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/*
* Copyright (c) 2015, Intel Corporation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/** \file
* \brief Reverse-acceleration optimizations for the NFA API block mode scans.
*/
#ifndef NFA_REV_API_H
#define NFA_REV_API_H
#include "accel.h"
#include "nfa_internal.h"
#include "vermicelli.h"
#include "util/unaligned.h"
static really_inline
size_t nfaRevAccel_i(const struct NFA *nfa, const u8 *buffer, size_t length) {
DEBUG_PRINTF("checking rev accel mw %u\n", nfa->minWidth);
assert(nfa->rAccelOffset >= 1);
assert(nfa->rAccelOffset <= nfa->minWidth);
const u8 *rv; // result for accel engine
switch (nfa->rAccelType) {
case ACCEL_RVERM:
DEBUG_PRINTF("ACCEL_RVERM\n");
if (length + 1 - nfa->rAccelOffset < 16) {
break;
}
rv = rvermicelliExec(nfa->rAccelData.c, 0, buffer,
buffer + length + 1 - nfa->rAccelOffset);
length = (size_t)(rv - buffer + nfa->rAccelOffset);
break;
case ACCEL_RVERM_NOCASE:
DEBUG_PRINTF("ACCEL_RVERM_NOCASE\n");
if (length + 1 - nfa->rAccelOffset < 16) {
break;
}
rv = rvermicelliExec(nfa->rAccelData.c, 1, buffer,
buffer + length + 1 - nfa->rAccelOffset);
length = (size_t)(rv - buffer + nfa->rAccelOffset);
break;
case ACCEL_RDVERM:
DEBUG_PRINTF("ACCEL_RDVERM\n");
if (length + 1 - nfa->rAccelOffset < 17) {
break;
}
rv = rvermicelliDoubleExec(nfa->rAccelData.array[0],
nfa->rAccelData.array[1], 0, buffer,
buffer + length + 1 - nfa->rAccelOffset);
length = (size_t)(rv - buffer + nfa->rAccelOffset);
break;
case ACCEL_RDVERM_NOCASE:
DEBUG_PRINTF("ACCEL_RVERM_NOCASE\n");
if (length + 1 - nfa->rAccelOffset < 17) {
break;
}
rv = rvermicelliDoubleExec(nfa->rAccelData.array[0],
nfa->rAccelData.array[1], 1, buffer,
buffer + length + 1 - nfa->rAccelOffset);
length = (size_t)(rv - buffer + nfa->rAccelOffset);
break;
case ACCEL_REOD:
DEBUG_PRINTF("ACCEL_REOD\n");
if (buffer[length - nfa->rAccelOffset] != nfa->rAccelData.c) {
return 0;
}
break;
case ACCEL_REOD_NOCASE:
DEBUG_PRINTF("ACCEL_REOD_NOCASE\n");
if ((buffer[length - nfa->rAccelOffset] & CASE_CLEAR) !=
nfa->rAccelData.c) {
return 0;
}
break;
case ACCEL_RDEOD:
DEBUG_PRINTF("ACCEL_RDEOD\n");
if (unaligned_load_u16(buffer + length - nfa->rAccelOffset) !=
nfa->rAccelData.dc) {
return 0;
}
break;
case ACCEL_RDEOD_NOCASE:
DEBUG_PRINTF("ACCEL_RDEOD_NOCASE\n");
if ((unaligned_load_u16(buffer + length - nfa->rAccelOffset) &
DOUBLE_CASE_CLEAR) != nfa->rAccelData.dc) {
return 0;
}
break;
default:
assert(!"not here");
}
if (nfa->minWidth > length) {
DEBUG_PRINTF("post-accel, scan skipped: %zu < min %u bytes\n", length,
nfa->minWidth);
return 0;
}
return length;
}
/** \brief Reverse acceleration check. Returns a new length for the block,
* guaranteeing that a match cannot occur beyond that point. */
static really_inline
size_t nfaRevAccelCheck(const struct NFA *nfa, const u8 *buffer,
size_t length) {
assert(nfa);
// If this block is not long enough to satisfy the minimum width
// constraint on this NFA, we can avoid the scan altogether.
if (nfa->minWidth > length) {
DEBUG_PRINTF("scan skipped: %zu < min %u bytes\n", length,
nfa->minWidth);
return 0;
}
if (nfa->rAccelType == ACCEL_NONE) {
DEBUG_PRINTF("no rev accel available\n");
return length;
}
size_t rv_length = nfaRevAccel_i(nfa, buffer, length);
assert(rv_length <= length);
return rv_length;
}
#endif
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