68 lines
2.3 KiB
C
68 lines
2.3 KiB
C
/*
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*
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* Copyright 2015 Google Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <libpayload.h>
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/*
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* Provide platform-independent backend implementation for __builtin_clz() in
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* <libpayload.h> in case GCC does not have an assembly version for this arch.
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*/
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int __clzsi2(u32 a);
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int __clzsi2(u32 a)
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{
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static const u8 four_bit_table[] = {
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[0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
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[0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
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[0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
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[0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
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};
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int r = 0;
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if (!(a & (0xffff << 16))) {
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r += 16;
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a <<= 16;
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}
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if (!(a & (0xff << 24))) {
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r += 8;
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a <<= 8;
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}
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if (!(a & (0xf << 28))) {
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r += 4;
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a <<= 4;
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}
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return r + four_bit_table[a >> 28];
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}
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