mesa: Fix packing/unpacking of MESA_FORMAT_R5G6B5_UNORM

Aparently, the packing/unpacking functions for these formats have differed
from the format description in formats.h.  Instead of fixing this, people
simply left a comment saying it was broken.  Let's actually fix it for
real.

v2 by Samuel Iglesias <[email protected]>:
- Fix comment in formats.h

Signed-off-by: Jason Ekstrand <[email protected]>
Reviewed-by: Jason Ekstrand <[email protected]>
Reviewed-by: Anuj Phogat <[email protected]>

6 files changed, 18 insertions, 27 deletions

diff --git a/src/mesa/main/format_pack.c b/src/mesa/main/format_pack.c
index 31c9f776797..20d2b1a4821 100644
--- a/src/mesa/main/format_pack.c
+++ b/src/mesa/main/format_pack.c
@@ -458,17 +458,11 @@ pack_row_float_B5G6R5_UNORM(GLuint n, const GLfloat src[][4], void *dst)
 }
 
 
-/*
- * MESA_FORMAT_R5G6B5_UNORM
- * Warning: these functions do not match the current Mesa definition
- * of MESA_FORMAT_R5G6B5_UNORM.
- */
-
 static void
 pack_ubyte_R5G6B5_UNORM(const GLubyte src[4], void *dst)
 {
    GLushort *d = ((GLushort *) dst);
-   *d = PACK_COLOR_565_REV(src[RCOMP], src[GCOMP], src[BCOMP]);
+   *d = PACK_COLOR_565(src[BCOMP], src[GCOMP], src[RCOMP]);
 }
 
 static void
@@ -479,7 +473,7 @@ pack_float_R5G6B5_UNORM(const GLfloat src[4], void *dst)
    UNCLAMPED_FLOAT_TO_UBYTE(r, src[RCOMP]);
    UNCLAMPED_FLOAT_TO_UBYTE(g, src[GCOMP]);
    UNCLAMPED_FLOAT_TO_UBYTE(b, src[BCOMP]);
-   *d = PACK_COLOR_565_REV(r, g, b);
+   *d = PACK_COLOR_565(b, g, r);
 }
 
 static void
diff --git a/src/mesa/main/format_unpack.c b/src/mesa/main/format_unpack.c
index d5628a9e7cb..69c76d354c7 100644
--- a/src/mesa/main/format_unpack.c
+++ b/src/mesa/main/format_unpack.c
@@ -2764,16 +2764,13 @@ unpack_ubyte_B5G6R5_UNORM(const void *src, GLubyte dst[][4], GLuint n)
 static void
 unpack_ubyte_R5G6B5_UNORM(const void *src, GLubyte dst[][4], GLuint n)
 {
-   /* Warning: this function does not match the current Mesa definition
-    * of MESA_FORMAT_R5G6B5_UNORM.
-    */
    const GLushort *s = ((const GLushort *) src);
    GLuint i;
    for (i = 0; i < n; i++) {
       GLuint t = (s[i] >> 8) | (s[i] << 8); /* byte swap */
-      dst[i][RCOMP] = EXPAND_5_8((t >> 11) & 0x1f);
+      dst[i][RCOMP] = EXPAND_5_8( t        & 0x1f);
       dst[i][GCOMP] = EXPAND_6_8((t >> 5 ) & 0x3f);
-      dst[i][BCOMP] = EXPAND_5_8( t        & 0x1f);
+      dst[i][BCOMP] = EXPAND_5_8((t >> 11) & 0x1f);
       dst[i][ACOMP] = 0xff;
    }
 }
diff --git a/src/mesa/main/formats.c b/src/mesa/main/formats.c
index 58c32e23b30..1315d368c27 100644
--- a/src/mesa/main/formats.c
+++ b/src/mesa/main/formats.c
@@ -1462,14 +1462,14 @@ _mesa_format_matches_format_and_type(mesa_format mesa_format,
       return format == GL_RGB && type == GL_UNSIGNED_BYTE && littleEndian;
 
    case MESA_FORMAT_B5G6R5_UNORM:
-      return format == GL_RGB && type == GL_UNSIGNED_SHORT_5_6_5 && !swapBytes;
+      return ((format == GL_RGB && type == GL_UNSIGNED_SHORT_5_6_5) ||
+              (format == GL_BGR && type == GL_UNSIGNED_SHORT_5_6_5_REV)) &&
+              !swapBytes;
 
    case MESA_FORMAT_R5G6B5_UNORM:
-      /* Some of the 16-bit MESA_FORMATs that would seem to correspond to
-       * GL_UNSIGNED_SHORT_* are byte-swapped instead of channel-reversed,
-       * according to formats.h, so they can't be matched.
-       */
-      return GL_FALSE;
+      return ((format == GL_BGR && type == GL_UNSIGNED_SHORT_5_6_5) ||
+              (format == GL_RGB && type == GL_UNSIGNED_SHORT_5_6_5_REV)) &&
+              !swapBytes;
 
    case MESA_FORMAT_B4G4R4A4_UNORM:
       return format == GL_BGRA && type == GL_UNSIGNED_SHORT_4_4_4_4_REV &&
diff --git a/src/mesa/main/formats.h b/src/mesa/main/formats.h
index 213ab563d2a..d0959906b3e 100644
--- a/src/mesa/main/formats.h
+++ b/src/mesa/main/formats.h
@@ -139,9 +139,9 @@ typedef enum
     *   ** when type applies to all components
     *
     *  examples:                   msb <------ TEXEL BITS -----------> lsb
-    *  MESA_FORMAT_A8B8G8R8_UNORM, AAAA AAAA BBBB BBBB GGGG GGGG RRRR RRRR
-    *  MESA_FORMAT_R5G6B5_UNORM                        RRRR RGGG GGGB BBBB
-    *  MESA_FORMAT_B4G4R4X4_UNORM                      BBBB GGGG RRRR XXXX
+    *  MESA_FORMAT_A8B8G8R8_UNORM, RRRR RRRR GGGG GGGG BBBB BBBB AAAA AAAA
+    *  MESA_FORMAT_R5G6B5_UNORM                        BBBB BGGG GGGR RRRR
+    *  MESA_FORMAT_B4G4R4X4_UNORM                      XXXX RRRR GGGG BBBB
     *  MESA_FORMAT_Z32_FLOAT_S8X24_UINT
     *  MESA_FORMAT_R10G10B10A2_UINT
     *  MESA_FORMAT_R9G9B9E5_FLOAT
diff --git a/src/mesa/main/texstore.c b/src/mesa/main/texstore.c
index 50aa1fd5ef0..b9407d2f739 100644
--- a/src/mesa/main/texstore.c
+++ b/src/mesa/main/texstore.c
@@ -923,7 +923,7 @@ _mesa_texstore_rgb565(TEXSTORE_PARAMS)
          }
          else {
             for (col = 0; col < srcWidth; col++) {
-               dstUS[col] = PACK_COLOR_565_REV( srcUB[0], srcUB[1], srcUB[2] );
+               dstUS[col] = PACK_COLOR_565( srcUB[2], srcUB[1], srcUB[0] );
                srcUB += 3;
             }
          }
diff --git a/src/mesa/swrast/s_texfetch_tmp.h b/src/mesa/swrast/s_texfetch_tmp.h
index 7ff30f6b4ae..23db48d969e 100644
--- a/src/mesa/swrast/s_texfetch_tmp.h
+++ b/src/mesa/swrast/s_texfetch_tmp.h
@@ -417,10 +417,10 @@ FETCH(R5G6B5_UNORM)(const struct swrast_texture_image *texImage,
                     GLint i, GLint j, GLint k, GLfloat *texel)
 {
    const GLushort *src = TEXEL_ADDR(GLushort, texImage, i, j, k, 1);
-   const GLushort s = (*src >> 8) | (*src << 8); /* byte swap */
-   texel[RCOMP] = UBYTE_TO_FLOAT( ((s >> 8) & 0xf8) | ((s >> 13) & 0x7) );
-   texel[GCOMP] = UBYTE_TO_FLOAT( ((s >> 3) & 0xfc) | ((s >>  9) & 0x3) );
-   texel[BCOMP] = UBYTE_TO_FLOAT( ((s << 3) & 0xf8) | ((s >>  2) & 0x7) );
+   const GLushort s = *src;
+   texel[RCOMP] = ((s      ) & 0x1f) * (1.0F / 31.0F);
+   texel[GCOMP] = ((s >> 5 ) & 0x3f) * (1.0F / 63.0F);
+   texel[BCOMP] = ((s >> 11) & 0x1f) * (1.0F / 31.0F);
    texel[ACOMP] = 1.0F;
 }