summaryrefslogtreecommitdiffstats
path: root/src/include/memory_chunk.h
blob: 3d9ea3559535fe4220fa8808c9bb461b064f1f5a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/* 
 *  libpinyin
 *  Library to deal with pinyin.
 *  
 *  Copyright (C) 2006-2007 Peng Wu
 *  
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 * 
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#ifndef MEMORY_CHUNK_H
#define MEMORY_CHUNK_H

#include <assert.h>
#include <unistd.h>
#include <stdlib.h>
#include "stl_lite.h"

/*  for unmanaged mode
 *  m_free_func == free , when memory is allocated by malloc
 *  m_free_func == NULL,
 *  when memory is in small protion of allocated area
 *  m_free_func == other,
 *  malloc then free.
 */

class MemoryChunk{
    typedef   void (* free_func_t)(void *);
private:
    char * m_data_begin;
    char * m_data_end; //one data pass the end.
    char * m_allocated; //one data pass the end.
    free_func_t m_free_func;
    
private:
    void reset(){
	if ( m_free_func )
	    (*m_free_func)(m_data_begin);
	m_data_begin = NULL;
	m_data_end = NULL;
	m_allocated = NULL;
	m_free_func = NULL;
    }
    
    void ensure_has_space(size_t new_size){
	int delta_size = m_data_begin + new_size - m_data_end;
	if ( delta_size <= 0 ) return;
	ensure_has_more_space ( delta_size );
    }
    
    /* enlarge function */
    void ensure_has_more_space(size_t extra_size){
	if ( 0 == extra_size ) return;
	size_t newsize;
	size_t cursize = size();
	if ( m_free_func != free ) {
	    /* copy on resize */
	    newsize = cursize + extra_size;
	    /* do the copy */
	    char * tmp = (char *) malloc(newsize);
	    assert(tmp);
	    memset(tmp, 0, newsize);
	    memmove(tmp, m_data_begin, cursize);
	    /* free the origin memory */
	    if ( m_free_func){
		(*m_free_func)(m_data_begin);
	    }
	    
	    /* change varibles */
	    m_data_begin = tmp;
	    m_data_end = m_data_begin + cursize;
	    m_allocated = m_data_begin + newsize;
	    m_free_func = free;
	    return;
	}
	/* the memory area is managed by this memory chunk */
	if ( extra_size <= (size_t) (m_allocated - m_data_end))
	    return;
	newsize = std_lite::max( capacity()<<1, cursize + extra_size);
	m_data_begin = (char *) realloc(m_data_begin, newsize);
	assert(m_data_begin);
	memset(m_data_begin + cursize, 0, newsize - cursize);
	m_data_end = m_data_begin + cursize;
	m_allocated = m_data_begin + newsize;
	return;
    }
    
public:
    /* constructors */
    MemoryChunk(){
	m_data_begin = NULL;
	m_data_end = NULL;
	m_allocated = NULL;
	m_free_func = NULL;
    }
    
    /* destructors */
    ~MemoryChunk(){
	reset();
    }

    /* read access method */
    void* begin() const{
	return m_data_begin;
    }
    
    void* end() const{
      return m_data_end;
    }

    size_t size() const{
	return m_data_end - m_data_begin;
    }
    
    void set_size(size_t newsize){
	ensure_has_space(newsize);
	m_data_end = m_data_begin + newsize;
    }
    
    size_t capacity(){
	return m_allocated - m_data_begin;
    }
  
    /* 
     *  Transfer management of a memory chunk allocated by other part system
     *  to the memory chunk.
     */
    void set_chunk(void* begin, size_t length, free_func_t free_func){
	if ( m_free_func )
	    m_free_func( m_data_begin );
	
	m_data_begin = (char *) begin;
	m_data_end = (char *) m_data_begin + length;
	m_allocated = (char *) m_data_begin + length;
	m_free_func = free_func;
    }
  
    /* subchunk
     * use set_buffer internally.
     * new chunk need to be deleted.
     */
    MemoryChunk * get_sub_chunk(size_t offset, size_t length){
	MemoryChunk * retval = new MemoryChunk();
	char * begin_pos = m_data_begin + offset;
	retval->set_chunk(begin_pos, length, NULL);
	return retval;
    }
    /* write function
     * Data are written directly to the memory area.
     */
    bool set_content(size_t offset, const void * data, size_t len){
	size_t cursize = std_lite::max(size(), offset + len);
	ensure_has_space(offset + len);
	memmove(m_data_begin + offset, data, len);
	m_data_end = m_data_begin + cursize;
	return true;
    }
    /* insert function
     * Data are written to the memory area,
     * the original content are moved towards the rear.
     * parameter offset start from zero.
     */
    bool insert_content(size_t offset, const void * data, size_t length){
	ensure_has_more_space(length);
	size_t move_size = size() - offset;
	memmove(m_data_begin + offset + length, m_data_begin + offset, move_size);
	memmove(m_data_begin + offset, data, length);
	m_data_end += length;
	return true;
    }
    /* remove function
     * Data are removed directly,
     * the following content are moved towards the front.
     */
    bool remove_content(size_t offset, size_t length){
	size_t move_size = size() - offset - length;
	memmove(m_data_begin + offset, m_data_begin + offset + length, move_size);
	m_data_end -= length;
	return true;
    }

    /* get_content function
     * Get the binary data
     */
    bool get_content(size_t offset, void * buffer, size_t length){
	if ( size() < offset + length )
	    return false;
	memcpy( buffer, m_data_begin + offset, length);
	return true;
    }

    /* compact memory, reduce the size */
    void compact_memory(){
	if ( m_free_func != free )
	    return;
	size_t newsize = size();
	m_data_begin = (char *) realloc(m_data_begin, newsize);
	m_allocated = m_data_begin + newsize;
    }
  
    /* file storage  functions */
    bool load(const char * filename){
	/* free old data */
	reset();

    size_t file_size;
	
	FILE* file = fopen(filename, "r");
	if ( !file )
	    return false;

    fseek(file, 0, SEEK_END);
    file_size = ftell(file);
    fseek(file, 0, SEEK_SET);

	int data_len = file_size;
	void* data = malloc(data_len);
	if ( !data ){
	    fclose(file);
	    return false;      
	}
	
	data_len = fread(data, 1, data_len, file);
	set_chunk(data, data_len, free);

	fclose(file);
	return true;
    }

    bool save(const char * filename){
	FILE* file = fopen(filename, "w");
	if ( !file )
	    return false;

	size_t data_len = fwrite(begin(), 1, size(), file);
	if ( data_len != size()){
	    fclose(file);
	    return false;
	}

	fsync(fileno(file));
	fclose(file);
	return true;
    }
};

#endif