Add fixed precision sin() and cos()

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1342 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 110 insertions, 0 deletions

diff --git a/nuttx/lib/lib_b16sin.c b/nuttx/lib/lib_b16sin.c
new file mode 100644
index 000000000..7e2bcac56
--- /dev/null
+++ b/nuttx/lib/lib_b16sin.c
@@ -0,0 +1,110 @@
+/****************************************************************************
+ * lib/lib_b16sin.c
+ *
+ *   Copyright (C) 2008 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 <fixedmath.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#define b16_P225       0x0000399a
+#define b16_P405284735 0x000067c1
+#define b16_1P27323954 0x000145f3
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: b16sin
+ * Ref: http://lab.polygonal.de/2007/07/18/fast-and-accurate-sinecosine-approximation/
+ ****************************************************************************/
+
+b16_t b16sin(b16_t rad)
+{
+  b16_t tmp1;
+  b16_t tmp2;
+  b16_t tmp3;
+
+  /* Force angle into the good range */
+
+  if (rad < -b16PI)
+    {
+      rad += b16TWOPI;
+    }
+  else if (rad > b16PI)
+   {
+      rad -= b16TWOPI;
+   }
+
+  /* tmp1 = 1.27323954 * rad
+   * tmp2 = .405284735 * rad * rad
+   */
+
+
+  tmp1 = b16mulb16(b16_1P27323954, rad);
+  tmp2 = b16mulb16(b16_P405284735, b16sqr(rad));
+
+  if (rad < 0)
+    {
+       /* tmp3 = 1.27323954 * rad + .405284735 * rad * rad */
+
+       tmp3 = tmp1 + tmp2;
+    }
+  else
+    {
+       /* tmp3 = 1.27323954 * rad - 0.405284735 * rad * rad */
+
+       tmp3 = tmp1 - tmp2;
+    }
+
+  /* tmp1 = tmp3*tmp3 */
+
+  tmp1 = b16sqr(tmp3);
+  if (tmp3 < 0)
+    {
+      /* tmp1 = tmp3 * -tmp3 */
+
+      tmp1 = -tmp1;
+    }
+
+  /* Return sin = .225 * (tmp3 * (+/-tmp3) - tmp3) + tmp3 */
+
+  return b16mulb16(b16_P225, (tmp1 - tmp3)) + tmp3;
+}