Add function _mesa_etc1_image_decode_to_abgr8888(). It is intended to be
used by glCompressedTexSubImage2D to translate ETC1 textures into ABGR.
Signed-off-by: Chad Versace <chad.vers...@linux.intel.com>
---
src/mesa/main/texcompress_etc.c | 82 +++++++++++++++++++++++++++++++++++++++++
src/mesa/main/texcompress_etc.h | 6 +++
2 files changed, 88 insertions(+)
diff --git a/src/mesa/main/texcompress_etc.c b/src/mesa/main/texcompress_etc.c
index e3b2e83..d84ee0e 100644
--- a/src/mesa/main/texcompress_etc.c
+++ b/src/mesa/main/texcompress_etc.c
@@ -178,3 +178,85 @@ _mesa_fetch_texel_2d_f_etc1_rgb8(const struct
swrast_texture_image *texImage,
texel[BCOMP] = UBYTE_TO_FLOAT(bgr888[2]);
texel[ACOMP] = 1.0f;
}
+
+static int
+align(int x, int m)
+{
+ return (m * x + m - 1) / m;
+}
+
+/**
+ * Decode texture data in format `MESA_FORMAT_ETC1_RGB8` to
+ * `MESA_FORMAT_ABGR8888`.
+ *
+ * The size of the source data must be a multiple of the ETC1 block size,
+ * which is 8, even if the texture image's dimensions are not aligned to 4.
+ * From the GL_OES_compressed_ETC1_RGB8_texture spec:
+ * The texture is described as a number of 4x4 pixel blocks. If the
+ * texture (or a particular mip-level) is smaller than 4 pixels in
+ * any dimension (such as a 2x2 or a 8x1 texture), the texture is
+ * found in the upper left part of the block(s), and the rest of the
+ * pixels are not used. For instance, a texture of size 4x2 will be
+ * placed in the upper half of a 4x4 block, and the lower half of the
+ * pixels in the block will not be accessed.
+ *
+ * \param src_width in pixels
+ * \param src_height in pixels
+ * \param dst_rowstride in bytes
+ */
+void
+_mesa_etc1_image_decode_to_abgr8888(const uint8_t *src,
+ int src_width,
+ int src_height,
+ uint8_t *dst,
+ int dst_rowstride)
+{
+ /* An XRGB pixel is 4 bytes. */
+ const int pixel_bytes = 4;
+
+ /* A block contains 4x4 pixels. */
+ const int block_width = 4;
+ const int block_height = 4;
+
+ /* A block contains 8 bytes. */
+ const int block_bytes = 8;
+
+ /* The stride in units of blocks. */
+ const int block_stride = align(src_width, block_width) / block_width;
+
+ /* The block being decoded. */
+ int block_x;
+ int block_y;
+
+ /* Iterate over each block. */
+ for (block_y = 0; block_y * block_height < src_height; ++block_y) {
+ for (block_x = 0; block_x * block_width < src_width; ++block_x) {
+ struct etc1_block block;
+
+ /* The pixel's position relative to the block's base. */
+ int pixel_x;
+ int pixel_y;
+
+ const uint8_t *src_block_base =
+ src + block_bytes * (block_y * block_stride + block_x);
+
+ uint8_t *dst_block_base = dst
+ + block_y * block_height * dst_rowstride
+ + block_x * block_width * pixel_bytes;
+
+ etc1_parse_block(&block, src_block_base);
+
+ /* Iterate over each pixel in block. */
+ for (pixel_y = 0; pixel_y < block_height; ++pixel_y) {
+ for (pixel_x = 0; pixel_x < block_width; ++pixel_x) {
+ uint8_t *dst_texel = dst_block_base
+ + pixel_y * dst_rowstride
+ + pixel_x * pixel_bytes;
+
+ etc1_fetch_texel(&block, pixel_x, pixel_y, dst_texel);
+ dst_texel[3] = 0xff;
+ }
+ }
+ }
+ }
+}
diff --git a/src/mesa/main/texcompress_etc.h b/src/mesa/main/texcompress_etc.h
index 8e8427f..552a7bd 100644
--- a/src/mesa/main/texcompress_etc.h
+++ b/src/mesa/main/texcompress_etc.h
@@ -36,5 +36,11 @@ _mesa_texstore_etc1_rgb8(TEXSTORE_PARAMS);
void
_mesa_fetch_texel_2d_f_etc1_rgb8(const struct swrast_texture_image *texImage,
GLint i, GLint j, GLint k, GLfloat *texel);
+void
+_mesa_etc1_image_decode_to_abgr8888(const uint8_t *src,
+ int src_width,
+ int src_height,
+ uint8_t *dst,
+ int dst_rowstride);
#endif
--
1.7.11.1
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