htcleo: add log function

arch/arm/mach-msm/Makefile

@@ -101,6 +101,7 @@ obj-$(CONFIG_MACH_BRAVOC) += board-bravoc-microp.o clock.o
 
 obj-$(CONFIG_MACH_HTCLEO) += board-htcleo.o board-htcleo-spi.o board-htcleo-panel.o board-htcleo-keypad.o
 obj-$(CONFIG_MACH_HTCLEO) += board-htcleo-ts.o board-htcleo-mmc.o ieee754-df.o
+obj-$(CONFIG_MACH_HTCLEO) += board-htcleo-log.o
 obj-$(CONFIG_MACH_HTCLEO) += clock-wince.o
 
 # MSM7x30 boards

arch/arm/mach-msm/board-htcleo-log.c

@@ -0,0 +1,121 @@
+/* arch/arm/mach-msm/board-htcleo-log.c
+*
+* Copyright (C) 2010 Cotulla
+* Copyright (C) Open Watcom Project
+*
+* This software is licensed under the terms of the GNU General Public
+* License version 2, as published by the Free Software Foundation, and
+* may be copied, distributed, and modified under those terms.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+*/
+#include <linux/module.h>
+#include <linux/param.h>
+#include <linux/jiffies.h>
+#include <linux/workqueue.h>
+#include <linux/kernel.h>
+
+
+
+#define sqrt_of_half    0.7071067811865475244
+#define C1              (355./512.)
+#define C2              (-2.121944400546905827679e-4)
+
+
+static const double     APoly[] =
+{
+    -0.78956112887491257267,
+     0.16383943563021534222e+2,
+    -0.64124943423745581147e+2
+};
+
+static const double     BPoly[] =
+{
+     1.0,
+    -0.35667977739034646171e+2,
+     0.31203222091924532844e+3,
+    -0.76949932108494879777e+3
+};
+
+static double _EvalPoly( double x, const double *poly, int degree )
+/********************************************************************/
+{
+    double  z;
+
+    z = *poly++;
+    do
+    {
+        z = z * x + *poly++;
+    } while( --degree != 0 );
+    return( z );
+}
+
+static double frexp( double value, int *exp )
+/**********************************************/
+{
+    int     n;
+    union
+    {
+        double          x;
+        unsigned short  a[4];
+    } u;
+
+    n = 0;
+    u.x = value;
+    if( value != 0.0 )
+    {
+        n = (u.a[3] & 0x7ff0) >> 4;
+        n -= 0x03fe;
+        u.a[3] &= 0x800f;
+        u.a[3] |= 0x3fe0;
+    }
+    *exp = n;
+    return( u.x );
+}
+
+
+double log(double x)
+/***********************************/
+{
+    int     exp;
+    double  z;
+
+    if( x <= 0.0 )
+    {
+	    BUG();
+        x = 0; // who cares? :)
+    }
+    else
+    {
+        x = frexp( x, &exp );
+        z = x - .5;
+        if( x > sqrt_of_half )
+        {
+            z -= .5;
+        }
+        else
+        {
+            x = z;
+            --exp;
+        }
+        z = z / (x * .5 + .5);
+        x = z * z;
+        x = z + z * x * _EvalPoly( x, APoly, 2 ) / _EvalPoly( x, BPoly, 3 );
+        if( exp != 0 )
+        {
+            z = exp;
+            x = (z * C2 + x) + z * C1;
+        }
+    }
+    return( x );
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Cotulla");
+MODULE_DESCRIPTION("htcleo log function");
+// END OF FILE