[PATCH v2 04/15] [media] cxd2880: Add math functions for the driver

[Yasunari.Takiguchi]

From: Yasunari Takiguchi <Yasunari.Takiguchi@xxxxxxxx>

Provide some math support functions (fixed-point log functions)
for the Sony CXD2880 DVB-T2/T tuner + demodulator driver.

Signed-off-by: Yasunari Takiguchi <Yasunari.Takiguchi@xxxxxxxx>
Signed-off-by: Masayuki Yamamoto <Masayuki.Yamamoto@xxxxxxxx>
Signed-off-by: Hideki Nozawa <Hideki.Nozawa@xxxxxxxx>
Signed-off-by: Kota Yonezawa <Kota.Yonezawa@xxxxxxxx>
Signed-off-by: Toshihiko Matsumoto <Toshihiko.Matsumoto@xxxxxxxx>
Signed-off-by: Satoshi Watanabe <Satoshi.C.Watanabe@xxxxxxxx>
---
 drivers/media/dvb-frontends/cxd2880/cxd2880_math.c | 89 ++++++++++++++++++++++
 drivers/media/dvb-frontends/cxd2880/cxd2880_math.h | 40 ++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 drivers/media/dvb-frontends/cxd2880/cxd2880_math.c
 create mode 100644 drivers/media/dvb-frontends/cxd2880/cxd2880_math.h

diff --git a/drivers/media/dvb-frontends/cxd2880/cxd2880_math.c b/drivers/media/dvb-frontends/cxd2880/cxd2880_math.c
new file mode 100644
index 000000000000..434c827898ff
--- /dev/null
+++ b/drivers/media/dvb-frontends/cxd2880/cxd2880_math.c
@@ -0,0 +1,89 @@
+/*
+ * cxd2880_math.c
+ * Sony CXD2880 DVB-T2/T tuner + demodulator driver
+ * mathmatics functions
+ *
+ * Copyright (C) 2016, 2017 Sony Semiconductor Solutions Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "cxd2880_math.h"
+
+#define MAX_BIT_PRECISION	  5
+#define FRAC_BITMASK	    0x1F
+#define LOG2_10_100X	     332
+#define LOG2_E_100X	      144
+
+static const u8 log2_look_up[] = {
+	0, 4,
+	9, 13,
+	17, 21,
+	25, 29,
+	32, 36,
+	39, 43,
+	46, 49,
+	52, 55,
+	58, 61,
+	64, 67,
+	70, 73,
+	75, 78,
+	81, 83,
+	86, 88,
+	91, 93,
+	95, 98
+};
+
+u32 cxd2880_math_log2(u32 x)
+{
+	u8 count = 0;
+	u8 index = 0;
+	u32 xval = x;
+
+	for (x >>= 1; x > 0; x >>= 1)
+		count++;
+
+	x = count * 100;
+
+	if (count > 0) {
+		if (count <= MAX_BIT_PRECISION) {
+			index =
+			    (u8)(xval << (MAX_BIT_PRECISION - count)) &
+			    FRAC_BITMASK;
+			x += log2_look_up[index];
+		} else {
+			index =
+			    (u8)(xval >> (count - MAX_BIT_PRECISION)) &
+			    FRAC_BITMASK;
+			x += log2_look_up[index];
+		}
+	}
+
+	return x;
+}
+
+u32 cxd2880_math_log10(u32 x)
+{
+	return ((100 * cxd2880_math_log2(x) + LOG2_10_100X / 2) / LOG2_10_100X);
+}
+
+u32 cxd2880_math_log(u32 x)
+{
+	return ((100 * cxd2880_math_log2(x) + LOG2_E_100X / 2) / LOG2_E_100X);
+}
diff --git a/drivers/media/dvb-frontends/cxd2880/cxd2880_math.h b/drivers/media/dvb-frontends/cxd2880/cxd2880_math.h
new file mode 100644
index 000000000000..94211835a4ad
--- /dev/null
+++ b/drivers/media/dvb-frontends/cxd2880/cxd2880_math.h
@@ -0,0 +1,40 @@
+/*
+ * cxd2880_math.h
+ * Sony CXD2880 DVB-T2/T tuner + demodulator driver
+ * mathmatics definitions
+ *
+ * Copyright (C) 2016, 2017 Sony Semiconductor Solutions Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; version 2 of the License.
+ *
+ * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef CXD2880_MATH_H_
+#define CXD2880_MATH_H_
+
+#include "cxd2880_common.h"
+
+u32 cxd2880_math_log2(u32 x);
+u32 cxd2880_math_log10(u32 x);
+u32 cxd2880_math_log(u32 x);
+
+#ifndef min
+#define min(a, b)	    (((a) < (b)) ? (a) : (b))
+#endif
+
+#endif
-- 
2.11.0