[Mesa-dev] [PATCH 16/22] mesa: Add decoding functions for GL_COMPRESSED_SIGNED_RG11_EAC

[Anuj Phogat]

v2: Fixed an issue with signed-rg11 decoding. 16 bit signed data is
now converted to 16 bit unsigned data by adding 2 ^ 15 and stored
in an unsigned texture format.

Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
---
 src/mesa/main/texcompress_etc.c |   87 +++++++++++++++++++++++++++++++++++++++
 src/mesa/main/texcompress_etc.h |    8 ++++
 2 files changed, 95 insertions(+), 0 deletions(-)

diff --git a/src/mesa/main/texcompress_etc.c b/src/mesa/main/texcompress_etc.c
index f7d0c43..dbacc62 100644
--- a/src/mesa/main/texcompress_etc.c
+++ b/src/mesa/main/texcompress_etc.c
@@ -32,6 +32,7 @@
  * GL_COMPRESSED_R11_EAC
  * GL_COMPRESSED_RG11_EAC
  * GL_COMPRESSED_SIGNED_R11_EAC
+ * GL_COMPRESSED_SIGNED_RG11_EAC
  */
 
 #include <stdbool.h>
@@ -919,6 +920,54 @@ etc2_unpack_signed_r11(uint8_t *dst_row,
     }
 }
 
+static void
+etc2_unpack_signed_rg11(uint8_t *dst_row,
+                        unsigned dst_stride,
+                        const uint8_t *src_row,
+                        unsigned src_stride,
+                        unsigned width,
+                        unsigned height)
+{
+   /* If internalformat is COMPRESSED_SIGNED_RG11_EAC, each 4 × 4 block of
+      RG color information is compressed to 128 bits.
+   */
+   const unsigned bw = 4, bh = 4, bs = 16, comps = 2, comp_size = 2;
+   struct etc2_block block;
+   unsigned x, y, i, j;
+
+   for (y = 0; y < height; y += bh) {
+      const uint8_t *src = src_row;
+
+      for (x = 0; x < width; x+= bw) {
+         /* red component */
+         etc2_r11_parse_block(&block, src);
+
+         for (j = 0; j < bh; j++) {
+            uint8_t *dst = dst_row + (y + j) * dst_stride +
+                          x * comps * comp_size;
+            for (i = 0; i < bw; i++) {
+               etc2_signed_r11_fetch_texel(&block, i, j, dst);
+               dst += comps * comp_size;
+            }
+         }
+         /* green component */
+         etc2_r11_parse_block(&block, src + 8);
+
+         for (j = 0; j < bh; j++) {
+            uint8_t *dst = dst_row + (y + j) * dst_stride +
+                           x * comps * comp_size;
+            for (i = 0; i < bw; i++) {
+               etc2_signed_r11_fetch_texel(&block, i, j, dst + comp_size);
+               dst += comps * comp_size;
+            }
+         }
+         src += bs;
+       }
+
+      src_row += src_stride;
+    }
+}
+
 /* ETC2 texture formats are valid in glCompressedTexImage2D and
  * glCompressedTexSubImage2D functions */
 GLboolean
@@ -977,6 +1026,14 @@ _mesa_texstore_etc2_rg11_eac(TEXSTORE_PARAMS)
    return GL_FALSE;
 }
 
+GLboolean
+_mesa_texstore_etc2_signed_rg11_eac(TEXSTORE_PARAMS)
+{
+   ASSERT(0);
+
+   return GL_FALSE;
+}
+
 void
 _mesa_fetch_texel_2d_f_etc2_rgb8(const struct swrast_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel)
@@ -1126,6 +1183,31 @@ _mesa_fetch_texel_2d_f_etc2_signed_r11_eac(const struct swrast_texture_image *te
    texel[ACOMP] = 1.0f;
 }
 
+void
+_mesa_fetch_texel_2d_f_etc2_signed_rg11_eac(const struct swrast_texture_image *texImage,
+                                            GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   struct etc2_block block;
+   GLushort dst[2];
+   const GLubyte *src;
+
+   src = (const GLubyte *) texImage->Map +
+      (((texImage->RowStride + 3) / 4) * (j / 4) + (i / 4)) * 16;
+
+   /* red component */
+   etc2_r11_parse_block(&block, src);
+   etc2_signed_r11_fetch_texel(&block, i % 4, j % 4, (GLubyte *)dst);
+
+   /* green component */
+   etc2_r11_parse_block(&block, src + 8);
+   etc2_signed_r11_fetch_texel(&block, i % 4, j % 4, (GLubyte *)(dst + 1));
+
+   texel[RCOMP] = SHORT_TO_FLOAT(dst[0]);
+   texel[GCOMP] = SHORT_TO_FLOAT(dst[1]);
+   texel[BCOMP] = 0.0f;
+   texel[ACOMP] = 1.0f;
+}
+
 /**
  * Decode texture data in any one of following formats:
  * `MESA_FORMAT_ETC2_RGB8`
@@ -1135,6 +1217,7 @@ _mesa_fetch_texel_2d_f_etc2_signed_r11_eac(const struct swrast_texture_image *te
  * `MESA_FORMAT_ETC2_R11_EAC`
  * `MESA_FORMAT_ETC2_RG11_EAC`
  * `MESA_FORMAT_ETC2_SIGNED_R11_EAC`
+ * `MESA_FORMAT_ETC2_SIGNED_RG11_EAC`
  *
  * The size of the source data must be a multiple of the ETC2 block size
  * even if the texture image's dimensions are not aligned to 4.
@@ -1181,4 +1264,8 @@ _mesa_unpack_etc2_format(uint8_t *dst_row,
       etc2_unpack_signed_r11(dst_row, dst_stride,
                              src_row, src_stride,
                              src_width, src_height);
+   else if (format == MESA_FORMAT_ETC2_SIGNED_RG11_EAC)
+      etc2_unpack_signed_rg11(dst_row, dst_stride,
+                              src_row, src_stride,
+                              src_width, src_height);
 }
diff --git a/src/mesa/main/texcompress_etc.h b/src/mesa/main/texcompress_etc.h
index 362fa78..d12a145 100644
--- a/src/mesa/main/texcompress_etc.h
+++ b/src/mesa/main/texcompress_etc.h
@@ -55,6 +55,9 @@ _mesa_texstore_etc2_rg11_eac(TEXSTORE_PARAMS);
 GLboolean
 _mesa_texstore_etc2_signed_r11_eac(TEXSTORE_PARAMS);
 
+GLboolean
+_mesa_texstore_etc2_signed_rg11_eac(TEXSTORE_PARAMS);
+
 void
 _mesa_fetch_texel_2d_f_etc1_rgb8(const struct swrast_texture_image *texImage,
                                  GLint i, GLint j, GLint k, GLfloat *texel);
@@ -84,6 +87,11 @@ _mesa_fetch_texel_2d_f_etc2_signed_r11_eac(const struct
                                            GLint i, GLint j,
 					   GLint k, GLfloat *texel);
 void
+_mesa_fetch_texel_2d_f_etc2_signed_rg11_eac(const struct
+                                            swrast_texture_image *texImage,
+                                            GLint i, GLint j,
+					    GLint k, GLfloat *texel);
+void
 _mesa_etc1_unpack_rgba8888(uint8_t *dst_row,
                            unsigned dst_stride,
                            const uint8_t *src_row,
-- 
1.7.7.6