From a774eaa57e290a4fe0bcf5827019ac7054d096e0 Mon Sep 17 00:00:00 2001
From: Brian Paul <brianp@vmware.com>
Date: Sat, 8 Dec 2012 15:19:44 -0700
Subject: mesa: add new texel fetch code for dxt formats

---
 src/mesa/main/texcompress_s3tc.c | 106 ++++++++++++++++++++++++++++++++++++++-
 src/mesa/main/texcompress_s3tc.h |   5 ++
 2 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/src/mesa/main/texcompress_s3tc.c b/src/mesa/main/texcompress_s3tc.c
index 476b998e078..9595c849b53 100644
--- a/src/mesa/main/texcompress_s3tc.c
+++ b/src/mesa/main/texcompress_s3tc.c
@@ -58,7 +58,7 @@
 #define DXTN_LIBNAME "libtxc_dxtn.so"
 #endif
 
-typedef void (*dxtFetchTexelFuncExt)( GLint srcRowstride, GLubyte *pixdata, GLint col, GLint row, GLvoid *texelOut );
+typedef void (*dxtFetchTexelFuncExt)( GLint srcRowstride, const GLubyte *pixdata, GLint col, GLint row, GLvoid *texelOut );
 
 static dxtFetchTexelFuncExt fetch_ext_rgb_dxt1 = NULL;
 static dxtFetchTexelFuncExt fetch_ext_rgba_dxt1 = NULL;
@@ -494,3 +494,107 @@ _mesa_fetch_texel_srgba_dxt5(const struct swrast_texture_image *texImage,
    texel[BCOMP] = _mesa_nonlinear_to_linear(rgba[BCOMP]);
    texel[ACOMP] = UBYTE_TO_FLOAT(rgba[ACOMP]);
 }
+
+
+/** Report problem with dxt texture decompression, once */
+static void
+problem(const char *func)
+{
+   static GLboolean warned = GL_FALSE;
+   if (!warned) {
+      _mesa_debug(NULL, "attempted to decode DXT texture without "
+                  "library available: %s\n", func);
+      warned = GL_TRUE;
+   }
+}
+
+
+static void
+fetch_rgb_dxt1(const GLubyte *map, const GLuint imageOffsets[],
+               GLint rowStride, GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   if (fetch_ext_rgb_dxt1) {
+      GLuint sliceOffset = k ? imageOffsets[k] / 2 : 0;
+      GLubyte tex[4];
+      fetch_ext_rgb_dxt1(rowStride, map + sliceOffset, i, j, tex);
+      texel[RCOMP] = UBYTE_TO_FLOAT(tex[RCOMP]);
+      texel[GCOMP] = UBYTE_TO_FLOAT(tex[GCOMP]);
+      texel[BCOMP] = UBYTE_TO_FLOAT(tex[BCOMP]);
+      texel[ACOMP] = UBYTE_TO_FLOAT(tex[ACOMP]);
+   }
+   else {
+      problem("rgb_dxt1");
+   }
+}
+
+static void
+fetch_rgba_dxt1(const GLubyte *map, const GLuint imageOffsets[],
+                GLint rowStride, GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   if (fetch_ext_rgba_dxt1) {
+      GLuint sliceOffset = k ? imageOffsets[k] / 2 : 0;
+      GLubyte tex[4];
+      fetch_ext_rgba_dxt1(rowStride, map + sliceOffset, i, j, tex);
+      texel[RCOMP] = UBYTE_TO_FLOAT(tex[RCOMP]);
+      texel[GCOMP] = UBYTE_TO_FLOAT(tex[GCOMP]);
+      texel[BCOMP] = UBYTE_TO_FLOAT(tex[BCOMP]);
+      texel[ACOMP] = UBYTE_TO_FLOAT(tex[ACOMP]);
+   }
+   else {
+      problem("rgba_dxt1");
+   }
+}
+
+static void
+fetch_rgba_dxt3(const GLubyte *map, const GLuint imageOffsets[],
+                GLint rowStride, GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   if (fetch_ext_rgba_dxt3) {
+      GLuint sliceOffset = k ? imageOffsets[k] : 0;
+      GLubyte tex[4];
+      fetch_ext_rgba_dxt3(rowStride, map + sliceOffset, i, j, tex);
+      texel[RCOMP] = UBYTE_TO_FLOAT(tex[RCOMP]);
+      texel[GCOMP] = UBYTE_TO_FLOAT(tex[GCOMP]);
+      texel[BCOMP] = UBYTE_TO_FLOAT(tex[BCOMP]);
+      texel[ACOMP] = UBYTE_TO_FLOAT(tex[ACOMP]);
+   }
+   else {
+      problem("rgba_dxt3");
+   }
+}
+
+static void
+fetch_rgba_dxt5(const GLubyte *map, const GLuint imageOffsets[],
+                GLint rowStride, GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   if (fetch_ext_rgba_dxt5) {
+      GLuint sliceOffset = k ? imageOffsets[k] : 0;
+      GLubyte tex[4];
+      fetch_ext_rgba_dxt5(rowStride, map + sliceOffset, i, j, tex);
+      texel[RCOMP] = UBYTE_TO_FLOAT(tex[RCOMP]);
+      texel[GCOMP] = UBYTE_TO_FLOAT(tex[GCOMP]);
+      texel[BCOMP] = UBYTE_TO_FLOAT(tex[BCOMP]);
+      texel[ACOMP] = UBYTE_TO_FLOAT(tex[ACOMP]);
+   }
+   else {
+      problem("rgba_dxt5");
+   }
+}
+
+
+compressed_fetch_func
+_mesa_get_dxt_fetch_func(gl_format format)
+{
+   switch (format) {
+   case MESA_FORMAT_RGB_DXT1:
+      return fetch_rgb_dxt1;
+   case MESA_FORMAT_RGBA_DXT1:
+      return fetch_rgba_dxt1;
+   case MESA_FORMAT_RGBA_DXT3:
+      return fetch_rgba_dxt3;
+   case MESA_FORMAT_RGBA_DXT5:
+      return fetch_rgba_dxt5;
+   default:
+      return NULL;
+   }
+}
diff --git a/src/mesa/main/texcompress_s3tc.h b/src/mesa/main/texcompress_s3tc.h
index 524ac0c134e..5758e8365c1 100644
--- a/src/mesa/main/texcompress_s3tc.h
+++ b/src/mesa/main/texcompress_s3tc.h
@@ -29,6 +29,7 @@
 #include "glheader.h"
 #include "mfeatures.h"
 #include "texstore.h"
+#include "texcompress.h"
 
 struct gl_context;
 struct swrast_texture_image;
@@ -80,4 +81,8 @@ _mesa_fetch_texel_srgba_dxt5(const struct swrast_texture_image *texImage,
 extern void
 _mesa_init_texture_s3tc(struct gl_context *ctx);
 
+extern compressed_fetch_func
+_mesa_get_dxt_fetch_func(gl_format format);
+
+
 #endif /* TEXCOMPRESS_S3TC_H */
-- 
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