[PATCH libdrm v2 03/10] util: Fix 16 bpp patterns on big-endian

[Geert Uytterhoeven]

DRM formats are defined to be little-endian, unless the
DRM_FORMAT_BIG_ENDIAN flag is set.  Hence writes of multi-byte pixel
values need to take endianness into account.

Introduce a swap16() helper to byteswap 16-bit values, and a
cpu_to_le16() helper to convert 16-bit values from CPU-endian to
little-endian, and use the latter in the various pattern fill functions
for 16-bit formats.

Signed-off-by: Geert Uytterhoeven <geert at linux-m68k.org>
---
Works now with both Linux' drm_fb_swab() and my own
drm_fb_rgb565_to_rgb332_line() (the latter uses le16_to_cpu() to read
pixel values from memory).

v2:
  - New.
---
 tests/util/pattern.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index 26e0614bd4faa620..c0bd382fbced90fb 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -61,6 +61,11 @@ struct color_yuv {
 	  .u = MAKE_YUV_601_U(r, g, b), \
 	  .v = MAKE_YUV_601_V(r, g, b) }
 
+static inline uint16_t swap16(uint16_t x)
+{
+	return ((x & 0x00ffU) << 8) | ((x & 0xff00U) >> 8);
+}
+
 static inline uint32_t swap32(uint32_t x)
 {
 	return ((x & 0x000000ffU) << 24) |
@@ -70,8 +75,10 @@ static inline uint32_t swap32(uint32_t x)
 }
 
 #if defined(__BIG_ENDIAN__) || defined(__ARM_BIG_ENDIAN) || defined(__mc68000__) || defined(__MIPSEB__) || defined(__s390__) || defined(__sparc__)
+#define cpu_to_le16(x)	swap16(x)
 #define cpu_to_le32(x)	swap32(x)
 #else
+#define cpu_to_le16(x)	(x)
 #define cpu_to_le32(x)	(x)
 #endif
 
@@ -410,26 +417,26 @@ static void fill_smpte_rgb16(const struct util_rgb_info *rgb, void *mem,
 
 	for (y = 0; y < height * 6 / 9; ++y) {
 		for (x = 0; x < width; ++x)
-			((uint16_t *)mem)[x] = colors_top[x * 7 / width];
+			((uint16_t *)mem)[x] = cpu_to_le16(colors_top[x * 7 / width]);
 		mem += stride;
 	}
 
 	for (; y < height * 7 / 9; ++y) {
 		for (x = 0; x < width; ++x)
-			((uint16_t *)mem)[x] = colors_middle[x * 7 / width];
+			((uint16_t *)mem)[x] = cpu_to_le16(colors_middle[x * 7 / width]);
 		mem += stride;
 	}
 
 	for (; y < height; ++y) {
 		for (x = 0; x < width * 5 / 7; ++x)
 			((uint16_t *)mem)[x] =
-				colors_bottom[x * 4 / (width * 5 / 7)];
+				cpu_to_le16(colors_bottom[x * 4 / (width * 5 / 7)]);
 		for (; x < width * 6 / 7; ++x)
 			((uint16_t *)mem)[x] =
-				colors_bottom[(x - width * 5 / 7) * 3
-					      / (width / 7) + 4];
+				cpu_to_le16(colors_bottom[(x - width * 5 / 7) * 3
+							  / (width / 7) + 4]);
 		for (; x < width; ++x)
-			((uint16_t *)mem)[x] = colors_bottom[7];
+			((uint16_t *)mem)[x] = cpu_to_le16(colors_bottom[7]);
 		mem += stride;
 	}
 }
@@ -1272,7 +1279,7 @@ static void fill_tiles_rgb16(const struct util_format_info *info, void *mem,
 					  (rgb32 >> 8) & 0xff, rgb32 & 0xff,
 					  255);
 
-			((uint16_t *)mem)[x] = color;
+			((uint16_t *)mem)[x] = cpu_to_le16(color);
 		}
 		mem += stride;
 	}
-- 
2.25.1