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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.
*/
#ifndef REPEAT_INTERNAL_H
#define REPEAT_INTERNAL_H
#include "ue2common.h"
/** \file
* \brief Bounded Repeat models.
*
* Used by the NFA, to represent bounded repeats managed via special POS and
* TUG exceptions, and by the LBR (limited bounded repeat) and Castle
* specialist engines.
*
* We currently have a number of different kinds of bounded repeat model, for
* different kinds of {N,M} repeats, described by ::RepeatType.
*/
/** Different types of bounded repeats. */
enum RepeatType {
/** General mechanism for tracking {N,M} repeats. Stores the first top as
* an absolute offset, then subsequent tops in the {N,M} range as a ring of
* relative top indices stored in a multibit. */
REPEAT_RING,
/** Used to track {N,} repeats. Uses the \ref RepeatOffsetControl structure,
* since only the first top encountered needs to be stored. */
REPEAT_FIRST,
/** Used to track {0,N} repeats. Much like ::REPEAT_FIRST, except that we
* store the most recent top encountered. */
REPEAT_LAST,
/** Like ::REPEAT_RING, this is also used for {N,M} repeats, but for cases
* where there is a large difference between N and M, and developed to
* reduce the state requirements of this case (relative to the RING model).
* Uses a small ordered array of top indices relative to \ref
* RepeatRangeControl::offset. */
REPEAT_RANGE,
/** Used for {N,M} repeats where 0 < M <= 64. Uses the \ref
* RepeatBitmapControl structure at runtime. */
REPEAT_BITMAP,
/** Optimal mechanism for tracking {N,M} repeats when there is a bound on
* how frequently they can be retriggered.
* Assume f(repeat, min) representing the number of possible bit patterns
* we can have for repeat size = repeat, minimum period = min
* We will have the following recurrence relation:
* f(repeat, min) = f(repeat - 1, min) + f(repeat - min, min);
* We use this recurrence to encode bit patterns with 64-bit values by
* referencing a table that stores values from f(0, min) to f(repeat, min)
* eg: repeat = 5, min = 2. 10001 => f(4,2) + f(0,2) = 9.
* We search the optimal patch size between min and repeat in advance and
* use the scheme above to do encoding and decoding to reduce stream state
* size. */
REPEAT_SPARSE_OPTIMAL_P,
/** Used for {N,M} repeats where 0 < N < 64. Uses the
* \ref RepeatTrailerControl structure at runtime. */
REPEAT_TRAILER,
/** Degenerate repeat that always returns true. Used by castle for pseudo
* [^X]* repeats. */
REPEAT_ALWAYS,
};
/**
* \brief Value used to represent an unbounded max repeat.
*
* Note that we do not support \ref RepeatInfo::repeatMax values larger than
* this.
*/
#define REPEAT_INF 65535
/** Max slots used by ::REPEAT_RANGE repeat model. */
#define REPEAT_RANGE_MAX_SLOTS 16
/** Structure describing a bounded repeat in the bytecode */
struct RepeatInfo {
u8 type; //!< from enum RepeatType.
u32 repeatMin; //!< minimum number of repeats.
u32 repeatMax; //!< maximum number of repeats, or REPEAT_INF if unbounded.
/** Maximum value that is required to be stored in the control block
* counters. Any value greater than this will be capped at the horizon.
*/
u32 horizon;
/** Size of the compressed control block in bytes. This is what is written
* out to stream state at stream boundaries. */
u32 packedCtrlSize;
/** Size of the repeat state block in bytes. This is where the REPEAT_RANGE
* vector and REPEAT_RING multibit are stored, in stream state, and they
* are manipulated directly (i.e. not copied at stream boundaries). */
u32 stateSize;
/** How soon after one trigger we can see the next trigger.
* Used by REPEAT_SPARSE_OPTIMAL_P. */
u32 minPeriod;
/** Packed control block field sizes (in bits), used by REPEAT_TRAILER. */
u32 packedFieldSizes[2];
/* Number of patches, used by REPEAT_SPARSE_OPTIMAL_P. */
u32 patchCount;
/* Optimal patch length, used by REPEAT_SPARSE_OPTIMAL_P. */
u32 patchSize;
/* Encoding patch length in bytes, used by REPEAT_SPARSE_OPTIMAL_P. */
u32 encodingSize;
/* RepeatInfo struct length including table size. */
u32 length;
/** Offset of patches relative to the start of repeat stream state,
* used by REPEAT_SPARSE_OPTIMAL_P. */
u32 patchesOffset;
};
/** Runtime control block structure for ::REPEAT_RING and
* ::REPEAT_SPARSE_OPTIMAL_P bounded repeats. Note that this struct is packed
* (may not be aligned). */
struct RepeatRingControl {
u64a offset; //!< index of first top.
u16 first; //!< start index in ring.
u16 last; //!< end index in ring.
};
/** Runtime control block structure for ::REPEAT_RANGE bounded repeats. Note
* that this struct is packed (may not be aligned). */
struct RepeatRangeControl {
u64a offset; //!< index of first top.
u8 num; //!< number of elements in array.
};
/** Runtime control block structure for cases where only a single offset is
* needed to track the repeat, both ::REPEAT_FIRST and ::REPEAT_LAST. Note that
* this struct is packed (may not be aligned). */
struct RepeatOffsetControl {
u64a offset; //!< index of a top.
};
/** Runtime control block structure for ::REPEAT_BITMAP bounded repeats. */
struct RepeatBitmapControl {
u64a offset; //!< index of first top.
u64a bitmap; //!< forward bitmap of tops relative to base offset.
};
/** Runtime control block structure for ::REPEAT_TRAILER bounded repeats. */
struct RepeatTrailerControl {
u64a offset; //!< min extent of most recent match window.
u64a bitmap; //!< trailing bitmap of earlier matches, relative to offset.
};
/** \brief Union of control block types, used at runtime. */
union RepeatControl {
struct RepeatRingControl ring;
struct RepeatRangeControl range;
struct RepeatOffsetControl offset;
struct RepeatBitmapControl bitmap;
struct RepeatTrailerControl trailer;
};
/** For debugging, returns the name of a repeat model. */
static really_inline UNUSED
const char *repeatTypeName(u8 type) {
switch ((enum RepeatType)type) {
case REPEAT_RING:
return "RING";
case REPEAT_FIRST:
return "FIRST";
case REPEAT_LAST:
return "LAST";
case REPEAT_RANGE:
return "RANGE";
case REPEAT_BITMAP:
return "BITMAP";
case REPEAT_SPARSE_OPTIMAL_P:
return "SPARSE_OPTIMAL_P";
case REPEAT_TRAILER:
return "TRAILER";
case REPEAT_ALWAYS:
return "ALWAYS";
}
assert(0);
return "UNKNOWN";
}
#endif // REPEAT_INTERNAL_H
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