Module Name: src
Committed By: jmcneill
Date: Fri Jul 15 20:27:42 UTC 2011
Modified Files:
src/sys/dev/dtv: dtvif.h files.dtv
src/sys/modules/dtv: Makefile
Added Files:
src/sys/dev/dtv: dtv_math.c
Log Message:
add dtv_intlog10 implementation, from apb@
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/sys/dev/dtv/dtv_math.c
cvs rdiff -u -r1.1 -r1.2 src/sys/dev/dtv/dtvif.h
cvs rdiff -u -r1.2 -r1.3 src/sys/dev/dtv/files.dtv
cvs rdiff -u -r1.2 -r1.3 src/sys/modules/dtv/Makefile
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/dtv/dtvif.h
diff -u src/sys/dev/dtv/dtvif.h:1.1 src/sys/dev/dtv/dtvif.h:1.2
--- src/sys/dev/dtv/dtvif.h:1.1 Sat Jul 9 14:46:56 2011
+++ src/sys/dev/dtv/dtvif.h Fri Jul 15 20:27:42 2011
@@ -1,4 +1,4 @@
-/* $NetBSD: dtvif.h,v 1.1 2011/07/09 14:46:56 jmcneill Exp $ */
+/* $NetBSD: dtvif.h,v 1.2 2011/07/15 20:27:42 jmcneill Exp $ */
/*-
* Copyright (c) 2011 Jared D. McNeill <jmcne...@invisible.ca>
@@ -35,6 +35,8 @@
#ifndef _DEV_DTV_DTVIF_H
#define _DEV_DTV_DTVIF_H
+#include <sys/device.h>
+
#include <dev/dtv/dtvio.h>
#define DTV_DEVICE_FRONTEND 0
@@ -77,4 +79,7 @@
void dtv_submit_payload(device_t, const struct dtv_payload *);
+/* dtv_math.c */
+uint32_t dtv_intlog10(uint32_t);
+
#endif /* !_DEV_DTV_DTVIF_H */
Index: src/sys/dev/dtv/files.dtv
diff -u src/sys/dev/dtv/files.dtv:1.2 src/sys/dev/dtv/files.dtv:1.3
--- src/sys/dev/dtv/files.dtv:1.2 Wed Jul 13 22:43:04 2011
+++ src/sys/dev/dtv/files.dtv Fri Jul 15 20:27:42 2011
@@ -1,4 +1,4 @@
-# $NetBSD: files.dtv,v 1.2 2011/07/13 22:43:04 jmcneill Exp $
+# $NetBSD: files.dtv,v 1.3 2011/07/15 20:27:42 jmcneill Exp $
define dtvbus { }
@@ -8,4 +8,5 @@
file dev/dtv/dtv_demux.c dtv
file dev/dtv/dtv_device.c dtv
file dev/dtv/dtv_ioctl.c dtv
+file dev/dtv/dtv_math.c dtv
file dev/dtv/dtv_scatter.c dtv
Index: src/sys/modules/dtv/Makefile
diff -u src/sys/modules/dtv/Makefile:1.2 src/sys/modules/dtv/Makefile:1.3
--- src/sys/modules/dtv/Makefile:1.2 Wed Jul 13 22:43:33 2011
+++ src/sys/modules/dtv/Makefile Fri Jul 15 20:27:41 2011
@@ -1,4 +1,4 @@
-# $NetBSD: Makefile,v 1.2 2011/07/13 22:43:33 jmcneill Exp $
+# $NetBSD: Makefile,v 1.3 2011/07/15 20:27:41 jmcneill Exp $
.include "../Makefile.inc"
@@ -10,6 +10,7 @@
dtv_demux.c \
dtv_device.c \
dtv_ioctl.c \
+ dtv_math.c \
dtv_scatter.c
WARNS= 4
Added files:
Index: src/sys/dev/dtv/dtv_math.c
diff -u /dev/null src/sys/dev/dtv/dtv_math.c:1.1
--- /dev/null Fri Jul 15 20:27:42 2011
+++ src/sys/dev/dtv/dtv_math.c Fri Jul 15 20:27:42 2011
@@ -0,0 +1,75 @@
+/* $NetBSD: dtv_math.c,v 1.1 2011/07/15 20:27:42 jmcneill Exp $ */
+
+/*-
+ * Copyright (c) 2011 Alan Barrett <a...@netbsd.org>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+#include <sys/cdefs.h>
+__KERNEL_RCSID(0, "$NetBSD: dtv_math.c,v 1.1 2011/07/15 20:27:42 jmcneill Exp $");
+
+#include <sys/bitops.h>
+
+#include <dev/dtv/dtvif.h>
+
+
+#define LOG10_2_x24 5050445 /* floor(log10(2.0) * 2**24 */
+
+/*
+ * dtv_intlog10 -- return an approximation to log10(x) * 1<<24,
+ * using integer arithmetic.
+ *
+ * As a special case, returns 0 when x == 0.
+ *
+ * Results should be approximately as follows, bearing in
+ * mind that this function returns only an approximation
+ * to the exact results.
+ *
+ * dtv_intlog10(0) = 0 (special case; the mathematical value is undefined)
+ * dtv_intlog10(1) = 0
+ * dtv_intlog10(2) = 5050445 (approx 0.30102999 * 2**24)
+ * dtv_intlog10(10) = 16777216 (1.0 * 2**24)
+ * dtv_intlog10(100) = 33554432 (2.0 * 2**24)
+ * dtv_intlog10(1000) = 50331648 (3.0 * 2**24)
+ * dtv_intlog10(10000) = 67108864 (4.0 * 2**24)
+ * dtv_intlog10(100000) = 83886080 (5.0 * 2**24)
+ * dtv_intlog10(1000000) = 100663296 (6.0 * 2**24)
+ * dtv_intlog10(10000000) = 117440512 (7.0 * 2**24)
+ * dtv_intlog10(100000000) = 134217728 (8.0 * 2**24)
+ * dtv_intlog10(1000000000) = 150994944 (9.0 * 2**24)
+ * dtv_intlog10(4294967295) = 161614248 (approx 9.63295986 * 2**24)
+ */
+uint32_t
+dtv_intlog10(uint32_t x)
+{
+ if (__predict_false(x == 0))
+ return 0;
+ /*
+ * all we do is find log2(x), as an integer between 0 and 31,
+ * and scale it. Thus, there are only 32 values that this
+ * function will ever return. To do a better job, we would
+ * need a lookup table and interpolation.
+ */
+ return (uint32_t)(LOG10_2_x24) * (uint32_t)ilog2(x);
+}
