][s + t*block_w + r*block_w*block_h] = i0;
+               infill_weights[1][s + t*block_w + r*block_w*block_h] = i1;
+            } else {
+               int p00, p01, p10, p11, i;
+               int v0 = js + jt * wt_w;
+               p00 = weights[v0];
+               p01 = weights[v0 + 1];
+               p10 = weights[v0 + wt_w];
+               p11 = weights[v0 + wt_w + 1];
+               assert(v0 + wt_w + 1 < (int)ARRAY_SIZE(weights));
+               i = (p00*w00 + p01*w01 + p10*w10 + p11*w11 + 8) >> 4;
+               assert(0 <= i && i <= 64);
+               infill_weights[0][s + t*block_w + r*block_w*block_h] = i;
+            }
+         }
+      }
+   }
+}
+
+void Block::unquantise_colour_endpoints()
+{
+   assert(num_cem_values <= (int)ARRAY_SIZE(colour_endpoints_quant));
+   assert(num_cem_values <= (int)ARRAY_SIZE(colour_endpoints));
+
+   for (int i = 0; i < num_cem_values; ++i) {
+      uint8_t v = colour_endpoints_quant[i];
+
+      if (ce_trits) {
+         uint16_t A, B, C, D;
+         uint16_t t;
+         A = (v & 0b1) ? 0b111111111 : 0b000000000;
+         switch (ce_bits) {
+         case 1:
+            B = 0;
+            C = 204;
+            D = v >> 1;
+            break;
+         case 2:
+            B = (v & 0b10) ? 0b100010110 : 0b000000000;
+            C = 93;
+            D = v >> 2;
+            break;
+         case 3:
+            t = ((v >> 1) & 0b11);
+            B = t | (t << 2) | (t << 7);
+            C = 44;
+            D = v >> 3;
+            break;
+         case 4:
+            t = ((v >> 1) & 0b111);
+            B = t | (t << 6);
+            C = 22;
+            D = v >> 4;
+            break;
+         case 5:
+            t = ((v >> 1) & 0b1111);
+            B = (t >> 2) | (t << 5);
+            C = 11;
+            D = v >> 5;
+            break;
+         case 6:
+            B = ((v & 0b111110) << 3) | ((v >> 5) & 0b1);
+            C = 5;
+            D = v >> 6;
+            break;
+         default:
+            unreachable("");
+         }
+         uint16_t T = D * C + B;
+         T = T ^ A;
+         T = (A & 0x80) | (T >> 2);
+         assert(T < 256);
+         colour_endpoints[i] = T;
+      } else if (ce_quints) {
+         uint16_t A, B, C, D;
+         uint16_t t;
+         A = (v & 0b1) ? 0b111111111 : 0b000000000;
+         switch (ce_bits) {
+         case 1:
+            B = 0;
+            C = 113;
+            D = v >> 1;
+            break;
+         case 2:
+            B = (v & 0b10) ? 0b100001100 : 0b000000000;
+            C = 54;
+            D = v >> 2;
+            break;
+         case 3:
+            t = ((v >> 1) & 0b11);
+            B = (t >> 1) | (t << 1) | (t << 7);
+            C = 26;
+            D = v >> 3;
+            break;
+         case 4:
+            t = ((v >> 1) & 0b111);
+            B = (t >> 1) | (t << 6);
+            C = 13;
+            D = v >> 4;
+            break;
+         case 5:
+            t = ((v >> 1) & 0b1111);
+            B = (t >> 4) | (t << 5);
+            C = 6;
+            D = v >> 5;
+            break;
+         default:
+            unreachable("");
+         }
+         uint16_t T = D * C + B;
+         T = T ^ A;
+         T = (A & 0x80) | (T >> 2);
+         assert(T < 256);
+         colour_endpoints[i] = T;
+      } else {
+         switch (ce_bits) {
+         case 1: v = v ? 0b11111111 : 0b00000000; break;
+         case 2: v = (v << 6) | (v << 4) | (v << 2) | v; break;
+         case 3: v = (v << 5) | (v << 2) | (v >> 1); break;
+         case 4: v = (v << 4) | v; break;
+         case 5: v = (v << 3) | (v >> 2); break;
+         case 6: v = (v << 2) | (v >> 4); break;
+         case 7: v = (v << 1) | (v >> 6); break;
+         case 8: break;
+         default: unreachable("");
+         }
+         colour_endpoints[i] = v;
+      }
+   }
+}
+
+decode_error::type Block::decode(const Decoder &decoder, InputBitVector in)
+{
+   decode_error::type err;
+
+   is_error = false;
+   bogus_colour_endpoints = false;
+   bogus_weights = false;
+   is_void_extent = false;
+
+   wt_d = 1;
+   /* TODO: 3D */
+
+   /* TODO: test for all the illegal encodings */
+
+   if (VERBOSE_DECODE)
+      in.printf_bits(0, 128);
+
+   err = decode_block_mode(in);
+   if (err != decode_error::ok)
+      return err;
+
+   if (is_void_extent)
+      return decode_error::ok;
+
+   /* TODO: 3D */
+
+   calculate_from_weights();
+
+   if (VERBOSE_DECODE)
+      printf("weights_grid=%dx%dx%d dual_plane=%d num_weights=%d high_prec=%d r=%d range=0..%d (%dt %dq %db) weight_bits=%d\n",
+             wt_w, wt_h, wt_d, dual_plane, num_weights, high_prec, wt_range, wt_max, wt_trits, wt_quints, wt_bits, weight_bits);
+
+   if (wt_w > decoder.block_w || wt_h > decoder.block_h || wt_d > decoder.block_d)
+      return decode_error::weight_grid_exceeds_block_size;
+
+   num_parts = in.get_bits(11, 2) + 1;
+
+   if (VERBOSE_DECODE)
+      in.printf_bits(11, 2, "partitions = %d", num_parts);
+
+   if (dual_plane && num_parts > 3)
+      return decode_error::dual_plane_and_too_many_partitions;
+
+   decode_cem(in);
+
+   if (VERBOSE_DECODE)
+      printf("cem=[%d,%d,%d,%d] base_cem_class=%d\n", cems[0], cems[1], cems[2], cems[3], cem_base_class);
+
+   int num_cem_pairs = (cem_base_class + 1) * num_parts + extra_cem_bits;
+   num_cem_values = num_cem_pairs * 2;
+
+   calculate_remaining_bits();
+   err = calculate_colour_endpoints_size();
+   if (err != decode_error::ok)
+      return err;
+
+   if (VERBOSE_DECODE)
+      in.printf_bits(colour_endpoint_data_offset, colour_endpoint_bits,
+                     "endpoint data (%d bits, %d vals, %dt %dq %db)",
+                     colour_endpoint_bits, num_cem_values, ce_trits, ce_quints, ce_bits);
+
+   unpack_colour_endpoints(in);
+
+   if (VERBOSE_DECODE) {
+      printf("cem values raw =[");
+      for (int i = 0; i < num_cem_values; i++) {
+         if (i)
+            printf(", ");
+         printf("%3d", colour_endpoints_quant[i]);
+      }
+      printf("]\n");
+   }
+
+   if (num_cem_values > 18)
+      return decode_error::invalid_colour_endpoints_count;
+
+   unquantise_colour_endpoints();
+
+   if (VERBOSE_DECODE) {
+      printf("cem values norm=[");
+      for (int i = 0; i < num_cem_values; i++) {
+         if (i)
+            printf(", ");
+         printf("%3d", colour_endpoints[i]);
+      }
+      printf("]\n");
+   }
+
+   decode_colour_endpoints();
+
+   if (dual_plane) {
+      int ccs_offset = 128 - weight_bits - num_extra_cem_bits - 2;
+      colour_component_selector = in.get_bits(ccs_offset, 2);
+
+      if (VERBOSE_DECODE)
+         in.printf_bits(ccs_offset, 2, "colour component selector = %d", colour_component_selector);
+   } else {
+      colour_component_selector = 0;
+   }
+
+
+   if (VERBOSE_DECODE)
+      in.printf_bits(128 - weight_bits, weight_bits, "weights (%d bits)", weight_bits);
+
+   if (num_weights > 64)
+      return decode_error::invalid_num_weights;
+
+   if (weight_bits < 24 || weight_bits > 96)
+      return decode_error::invalid_weight_bits;
+
+   unpack_weights(in);
+
+   unquantise_weights();
+
+   if (VERBOSE_DECODE) {
+      printf("weights=[");
+      for (int i = 0; i < num_weights; ++i) {
+         if (i)
+            printf(", ");
+         printf("%d", weights[i]);
+      }
+      printf("]\n");
+
+      for (int plane = 0; plane <= dual_plane; ++plane) {
+         printf("weights (plane %d):\n", plane);
+         int i = 0;
+         (void)i;
+
+         for (int r = 0; r < wt_d; ++r) {
+            for (int t = 0; t < wt_h; ++t) {
+               for (int s = 0; s < wt_w; ++s) {
+                  printf("%3d", weights[i++ * (1 + dual_plane) + plane]);
+               }
+               printf("\n");
+            }
+            if (r < wt_d - 1)
+               printf("\n");
+         }
+      }
+   }
+
+   compute_infill_weights(decoder.block_w, decoder.block_h, decoder.block_d);
+
+   if (VERBOSE_DECODE) {
+      for (int plane = 0; plane <= dual_plane; ++plane) {
+         printf("infilled weights (plane %d):\n", plane);
+         int i = 0;
+         (void)i;
+
+         for (int r = 0; r < decoder.block_d; ++r) {
+            for (int t = 0; t < decoder.block_h; ++t) {
+               for (int s = 0; s < decoder.block_w; ++s) {
+                  printf("%3d", infill_weights[plane][i++]);
+               }
+               printf("\n");
+            }
+            if (r < decoder.block_d - 1)
+               printf("\n");
+         }
+      }
+   }
+   if (VERBOSE_DECODE)
+      printf("\n");
+
+   return decode_error::ok;
+}
+
+void Block::write_decoded(const Decoder &decoder, uint16_t *output)
+{
+   /* sRGB can only be stored as unorm8. */
+   assert(!decoder.srgb || decoder.output_unorm8);
+
+   if (is_void_extent) {
+      for (int idx = 0; idx < decoder.block_w*decoder.block_h*decoder.block_d; ++idx) {
+         if (decoder.output_unorm8) {
+            if (decoder.srgb) {
+               output[idx*4+0] = void_extent_colour_r >> 8;
+               output[idx*4+1] = void_extent_colour_g >> 8;
+               output[idx*4+2] = void_extent_colour_b >> 8;
+            } else {
+               output[idx*4+0] = uint16_div_64k_to_half_to_unorm8(void_extent_colour_r);
+               output[idx*4+1] = uint16_div_64k_to_half_to_unorm8(void_extent_colour_g);
+               output[idx*4+2] = uint16_div_64k_to_half_to_unorm8(void_extent_colour_b);
+            }
+            output[idx*4+3] = uint16_div_64k_to_half_to_unorm8(void_extent_colour_a);
+         } else {
+            /* Store the color as FP16. */
+            output[idx*4+0] = _mesa_uint16_div_64k_to_half(void_extent_colour_r);
+            output[idx*4+1] = _mesa_uint16_div_64k_to_half(void_extent_colour_g);
+            output[idx*4+2] = _mesa_uint16_div_64k_to_half(void_extent_colour_b);
+            output[idx*4+3] = _mesa_uint16_div_64k_to_half(void_extent_colour_a);
+         }
+      }
+      return;
+   }
+
+   int small_block = (decoder.block_w * decoder.block_h * decoder.block_d) < 31;
+
+   int idx = 0;
+   for (int z = 0; z < decoder.block_d; ++z) {
+      for (int y = 0; y < decoder.block_h; ++y) {
+         for (int x = 0; x < decoder.block_w; ++x) {
+
+            int partition;
+            if (num_parts > 1) {
+               partition = select_partition(partition_index, x, y, z, num_parts, small_block);
+               assert(partition < num_parts);
+            } else {
+               partition = 0;
+            }
+
+            /* TODO: HDR */
+
+            uint8x4_t e0 = endpoints_decoded[0][partition];
+            uint8x4_t e1 = endpoints_decoded[1][partition];
+            uint16_t c0[4], c1[4];
+
+            /* Expand to 16 bits. */
+            if (decoder.srgb) {
+               c0[0] = (uint16_t)((e0.v[0] << 8) | 0x80);
+               c0[1] = (uint16_t)((e0.v[1] << 8) | 0x80);
+               c0[2] = (uint16_t)((e0.v[2] << 8) | 0x80);
+               c0[3] = (uint16_t)((e0.v[3] << 8) | 0x80);
+
+               c1[0] = (uint16_t)((e1.v[0] << 8) | 0x80);
+               c1[1] = (uint16_t)((e1.v[1] << 8) | 0x80);
+               c1[2] = (uint16_t)((e1.v[2] << 8) | 0x80);
+               c1[3] = (uint16_t)((e1.v[3] << 8) | 0x80);
+            } else {
+               c0[0] = (uint16_t)((e0.v[0] << 8) | e0.v[0]);
+               c0[1] = (uint16_t)((e0.v[1] << 8) | e0.v[1]);
+               c0[2] = (uint16_t)((e0.v[2] << 8) | e0.v[2]);
+               c0[3] = (uint16_t)((e0.v[3] << 8) | e0.v[3]);
+
+               c1[0] = (uint16_t)((e1.v[0] << 8) | e1.v[0]);
+               c1[1] = (uint16_t)((e1.v[1] << 8) | e1.v[1]);
+               c1[2] = (uint16_t)((e1.v[2] << 8) | e1.v[2]);
+               c1[3] = (uint16_t)((e1.v[3] << 8) | e1.v[3]);
+            }
+
+            int w[4];
+            if (dual_plane) {
+               int w0 = infill_weights[0][idx];
+               int w1 = infill_weights[1][idx];
+               w[0] = w[1] = w[2] = w[3] = w0;
+               w[colour_component_selector] = w1;
+            } else {
+               int w0 = infill_weights[0][idx];
+               w[0] = w[1] = w[2] = w[3] = w0;
+            }
+
+            /* Interpolate to produce UNORM16, applying weights. */
+            uint16_t c[4] = {
+               (uint16_t)((c0[0] * (64 - w[0]) + c1[0] * w[0] + 32) >> 6),
+               (uint16_t)((c0[1] * (64 - w[1]) + c1[1] * w[1] + 32) >> 6),
+               (uint16_t)((c0[2] * (64 - w[2]) + c1[2] * w[2] + 32) >> 6),
+               (uint16_t)((c0[3] * (64 - w[3]) + c1[3] * w[3] + 32) >> 6),
+            };
+
+            if (decoder.output_unorm8) {
+               if (decoder.srgb) {
+                  output[idx*4+0] = c[0] >> 8;
+                  output[idx*4+1] = c[1] >> 8;
+                  output[idx*4+2] = c[2] >> 8;
+               } else {
+                  output[idx*4+0] = c[0] == 65535 ? 0xff : uint16_div_64k_to_half_to_unorm8(c[0]);
+                  output[idx*4+1] = c[1] == 65535 ? 0xff : uint16_div_64k_to_half_to_unorm8(c[1]);
+                  output[idx*4+2] = c[2] == 65535 ? 0xff : uint16_div_64k_to_half_to_unorm8(c[2]);
+               }
+               output[idx*4+3] = c[3] == 65535 ? 0xff : uint16_div_64k_to_half_to_unorm8(c[3]);
+            } else {
+               /* Store the color as FP16. */
+               output[idx*4+0] = c[0] == 65535 ? FP16_ONE : _mesa_uint16_div_64k_to_half(c[0]);
+               output[idx*4+1] = c[1] == 65535 ? FP16_ONE : _mesa_uint16_div_64k_to_half(c[1]);
+               output[idx*4+2] = c[2] == 65535 ? FP16_ONE : _mesa_uint16_div_64k_to_half(c[2]);
+               output[idx*4+3] = c[3] == 65535 ? FP16_ONE : _mesa_uint16_div_64k_to_half(c[3]);
+            }
+
+            idx++;
+         }
+      }
+   }
+}
+
+void Block::calculate_from_weights()
+{
+   wt_trits = 0;
+   wt_quints = 0;
+   wt_bits = 0;
+   switch (high_prec) {
+   case 0:
+      switch (wt_range) {
+      case 0x2: wt_max = 1; wt_bits = 1; break;
+      case 0x3: wt_max = 2; wt_trits = 1; break;
+      case 0x4: wt_max = 3; wt_bits = 2; break;
+      case 0x5: wt_max = 4; wt_quints = 1; break;
+      case 0x6: wt_max = 5; wt_trits = 1; wt_bits = 1; break;
+      case 0x7: wt_max = 7; wt_bits = 3; break;
+      default: abort();
+      }
+      break;
+   case 1:
+      switch (wt_range) {
+      case 0x2: wt_max = 9; wt_quints = 1; wt_bits = 1; break;
+      case 0x3: wt_max = 11; wt_trits = 1; wt_bits = 2; break;
+      case 0x4: wt_max = 15; wt_bits = 4; break;
+      case 0x5: wt_max = 19; wt_quints = 1; wt_bits = 2; break;
+      case 0x6: wt_max = 23; wt_trits = 1; wt_bits = 3; break;
+      case 0x7: wt_max = 31; wt_bits = 5; break;
+      default: abort();
+      }
+      break;
+   }
+
+   assert(wt_trits || wt_quints || wt_bits);
+
+   num_weights = wt_w * wt_h * wt_d;
+
+   if (dual_plane)
+      num_weights *= 2;
+
+   weight_bits =
+         (num_weights * 8 * wt_trits + 4) / 5
+         + (num_weights * 7 * wt_quints + 2) / 3
+         +  num_weights * wt_bits;
+}
+
+void Block::calculate_remaining_bits()
+{
+   int config_bits;
+   if (num_parts > 1) {
+      if (!is_multi_cem)
+         config_bits = 29;
+      else
+         config_bits = 25 + 3 * num_parts;
+   } else {
+      config_bits = 17;
+   }
+
+   if (dual_plane)
+      config_bits += 2;
+
+   remaining_bits = 128 - config_bits - weight_bits;
+}
+
+decode_error::type Block::calculate_colour_endpoints_size()
+{
+   /* Specified as illegal */
+   if (remaining_bits < (13 * num_cem_values + 4) / 5) {
+      colour_endpoint_bits = ce_max = ce_trits = ce_quints = ce_bits = 0;
+      return decode_error::invalid_colour_endpoints_size;
+   }
+
+   /* Find the largest cem_ranges that fits within remaining_bits */
+   for (int i = ARRAY_SIZE(cem_ranges)-1; i >= 0; --i) {
+      int cem_bits;
+      cem_bits = (num_cem_values * 8 * cem_ranges[i].t + 4) / 5
+                 + (num_cem_values * 7 * cem_ranges[i].q + 2) / 3
+                 +  num_cem_values * cem_ranges[i].b;
+
+      if (cem_bits <= remaining_bits)
+      {
+         colour_endpoint_bits = cem_bits;
+         ce_max = cem_ranges[i].max;
+         ce_trits = cem_ranges[i].t;
+         ce_quints = cem_ranges[i].q;
+         ce_bits = cem_ranges[i].b;
+         return decode_error::ok;
+      }
+   }
+
+   assert(0);
+   return decode_error::invalid_colour_endpoints_size;
+}
+
+/**
+ * Decode ASTC 2D LDR texture data.
+ *
+ * \param src_width in pixels
+ * \param src_height in pixels
+ * \param dst_stride in bytes
+ */
+extern "C" void
+_mesa_unpack_astc_2d_ldr(uint8_t *dst_row,
+                         unsigned dst_stride,
+                         const uint8_t *src_row,
+                         unsigned src_stride,
+                         unsigned src_width,
+                         unsigned src_height,
+                         mesa_format format)
+{
+   assert(_mesa_is_format_astc_2d(format));
+   bool srgb = _mesa_get_format_color_encoding(format) == GL_SRGB;
+
+   unsigned blk_w, blk_h;
+   _mesa_get_format_block_size(format, &blk_w, &blk_h);
+
+   const unsigned block_size = 16;
+   unsigned x_blocks = (src_width + blk_w - 1) / blk_w;
+   unsigned y_blocks = (src_height + blk_h - 1) / blk_h;
+
+   Decoder dec(blk_w, blk_h, 1, srgb, true);
+
+   for (unsigned y = 0; y < y_blocks; ++y) {
+      for (unsigned x = 0; x < x_blocks; ++x) {
+         /* Same size as the largest block. */
+         uint16_t block_out[12 * 12 * 4];
+
+         dec.decode(src_row + x * block_size, block_out);
+
+         /* This can be smaller with NPOT dimensions. */
+         unsigned dst_blk_w = MIN2(blk_w, src_width  - x*blk_w);
+         unsigned dst_blk_h = MIN2(blk_h, src_height - y*blk_h);
+
+         for (unsigned sub_y = 0; sub_y < dst_blk_h; ++sub_y) {
+            for (unsigned sub_x = 0; sub_x < dst_blk_w; ++sub_x) {
+               uint8_t *dst = dst_row + sub_y * dst_stride +
+                              (x * blk_w + sub_x) * 4;
+               const uint16_t *src = &block_out[(sub_y * blk_w + sub_x) * 4];
+
+               dst[0] = src[0];
+               dst[1] = src[1];
+               dst[2] = src[2];
+               dst[3] = src[3];
+            }
+         }
+      }
+      src_row += src_stride;
+      dst_row += dst_stride * blk_h;
+   }
+}