mirror of
https://github.com/tesseract-ocr/tesseract.git
synced 2024-12-15 17:49:29 +08:00
d11dc049e3
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@1015 d0cd1f9f-072b-0410-8dd7-cf729c803f20
144 lines
4.8 KiB
C++
144 lines
4.8 KiB
C++
// Copyright 2011 Google Inc. All Rights Reserved.
|
|
// Author: rays@google.com (Ray Smith)
|
|
///////////////////////////////////////////////////////////////////////
|
|
// File: bitvector.h
|
|
// Description: Class replacement for BITVECTOR.
|
|
// Author: Ray Smith
|
|
// Created: Mon Jan 10 17:44:01 PST 2011
|
|
//
|
|
// (C) Copyright 2011, Google Inc.
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
//
|
|
///////////////////////////////////////////////////////////////////////
|
|
|
|
|
|
#ifndef TESSERACT_CCUTIL_BITVECTOR_H__
|
|
#define TESSERACT_CCUTIL_BITVECTOR_H__
|
|
|
|
#include <assert.h>
|
|
#include <stdio.h>
|
|
#include "host.h"
|
|
|
|
namespace tesseract {
|
|
|
|
// Trivial class to encapsulate a fixed-length array of bits, with
|
|
// Serialize/DeSerialize. Replaces the old macros.
|
|
class BitVector {
|
|
public:
|
|
// Fast lookup table to get the first least significant set bit in a byte.
|
|
// For zero, the table has 255, but since it is a special case, most code
|
|
// that uses this table will check for zero before looking up lsb_index_.
|
|
static const uinT8 lsb_index_[256];
|
|
// Fast lookup table to get the residual bits after zeroing the least
|
|
// significant set bit in a byte.
|
|
static const uinT8 lsb_eroded_[256];
|
|
// Fast lookup table to give the number of set bits in a byte.
|
|
static const int hamming_table_[256];
|
|
|
|
BitVector();
|
|
// Initializes the array to length * false.
|
|
explicit BitVector(int length);
|
|
BitVector(const BitVector& src);
|
|
BitVector& operator=(const BitVector& src);
|
|
~BitVector();
|
|
|
|
// Initializes the array to length * false.
|
|
void Init(int length);
|
|
|
|
// Returns the number of bits that are accessible in the vector.
|
|
int size() const {
|
|
return bit_size_;
|
|
}
|
|
|
|
// Writes to the given file. Returns false in case of error.
|
|
bool Serialize(FILE* fp) const;
|
|
// Reads from the given file. Returns false in case of error.
|
|
// If swap is true, assumes a big/little-endian swap is needed.
|
|
bool DeSerialize(bool swap, FILE* fp);
|
|
|
|
void SetAllFalse();
|
|
void SetAllTrue();
|
|
|
|
// Accessors to set/reset/get bits.
|
|
// The range of index is [0, size()-1].
|
|
// There is debug-only bounds checking.
|
|
void SetBit(int index) {
|
|
array_[WordIndex(index)] |= BitMask(index);
|
|
}
|
|
void ResetBit(int index) {
|
|
array_[WordIndex(index)] &= ~BitMask(index);
|
|
}
|
|
void SetValue(int index, bool value) {
|
|
if (value)
|
|
SetBit(index);
|
|
else
|
|
ResetBit(index);
|
|
}
|
|
bool At(int index) const {
|
|
return (array_[WordIndex(index)] & BitMask(index)) != 0;
|
|
}
|
|
bool operator[](int index) const {
|
|
return (array_[WordIndex(index)] & BitMask(index)) != 0;
|
|
}
|
|
|
|
// Returns the index of the next set bit after the given index.
|
|
// Useful for quickly iterating through the set bits in a sparse vector.
|
|
int NextSetBit(int prev_bit) const;
|
|
|
|
// Returns the number of set bits in the vector.
|
|
int NumSetBits() const;
|
|
|
|
// Logical in-place operations on whole bit vectors. Tries to do something
|
|
// sensible if they aren't the same size, but they should be really.
|
|
void operator|=(const BitVector& other);
|
|
void operator&=(const BitVector& other);
|
|
void operator^=(const BitVector& other);
|
|
// Set subtraction *this = v1 - v2.
|
|
void SetSubtract(const BitVector& v1, const BitVector& v2);
|
|
|
|
private:
|
|
// Allocates memory for a vector of the given length.
|
|
void Alloc(int length);
|
|
|
|
// Computes the index to array_ for the given index, with debug range
|
|
// checking.
|
|
int WordIndex(int index) const {
|
|
assert(0 <= index && index < bit_size_);
|
|
return index / kBitFactor;
|
|
}
|
|
// Returns a mask to select the appropriate bit for the given index.
|
|
uinT32 BitMask(int index) const {
|
|
return 1 << (index & (kBitFactor - 1));
|
|
}
|
|
// Returns the number of array elements needed to represent the current
|
|
// bit_size_.
|
|
int WordLength() const {
|
|
return (bit_size_ + kBitFactor - 1) / kBitFactor;
|
|
}
|
|
// Returns the number of bytes consumed by the array_.
|
|
int ByteLength() const {
|
|
return WordLength() * sizeof(*array_);
|
|
}
|
|
|
|
// Number of bits in this BitVector.
|
|
inT32 bit_size_;
|
|
// Array of words used to pack the bits.
|
|
// Bits are stored little-endian by uinT32 word, ie by word first and then
|
|
// starting with the least significant bit in each word.
|
|
uinT32* array_;
|
|
// Number of bits in an array_ element.
|
|
static const int kBitFactor = sizeof(uinT32) * 8;
|
|
};
|
|
|
|
} // namespace tesseract.
|
|
|
|
#endif // TESSERACT_CCUTIL_BITVECTOR_H__
|