142 lines
3.7 KiB
C
142 lines
3.7 KiB
C
/*
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* This file is part of the libpayload project.
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*
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* Copyright 2014 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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* 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-config.h>
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#include <stdlib.h>
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#ifndef CONFIG_LP_LITTLE_ENDIAN
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#error this code is for little endian only
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#endif
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union overlay64 {
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uint64_t longw;
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struct {
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uint32_t lower;
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uint32_t higher;
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} words;
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};
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uint64_t __ashldi3(uint64_t num, unsigned shift)
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{
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union overlay64 output;
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output.longw = num;
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if (shift >= 32) {
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output.words.higher = output.words.lower << (shift - 32);
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output.words.lower = 0;
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} else {
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if (!shift)
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return num;
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output.words.higher = (output.words.higher << shift) |
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(output.words.lower >> (32 - shift));
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output.words.lower = output.words.lower << shift;
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}
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return output.longw;
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}
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uint64_t __lshrdi3(uint64_t num, unsigned shift)
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{
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union overlay64 output;
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output.longw = num;
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if (shift >= 32) {
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output.words.lower = output.words.higher >> (shift - 32);
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output.words.higher = 0;
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} else {
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if (!shift)
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return num;
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output.words.lower = output.words.lower >> shift |
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(output.words.higher << (32 - shift));
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output.words.higher = output.words.higher >> shift;
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}
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return output.longw;
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}
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#define MAX_32BIT_UINT ((((uint64_t)1) << 32) - 1)
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static uint64_t _64bit_divide(uint64_t dividend,
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uint64_t divider, uint64_t *rem_p)
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{
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uint64_t result = 0;
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/*
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* If divider is zero - let the rest of the system care about the
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* exception.
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*/
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if (!divider)
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return 1/(uint32_t)divider;
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/* As an optimization, let's not use 64 bit division unless we must. */
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if (dividend <= MAX_32BIT_UINT) {
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if (divider > MAX_32BIT_UINT) {
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result = 0;
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if (rem_p)
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*rem_p = divider;
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} else {
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result = (uint32_t) dividend / (uint32_t) divider;
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if (rem_p)
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*rem_p = (uint32_t) dividend %
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(uint32_t) divider;
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}
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return result;
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}
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while (divider <= dividend) {
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uint64_t locald = divider;
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uint64_t limit = __lshrdi3(dividend, 1);
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int shifts = 0;
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while (locald <= limit) {
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shifts++;
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locald = locald + locald;
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}
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result |= __ashldi3(1, shifts);
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dividend -= locald;
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}
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if (rem_p)
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*rem_p = dividend;
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return result;
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}
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uint64_t __udivdi3(uint64_t num, uint64_t den)
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{
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return _64bit_divide(num, den, NULL);
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}
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uint64_t __umoddi3(uint64_t num, uint64_t den)
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{
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uint64_t v = 0;
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_64bit_divide(num, den, &v);
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return v;
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}
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