mesa: Add decoding functions for GL_COMPRESSED_R11_EAC

Data in GL_COMPRESSED_R11_EAC format is decoded and stored in
MESA_FORMAT_R16.

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

4 files changed, 127 insertions, 5 deletions

diff --git a/src/mesa/main/texcompress.c b/src/mesa/main/texcompress.c
index 2d4c6df85a8..3d34d9b808b 100644
--- a/src/mesa/main/texcompress.c
+++ b/src/mesa/main/texcompress.c
@@ -620,7 +620,7 @@ _mesa_decompress_image(gl_format format, GLuint width, GLuint height,
       fetch = _mesa_fetch_texel_2d_f_etc2_srgb8_alpha8_eac;
       break;
    case MESA_FORMAT_ETC2_R11_EAC:
-      /* fetch = _mesa_fetch_texel_2d_f_etc2_r11_eac; -- not implemented yet */
+      fetch = _mesa_fetch_texel_2d_f_etc2_r11_eac;
       break;
    case MESA_FORMAT_ETC2_RG11_EAC:
       /* fetch = _mesa_fetch_texel_2d_f_etc2_rg11_eac; -- not implemented yet */
diff --git a/src/mesa/main/texcompress_etc.c b/src/mesa/main/texcompress_etc.c
index d704388d630..7137eca909d 100644
--- a/src/mesa/main/texcompress_etc.c
+++ b/src/mesa/main/texcompress_etc.c
@@ -29,6 +29,7 @@
  * GL_COMPRESSED_SRGB8_ETC2
  * GL_COMPRESSED_RGBA8_ETC2_EAC
  * GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC
+ * GL_COMPRESSED_R11_EAC
  */
 
 #include <stdbool.h>
@@ -304,6 +305,14 @@ etc2_base_color_v_planar(const uint8_t *in, GLuint index)
    }
 }
 
+static GLint
+etc2_get_pixel_index(const struct etc2_block *block, int x, int y)
+{
+   int bit = ((3 - y) + (3 - x) * 4) * 3;
+   int idx = (block->pixel_indices[1] >> bit) & 0x7;
+   return idx;
+}
+
 static uint8_t
 etc2_clamp(int color)
 {
@@ -311,6 +320,13 @@ etc2_clamp(int color)
    return (uint8_t) CLAMP(color, 0, 255);
 }
 
+static GLushort
+etc2_clamp2(int color)
+{
+   /* CLAMP(color, 0, 2047) */
+   return (GLushort) CLAMP(color, 0, 2047);
+}
+
 static void
 etc2_rgb8_parse_block(struct etc2_block *block, const uint8_t *src)
 {
@@ -486,16 +502,41 @@ static void
 etc2_alpha8_fetch_texel(const struct etc2_block *block,
       int x, int y, uint8_t *dst)
 {
-   int modifier, alpha, bit, idx;
+   int modifier, alpha, idx;
    /* get pixel index */
-   bit = ((3 - y) + (3 - x) * 4) * 3;
-   idx = (block->pixel_indices[1] >> bit) & 0x7;
+   idx = etc2_get_pixel_index(block, x, y);
    modifier = etc2_modifier_tables[block->table_index][idx];
    alpha = block->base_codeword + modifier * block->multiplier;
    dst[3] = etc2_clamp(alpha);
 }
 
 static void
+etc2_r11_fetch_texel(const struct etc2_block *block,
+                     int x, int y, uint8_t *dst)
+{
+   GLint modifier, idx;
+   GLshort color;
+   /* Get pixel index */
+   idx = etc2_get_pixel_index(block, x, y);
+   modifier = etc2_modifier_tables[block->table_index][idx];
+
+   if (block->multiplier != 0)
+      /* clamp2(base codeword × 8 + 4 + modifier × multiplier × 8) */
+      color = etc2_clamp2(((block->base_codeword << 3) | 0x4)  +
+                          ((modifier * block->multiplier) << 3));
+   else
+      color = etc2_clamp2(((block->base_codeword << 3) | 0x4)  + modifier);
+
+   /* Extend 11 bits color value to 16 bits. OpenGL ES 3.0 specification
+    * allows extending the color value to any number of bits. But, an
+    * implementation is not allowed to truncate the 11-bit value to less than
+    * 11 bits."
+    */
+   color = (color << 5) | (color >> 6);
+   ((GLushort *)dst)[0] = color;
+}
+
+static void
 etc2_alpha8_parse_block(struct etc2_block *block, const uint8_t *src)
 {
    block->base_codeword = src[0];
@@ -510,6 +551,13 @@ etc2_alpha8_parse_block(struct etc2_block *block, const uint8_t *src)
 }
 
 static void
+etc2_r11_parse_block(struct etc2_block *block, const uint8_t *src)
+{
+   /* Parsing logic remains same as for etc2_alpha8_parse_block */
+    etc2_alpha8_parse_block(block, src);
+}
+
+static void
 etc2_rgba8_parse_block(struct etc2_block *block, const uint8_t *src)
 {
    /* RGB component is parsed the same way as for MESA_FORMAT_ETC2_RGB8 */
@@ -680,6 +728,41 @@ etc2_unpack_srgb8_alpha8(uint8_t *dst_row,
     }
 }
 
+static void
+etc2_unpack_r11(uint8_t *dst_row,
+                unsigned dst_stride,
+                const uint8_t *src_row,
+                unsigned src_stride,
+                unsigned width,
+                unsigned height)
+{
+   /* If internalformat is COMPRESSED_R11_EAC, each 4 × 4 block of
+      color information is compressed to 64 bits.
+   */
+   const unsigned bw = 4, bh = 4, bs = 8, comps = 1, 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) {
+         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_r11_fetch_texel(&block, i, j, dst);
+               dst += comps * comp_size;
+            }
+         }
+         src += bs;
+       }
+
+      src_row += src_stride;
+    }
+}
+
 /* ETC2 texture formats are valid in glCompressedTexImage2D and
  * glCompressedTexSubImage2D functions */
 GLboolean
@@ -714,6 +797,14 @@ _mesa_texstore_etc2_srgb8_alpha8_eac(TEXSTORE_PARAMS)
    return GL_FALSE;
 }
 
+GLboolean
+_mesa_texstore_etc2_r11_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)
@@ -796,12 +887,33 @@ _mesa_fetch_texel_2d_f_etc2_srgb8_alpha8_eac(const struct
    texel[ACOMP] = UBYTE_TO_FLOAT(dst[3]);
 }
 
+void
+_mesa_fetch_texel_2d_f_etc2_r11_eac(const struct swrast_texture_image *texImage,
+                                    GLint i, GLint j, GLint k, GLfloat *texel)
+{
+   struct etc2_block block;
+   GLushort dst;
+   const uint8_t *src;
+
+   src = texImage->Map +
+      (((texImage->RowStride + 3) / 4) * (j / 4) + (i / 4)) * 8;
+
+   etc2_r11_parse_block(&block, src);
+   etc2_r11_fetch_texel(&block, i % 4, j % 4, (uint8_t *)&dst);
+
+   texel[RCOMP] = USHORT_TO_FLOAT(dst);
+   texel[GCOMP] = 0.0f;
+   texel[BCOMP] = 0.0f;
+   texel[ACOMP] = 1.0f;
+}
+
 /**
  * Decode texture data in any one of following formats:
  * `MESA_FORMAT_ETC2_RGB8`
  * `MESA_FORMAT_ETC2_SRGB8`
  * `MESA_FORMAT_ETC2_RGBA8_EAC`
  * `MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC`
+ * `MESA_FORMAT_ETC2_R11_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.
@@ -836,4 +948,8 @@ _mesa_unpack_etc2_format(uint8_t *dst_row,
       etc2_unpack_srgb8_alpha8(dst_row, dst_stride,
                                src_row, src_stride,
                                src_width, src_height);
+   else if (format == MESA_FORMAT_ETC2_R11_EAC)
+      etc2_unpack_r11(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 cfe8da3dabc..85c474c0186 100644
--- a/src/mesa/main/texcompress_etc.h
+++ b/src/mesa/main/texcompress_etc.h
@@ -46,6 +46,9 @@ _mesa_texstore_etc2_rgba8_eac(TEXSTORE_PARAMS);
 GLboolean
 _mesa_texstore_etc2_srgb8_alpha8_eac(TEXSTORE_PARAMS);
 
+GLboolean
+_mesa_texstore_etc2_r11_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);
@@ -64,6 +67,9 @@ _mesa_fetch_texel_2d_f_etc2_srgb8_alpha8_eac(const struct
                                             swrast_texture_image *texImage,
                                             GLint i, GLint j,
                                             GLint k, GLfloat *texel);
+void
+_mesa_fetch_texel_2d_f_etc2_r11_eac(const struct swrast_texture_image *texImage,
+                                    GLint i, GLint j, GLint k, GLfloat *texel);
 
 void
 _mesa_etc1_unpack_rgba8888(uint8_t *dst_row,
diff --git a/src/mesa/main/texstore.c b/src/mesa/main/texstore.c
index 6007775169b..6da9473d699 100644
--- a/src/mesa/main/texstore.c
+++ b/src/mesa/main/texstore.c
@@ -4128,7 +4128,7 @@ _mesa_get_texstore_func(gl_format format)
       table[MESA_FORMAT_ETC2_SRGB8] = _mesa_texstore_etc2_srgb8;
       table[MESA_FORMAT_ETC2_RGBA8_EAC] = _mesa_texstore_etc2_rgba8_eac;
       table[MESA_FORMAT_ETC2_SRGB8_ALPHA8_EAC] = _mesa_texstore_etc2_srgb8_alpha8_eac;
-      /* table[MESA_FORMAT_ETC2_R11_EAC] = _mesa_texstore_etc2_r11_eac; -- not implemented yet */
+      table[MESA_FORMAT_ETC2_R11_EAC] = _mesa_texstore_etc2_r11_eac;
       /* table[MESA_FORMAT_ETC2_RG11_EAC] = _mesa_texstore_etc2_rg11_eac; -- not implemented yet */
       /* table[MESA_FORMAT_ETC2_SIGNED_R11_EAC] = _mesa_texstore_etc2_signed_r11_eac; -- not implemented yet */
       /* table[MESA_FORMAT_ETC2_SIGNED_RG11_EAC] = _mesa_texstore_etc2_signed_rg11_eac; -- not implemented yet */