gallium/util: added util_format_linear()

diff --git a/src/gallium/auxiliary/util/u_format.h b/src/gallium/auxiliary/util/u_format.h
index 03b73c0e98f5fa08adddfec177b3b6b329aa501a..7659a802a41605fdc1fed38cb8717db03750be8c 100644 (file)
--- a/src/gallium/auxiliary/util/u_format.h
+++ b/src/gallium/auxiliary/util/u_format.h
@@ -673,7 +673,8 @@ util_format_has_alpha(enum pipe_format format)
 }
 
 /**
- * Return the matching SRGB format, or PIPE_FORMAT_NONE if none.
+ * Given a linear RGB colorspace format, return the corresponding SRGB
+ * format, or PIPE_FORMAT_NONE if none.
  */
 static INLINE enum pipe_format
 util_format_srgb(enum pipe_format format)
@@ -710,6 +711,45 @@ util_format_srgb(enum pipe_format format)
    }
 }
 
+/**
+ * Given an sRGB format, return the corresponding linear colorspace format.
+ * For non sRGB formats, return the format unchanged.
+ */
+static INLINE enum pipe_format
+util_format_linear(enum pipe_format format)
+{
+   switch (format) {
+   case PIPE_FORMAT_L8_SRGB:
+      return PIPE_FORMAT_L8_UNORM;
+   case PIPE_FORMAT_L8A8_SRGB:
+      return PIPE_FORMAT_L8A8_UNORM;
+   case PIPE_FORMAT_R8G8B8_SRGB:
+      return PIPE_FORMAT_R8G8B8_UNORM;
+   case PIPE_FORMAT_A8B8G8R8_SRGB:
+      return PIPE_FORMAT_A8B8G8R8_UNORM;
+   case PIPE_FORMAT_X8B8G8R8_SRGB:
+      return PIPE_FORMAT_X8B8G8R8_UNORM;
+   case PIPE_FORMAT_B8G8R8A8_SRGB:
+      return PIPE_FORMAT_B8G8R8A8_UNORM;
+   case PIPE_FORMAT_B8G8R8X8_SRGB:
+      return PIPE_FORMAT_B8G8R8X8_UNORM;
+   case PIPE_FORMAT_A8R8G8B8_SRGB:
+      return PIPE_FORMAT_A8R8G8B8_UNORM;
+   case PIPE_FORMAT_X8R8G8B8_SRGB:
+      return PIPE_FORMAT_X8R8G8B8_UNORM;
+   case PIPE_FORMAT_DXT1_SRGB:
+      return PIPE_FORMAT_DXT1_RGB;
+   case PIPE_FORMAT_DXT1_SRGBA:
+      return PIPE_FORMAT_DXT1_RGBA;
+   case PIPE_FORMAT_DXT3_SRGBA:
+      return PIPE_FORMAT_DXT3_RGBA;
+   case PIPE_FORMAT_DXT5_SRGBA:
+      return PIPE_FORMAT_DXT5_RGBA;
+   default:
+      return format;
+   }
+}
+
 /**
  * Return the number of components stored.
  * Formats with block size != 1x1 will always have 1 component (the block).