[PATCH 1/4] wined3d: Properly up-scale WINED3DFMT_R5G5_SNORM_L6_UNORM.

[Stefan Dösinger]

Simply left-shifting is not enough in positive ranges. 0xff / 255 !=
0xff00 / 65535.

Using the compiler to read 5 bit signed values seems a lot easier than
operating with masks.
---
 dlls/wined3d/utils.c | 44 +++++++++++++++++++++++++-------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/dlls/wined3d/utils.c b/dlls/wined3d/utils.c
index 1ce23ac..67457d5 100644
--- a/dlls/wined3d/utils.c
+++ b/dlls/wined3d/utils.c
@@ -290,6 +290,15 @@ static void convert_l4a4_unorm(const BYTE *src, BYTE *dst, UINT src_row_pitch, U
     }
 }
 
+#include <pshpack1.h>
+struct r5g5l6
+{
+    signed r : 5;
+    signed g : 5;
+    unsigned l : 6;
+};
+#include <poppack.h>
+
 static void convert_r5g5_snorm_l6_unorm(const BYTE *src, BYTE *dst, UINT src_row_pitch, UINT src_slice_pitch,
         UINT dst_row_pitch, UINT dst_slice_pitch, UINT width, UINT height, UINT depth)
 {
@@ -322,8 +331,8 @@ static void convert_r5g5_snorm_l6_unorm_nv(const BYTE *src, BYTE *dst, UINT src_
         UINT dst_row_pitch, UINT dst_slice_pitch, UINT width, UINT height, UINT depth)
 {
     unsigned int x, y, z;
-    const WORD *Source;
-    unsigned char *Dest;
+    unsigned char *texel_out, out_ds, out_dt;
+    const struct r5g5l6 *texel_in;
 
     /* This makes the gl surface bigger(24 bit instead of 16), but it works with
      * fixed function and shaders without further conversion once the surface is
@@ -333,27 +342,24 @@ static void convert_r5g5_snorm_l6_unorm_nv(const BYTE *src, BYTE *dst, UINT src_
     {
         for (y = 0; y < height; y++)
         {
-            Source = (const WORD *)(src + z * src_slice_pitch + y * src_row_pitch);
-            Dest = dst + z * dst_slice_pitch + y * dst_row_pitch;
+            texel_in = (const struct r5g5l6 *)(src + z * src_slice_pitch + y * src_row_pitch);
+            texel_out = dst + z * dst_slice_pitch + y * dst_row_pitch;
             for (x = 0; x < width; x++ )
             {
-                short color = (*Source++);
-                unsigned char l = ((color >> 10) & 0xfc);
-                         char v = ((color >>  5) & 0x3e);
-                         char u = ((color      ) & 0x1f);
+                out_ds = texel_in->r << 3;
+                if (texel_in->r > 0)
+                    out_ds |= texel_in->r >> 1;
 
-                /* 8 bits destination, 6 bits source, 8th bit is the sign. gl ignores the sign
-                 * and doubles the positive range. Thus shift left only once, gl does the 2nd
-                 * shift. GL reads a signed value and converts it into an unsigned value.
-                 */
-                /* M */ Dest[2] = l << 1;
+                out_dt = texel_in->g << 3;
+                if (texel_in->g > 0)
+                    out_dt |= texel_in->g >> 1;
 
-                /* Those are read as signed, but kept signed. Just left-shift 3 times to scale
-                 * from 5 bit values to 8 bit values.
-                 */
-                /* V */ Dest[1] = v << 3;
-                /* U */ Dest[0] = u << 3;
-                Dest += 3;
+                texel_out[0] = out_ds;
+                texel_out[1] = out_dt;
+                texel_out[2] = texel_in->l << 1 | texel_in->l >> 5;
+
+                texel_out += 3;
+                texel_in++;
             }
         }
     }
-- 
2.3.0