Tile Compression

cc/resources/texture_compress/atc_dxt.h

+// Copyright 2014 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.
+
+#ifndef CC_RESOURCES_TEXTURE_COMPRESS_ATC_DXT_H_
+#define CC_RESOURCES_TEXTURE_COMPRESS_ATC_DXT_H_
+
+#include <stdint.h>
+
+#include "cc/base/cc_export.h"
+
+#if defined(__GNUC__)
+#define ALWAYS_INLINE inline __attribute__((always_inline))
+#else
+#define ALWAYS_INLINE inline
+#endif
+
+namespace cc {
+namespace texture_compress {
+
+enum Quality {
+  kQualityLow,
+  kQualityMedium,
+  kQualityHigh,
+};
+
+// Types used to explicitly instantiate template functions.
+struct TYPE_ATC {
+  static const uint32_t kConstantColorIndices = 0x55555555;
+};
+
+struct TYPE_DXT {
+  static const uint32_t kConstantColorIndices = 0xaaaaaaaa;
+};
+
+extern uint8_t g_o_match55[256][2];
+extern uint8_t g_o_match66[256][2];
+extern uint8_t g_o_match56[256][2];
+
+// Returns max and min base colors matching the given single color when solved
+// via linear interpolation. Output format differs for ATC and DXT. See
+// explicitly instantiated template functions below.
+template <typename T>
+inline uint16_t MatchSingleColorMax(int r, int g, int b);
+template <typename T>
+inline uint16_t MatchSingleColorMin(int r, int g, int b);
+
+template <>
+inline uint16_t MatchSingleColorMax<TYPE_ATC>(int r, int g, int b) {
+  return (g_o_match55[r][0] << 11) | (g_o_match56[g][0] << 6) |
+         g_o_match55[b][0];
+}
+
+template <>
+inline uint16_t MatchSingleColorMin<TYPE_ATC>(int r, int g, int b) {
+  return (g_o_match55[r][1] << 11) | (g_o_match56[g][1] << 5) |
+         g_o_match55[b][1];
+}
+
+template <>
+inline uint16_t MatchSingleColorMax<TYPE_DXT>(int r, int g, int b) {
+  return (g_o_match55[r][0] << 11) | (g_o_match66[g][0] << 5) |
+         g_o_match55[b][0];
+}
+
+template <>
+inline uint16_t MatchSingleColorMin<TYPE_DXT>(int r, int g, int b) {
+  return (g_o_match55[r][1] << 11) | (g_o_match66[g][1] << 5) |
+         g_o_match55[b][1];
+}
+
+// This converts the output data to either ATC or DXT format.
+// See explicitly instantiated template functions below.
+template <typename T>
+inline void FormatFixup_Generic(uint16_t* max16,
+                                uint16_t* min16,
+                                uint32_t* mask);
+
+template <>
+inline void FormatFixup_Generic<TYPE_ATC>(uint16_t* max16,
+                                          uint16_t* min16,
+                                          uint32_t* mask) {
+  // First color in ATC format is 555.
+  *max16 = (*max16 & 0x001f) | ((*max16 & 0xffC0) >> 1);
+}
+
+template <>
+inline void FormatFixup_Generic<TYPE_DXT>(uint16_t* max16,
+                                          uint16_t* min16,
+                                          uint32_t* mask) {
+  // Swap min/max colors if necessary.
+  if (*max16 < *min16) {
+    uint16_t t = *min16;
+    *min16 = *max16;
+    *max16 = t;
+    *mask ^= 0x55555555;
+  }
+}
+
+CC_EXPORT void Init_ATC_DXT();
+
+CC_EXPORT void CompressATC_Generic(const uint8_t* src,
+                                   uint8_t* dst,
+                                   int width,
+                                   int height);
+CC_EXPORT void CompressATCIA_Generic(const uint8_t* src,
+                                     uint8_t* dst,
+                                     int width,
+                                     int height);
+CC_EXPORT void CompressDXT1_Generic(const uint8_t* src,
+                                    uint8_t* dst,
+                                    int width,
+                                    int height);
+CC_EXPORT void CompressDXT5_Generic(const uint8_t* src,
+                                    uint8_t* dst,
+                                    int width,
+                                    int height);
+
+}  // namespace texture_compress
+}  // namespace cc
+
+#endif  // CC_RESOURCES_TEXTURE_COMPRESS_ATC_DXT_H_