Diff: util.c

Revision:

0:da10b9c9db7a

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util.c	Mon Jul 16 03:42:01 2012 +0000
@@ -0,0 +1,78 @@
+/**
+ *****************************************************************************
+ * File Name    : util.c
+ *
+ * Title        : Utility functions Source File
+ * Revision     : 0.1
+ * Notes        :
+ * Target Board : mbed NXP LPC1768
+ * Tool Chain   : ????
+ *
+ * Revision History:
+ * When         Who         Description of change
+ * -----------  ----------- -----------------------
+ * 2012/07/10   Hiroshi M   init
+ *****************************************************************************
+ *
+ * Copyright (C) 2012 Hiroshi M, MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
+ * and associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
+ * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **/
+
+/* Includes ----------------------------------------------------------------- */
+#include "util.h"
+
+/* Private typedef ---------------------------------------------------------- */
+/* Private define ----------------------------------------------------------- */
+/* Private macro ------------------------------------------------------------ */
+/* Private variables -------------------------------------------------------- */
+/* Private function prototypes -----------------------------------------------*/
+
+/**
+ * least squares method
+ *
+ */
+int lsm(int *y, int x)
+{
+    int n;
+    static long a0, a1, a2;
+    long s01 = 0, s02 = 0, s11 = 0, s12 = 0;
+
+    if (x == 0) {
+        for (n = 0; n < N; n++) {
+            s01 += n;
+            s02 += (long)y[n];
+            s11 += n * n;
+            s12 += n * (long)y[n];
+        }
+
+        a0 = (s02 * s11 - s01 * s12) / (N * s11 - s01 * s01);
+        a1 = (N * s12 - s01 * s02);
+        a2 = (N * s11 - s01 * s01 * 2);
+    }
+    return (int)(a0 + a1 * (N + x) / a2);
+}
+
+
+int xabs(int x,int y)
+{
+    if(x >= y) {
+        return (x - y);
+    } else {
+        return (y - x);
+    }
+}
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