[PATCH/RFC 1/3] video: fbdev: c2p: Add transp2() and transp2x()

[Geert Uytterhoeven <geert@linux-m68k.org>]

Add transpose operations on two 32-bit words, using normal or reverse
order.

To be used by the Atari DRM driver.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 drivers/video/fbdev/c2p_core.h | 38 ++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/video/fbdev/c2p_core.h b/drivers/video/fbdev/c2p_core.h
index cf5f1ebce65e6afd..480bd80fb31b57c0 100644
--- a/drivers/video/fbdev/c2p_core.h
+++ b/drivers/video/fbdev/c2p_core.h
@@ -142,6 +142,44 @@ static __always_inline void transp4x(u32 d[], unsigned int n, unsigned int m)
 }
 
 
+    /*
+     *  Transpose operations on 2 32-bit words
+     */
+
+static __always_inline void transp2(u32 d[], unsigned int n, unsigned int m)
+{
+	u32 mask = get_mask(n);
+
+	switch (m) {
+	case 1:
+		/* Single n x 1 block */
+		_transp(d, 0, 1, n, mask);
+		return;
+	}
+
+	BUILD_BUG();
+}
+
+
+    /*
+     *  Transpose operations on 2 32-bit words (reverse order)
+     */
+
+static __always_inline void transp2x(u32 d[], unsigned int n, unsigned int m)
+{
+	u32 mask = get_mask(n);
+
+	switch (m) {
+	case 1:
+		/* Single n x 1 block */
+		_transp(d, 1, 0, n, mask);
+		return;
+	}
+
+	BUILD_BUG();
+}
+
+
     /*
      *  Compose two values, using a bitmask as decision value
      *  This is equivalent to (a & mask) | (b & ~mask)
-- 
2.25.1