1 files changed, 58 insertions, 0 deletions
diff --git a/drivers/media/dvb/dvb-core/dvb_math.h b/drivers/media/dvb/dvb-core/dvb_math.h
new file mode 100644
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+++ b/drivers/media/dvb/dvb-core/dvb_math.h
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+/*
+ * dvb-math provides some complex fixed-point math
+ * operations shared between the dvb related stuff
+ *
+ * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com)
+ *
+ * This library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef __DVB_MATH_H
+#define __DVB_MATH_H
+
+#include <linux/types.h>
+
+/**
+ * computes log2 of a value; the result is shifted left by 24 bits
+ *
+ * to use rational values you can use the following method:
+ *   intlog2(value) = intlog2(value * 2^x) - x * 2^24
+ *
+ * example: intlog2(8) will give 3 << 24 = 3 * 2^24
+ * example: intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24
+ * example: intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24
+ *
+ * @param value The value (must be != 0)
+ * @return log2(value) * 2^24
+ */
+extern unsigned int intlog2(u32 value);
+
+/**
+ * computes log10 of a value; the result is shifted left by 24 bits
+ *
+ * to use rational values you can use the following method:
+ *   intlog10(value) = intlog10(value * 10^x) - x * 2^24
+ *
+ * example: intlog10(1000) will give 3 << 24 = 3 * 2^24
+ *   due to the implementation intlog10(1000) might be not exactly 3 * 2^24
+ *
+ * look at intlog2 for similar examples
+ *
+ * @param value The value (must be != 0)
+ * @return log10(value) * 2^24
+ */
+extern unsigned int intlog10(u32 value);
+
+#endif