gallium/util: add functions for manipulating swizzles

Some of those have been in drivers already.

2 files changed, 69 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/util/u_format.c b/src/gallium/auxiliary/util/u_format.c
index 9cbdd0a5b99..3a8aeab5fed 100644
--- a/src/gallium/auxiliary/util/u_format.c
+++ b/src/gallium/auxiliary/util/u_format.c
@@ -390,3 +390,53 @@ util_format_translate(enum pipe_format dst_format,
       FREE(tmp_row);
    }
 }
+
+void util_format_compose_swizzles(const unsigned char swz1[4],
+                                  const unsigned char swz2[4],
+                                  unsigned char dst[4])
+{
+   unsigned i;
+
+   for (i = 0; i < 4; i++) {
+      dst[i] = swz2[i] <= UTIL_FORMAT_SWIZZLE_W ?
+               swz1[swz2[i]] : swz2[i];
+   }
+}
+
+void util_format_swizzle_4f(float *dst, const float *src,
+                            const unsigned char swz[4])
+{
+   unsigned i;
+
+   for (i = 0; i < 4; i++) {
+      if (swz[i] < UTIL_FORMAT_SWIZZLE_W)
+         dst[i] = src[swz[i]];
+      else if (swz[i] == UTIL_FORMAT_SWIZZLE_0)
+         dst[i] = 0;
+      else if (swz[i] == UTIL_FORMAT_SWIZZLE_1)
+         dst[i] = 1;
+   }
+}
+
+void util_format_unswizzle_4f(float *dst, const float *src,
+                              const unsigned char swz[4])
+{
+   unsigned i;
+
+   for (i = 0; i < 4; i++) {
+      switch (swz[i]) {
+      case UTIL_FORMAT_SWIZZLE_X:
+         dst[0] = src[i];
+         break;
+      case UTIL_FORMAT_SWIZZLE_Y:
+         dst[1] = src[i];
+         break;
+      case UTIL_FORMAT_SWIZZLE_Z:
+         dst[2] = src[i];
+         break;
+      case UTIL_FORMAT_SWIZZLE_W:
+         dst[3] = src[i];
+         break;
+      }
+   }
+}
diff --git a/src/gallium/auxiliary/util/u_format.h b/src/gallium/auxiliary/util/u_format.h
index bb3ed72e932..566fa79e781 100644
--- a/src/gallium/auxiliary/util/u_format.h
+++ b/src/gallium/auxiliary/util/u_format.h
@@ -815,6 +815,25 @@ util_format_translate(enum pipe_format dst_format,
                       unsigned src_x, unsigned src_y,
                       unsigned width, unsigned height);
 
+/*
+ * Swizzle operations.
+ */
+
+/* Compose two sets of swizzles.
+ * If V is a 4D vector and the function parameters represent functions that
+ * swizzle vector components, this holds:
+ *     swz2(swz1(V)) = dst(V)
+ */
+void util_format_compose_swizzles(const unsigned char swz1[4],
+                                  const unsigned char swz2[4],
+                                  unsigned char dst[4]);
+
+void util_format_swizzle_4f(float *dst, const float *src,
+                            const unsigned char swz[4]);
+
+void util_format_unswizzle_4f(float *dst, const float *src,
+                              const unsigned char swz[4]);
+
 #ifdef __cplusplus
 } // extern "C" {
 #endif