initial commit, 4.5 stable

thirdparty/libktx/lib/basis_sgd.h

@@ -0,0 +1,85 @@
+/* -*- tab-width: 4; -*- */
+/* vi: set sw=2 ts=4 expandtab textwidth=70: */
+
+/*
+ * Copyright 2019-2020 The Khronos Group Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @internal
+ * @file basisu_sgd.h
+ * @~English
+ *
+ * @brief Declare global data for Basis LZ supercompression with ETC1S.
+ *
+ * These functions are private and should not be used outside the library.
+ */
+
+#ifndef _BASIS_SGD_H_
+#define _BASIS_SGD_H_
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// This must be the same value as cSliceDescFlagsFrameIsIFrame so we can just
+// invert the bit when passing back & forth. As FrameIsIFrame is within
+// a C namespace it can't easily be accessed from a c header.
+enum bu_image_flags__bits_e { ETC1S_P_FRAME = 0x02 };
+
+typedef uint32_t buFlags;
+
+typedef struct ktxBasisLzGlobalHeader {
+    uint16_t endpointCount;
+    uint16_t selectorCount;
+    uint32_t endpointsByteLength;
+    uint32_t selectorsByteLength;
+    uint32_t tablesByteLength;
+    uint32_t extendedByteLength;
+} ktxBasisLzGlobalHeader;
+
+// This header is followed by imageCount "slice" descriptions.
+
+// 1, or 2 slices per image (i.e. layer, face & slice).
+// These offsets are relative to start of a mip level as given by the
+// main levelIndex.
+typedef struct ktxBasisLzEtc1sImageDesc {
+    buFlags imageFlags;
+    uint32_t rgbSliceByteOffset;
+    uint32_t rgbSliceByteLength;
+    uint32_t alphaSliceByteOffset;
+    uint32_t alphaSliceByteLength;
+} ktxBasisLzEtc1sImageDesc;
+
+#define BGD_ETC1S_IMAGE_DESCS(bgd) \
+        reinterpret_cast<ktxBasisLzEtc1sImageDesc*>(bgd + sizeof(ktxBasisLzGlobalHeader))
+
+// The are followed in the global data by these ...
+//    uint8_t[endpointsByteLength] endpointsData;
+//    uint8_t[selectorsByteLength] selectorsData;
+//    uint8_t[tablesByteLength] tablesData;
+
+#define BGD_ENDPOINTS_ADDR(bgd, imageCount) \
+    (bgd + sizeof(ktxBasisLzGlobalHeader) + sizeof(ktxBasisLzEtc1sImageDesc) * imageCount)
+
+#define BGD_SELECTORS_ADDR(bgd, bgdh, imageCount) (BGD_ENDPOINTS_ADDR(bgd, imageCount) + bgdh.endpointsByteLength)
+
+#define BGD_TABLES_ADDR(bgd, bgdh, imageCount) (BGD_SELECTORS_ADDR(bgd, bgdh, imageCount) + bgdh.selectorsByteLength)
+
+#define BGD_EXTENDED_ADDR(bgd, bgdh, imageCount) (BGD_TABLES_ADDR(bgd, bgdh, imageCount) + bgdh.tablesByteLength)
+
+// Just because this is a convenient place to put it for basis_{en,trans}code.
+enum alpha_content_e {
+    eNone,
+    eAlpha,
+    eGreen
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _BASIS_SGD_H_ */