forked from Minki/linux
bcb63314e2
Drop the FSF's postal address from the source code files that typically
contain mostly the license text. Of the 628 removed instances, 578 are
outdated.
The patch has been created with the following command without manual edits:
git grep -l "675 Mass Ave\|59 Temple Place\|51 Franklin St" -- \
drivers/media/ include/media|while read i; do i=$i perl -e '
open(F,"< $ENV{i}");
$a=join("", <F>);
$a =~ s/[ \t]*\*\n.*You should.*\n.*along with.*\n.*(\n.*USA.*$)?\n//m
&& $a =~ s/(^.*)Or, (point your browser to) /$1To obtain the license, $2\n$1/m;
close(F);
open(F, "> $ENV{i}");
print F $a;
close(F);'; done
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
142 lines
5.1 KiB
C
142 lines
5.1 KiB
C
/*
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* dvb-math provides some complex fixed-point math
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* operations shared between the dvb related stuff
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*
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* Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com)
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*/
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#include <linux/bitops.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <asm/bug.h>
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#include "dvb_math.h"
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static const unsigned short logtable[256] = {
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0x0000, 0x0171, 0x02e0, 0x044e, 0x05ba, 0x0725, 0x088e, 0x09f7,
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0x0b5d, 0x0cc3, 0x0e27, 0x0f8a, 0x10eb, 0x124b, 0x13aa, 0x1508,
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0x1664, 0x17bf, 0x1919, 0x1a71, 0x1bc8, 0x1d1e, 0x1e73, 0x1fc6,
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0x2119, 0x226a, 0x23ba, 0x2508, 0x2656, 0x27a2, 0x28ed, 0x2a37,
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0x2b80, 0x2cc8, 0x2e0f, 0x2f54, 0x3098, 0x31dc, 0x331e, 0x345f,
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0x359f, 0x36de, 0x381b, 0x3958, 0x3a94, 0x3bce, 0x3d08, 0x3e41,
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0x3f78, 0x40af, 0x41e4, 0x4319, 0x444c, 0x457f, 0x46b0, 0x47e1,
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0x4910, 0x4a3f, 0x4b6c, 0x4c99, 0x4dc5, 0x4eef, 0x5019, 0x5142,
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0x526a, 0x5391, 0x54b7, 0x55dc, 0x5700, 0x5824, 0x5946, 0x5a68,
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0x5b89, 0x5ca8, 0x5dc7, 0x5ee5, 0x6003, 0x611f, 0x623a, 0x6355,
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0x646f, 0x6588, 0x66a0, 0x67b7, 0x68ce, 0x69e4, 0x6af8, 0x6c0c,
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0x6d20, 0x6e32, 0x6f44, 0x7055, 0x7165, 0x7274, 0x7383, 0x7490,
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0x759d, 0x76aa, 0x77b5, 0x78c0, 0x79ca, 0x7ad3, 0x7bdb, 0x7ce3,
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0x7dea, 0x7ef0, 0x7ff6, 0x80fb, 0x81ff, 0x8302, 0x8405, 0x8507,
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0x8608, 0x8709, 0x8809, 0x8908, 0x8a06, 0x8b04, 0x8c01, 0x8cfe,
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0x8dfa, 0x8ef5, 0x8fef, 0x90e9, 0x91e2, 0x92db, 0x93d2, 0x94ca,
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0x95c0, 0x96b6, 0x97ab, 0x98a0, 0x9994, 0x9a87, 0x9b7a, 0x9c6c,
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0x9d5e, 0x9e4f, 0x9f3f, 0xa02e, 0xa11e, 0xa20c, 0xa2fa, 0xa3e7,
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0xa4d4, 0xa5c0, 0xa6ab, 0xa796, 0xa881, 0xa96a, 0xaa53, 0xab3c,
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0xac24, 0xad0c, 0xadf2, 0xaed9, 0xafbe, 0xb0a4, 0xb188, 0xb26c,
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0xb350, 0xb433, 0xb515, 0xb5f7, 0xb6d9, 0xb7ba, 0xb89a, 0xb97a,
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0xba59, 0xbb38, 0xbc16, 0xbcf4, 0xbdd1, 0xbead, 0xbf8a, 0xc065,
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0xc140, 0xc21b, 0xc2f5, 0xc3cf, 0xc4a8, 0xc580, 0xc658, 0xc730,
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0xc807, 0xc8de, 0xc9b4, 0xca8a, 0xcb5f, 0xcc34, 0xcd08, 0xcddc,
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0xceaf, 0xcf82, 0xd054, 0xd126, 0xd1f7, 0xd2c8, 0xd399, 0xd469,
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0xd538, 0xd607, 0xd6d6, 0xd7a4, 0xd872, 0xd93f, 0xda0c, 0xdad9,
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0xdba5, 0xdc70, 0xdd3b, 0xde06, 0xded0, 0xdf9a, 0xe063, 0xe12c,
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0xe1f5, 0xe2bd, 0xe385, 0xe44c, 0xe513, 0xe5d9, 0xe69f, 0xe765,
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0xe82a, 0xe8ef, 0xe9b3, 0xea77, 0xeb3b, 0xebfe, 0xecc1, 0xed83,
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0xee45, 0xef06, 0xefc8, 0xf088, 0xf149, 0xf209, 0xf2c8, 0xf387,
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0xf446, 0xf505, 0xf5c3, 0xf680, 0xf73e, 0xf7fb, 0xf8b7, 0xf973,
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0xfa2f, 0xfaea, 0xfba5, 0xfc60, 0xfd1a, 0xfdd4, 0xfe8e, 0xff47
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};
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unsigned int intlog2(u32 value)
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{
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/**
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* returns: log2(value) * 2^24
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* wrong result if value = 0 (log2(0) is undefined)
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*/
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unsigned int msb;
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unsigned int logentry;
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unsigned int significand;
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unsigned int interpolation;
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if (unlikely(value == 0)) {
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WARN_ON(1);
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return 0;
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}
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/* first detect the msb (count begins at 0) */
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msb = fls(value) - 1;
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/**
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* now we use a logtable after the following method:
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*
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* log2(2^x * y) * 2^24 = x * 2^24 + log2(y) * 2^24
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* where x = msb and therefore 1 <= y < 2
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* first y is determined by shifting the value left
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* so that msb is bit 31
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* 0x00231f56 -> 0x8C7D5800
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* the result is y * 2^31 -> "significand"
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* then the highest 9 bits are used for a table lookup
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* the highest bit is discarded because it's always set
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* the highest nine bits in our example are 100011000
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* so we would use the entry 0x18
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*/
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significand = value << (31 - msb);
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logentry = (significand >> 23) & 0xff;
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/**
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* last step we do is interpolation because of the
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* limitations of the log table the error is that part of
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* the significand which isn't used for lookup then we
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* compute the ratio between the error and the next table entry
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* and interpolate it between the log table entry used and the
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* next one the biggest error possible is 0x7fffff
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* (in our example it's 0x7D5800)
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* needed value for next table entry is 0x800000
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* so the interpolation is
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* (error / 0x800000) * (logtable_next - logtable_current)
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* in the implementation the division is moved to the end for
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* better accuracy there is also an overflow correction if
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* logtable_next is 256
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*/
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interpolation = ((significand & 0x7fffff) *
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((logtable[(logentry + 1) & 0xff] -
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logtable[logentry]) & 0xffff)) >> 15;
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/* now we return the result */
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return ((msb << 24) + (logtable[logentry] << 8) + interpolation);
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}
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EXPORT_SYMBOL(intlog2);
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unsigned int intlog10(u32 value)
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{
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/**
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* returns: log10(value) * 2^24
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* wrong result if value = 0 (log10(0) is undefined)
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*/
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u64 log;
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if (unlikely(value == 0)) {
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WARN_ON(1);
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return 0;
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}
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log = intlog2(value);
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/**
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* we use the following method:
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* log10(x) = log2(x) * log10(2)
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*/
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return (log * 646456993) >> 31;
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}
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EXPORT_SYMBOL(intlog10);
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