ZenLib
BitStream_Fast.h
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1/* Copyright (c) MediaArea.net SARL. All Rights Reserved.
2 *
3 * Use of this source code is governed by a zlib-style license that can
4 * be found in the License.txt file in the root of the source tree.
5 */
6
7//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
8//
9// Read a stream bit per bit
10// Can read up to 32 bits at once
11//
12//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
13
14//---------------------------------------------------------------------------
15#ifndef ZenBitStream_FastH
16#define ZenBitStream_FastH
17//---------------------------------------------------------------------------
18
19//---------------------------------------------------------------------------
20#include "ZenLib/Conf.h"
21//---------------------------------------------------------------------------
22
23namespace ZenLib
24{
25
26#ifndef MIN
27 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
28#endif
29
30class BitStream_Fast
31{
32public:
33 BitStream_Fast () {Buffer=NULL;
34 Buffer_Size=Buffer_Size_Init=0;
35 BufferUnderRun=false;}
36 BitStream_Fast (const int8u* Buffer_, size_t Size_) {Buffer=Buffer_;
37 Buffer_Size=Buffer_Size_Init=Size_*8; //Size is in bits
38 BufferUnderRun=false;}
39 ~BitStream_Fast () {}
40
41 void Attach(const int8u* Buffer_, size_t Size_)
42 {
43 Buffer=Buffer_;
44 Buffer_Size=Buffer_Size_Init=Size_*8; //Size is in bits
45 BufferUnderRun=false;
46 }
47
48 bool GetB ()
49 {
50 if (Buffer_Size%8)
51 {
52 Buffer_Size--;
53 return ((LastByte>>(Buffer_Size%8))&0x1)?true:false;
54 }
55
56 if (!Buffer_Size)
57 {
58 Buffer_Size=0;
59 BufferUnderRun=true;
60 return false;
61 }
62
63 LastByte=*Buffer;
64 Buffer++;
65 Buffer_Size--;
66 return (LastByte&0x80)?true:false;
67 }
68
69 int8u Get1 (int8u HowMany)
70 {
71 int8u ToReturn;
72 static const int8u Mask[9]=
73 {
74 0x00,
75 0x01, 0x03, 0x07, 0x0f,
76 0x1f, 0x3f, 0x7f, 0xff,
77 };
78
79 if (HowMany<=(Buffer_Size%8))
80 {
81 Buffer_Size-=HowMany;
82 return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
83 }
84
85 if (HowMany>Buffer_Size)
86 {
87 Buffer_Size=0;
88 BufferUnderRun=true;
89 return 0;
90 }
91
92 int8u NewBits=HowMany-(Buffer_Size%8);
93 if (NewBits==8)
94 ToReturn=0;
95 else
96 ToReturn=LastByte<<NewBits;
97 LastByte=*Buffer;
98 Buffer++;
99 Buffer_Size-=HowMany;
100 ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
101 return ToReturn&Mask[HowMany];
102 }
103
104 int16u Get2 (int8u HowMany)
105 {
106 int16u ToReturn;
107 static const int16u Mask[17]=
108 {
109 0x0000,
110 0x0001, 0x0003, 0x0007, 0x000f,
111 0x001f, 0x003f, 0x007f, 0x00ff,
112 0x01ff, 0x03ff, 0x07ff, 0x0fff,
113 0x1fff, 0x3fff, 0x7fff, 0xffff,
114 };
115
116 if (HowMany<=(Buffer_Size%8))
117 {
118 Buffer_Size-=HowMany;
119 return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
120 }
121
122 if (HowMany>Buffer_Size)
123 {
124 Buffer_Size=0;
125 BufferUnderRun=true;
126 return 0;
127 }
128
129 int8u NewBits=HowMany-(Buffer_Size%8);
130 if (NewBits==16)
131 ToReturn=0;
132 else
133 ToReturn=LastByte<<NewBits;
134 if ((NewBits-1)>>3)
135 {
136 NewBits-=8;
137 ToReturn|=*Buffer<<NewBits;
138 Buffer++;
139 }
140 LastByte=*Buffer;
141 Buffer++;
142 Buffer_Size-=HowMany;
143 ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
144 return ToReturn&Mask[HowMany];
145 }
146
147 int32u Get4 (int8u HowMany)
148 {
149 int32u ToReturn;
150 static const int32u Mask[33]=
151 {
152 0x00000000,
153 0x00000001, 0x00000003, 0x00000007, 0x0000000f,
154 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
155 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
156 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
157 0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
158 0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
159 0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
160 0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff,
161 };
162
163 if (HowMany<=(Buffer_Size%8))
164 {
165 Buffer_Size-=HowMany;
166 return (LastByte>>(Buffer_Size%8))&Mask[HowMany];
167 }
168
169 if (HowMany>Buffer_Size)
170 {
171 Buffer_Size=0;
172 BufferUnderRun=true;
173 return 0;
174 }
175
176 int8u NewBits=HowMany-(Buffer_Size%8);
177 if (NewBits==32)
178 ToReturn=0;
179 else
180 ToReturn=LastByte<<NewBits;
181 switch ((NewBits-1)>>3)
182 {
183 case 3 : NewBits-=8;
184 ToReturn|=*Buffer<<NewBits;
185 Buffer++;
186 case 2 : NewBits-=8;
187 ToReturn|=*Buffer<<NewBits;
188 Buffer++;
189 case 1 : NewBits-=8;
190 ToReturn|=*Buffer<<NewBits;
191 Buffer++;
192 default: ;
193 }
194 LastByte=*Buffer;
195 Buffer++;
196 Buffer_Size-=HowMany;
197 ToReturn|=(LastByte>>(Buffer_Size%8))&Mask[NewBits];
198 return ToReturn&Mask[HowMany];
199 }
200
201 int64u Get8 (int8u HowMany)
202 {
203 if (HowMany>64)
204 return 0; //Not supported
205 int8u HowMany1, HowMany2;
206 int64u Value1, Value2;
207 if (HowMany>32)
208 HowMany1=HowMany-32;
209 else
210 HowMany1=0;
211 HowMany2=HowMany-HowMany1;
212 Value1=Get4(HowMany1);
213 Value2=Get4(HowMany2);
214 if (BufferUnderRun)
215 return 0;
216 return Value1*0x100000000LL+Value2;
217 }
218
219 void Skip (size_t HowMany)
220 {
221 if (HowMany<=(Buffer_Size%8))
222 {
223 Buffer_Size-=HowMany;
224 return;
225 }
226
227 if (HowMany>Buffer_Size)
228 {
229 Buffer_Size=0;
230 BufferUnderRun=true;
231 return;
232 }
233
234 Buffer+=(HowMany-(Buffer_Size%8)-1)>>3;
235 LastByte=*Buffer;
236 Buffer++;
237 Buffer_Size-=HowMany;
238 }
239
240 bool PeekB()
241 {
242 if (Buffer_Size%8)
243 return ((LastByte>>((Buffer_Size-1)%8))&0x1)?true:false;
244
245 if (!Buffer_Size)
246 {
247 Buffer_Size=0;
248 BufferUnderRun=true;
249 return false;
250 }
251
252 return ((*Buffer)&0x80)?true:false;
253 }
254
255 int8u Peek1(int8u HowMany)
256 {
257 int8u ToReturn;
258 static const int8u Mask[9]=
259 {
260 0x00,
261 0x01, 0x03, 0x07, 0x0f,
262 0x1f, 0x3f, 0x7f, 0xff,
263 };
264
265 if (HowMany<=(Buffer_Size%8))
266 return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
267
268 if (HowMany>Buffer_Size)
269 {
270 Buffer_Size=0;
271 BufferUnderRun=true;
272 return 0;
273 }
274
275 int8u NewBits=HowMany-(Buffer_Size%8);
276 if (NewBits==8)
277 ToReturn=0;
278 else
279 ToReturn=LastByte<<NewBits;
280 ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
281
282 return ToReturn&Mask[HowMany];
283 }
284
285 int16u Peek2(int8u HowMany)
286 {
287 int16u ToReturn;
288 static const int16u Mask[17]=
289 {
290 0x0000,
291 0x0001, 0x0003, 0x0007, 0x000f,
292 0x001f, 0x003f, 0x007f, 0x00ff,
293 0x01ff, 0x03ff, 0x07ff, 0x0fff,
294 0x1fff, 0x3fff, 0x7fff, 0xffff,
295 };
296
297 if (HowMany<=(Buffer_Size%8))
298 return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
299
300 if (HowMany>Buffer_Size)
301 {
302 Buffer_Size=0;
303 BufferUnderRun=true;
304 return 0;
305 }
306
307 const int8u* Buffer_Save=Buffer;
308
309 int8u NewBits=HowMany-(Buffer_Size%8);
310 if (NewBits==16)
311 ToReturn=0;
312 else
313 ToReturn=LastByte<<NewBits;
314 if ((NewBits-1)>>3)
315 {
316 NewBits-=8;
317 ToReturn|=*Buffer<<NewBits;
318 Buffer++;
319 }
320 ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
321
322 Buffer=Buffer_Save;
323
324 return ToReturn&Mask[HowMany];
325 }
326
327 int32u Peek4(int8u HowMany)
328 {
329 int32u ToReturn;
330 static const int32u Mask[33]=
331 {
332 0x00000000,
333 0x00000001, 0x00000003, 0x00000007, 0x0000000f,
334 0x0000001f, 0x0000003f, 0x0000007f, 0x000000ff,
335 0x000001ff, 0x000003ff, 0x000007ff, 0x00000fff,
336 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff,
337 0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff,
338 0x001fffff, 0x003fffff, 0x007fffff, 0x00ffffff,
339 0x01ffffff, 0x03ffffff, 0x07ffffff, 0x0fffffff,
340 0x1fffffff, 0x3fffffff, 0x7fffffff, 0xffffffff,
341 };
342
343 if (HowMany<=(Buffer_Size%8))
344 return (LastByte>>((Buffer_Size-HowMany)%8))&Mask[HowMany];
345
346 if (HowMany>Buffer_Size)
347 {
348 Buffer_Size=0;
349 BufferUnderRun=true;
350 return 0;
351 }
352
353 const int8u* Buffer_Save=Buffer;
354
355 int8u NewBits=HowMany-(Buffer_Size%8);
356 if (NewBits==32)
357 ToReturn=0;
358 else
359 ToReturn=LastByte<<NewBits;
360 switch ((NewBits-1)>>3)
361 {
362 case 3 : NewBits-=8;
363 ToReturn|=*Buffer<<NewBits;
364 Buffer++;
365 case 2 : NewBits-=8;
366 ToReturn|=*Buffer<<NewBits;
367 Buffer++;
368 case 1 : NewBits-=8;
369 ToReturn|=*Buffer<<NewBits;
370 Buffer++;
371 default: ;
372 }
373 ToReturn|=((*Buffer)>>((Buffer_Size-HowMany)%8))&Mask[NewBits];
374
375 Buffer=Buffer_Save;
376
377 return ToReturn&Mask[HowMany];
378 }
379
380 int64u Peek8(int8u HowMany)
381 {
382 return (int64u)Peek4(HowMany); //Not yet implemented
383 }
384
385 inline size_t Remain () const //How many bits remain?
386 {
387 return Buffer_Size;
388 }
389
390 inline void Byte_Align()
391 {
392 Skip (Buffer_Size%8);
393 }
394
395 inline size_t Offset_Get() const
396 {
397 return (Buffer_Size_Init-Buffer_Size)/8;
398 }
399
400 inline size_t BitOffset_Get() const
401 {
402 return Buffer_Size%8;
403 }
404
405 inline size_t OffsetBeforeLastCall_Get() const //No more valid
406 {
407 return Buffer_Size%8;
408 }
409
410private :
411 const int8u* Buffer;
412 size_t Buffer_Size;
413 size_t Buffer_Size_Init;
414 int8u LastByte;
415public :
416 bool BufferUnderRun;
417};
418
419} //namespace ZenLib
420#endif
NULL
#define NULL
Definition: HTTPClientWrapper.h:93
ZenLib::BitStream_Fast
Definition: BitStream_Fast.h:31
ZenLib::BitStream_Fast::BitStream_Fast
BitStream_Fast(const int8u *Buffer_, size_t Size_)
Definition: BitStream_Fast.h:36
ZenLib::BitStream_Fast::Get8
int64u Get8(int8u HowMany)
Definition: BitStream_Fast.h:201
ZenLib::BitStream_Fast::Skip
void Skip(size_t HowMany)
Definition: BitStream_Fast.h:219
ZenLib::BitStream_Fast::Get4
int32u Get4(int8u HowMany)
Definition: BitStream_Fast.h:147
ZenLib::BitStream_Fast::GetB
bool GetB()
Definition: BitStream_Fast.h:48
ZenLib::BitStream_Fast::OffsetBeforeLastCall_Get
size_t OffsetBeforeLastCall_Get() const
Definition: BitStream_Fast.h:405
ZenLib::BitStream_Fast::Peek2
int16u Peek2(int8u HowMany)
Definition: BitStream_Fast.h:285
ZenLib::BitStream_Fast::BufferUnderRun
bool BufferUnderRun
Definition: BitStream_Fast.h:416
ZenLib::BitStream_Fast::BitOffset_Get
size_t BitOffset_Get() const
Definition: BitStream_Fast.h:400
ZenLib::BitStream_Fast::Peek1
int8u Peek1(int8u HowMany)
Definition: BitStream_Fast.h:255
ZenLib::BitStream_Fast::PeekB
bool PeekB()
Definition: BitStream_Fast.h:240
ZenLib::BitStream_Fast::~BitStream_Fast
~BitStream_Fast()
Definition: BitStream_Fast.h:39
ZenLib::BitStream_Fast::Offset_Get
size_t Offset_Get() const
Definition: BitStream_Fast.h:395
ZenLib::BitStream_Fast::Peek8
int64u Peek8(int8u HowMany)
Definition: BitStream_Fast.h:380
ZenLib::BitStream_Fast::Byte_Align
void Byte_Align()
Definition: BitStream_Fast.h:390
ZenLib::BitStream_Fast::Attach
void Attach(const int8u *Buffer_, size_t Size_)
Definition: BitStream_Fast.h:41
ZenLib::BitStream_Fast::Peek4
int32u Peek4(int8u HowMany)
Definition: BitStream_Fast.h:327
ZenLib::BitStream_Fast::Get2
int16u Get2(int8u HowMany)
Definition: BitStream_Fast.h:104
ZenLib::BitStream_Fast::BitStream_Fast
BitStream_Fast()
Definition: BitStream_Fast.h:33
ZenLib::BitStream_Fast::Remain
size_t Remain() const
Definition: BitStream_Fast.h:385
ZenLib::BitStream_Fast::Get1
int8u Get1(int8u HowMany)
Definition: BitStream_Fast.h:69
ZenLib
Definition: BitStream.h:24
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