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78 lines
3.3 KiB
C
78 lines
3.3 KiB
C
/*
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* Copyright (c) 2016, Intel Corporation
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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 are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * 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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* * Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND 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 COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "ue2common.h"
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// check positive bytes in cmp_result.
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// return one if the check passed, zero otherwise.
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static really_inline
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int posValidateMask(const u64a cmp_result, const u64a pos_mask) {
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return !(cmp_result & pos_mask);
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}
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/*
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* check negative bytes in cmp_result.
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* return one if any byte in cmp_result is not 0, zero otherwise.
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* check lowest 7 bits and highest bit of every byte respectively.
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*/
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static really_inline
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int negValidateMask(const u64a cmp_result, const u64a neg_mask) {
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const u64a count_mask = 0x7f7f7f7f7f7f7f7f;
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// check lowest 7 bits of every byte.
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// the highest bit should be 1 if check passed.
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u64a check_low = (cmp_result & count_mask) + count_mask;
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// check the highest bit of every byte.
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// combine the highest bit and 0x7f to 0xff if check passes.
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// flip all 0xff to 0x00 and 0x7f to 0x80.
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u64a check_all = ~(check_low | cmp_result | count_mask);
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return !(check_all & neg_mask);
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}
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static really_inline
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int validateMask(u64a data, u64a valid_data_mask, u64a and_mask,
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u64a cmp_mask, u64a neg_mask) {
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// skip some byte where valid_data_mask is 0x00 there.
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and_mask &= valid_data_mask;
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cmp_mask &= valid_data_mask;
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neg_mask &= valid_data_mask;
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u64a cmp_result = (data & and_mask) ^ cmp_mask;
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/* do the positive check first since it's cheaper */
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if (posValidateMask(cmp_result, ~neg_mask)
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&& negValidateMask(cmp_result, neg_mask)) {
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return 1;
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} else {
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DEBUG_PRINTF("data %llx valid_data_mask(vdm) %llx\n",
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data, valid_data_mask);
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DEBUG_PRINTF("and_mask & vdm %llx cmp_mask & vdm %llx\n", and_mask,
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cmp_mask);
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DEBUG_PRINTF("cmp_result %llx neg_mask & vdm %llx\n",
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cmp_result, neg_mask);
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return 0;
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}
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}
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