1 files changed, 103 insertions, 0 deletions
diff --git a/nuttx/graphics/nxglib/nxglib_rgb2yuv.c b/nuttx/graphics/nxglib/nxglib_rgb2yuv.c
new file mode 100644
index 000000000..c439c4fe0
--- /dev/null
+++ b/nuttx/graphics/nxglib/nxglib_rgb2yuv.c
@@ -0,0 +1,103 @@
+/****************************************************************************
+ * graphics/color/nxglib_rgb2yuv.c
+ *
+ *   Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <debug.h>
+#include <fixedmath.h>
+
+#include <nuttx/nx/nxglib.h>
+
+/****************************************************************************
+ * Pre-Processor Definitions
+ ****************************************************************************/
+
+#define b16_P0813 0x000014d0    /* 0.0813 */
+#define b16_P1140 0x00001d2f    /* 0.1140 */
+#define b16_P1687 0x00002b30    /* 0.1687 */
+#define b16_P2990 0x00004c8b    /* 0.2990 */
+#define b16_P3313 0x000054d0    /* 0.3313 */
+#define b16_P4187 0x00006b30    /* 0.4187 */
+#define b16_P5000 0x00008000    /* 0.5000 */
+#define b16_P5870 0x00009646    /* 0.5870 */
+#define b16_128P0 0x00800000    /* 128.0 */
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxgl_rgb2yuv
+ *
+ * Description:
+ *   Convert 8-bit RGB triplet to 8-bit YUV triplet
+ *
+ ****************************************************************************/
+
+void nxgl_rgb2yuv(uint8_t r, uint8_t g, uint8_t b,
+                  uint8_t *y, uint8_t *u, uint8_t *v)
+{
+  /* Per the JFIF specification:
+   *
+   * Y =       (0.2990 * R) + (0.5870 * G) + (0.1140 * B)
+   * U = 128 - (0.1687 * R) - (0.3313 * G) + (0.5000 * B)
+   * V = 128 + (0.5000 * R) - (0.4187 * G) - (0.0813 * B);
+   */
+
+  *y = (uint8_t)b16toi(b16muli(b16_P2990, r) + b16muli(b16_P5870, g) + b16muli(b16_P1140, b));
+  *u = (uint8_t)b16toi(b16_128P0 - b16muli(b16_P1687, r) - b16muli(b16_P3313, g) + b16muli(b16_P5000, b));
+  *v = (uint8_t)b16toi(b16_128P0 + b16muli(b16_P5000, r) - b16muli(b16_P4187, g) - b16muli(b16_P0813, b));
+}