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9051f6189c
changes. There is still debug crap in lar.c which will be pulled soon. Signed-off-by: Ronald G. Minnich <rminnich@gmail.com> Acked-by: Ronald G. Minnich <rminnich@gmail.com> Acked-by: Stefan Reinauer <stepan@coresystems.de> git-svn-id: svn://coreboot.org/repository/LinuxBIOSv3@75 f3766cd6-281f-0410-b1cd-43a5c92072e9
39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
/*
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* clog2 -- get a log2 in C.
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*
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*
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* Author(s) unknown, but this classic code was found by
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* Ronald G. Minnich somewhere.
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA, 02110-1301 USA
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*
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*/
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/* Assume 8 bits per byte */
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#define CHAR_BIT 8
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unsigned long log2(unsigned long x)
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{
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unsigned long i = 1ULL << (sizeof(x)* CHAR_BIT - 1ULL);
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unsigned long pow = sizeof(x) * CHAR_BIT - 1ULL;
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if (! x) {
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return -1;
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}
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for(; i > x; i >>= 1, pow--)
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;
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return pow;
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}
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