mesa: add ETC1 decoding routines

The format is defined by GL_OES_compressed_ETC1_RGB8_texture.  These routines
will be used in the following commit.

Reviewed-by: Brian Paul <brianp@vmware.com>

1 files changed, 71 insertions, 0 deletions

diff --git a/src/mesa/main/texcompress_etc.c b/src/mesa/main/texcompress_etc.c
new file mode 100644
index 0000000..4d3b857
--- /dev/null
+++ b/src/mesa/main/texcompress_etc.c
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2011 LunarG, 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_etc.c
+ * GL_OES_compressed_ETC1_RGB8_texture support.
+ */
+
+
+#include "mfeatures.h"
+#include "texcompress.h"
+#include "texcompress_etc.h"
+#include "texstore.h"
+#include "macros.h"
+#include "swrast/s_context.h"
+
+GLboolean
+_mesa_texstore_etc1_rgb8(TEXSTORE_PARAMS)
+{
+   /* GL_ETC1_RGB8_OES is only valid in glCompressedTexImage2D */
+   ASSERT(0);
+
+   return GL_FALSE;
+}
+
+/* define etc1_parse_block and etc. */
+#define UINT8_TYPE GLubyte
+#define TAG(x) x
+#include "texcompress_etc_tmp.h"
+#undef TAG
+#undef UINT8_TYPE
+
+void
+_mesa_fetch_texel_2d_f_etc1_rgb8(const struct swrast_texture_image *texImage,
+                                 GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   struct etc1_block block;
+   GLubyte dst[3];
+   const GLubyte *src;
+
+   src = (const GLubyte *) texImage->Data +
+      (((texImage->RowStride + 3) / 4) * (j / 4) + (i / 4)) * 8;
+
+   etc1_parse_block(&block, src);
+   etc1_fetch_texel(&block, i % 4, j % 4, dst);
+
+   texel[RCOMP] = UBYTE_TO_FLOAT(dst[0]);
+   texel[GCOMP] = UBYTE_TO_FLOAT(dst[1]);
+   texel[BCOMP] = UBYTE_TO_FLOAT(dst[2]);
+   texel[ACOMP] = 1.0f;
+}