Reland: Add ETC1 powered SSE encoder for tile texture compression

cc/resources/texture_compressor_etc1_sse.cc

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/resources/texture_compressor_etc1_sse.h"
+
+#include <assert.h>
+#include <emmintrin.h>
+#include <cmath>
+#include <limits>
+
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+// using this header for common functions such as Color handling
+// and codeword table
+#include "cc/resources/texture_compressor_etc1.h"
+
+namespace {
+
+#define ETC1_SET_ERROR(x) (x + x / 2 + 384)

[reveman, 2015/05/07 14:24:35]

nit: inline function instead of macro

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+struct __sse_data {
+  // raw data
+  uint8_t* block;
+  // 8 bit packed values
+  __m128i* packed;
+  // 32 bit zero extended values - 4x4 arrays
+  __m128i* blue;
+  __m128i* green;
+  __m128i* red;
+};
+
+// commonly used registers

[reveman, 2015/05/07 14:24:35]

nit: I don't feel too strongly about this but there's some inconsistency between
comments in this patch. It's recommended to write comments as real sentences in
chromium. First word capitalized and a period at the end. "// Commonly used
registers." in this case. If you like to update all the comments in this patch
to be more consistent in this regard then that's great but it's also fine with
me to leave it as is. Up to you.

[radu.velea, 2015/05/07 15:53:46]

Done.

+static const __m128i __sse_zero = _mm_set1_epi32(0);
+static const __m128i __sse_max_int = _mm_set1_epi32(0x7FFFFFFF);
+
+inline __m128i AddAndClamp(const __m128i x, const __m128i y) {
+  static const __m128i color_max = _mm_set1_epi32(0xFF);
+  return _mm_max_epi16(__sse_zero,
+                       _mm_min_epi16(_mm_add_epi16(x, y), color_max));
+}
+
+inline __m128i GetColorErrorSSE(const __m128i x, const __m128i y) {
+  // changed from _mm_mullo_epi32 (SSE4) to _mm_mullo_epi16 (SSE2)
+  __m128i ret = _mm_sub_epi16(x, y);
+  return _mm_mullo_epi16(ret, ret);
+}
+
+inline __m128i AddChannelError(const __m128i x,
+                               const __m128i y,
+                               const __m128i z) {
+  return _mm_add_epi32(x, _mm_add_epi32(y, z));
+}
+
+inline uint32_t SumSSE(const __m128i x) {
+  __m128i sum = _mm_add_epi32(x, _mm_shuffle_epi32(x, 0x4E));
+  sum = _mm_add_epi32(sum, _mm_shuffle_epi32(sum, 0xB1));
+
+  return _mm_cvtsi128_si32(sum);
+}
+
+inline uint32_t GetVerticalError(const __sse_data* data,
+                                 const __m128i* blue_avg,
+                                 const __m128i* green_avg,
+                                 const __m128i* red_avg,
+                                 uint32_t* verror) {
+  __m128i error = __sse_zero;
+
+  for (int i = 0; i < 4; i++) {
+    error = _mm_add_epi32(error, GetColorErrorSSE(data->blue[i], blue_avg[0]));
+    error =
+        _mm_add_epi32(error, GetColorErrorSSE(data->green[i], green_avg[0]));
+    error = _mm_add_epi32(error, GetColorErrorSSE(data->red[i], red_avg[0]));
+  }
+
+  error = _mm_add_epi32(error, _mm_shuffle_epi32(error, 0x4E));
+
+  verror[0] = _mm_cvtsi128_si32(error);
+  verror[1] = _mm_cvtsi128_si32(_mm_shuffle_epi32(error, 0xB1));
+
+  return verror[0] + verror[1];
+}
+
+inline uint32_t GetHorizontalError(const __sse_data* data,
+                                   const __m128i* blue_avg,
+                                   const __m128i* green_avg,
+                                   const __m128i* red_avg,
+                                   uint32_t* verror) {
+  __m128i error = __sse_zero;
+  int first_index, second_index;
+
+  for (int i = 0; i < 2; i++) {
+    first_index = 2 * i;
+    second_index = first_index + 1;
+
+    error = _mm_add_epi32(
+        error, GetColorErrorSSE(data->blue[first_index], blue_avg[i]));
+    error = _mm_add_epi32(
+        error, GetColorErrorSSE(data->blue[second_index], blue_avg[i]));
+    error = _mm_add_epi32(
+        error, GetColorErrorSSE(data->green[first_index], green_avg[i]));
+    error = _mm_add_epi32(
+        error, GetColorErrorSSE(data->green[second_index], green_avg[i]));
+    error = _mm_add_epi32(error,
+                          GetColorErrorSSE(data->red[first_index], red_avg[i]));
+    error = _mm_add_epi32(
+        error, GetColorErrorSSE(data->red[second_index], red_avg[i]));
+  }
+
+  error = _mm_add_epi32(error, _mm_shuffle_epi32(error, 0x4E));
+
+  verror[0] = _mm_cvtsi128_si32(error);
+  verror[1] = _mm_cvtsi128_si32(_mm_shuffle_epi32(error, 0xB1));
+
+  return verror[0] + verror[1];
+}
+
+inline void GetAvgColors(const __sse_data* data,
+                         float* output,
+                         bool* __sse_use_diff) {
+  __m128i sum[2], tmp;
+
+  // TODO(radu.velea): _mm_avg_epu8 on packed data maybe
+
+  // get avg red
+  // [S0 S0 S1 S1]
+  sum[0] = _mm_add_epi32(data->red[0], data->red[1]);
+  sum[0] = _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0xB1));
+
+  // [S2 S2 S3 S3]
+  sum[1] = _mm_add_epi32(data->red[2], data->red[3]);
+  sum[1] = _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0xB1));
+
+  float hred[2], vred[2];
+  hred[0] = (_mm_cvtsi128_si32(
+                _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0x4E)))) /
+            8.0f;
+  hred[1] = (_mm_cvtsi128_si32(
+                _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0x4E)))) /
+            8.0f;
+
+  tmp = _mm_add_epi32(sum[0], sum[1]);
+  vred[0] = (_mm_cvtsi128_si32(tmp)) / 8.0f;
+  vred[1] = (_mm_cvtsi128_si32(_mm_shuffle_epi32(tmp, 0x2))) / 8.0f;
+
+  // get avg green
+  // [S0 S0 S1 S1]
+  sum[0] = _mm_add_epi32(data->green[0], data->green[1]);
+  sum[0] = _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0xB1));
+
+  // [S2 S2 S3 S3]
+  sum[1] = _mm_add_epi32(data->green[2], data->green[3]);
+  sum[1] = _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0xB1));
+
+  float hgreen[2], vgreen[2];
+  hgreen[0] = (_mm_cvtsi128_si32(
+                  _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0x4E)))) /
+              8.0f;
+  hgreen[1] = (_mm_cvtsi128_si32(
+                  _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0x4E)))) /
+              8.0f;
+
+  tmp = _mm_add_epi32(sum[0], sum[1]);
+  vgreen[0] = (_mm_cvtsi128_si32(tmp)) / 8.0f;
+  vgreen[1] = (_mm_cvtsi128_si32(_mm_shuffle_epi32(tmp, 0x2))) / 8.0f;
+
+  // get avg blue
+  // [S0 S0 S1 S1]
+  sum[0] = _mm_add_epi32(data->blue[0], data->blue[1]);
+  sum[0] = _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0xB1));
+
+  // [S2 S2 S3 S3]
+  sum[1] = _mm_add_epi32(data->blue[2], data->blue[3]);
+  sum[1] = _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0xB1));
+
+  float hblue[2], vblue[2];
+  hblue[0] = (_mm_cvtsi128_si32(
+                 _mm_add_epi32(sum[0], _mm_shuffle_epi32(sum[0], 0x4E)))) /
+             8.0f;
+  hblue[1] = (_mm_cvtsi128_si32(
+                 _mm_add_epi32(sum[1], _mm_shuffle_epi32(sum[1], 0x4E)))) /
+             8.0f;
+
+  tmp = _mm_add_epi32(sum[0], sum[1]);
+  vblue[0] = (_mm_cvtsi128_si32(tmp)) / 8.0f;
+  vblue[1] = (_mm_cvtsi128_si32(_mm_shuffle_epi32(tmp, 0x2))) / 8.0f;
+
+  // TODO(radu.velea): return int's instead of floats, based on Quality
+  output[0] = vblue[0];
+  output[1] = vgreen[0];
+  output[2] = vred[0];
+
+  output[3] = vblue[1];
+  output[4] = vgreen[1];
+  output[5] = vred[1];
+
+  output[6] = hblue[0];
+  output[7] = hgreen[0];
+  output[8] = hred[0];
+
+  output[9] = hblue[1];
+  output[10] = hgreen[1];
+  output[11] = hred[1];
+
+  __m128i threshold_upper = _mm_set1_epi32(3);
+  __m128i threshold_lower = _mm_set1_epi32(-4);
+
+  __m128 factor_v = _mm_set1_ps(31.0f / 255.0f);
+  __m128 rounding_v = _mm_set1_ps(0.5f);
+  __m128 h_avg_0 = _mm_set_ps(hblue[0], hgreen[0], hred[0], 0);
+  __m128 h_avg_1 = _mm_set_ps(hblue[1], hgreen[1], hred[1], 0);
+
+  __m128 v_avg_0 = _mm_set_ps(vblue[0], vgreen[0], vred[0], 0);
+  __m128 v_avg_1 = _mm_set_ps(vblue[1], vgreen[1], vred[1], 0);
+
+  h_avg_0 = _mm_mul_ps(h_avg_0, factor_v);
+  h_avg_1 = _mm_mul_ps(h_avg_1, factor_v);
+  v_avg_0 = _mm_mul_ps(v_avg_0, factor_v);
+  v_avg_1 = _mm_mul_ps(v_avg_1, factor_v);
+
+  h_avg_0 = _mm_add_ps(h_avg_0, rounding_v);
+  h_avg_1 = _mm_add_ps(h_avg_1, rounding_v);
+  v_avg_0 = _mm_add_ps(v_avg_0, rounding_v);
+  v_avg_1 = _mm_add_ps(v_avg_1, rounding_v);
+
+  __m128i h_avg_0i = _mm_cvttps_epi32(h_avg_0);
+  __m128i h_avg_1i = _mm_cvttps_epi32(h_avg_1);
+
+  __m128i v_avg_0i = _mm_cvttps_epi32(v_avg_0);
+  __m128i v_avg_1i = _mm_cvttps_epi32(v_avg_1);
+
+  h_avg_0i = _mm_sub_epi32(h_avg_1i, h_avg_0i);
+  v_avg_0i = _mm_sub_epi32(v_avg_1i, v_avg_0i);
+
+  __sse_use_diff[0] =
+      (0 == _mm_movemask_epi8(_mm_cmplt_epi32(v_avg_0i, threshold_lower)));
+  __sse_use_diff[0] &=
+      (0 == _mm_movemask_epi8(_mm_cmpgt_epi32(v_avg_0i, threshold_upper)));
+
+  __sse_use_diff[1] =
+      (0 == _mm_movemask_epi8(_mm_cmplt_epi32(h_avg_0i, threshold_lower)));
+  __sse_use_diff[1] &=
+      (0 == _mm_movemask_epi8(_mm_cmpgt_epi32(h_avg_0i, threshold_upper)));
+}
+
+void ComputeLuminance(uint8_t* block,
+                      const cc::Color& base,
+                      const int sub_block_id,
+                      const uint8_t* idx_to_num_tab,
+                      const __sse_data* data,
+                      const uint32_t expected_error) {
+  uint8_t best_tbl_idx = 0;
+  uint32_t best_error = 0x7FFFFFFF;
+  uint8_t best_mod_idx[8][8];  // [table][texel]
+
+  const __m128i base_blue = _mm_set1_epi32(base.channels.b);
+  const __m128i base_green = _mm_set1_epi32(base.channels.g);
+  const __m128i base_red = _mm_set1_epi32(base.channels.r);
+
+  __m128i test_red, test_blue, test_green, tmp, tmp_blue, tmp_green, tmp_red;
+  __m128i block_error, mask;
+
+  // this will have the minimum errors for each 4 pixels
+  __m128i first_half_min;
+  __m128i second_half_min;
+
+  // this will have the matching table index combo for each 4 pixels
+  __m128i first_half_pattern;
+  __m128i second_half_pattern;
+
+  const __m128i first_blue_data_block = data->blue[2 * sub_block_id];
+  const __m128i first_green_data_block = data->green[2 * sub_block_id];
+  const __m128i first_red_data_block = data->red[2 * sub_block_id];
+
+  const __m128i second_blue_data_block = data->blue[2 * sub_block_id + 1];
+  const __m128i second_green_data_block = data->green[2 * sub_block_id + 1];
+  const __m128i second_red_data_block = data->red[2 * sub_block_id + 1];
+
+  uint32_t min;
+  // fail early to increase speed
+  long delta = INT32_MAX;
+  uint32_t last_min = INT32_MAX;
+
+  const uint8_t shuffle_mask[] = {
+      0x1B, 0x4E, 0xB1, 0xE4};  // important they are sorted ascending
+
+  for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) {
+    tmp = _mm_set_epi32(
+        cc::g_codeword_tables[tbl_idx][3], cc::g_codeword_tables[tbl_idx][2],
+        cc::g_codeword_tables[tbl_idx][1], cc::g_codeword_tables[tbl_idx][0]);
+
+    test_blue = AddAndClamp(tmp, base_blue);
+    test_green = AddAndClamp(tmp, base_green);
+    test_red = AddAndClamp(tmp, base_red);
+
+    first_half_min = __sse_max_int;
+    second_half_min = __sse_max_int;
+
+    first_half_pattern = __sse_zero;
+    second_half_pattern = __sse_zero;
+
+    for (uint8_t imm8 : shuffle_mask) {
+      switch (imm8) {
+        case 0x1B:
+          tmp_blue = _mm_shuffle_epi32(test_blue, 0x1B);
+          tmp_green = _mm_shuffle_epi32(test_green, 0x1B);
+          tmp_red = _mm_shuffle_epi32(test_red, 0x1B);
+          break;
+        case 0x4E:
+          tmp_blue = _mm_shuffle_epi32(test_blue, 0x4E);
+          tmp_green = _mm_shuffle_epi32(test_green, 0x4E);
+          tmp_red = _mm_shuffle_epi32(test_red, 0x4E);
+          break;
+        case 0xB1:
+          tmp_blue = _mm_shuffle_epi32(test_blue, 0xB1);
+          tmp_green = _mm_shuffle_epi32(test_green, 0xB1);
+          tmp_red = _mm_shuffle_epi32(test_red, 0xB1);
+          break;
+        case 0xE4:
+          tmp_blue = _mm_shuffle_epi32(test_blue, 0xE4);
+          tmp_green = _mm_shuffle_epi32(test_green, 0xE4);
+          tmp_red = _mm_shuffle_epi32(test_red, 0xE4);
+          break;
+        default:
+          tmp_blue = test_blue;
+          tmp_green = test_green;
+          tmp_red = test_red;
+      }
+
+      tmp = _mm_set1_epi32(imm8);
+
+      block_error =
+          AddChannelError(GetColorErrorSSE(tmp_blue, first_blue_data_block),
+                          GetColorErrorSSE(tmp_green, first_green_data_block),
+                          GetColorErrorSSE(tmp_red, first_red_data_block));
+
+      // save winning pattern
+      first_half_pattern = _mm_max_epi16(
+          first_half_pattern,
+          _mm_and_si128(tmp, _mm_cmpgt_epi32(first_half_min, block_error)));
+      // should use _mm_min_epi32(first_half_min, block_error); from SSE4
+      // otherwise small performance penalty
+      mask = _mm_cmplt_epi32(block_error, first_half_min);
+      first_half_min = _mm_add_epi32(_mm_and_si128(mask, block_error),
+                                     _mm_andnot_si128(mask, first_half_min));
+
+      // Second part of the block
+      block_error =
+          AddChannelError(GetColorErrorSSE(tmp_blue, second_blue_data_block),
+                          GetColorErrorSSE(tmp_green, second_green_data_block),
+                          GetColorErrorSSE(tmp_red, second_red_data_block));
+
+      // save winning pattern
+      second_half_pattern = _mm_max_epi16(
+          second_half_pattern,
+          _mm_and_si128(tmp, _mm_cmpgt_epi32(second_half_min, block_error)));
+      // should use _mm_min_epi32(second_half_min, block_error); from SSE4
+      // otherwise performance penalty
+      mask = _mm_cmplt_epi32(block_error, second_half_min);
+      second_half_min = _mm_add_epi32(_mm_and_si128(mask, block_error),
+                                      _mm_andnot_si128(mask, second_half_min));
+    }
+
+    first_half_min = _mm_add_epi32(first_half_min, second_half_min);
+    first_half_min =
+        _mm_add_epi32(first_half_min, _mm_shuffle_epi32(first_half_min, 0x4E));
+    first_half_min =
+        _mm_add_epi32(first_half_min, _mm_shuffle_epi32(first_half_min, 0xB1));
+
+    min = _mm_cvtsi128_si32(first_half_min);
+
+    delta = min - last_min;
+    last_min = min;
+
+    if (min < best_error) {
+      best_tbl_idx = tbl_idx;
+      best_error = min;
+
+      best_mod_idx[tbl_idx][0] =
+          (_mm_cvtsi128_si32(first_half_pattern) >> (0)) & 3;
+      best_mod_idx[tbl_idx][4] =
+          (_mm_cvtsi128_si32(second_half_pattern) >> (0)) & 3;
+
+      best_mod_idx[tbl_idx][1] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(first_half_pattern, 0x1)) >>
+           (2)) &
+          3;
+      best_mod_idx[tbl_idx][5] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(second_half_pattern, 0x1)) >>
+           (2)) &
+          3;
+
+      best_mod_idx[tbl_idx][2] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(first_half_pattern, 0x2)) >>
+           (4)) &
+          3;
+      best_mod_idx[tbl_idx][6] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(second_half_pattern, 0x2)) >>
+           (4)) &
+          3;
+
+      best_mod_idx[tbl_idx][3] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(first_half_pattern, 0x3)) >>
+           (6)) &
+          3;
+      best_mod_idx[tbl_idx][7] =
+          (_mm_cvtsi128_si32(_mm_shuffle_epi32(second_half_pattern, 0x3)) >>
+           (6)) &
+          3;
+
+      if (best_error == 0) {
+        break;
+      }
+    } else if (delta > 0 && expected_error < min) {
+      // error is growing and is well beyond expected error
+      break;
+    }
+  }
+
+  cc::WriteCodewordTable(block, sub_block_id, best_tbl_idx);
+
+  uint32_t pix_data = 0;
+  uint8_t mod_idx;
+  uint8_t pix_idx;
+  uint32_t lsb;
+  uint32_t msb;
+  int texel_num;
+
+  for (unsigned int i = 0; i < 8; ++i) {
+    mod_idx = best_mod_idx[best_tbl_idx][i];
+    pix_idx = cc::g_mod_to_pix[mod_idx];
+
+    lsb = pix_idx & 0x1;
+    msb = pix_idx >> 1;
+
+    // Obtain the texel number as specified in the standard.
+    texel_num = idx_to_num_tab[i];
+    pix_data |= msb << (texel_num + 16);
+    pix_data |= lsb << (texel_num);
+  }
+
+  cc::WritePixelData(block, pix_data);
+}
+
+void CompressBlock(uint8_t* dst, __sse_data* data) {
+  // first 3 vertical 1, second 3 vertical 2, third 3 horizontal 1, last 3
+  // horizontal 2
+  float __sse_avg_colors[12] = {
+      0,
+  };
+  bool use_differential[2] = {true, true};
+  GetAvgColors(data, __sse_avg_colors, use_differential);
+  cc::Color sub_block_avg[4];
+
+  // TODO(radu.velea): remove floating point operations and use only int's +
+  // normal rounding and shifts for reduced Quality
+  for (int i = 0, j = 1; i < 4; i += 2, j += 2) {
+    if (use_differential[i / 2] == false) {
+      sub_block_avg[i] = cc::MakeColor444(&__sse_avg_colors[i * 3]);
+      sub_block_avg[j] = cc::MakeColor444(&__sse_avg_colors[j * 3]);
+    } else {
+      sub_block_avg[i] = cc::MakeColor555(&__sse_avg_colors[i * 3]);
+      sub_block_avg[j] = cc::MakeColor555(&__sse_avg_colors[j * 3]);
+    }
+  }
+
+  __m128i red_avg[2], green_avg[2], blue_avg[2];
+
+  // TODO(radu.velea): perfect accuracy, maybe skip floating variables
+  blue_avg[0] =
+      _mm_set_epi32((int)__sse_avg_colors[3], (int)__sse_avg_colors[3],
+                    (int)__sse_avg_colors[0], (int)__sse_avg_colors[0]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  green_avg[0] =
+      _mm_set_epi32((int)__sse_avg_colors[4], (int)__sse_avg_colors[4],
+                    (int)__sse_avg_colors[1], (int)__sse_avg_colors[1]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:46]

Done.

+
+  red_avg[0] =
+      _mm_set_epi32((int)__sse_avg_colors[5], (int)__sse_avg_colors[5],
+                    (int)__sse_avg_colors[2], (int)__sse_avg_colors[2]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  uint32_t vertical_error[2];
+  GetVerticalError(data, blue_avg, green_avg, red_avg, vertical_error);
+
+  // TODO(radu.velea): perfect accuracy, maybe skip floating variables
+  blue_avg[0] = _mm_set1_epi32((int)__sse_avg_colors[6]);
+  blue_avg[1] = _mm_set1_epi32((int)__sse_avg_colors[9]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  green_avg[0] = _mm_set1_epi32((int)__sse_avg_colors[7]);
+  green_avg[1] = _mm_set1_epi32((int)__sse_avg_colors[10]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  red_avg[0] = _mm_set1_epi32((int)__sse_avg_colors[8]);
+  red_avg[1] = _mm_set1_epi32((int)__sse_avg_colors[11]);

[reveman, 2015/05/07 14:24:35]

nit: please avoid c-style casts. static_cast<int>() instead

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  uint32_t horizontal_error[2];
+  GetHorizontalError(data, blue_avg, green_avg, red_avg, horizontal_error);
+
+  bool flip = (horizontal_error[0] + horizontal_error[1]) <
+              (vertical_error[0] + vertical_error[1]);
+  uint32_t* expected_errors = flip == true ? horizontal_error : vertical_error;

[reveman, 2015/05/07 14:24:35]

nit: s/flip == true/flip/

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+  // Clear destination buffer so that we can "or" in the results.
+  memset(dst, 0, 8);
+
+  cc::WriteDiff(dst, use_differential[!!flip]);
+  cc::WriteFlip(dst, flip);
+
+  uint8_t sub_block_off_0 = flip ? 2 : 0;
+  uint8_t sub_block_off_1 = sub_block_off_0 + 1;
+
+  if (use_differential[!!flip]) {
+    cc::WriteColors555(dst, sub_block_avg[sub_block_off_0],
+                       sub_block_avg[sub_block_off_1]);
+  } else {
+    cc::WriteColors444(dst, sub_block_avg[sub_block_off_0],
+                       sub_block_avg[sub_block_off_1]);
+  }
+
+  if (flip == false) {

[reveman, 2015/05/07 14:24:35]

nit: if (!flip)

[radu.velea, 2015/05/07 15:53:45]

Done.

+    // transpose vertical data into horizontal lines
+    __m128i tmp;
+    for (int i = 0; i < 4; i += 2) {
+      tmp = data->blue[i];
+      data->blue[i] = _mm_add_epi32(
+          _mm_move_epi64(data->blue[i]),
+          _mm_shuffle_epi32(_mm_move_epi64(data->blue[i + 1]), 0x4E));
+      data->blue[i + 1] = _mm_add_epi32(
+          _mm_move_epi64(_mm_shuffle_epi32(tmp, 0x4E)),
+          _mm_shuffle_epi32(
+              _mm_move_epi64(_mm_shuffle_epi32(data->blue[i + 1], 0x4E)),
+              0x4E));
+
+      tmp = data->green[i];
+      data->green[i] = _mm_add_epi32(
+          _mm_move_epi64(data->green[i]),
+          _mm_shuffle_epi32(_mm_move_epi64(data->green[i + 1]), 0x4E));
+      data->green[i + 1] = _mm_add_epi32(
+          _mm_move_epi64(_mm_shuffle_epi32(tmp, 0x4E)),
+          _mm_shuffle_epi32(
+              _mm_move_epi64(_mm_shuffle_epi32(data->green[i + 1], 0x4E)),
+              0x4E));
+
+      tmp = data->red[i];
+      data->red[i] = _mm_add_epi32(
+          _mm_move_epi64(data->red[i]),
+          _mm_shuffle_epi32(_mm_move_epi64(data->red[i + 1]), 0x4E));
+      data->red[i + 1] = _mm_add_epi32(
+          _mm_move_epi64(_mm_shuffle_epi32(tmp, 0x4E)),
+          _mm_shuffle_epi32(
+              _mm_move_epi64(_mm_shuffle_epi32(data->red[i + 1], 0x4E)), 0x4E));
+    }
+
+    tmp = data->blue[1];
+    data->blue[1] = data->blue[2];
+    data->blue[2] = tmp;
+
+    tmp = data->green[1];
+    data->green[1] = data->green[2];
+    data->green[2] = tmp;
+
+    tmp = data->red[1];
+    data->red[1] = data->red[2];
+    data->red[2] = tmp;
+  }
+
+  // Compute luminance for the first sub block.
+  ComputeLuminance(dst, sub_block_avg[sub_block_off_0], 0,
+                   cc::g_idx_to_num[sub_block_off_0], data,
+                   ETC1_SET_ERROR(expected_errors[0]));
+  // Compute luminance for the second sub block.
+  ComputeLuminance(dst, sub_block_avg[sub_block_off_1], 1,
+                   cc::g_idx_to_num[sub_block_off_1], data,
+                   ETC1_SET_ERROR(expected_errors[1]));
+}
+
+static void ExtractBlock(uint8_t* dst, const uint8_t* src, int width) {
+  for (int j = 0; j < 4; ++j) {
+    memcpy(&dst[j * 4 * 4], src, 4 * 4);
+    src += width * 4;
+  }
+}
+
+inline bool TransposeBlock(uint8_t* block, __m128i* transposed) {
+  // This function transforms an incommig block of RGBA or GBRA pixels into 4
+  // registers, each containing the data corresponding for a single channel.
+  // Ex: transposed[0] will have all the R values for a RGBA block,
+  // transposed[1] will have G, etc.
+  // The values are packed as 8 bit unsigned values in the SSE registers.
+
+  // Before doing any work we check if the block is solid.
+  __m128i tmp3, tmp2, tmp1, tmp0;
+  __m128i test_solid = _mm_set1_epi32(*((uint32_t*)block));
+  uint16_t mask = 0xFFFF;
+
+  // a0,a1,a2,...a7, ...a15
+  transposed[0] = _mm_loadu_si128((__m128i*)(block));
+  // b0, b1,b2,...b7.... b15
+  transposed[1] = _mm_loadu_si128((__m128i*)(block + 16));
+  // c0, c1,c2,...c7....c15
+  transposed[2] = _mm_loadu_si128((__m128i*)(block + 32));
+  // d0,d1,d2,...d7....d15
+  transposed[3] = _mm_loadu_si128((__m128i*)(block + 48));
+
+  for (int i = 0; i < 4; i++) {
+    mask &= _mm_movemask_epi8(_mm_cmpeq_epi8(transposed[i], test_solid));
+  }
+
+  if (mask == 0xFFFF) {
+    return false;  // block is solid, no need to do any more work
+  }
+
+  // a0,b0, a1,b1, a2,b2, a3,b3,....a7,b7
+  tmp0 = _mm_unpacklo_epi8(transposed[0], transposed[1]);
+  // c0,d0, c1,d1, c2,d2, c3,d3,... c7,d7
+  tmp1 = _mm_unpacklo_epi8(transposed[2], transposed[3]);
+  // a8,b8, a9,b9, a10,b10, a11,b11,...a15,b15
+  tmp2 = _mm_unpackhi_epi8(transposed[0], transposed[1]);
+  // c8,d8, c9,d9, c10,d10, c11,d11,...c15,d15
+  tmp3 = _mm_unpackhi_epi8(transposed[2], transposed[3]);
+
+  // a0,a8, b0,b8,  a1,a9, b1,b9, ....a3,a11, b3,b11
+  transposed[0] = _mm_unpacklo_epi8(tmp0, tmp2);
+  // a4,a12, b4,b12, a5,a13, b5,b13,....a7,a15,b7,b15
+  transposed[1] = _mm_unpackhi_epi8(tmp0, tmp2);
+  // c0,c8, d0,d8, c1,c9, d1,d9.....d3,d11
+  transposed[2] = _mm_unpacklo_epi8(tmp1, tmp3);
+  // c4,c12,d4,d12, c5,c13, d5,d13,....d7,d15
+  transposed[3] = _mm_unpackhi_epi8(tmp1, tmp3);
+
+  // a0,a8, b0,b8, c0,c8, d0,d8, a1,a9, b1,b9, c1,c9, d1,d9
+  tmp0 = _mm_unpacklo_epi32(transposed[0], transposed[2]);
+  // a2,a10, b2,b10, c2,c10, d2,d10, a3,a11, b3,b11, c3,c11, d3,d11
+  tmp1 = _mm_unpackhi_epi32(transposed[0], transposed[2]);
+  // a4,a12, b4,b12, c4,c12, d4,d12, a5,a13, b5,b13, c5,c13, d5,d13
+  tmp2 = _mm_unpacklo_epi32(transposed[1], transposed[3]);
+  // a6,a14, b6,b14, c6,c14, d6,d14, a7,a15, b7,b15, c7,c15, d7,d15
+  tmp3 = _mm_unpackhi_epi32(transposed[1], transposed[3]);
+
+  // a0,a4, a8,a12, b0,b4, b8,b12,  c0,c4, c8,c12, d0,d4, d8,d12
+  transposed[0] = _mm_unpacklo_epi8(tmp0, tmp2);
+  // a1,a5, a9,a13, b1,b5, b9,b13,  c1,c5, c9,c13, d1,d5, d9,d13
+  transposed[1] = _mm_unpackhi_epi8(tmp0, tmp2);
+  // a2,a6, a10,a14, b2,b6, b10,b14, c2,c6, c10,c14, d2,d6, d10,d14
+  transposed[2] = _mm_unpacklo_epi8(tmp1, tmp3);
+  // a3,a7, a11,a15, b3,b7, b11,b15, c3,c7, c11,c15, d3,d7, d11,d15
+  transposed[3] = _mm_unpackhi_epi8(tmp1, tmp3);
+
+  return true;
+}
+
+inline void UnpackBlock(__m128i* packed,
+                        __m128i* red,
+                        __m128i* green,
+                        __m128i* blue,
+                        __m128i* alpha) {
+  const __m128i zero = _mm_set1_epi8(0);
+  __m128i tmp_low, tmp_high;
+
+  // unpack red
+  tmp_low = _mm_unpacklo_epi8(packed[0], zero);
+  tmp_high = _mm_unpackhi_epi8(packed[0], zero);
+
+  red[0] = _mm_unpacklo_epi16(tmp_low, zero);
+  red[1] = _mm_unpackhi_epi16(tmp_low, zero);
+
+  red[2] = _mm_unpacklo_epi16(tmp_high, zero);
+  red[3] = _mm_unpackhi_epi16(tmp_high, zero);
+
+  // unpack green
+  tmp_low = _mm_unpacklo_epi8(packed[1], zero);
+  tmp_high = _mm_unpackhi_epi8(packed[1], zero);
+
+  green[0] = _mm_unpacklo_epi16(tmp_low, zero);
+  green[1] = _mm_unpackhi_epi16(tmp_low, zero);
+
+  green[2] = _mm_unpacklo_epi16(tmp_high, zero);
+  green[3] = _mm_unpackhi_epi16(tmp_high, zero);
+
+  // unpack blue
+  tmp_low = _mm_unpacklo_epi8(packed[2], zero);
+  tmp_high = _mm_unpackhi_epi8(packed[2], zero);
+
+  blue[0] = _mm_unpacklo_epi16(tmp_low, zero);
+  blue[1] = _mm_unpackhi_epi16(tmp_low, zero);
+
+  blue[2] = _mm_unpacklo_epi16(tmp_high, zero);
+  blue[3] = _mm_unpackhi_epi16(tmp_high, zero);
+
+  // unpack alpha - unused for ETC1
+  tmp_low = _mm_unpacklo_epi8(packed[3], zero);
+  tmp_high = _mm_unpackhi_epi8(packed[3], zero);
+
+  alpha[0] = _mm_unpacklo_epi16(tmp_low, zero);
+  alpha[1] = _mm_unpackhi_epi16(tmp_low, zero);
+
+  alpha[2] = _mm_unpacklo_epi16(tmp_high, zero);
+  alpha[3] = _mm_unpackhi_epi16(tmp_high, zero);
+}
+
+inline void CompressSolid(uint8_t* dst, uint8_t* block) {
+  // Clear destination buffer so that we can "or" in the results.
+  memset(dst, 0, 8);
+
+  const float src_color_float[3] = {static_cast<float>(block[0]),
+                                    static_cast<float>(block[1]),
+                                    static_cast<float>(block[2])};
+  const cc::Color base = cc::MakeColor555(src_color_float);
+  const __m128i base_v =
+      _mm_set_epi32(0, base.channels.r, base.channels.g, base.channels.b);
+
+  const __m128i constant = _mm_set_epi32(0, block[2], block[1], block[0]);
+  __m128i lum;
+  __m128i colors[4];
+  static const __m128i rgb =
+      _mm_set_epi32(0, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF);
+
+  cc::WriteDiff(dst, true);
+  cc::WriteFlip(dst, false);
+
+  cc::WriteColors555(dst, base, base);
+
+  uint8_t best_tbl_idx = 0;
+  uint8_t best_mod_idx = 0;
+  uint32_t best_mod_err = INT32_MAX;
+
+  for (unsigned int tbl_idx = 0; tbl_idx < 8; ++tbl_idx) {
+    lum = _mm_set_epi32(
+        cc::g_codeword_tables[tbl_idx][3], cc::g_codeword_tables[tbl_idx][2],
+        cc::g_codeword_tables[tbl_idx][1], cc::g_codeword_tables[tbl_idx][0]);
+    colors[0] = AddAndClamp(base_v, _mm_shuffle_epi32(lum, 0x0));
+    colors[1] = AddAndClamp(base_v, _mm_shuffle_epi32(lum, 0x55));
+    colors[2] = AddAndClamp(base_v, _mm_shuffle_epi32(lum, 0xAA));
+    colors[3] = AddAndClamp(base_v, _mm_shuffle_epi32(lum, 0xFF));
+
+    for (int i = 0; i < 4; i++) {
+      uint32_t mod_err =
+          SumSSE(GetColorErrorSSE(constant, _mm_and_si128(colors[i], rgb)));
+      colors[i] = _mm_and_si128(colors[i], rgb);
+      if (mod_err < best_mod_err) {
+        best_tbl_idx = tbl_idx;
+        best_mod_idx = i;
+        best_mod_err = mod_err;
+
+        if (mod_err == 0) {
+          break;  // We cannot do any better than this.
+        }
+      }
+    }
+  }
+
+  cc::WriteCodewordTable(dst, 0, best_tbl_idx);
+  cc::WriteCodewordTable(dst, 1, best_tbl_idx);
+
+  uint8_t pix_idx = cc::g_mod_to_pix[best_mod_idx];
+  uint32_t lsb = pix_idx & 0x1;
+  uint32_t msb = pix_idx >> 1;
+
+  uint32_t pix_data = 0;
+  for (unsigned int i = 0; i < 2; ++i) {
+    for (unsigned int j = 0; j < 8; ++j) {
+      // Obtain the texel number as specified in the standard.
+      int texel_num = cc::g_idx_to_num[i][j];
+      pix_data |= msb << (texel_num + 16);
+      pix_data |= lsb << (texel_num);
+    }
+  }
+
+  cc::WritePixelData(dst, pix_data);
+}
+
+}  // namespace
+
+namespace cc {

[reveman, 2015/05/07 14:24:35]

nit: please move this up to line 17 just before "namespace {" and remove the
cc:: prefix in the code above

[radu.velea, 2015/05/07 15:53:45]

Done.

+
+void TextureCompressorETC1SSE::Compress(const uint8_t* src,
+                                        uint8_t* dst,
+                                        int width,
+                                        int height,
+                                        Quality quality) {
+  DCHECK_GE(width, 4);
+  DCHECK_EQ((width & 3), 0);
+  DCHECK_GE(height, 4);
+  DCHECK_EQ((height & 3), 0);
+
+  ALIGNAS(16) uint8_t block[64];
+  __m128i packed[4];
+  __m128i red[4], green[4], blue[4], alpha[4];
+  __sse_data data;
+
+  for (int y = 0; y < height; y += 4, src += width * 4 * 4) {
+    for (int x = 0; x < width; x += 4, dst += 8) {
+      ExtractBlock(block, src + x * 4, width);
+      if (TransposeBlock(block, packed) == false) {
+        CompressSolid(dst, block);
+      } else {
+        UnpackBlock(packed, blue, green, red, alpha);
+
+        data.block = block;
+        data.packed = packed;
+        data.red = red;
+        data.blue = blue;
+        data.green = green;
+
+        CompressBlock(dst, &data);
+      }
+    }
+  }
+}
+
+}  // namespace cc