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-rw-r--r-- | src/world/TerrainDecoder.cs | 683 |
1 files changed, 683 insertions, 0 deletions
diff --git a/src/world/TerrainDecoder.cs b/src/world/TerrainDecoder.cs new file mode 100644 index 0000000..0f1b733 --- /dev/null +++ b/src/world/TerrainDecoder.cs | |||
@@ -0,0 +1,683 @@ | |||
1 | /* | ||
2 | * Copyright (c) OpenSim project, http://sim.opensecondlife.org/ | ||
3 | * | ||
4 | * Redistribution and use in source and binary forms, with or without | ||
5 | * modification, are permitted provided that the following conditions are met: | ||
6 | * * Redistributions of source code must retain the above copyright | ||
7 | * notice, this list of conditions and the following disclaimer. | ||
8 | * * Redistributions in binary form must reproduce the above copyright | ||
9 | * notice, this list of conditions and the following disclaimer in the | ||
10 | * documentation and/or other materials provided with the distribution. | ||
11 | * * Neither the name of the <organization> nor the | ||
12 | * names of its contributors may be used to endorse or promote products | ||
13 | * derived from this software without specific prior written permission. | ||
14 | * | ||
15 | * THIS SOFTWARE IS PROVIDED BY <copyright holder> ``AS IS'' AND ANY | ||
16 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | ||
17 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | ||
18 | * DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY | ||
19 | * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | ||
20 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | ||
21 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND | ||
22 | * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | ||
24 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
25 | * | ||
26 | */ | ||
27 | |||
28 | using System; | ||
29 | using System.Collections.Generic; | ||
30 | //using libsecondlife; | ||
31 | using libsecondlife.Packets; | ||
32 | |||
33 | namespace OpenSim | ||
34 | { | ||
35 | /// <summary> | ||
36 | /// Description of TerrainDecoder. | ||
37 | /// </summary> | ||
38 | public class TerrainDecode | ||
39 | { | ||
40 | |||
41 | public enum LayerType : byte | ||
42 | { | ||
43 | Land = 0x4C, | ||
44 | Water = 0x57, | ||
45 | Wind = 0x37, | ||
46 | Cloud = 0x38 | ||
47 | } | ||
48 | |||
49 | public struct GroupHeader | ||
50 | { | ||
51 | public int Stride; | ||
52 | public int PatchSize; | ||
53 | public LayerType Type; | ||
54 | } | ||
55 | |||
56 | public struct PatchHeader | ||
57 | { | ||
58 | public float DCOffset; | ||
59 | public int Range; | ||
60 | public int QuantWBits; | ||
61 | public int PatchIDs; | ||
62 | public uint WordBits; | ||
63 | } | ||
64 | |||
65 | public class Patch | ||
66 | { | ||
67 | public float[] Heightmap; | ||
68 | } | ||
69 | |||
70 | |||
71 | /// <summary> | ||
72 | /// | ||
73 | /// </summary> | ||
74 | /// <param name="simulator"></param> | ||
75 | /// <param name="x"></param> | ||
76 | /// <param name="y"></param> | ||
77 | /// <param name="width"></param> | ||
78 | /// <param name="data"></param> | ||
79 | // public delegate void LandPatchCallback(Simulator simulator, int x, int y, int width, float[] data); | ||
80 | |||
81 | |||
82 | /// <summary> | ||
83 | /// | ||
84 | /// </summary> | ||
85 | //public event LandPatchCallback OnLandPatch; | ||
86 | |||
87 | private Random RandomClass = new Random(); | ||
88 | |||
89 | private const byte END_OF_PATCHES = 97; | ||
90 | private const int PATCHES_PER_EDGE = 16; | ||
91 | private const float OO_SQRT2 = 0.7071067811865475244008443621049f; | ||
92 | |||
93 | //private SecondLife Client; | ||
94 | private Dictionary<ulong, Patch[]> SimPatches = new Dictionary<ulong, Patch[]>(); | ||
95 | private float[] DequantizeTable16 = new float[16 * 16]; | ||
96 | private float[] DequantizeTable32 = new float[32 * 32]; | ||
97 | private float[] ICosineTable16 = new float[16 * 16]; | ||
98 | private float[] ICosineTable32 = new float[32 * 32]; | ||
99 | private int[] DeCopyMatrix16 = new int[16 * 16]; | ||
100 | private int[] DeCopyMatrix32 = new int[32 * 32]; | ||
101 | |||
102 | |||
103 | /// <summary> | ||
104 | /// | ||
105 | /// </summary> | ||
106 | /// <param name="client"></param> | ||
107 | public TerrainDecode() | ||
108 | { | ||
109 | |||
110 | // Initialize the decompression tables | ||
111 | BuildDequantizeTable16(); | ||
112 | BuildDequantizeTable32(); | ||
113 | SetupICosines16(); | ||
114 | SetupICosines32(); | ||
115 | BuildDecopyMatrix16(); | ||
116 | BuildDecopyMatrix32(); | ||
117 | |||
118 | } | ||
119 | |||
120 | |||
121 | private void BuildDequantizeTable16() | ||
122 | { | ||
123 | for (int j = 0; j < 16; j++) | ||
124 | { | ||
125 | for (int i = 0; i < 16; i++) | ||
126 | { | ||
127 | DequantizeTable16[j * 16 + i] = 1.0f + 2.0f * (float)(i + j); | ||
128 | } | ||
129 | } | ||
130 | } | ||
131 | |||
132 | private void BuildDequantizeTable32() | ||
133 | { | ||
134 | for (int j = 0; j < 32; j++) | ||
135 | { | ||
136 | for (int i = 0; i < 32; i++) | ||
137 | { | ||
138 | DequantizeTable32[j * 32 + i] = 1.0f + 2.0f * (float)(i + j); | ||
139 | } | ||
140 | } | ||
141 | } | ||
142 | |||
143 | private void SetupICosines16() | ||
144 | { | ||
145 | const float hposz = (float)Math.PI * 0.5f / 16.0f; | ||
146 | |||
147 | for (int u = 0; u < 16; u++) | ||
148 | { | ||
149 | for (int n = 0; n < 16; n++) | ||
150 | { | ||
151 | ICosineTable16[u * 16 + n] = (float)Math.Cos((2.0f * (float)n + 1.0f) * (float)u * hposz); | ||
152 | } | ||
153 | } | ||
154 | } | ||
155 | |||
156 | private void SetupICosines32() | ||
157 | { | ||
158 | const float hposz = (float)Math.PI * 0.5f / 32.0f; | ||
159 | |||
160 | for (int u = 0; u < 32; u++) | ||
161 | { | ||
162 | for (int n = 0; n < 32; n++) | ||
163 | { | ||
164 | ICosineTable32[u * 32 + n] = (float)Math.Cos((2.0f * (float)n + 1.0f) * (float)u * hposz); | ||
165 | } | ||
166 | } | ||
167 | } | ||
168 | |||
169 | private void BuildDecopyMatrix16() | ||
170 | { | ||
171 | bool diag = false; | ||
172 | bool right = true; | ||
173 | int i = 0; | ||
174 | int j = 0; | ||
175 | int count = 0; | ||
176 | |||
177 | while (i < 16 && j < 16) | ||
178 | { | ||
179 | DeCopyMatrix16[j * 16 + i] = count++; | ||
180 | |||
181 | if (!diag) | ||
182 | { | ||
183 | if (right) | ||
184 | { | ||
185 | if (i < 16 - 1) i++; | ||
186 | else j++; | ||
187 | |||
188 | right = false; | ||
189 | diag = true; | ||
190 | } | ||
191 | else | ||
192 | { | ||
193 | if (j < 16 - 1) j++; | ||
194 | else i++; | ||
195 | |||
196 | right = true; | ||
197 | diag = true; | ||
198 | } | ||
199 | } | ||
200 | else | ||
201 | { | ||
202 | if (right) | ||
203 | { | ||
204 | i++; | ||
205 | j--; | ||
206 | if (i == 16 - 1 || j == 0) diag = false; | ||
207 | } | ||
208 | else | ||
209 | { | ||
210 | i--; | ||
211 | j++; | ||
212 | if (j == 16 - 1 || i == 0) diag = false; | ||
213 | } | ||
214 | } | ||
215 | } | ||
216 | } | ||
217 | |||
218 | private void BuildDecopyMatrix32() | ||
219 | { | ||
220 | bool diag = false; | ||
221 | bool right = true; | ||
222 | int i = 0; | ||
223 | int j = 0; | ||
224 | int count = 0; | ||
225 | |||
226 | while (i < 32 && j < 32) | ||
227 | { | ||
228 | DeCopyMatrix32[j * 32 + i] = count++; | ||
229 | |||
230 | if (!diag) | ||
231 | { | ||
232 | if (right) | ||
233 | { | ||
234 | if (i < 32 - 1) i++; | ||
235 | else j++; | ||
236 | |||
237 | right = false; | ||
238 | diag = true; | ||
239 | } | ||
240 | else | ||
241 | { | ||
242 | if (j < 32 - 1) j++; | ||
243 | else i++; | ||
244 | |||
245 | right = true; | ||
246 | diag = true; | ||
247 | } | ||
248 | } | ||
249 | else | ||
250 | { | ||
251 | if (right) | ||
252 | { | ||
253 | i++; | ||
254 | j--; | ||
255 | if (i == 32 - 1 || j == 0) diag = false; | ||
256 | } | ||
257 | else | ||
258 | { | ||
259 | i--; | ||
260 | j++; | ||
261 | if (j == 32 - 1 || i == 0) diag = false; | ||
262 | } | ||
263 | } | ||
264 | } | ||
265 | } | ||
266 | |||
267 | private void EncodePatchHeader(BitPacker bitpack, PatchHeader header) | ||
268 | { | ||
269 | bitpack.PackBits(header.QuantWBits,8); | ||
270 | |||
271 | if (header.QuantWBits == END_OF_PATCHES) | ||
272 | return; | ||
273 | |||
274 | bitpack.PackFloat(header.DCOffset); | ||
275 | bitpack.PackBits(header.Range,16); | ||
276 | bitpack.PackBits(header.PatchIDs,10); | ||
277 | |||
278 | } | ||
279 | |||
280 | public void DCTLine16(float[] In, float[] Out, int line) | ||
281 | { | ||
282 | int N =16; | ||
283 | int lineSize = line * 16; | ||
284 | |||
285 | for(int k = 0; k < N;k++) | ||
286 | { | ||
287 | float sum = 0.0f; | ||
288 | for(int n = 0; n < N; n++) | ||
289 | { | ||
290 | float num = (float)(Math.PI*k*(2.0f*n+1)/(2*N)); | ||
291 | float cosine = (float)Math.Cos(num); | ||
292 | float product = In[lineSize +n] * cosine; | ||
293 | sum += product; | ||
294 | } | ||
295 | |||
296 | float alpha; | ||
297 | if(k == 0) | ||
298 | { | ||
299 | alpha = (float)(1.0f/Math.Sqrt(2)); | ||
300 | } | ||
301 | else | ||
302 | { | ||
303 | alpha = 1; | ||
304 | } | ||
305 | Out[lineSize + k] =(float)( sum * alpha ); | ||
306 | |||
307 | } | ||
308 | } | ||
309 | public void DCTColumn16(float[] In, float[] Out, int Column) | ||
310 | { | ||
311 | int N =16; | ||
312 | int uSize; | ||
313 | |||
314 | for(int k = 0; k < N; k++){ | ||
315 | float sum = 0.0f; | ||
316 | for(int n = 0; n < N; n++) | ||
317 | { | ||
318 | uSize = n * 16; | ||
319 | float num = (float)(Math.PI*k*(2.0f*n+1)/(2*N)); | ||
320 | float cosine = (float)Math.Cos(num); | ||
321 | float product = In[uSize + Column] * cosine; | ||
322 | sum += product; | ||
323 | } | ||
324 | |||
325 | float alpha; | ||
326 | if(k == 0) | ||
327 | { | ||
328 | alpha = (float)(1.0f/Math.Sqrt(2)); | ||
329 | } | ||
330 | else | ||
331 | { | ||
332 | alpha = 1; | ||
333 | } | ||
334 | Out[16 * k + Column] = (float)( sum * alpha * (2.0f /N)); | ||
335 | |||
336 | } | ||
337 | } | ||
338 | |||
339 | private void EncodePatch(int[] patches, BitPacker bitpack, int size) | ||
340 | { | ||
341 | int lastnum =0; | ||
342 | for(int n = 0; n < size * size; n++) | ||
343 | { | ||
344 | if(patches[n]!=0) | ||
345 | lastnum=n; | ||
346 | } | ||
347 | for (int n = 0; n < lastnum+1; n++) | ||
348 | { | ||
349 | if(patches[n] != 0) | ||
350 | { | ||
351 | bitpack.PackBits(1,1); //value or EOB | ||
352 | bitpack.PackBits(1,1); //value | ||
353 | if(patches[n] > 0) | ||
354 | { | ||
355 | |||
356 | bitpack.PackBits(0,1); // positive | ||
357 | bitpack.PackBits(patches[n],13); | ||
358 | |||
359 | } | ||
360 | else | ||
361 | { | ||
362 | bitpack.PackBits(1,1); // negative | ||
363 | |||
364 | int temp = patches[n] * -1; | ||
365 | bitpack.PackBits(temp,13); | ||
366 | |||
367 | } | ||
368 | } | ||
369 | else | ||
370 | { | ||
371 | bitpack.PackBits(0,1); // no value | ||
372 | } | ||
373 | } | ||
374 | |||
375 | bitpack.PackBits(1,1); //value or EOB | ||
376 | bitpack.PackBits(0,1); // EOB | ||
377 | } | ||
378 | |||
379 | public int[] CompressPatch(float[] patches) | ||
380 | { | ||
381 | int size = 16; | ||
382 | float[] block = new float[size * size]; | ||
383 | int[] output = new int[size * size]; | ||
384 | int prequant = (139 >> 4) + 2; | ||
385 | int quantize = 1 << prequant; | ||
386 | float ooq = 1.0f / (float)quantize; | ||
387 | float mult = ooq * (float)1; | ||
388 | float addval = mult * (float)(1 << (prequant - 1)) + 20.4989f; | ||
389 | |||
390 | if (size == 16) | ||
391 | { | ||
392 | for (int n = 0; n < 16 * 16; n++) | ||
393 | { | ||
394 | block[n] = (float)((patches[n] - addval)/ mult); | ||
395 | } | ||
396 | |||
397 | float[] ftemp = new float[32 * 32]; | ||
398 | |||
399 | for (int o = 0; o < 16; o++) | ||
400 | this.DCTColumn16(block, ftemp, o); | ||
401 | for (int o = 0; o < 16; o++) | ||
402 | this.DCTLine16(ftemp, block, o); | ||
403 | } | ||
404 | |||
405 | for (int j = 0; j < block.Length; j++) | ||
406 | { | ||
407 | output[DeCopyMatrix16[j]] = (int)(block[j] / DequantizeTable16[j]); | ||
408 | } | ||
409 | |||
410 | return output; | ||
411 | } | ||
412 | |||
413 | public Packet CreateLayerPacket(float[] heightmap, int minX, int maxX, int minY, int maxY) | ||
414 | { | ||
415 | //int minX = 0, maxX = 2, minY = 0, maxY = 1; //these should be passed to this function | ||
416 | LayerDataPacket layer = new LayerDataPacket(); | ||
417 | byte[] Encoded = new byte[2048]; | ||
418 | layer.LayerID.Type = 76; | ||
419 | GroupHeader header = new GroupHeader(); | ||
420 | header.Stride = 264; | ||
421 | header.PatchSize = 16; | ||
422 | header.Type = LayerType.Land; | ||
423 | BitPacker newpack = new BitPacker(Encoded,0); | ||
424 | newpack.PackBits(header.Stride,16); | ||
425 | newpack.PackBits(header.PatchSize,8); | ||
426 | newpack.PackBits((int)header.Type,8); | ||
427 | |||
428 | |||
429 | float[] height; | ||
430 | for(int y = minY; y< maxY; y++) | ||
431 | { | ||
432 | for(int x = minX ; x < maxX ; x++) | ||
433 | { | ||
434 | height = new float[256]; | ||
435 | Array.Copy(heightmap, (4096 *y) +(x *256), height, 0, 256); | ||
436 | |||
437 | this.CreatePatch(height, newpack, x, y); | ||
438 | } | ||
439 | } | ||
440 | |||
441 | PatchHeader headers = new PatchHeader(); | ||
442 | headers.QuantWBits = END_OF_PATCHES; | ||
443 | this.EncodePatchHeader(newpack, headers); | ||
444 | |||
445 | int lastused=0; | ||
446 | for(int i = 0; i < 1024 ; i++) | ||
447 | { | ||
448 | if(Encoded[i] !=0) | ||
449 | lastused = i; | ||
450 | } | ||
451 | |||
452 | byte[] data = new byte[lastused+1]; | ||
453 | Array.Copy(Encoded, data, lastused+1); | ||
454 | layer.LayerData.Data =data; | ||
455 | |||
456 | return(layer); | ||
457 | } | ||
458 | public void CreatePatch(float[] heightmap, BitPacker newpack, int x, int y) | ||
459 | { | ||
460 | PatchHeader header = new PatchHeader(); | ||
461 | header.DCOffset = 20.4989f; | ||
462 | header.QuantWBits = 139; | ||
463 | header.Range = 1; | ||
464 | header.PatchIDs = (y & 0x1F); | ||
465 | header.PatchIDs += x <<5 ; | ||
466 | |||
467 | this.EncodePatchHeader(newpack, header); | ||
468 | |||
469 | int[] newpatch = this.CompressPatch(heightmap); | ||
470 | this.EncodePatch(newpatch, newpack, 16); | ||
471 | |||
472 | } | ||
473 | } | ||
474 | |||
475 | //*************************************************** | ||
476 | public class BitPacker | ||
477 | { | ||
478 | private const int MAX_BITS = 8; | ||
479 | |||
480 | private byte[] Data; | ||
481 | public int bytePos; | ||
482 | public int bitPos; | ||
483 | |||
484 | /// <summary> | ||
485 | /// Default constructor, initialize the bit packer / bit unpacker | ||
486 | /// with a byte array and starting position | ||
487 | /// </summary> | ||
488 | /// <param name="data">Byte array to pack bits in to or unpack from</param> | ||
489 | /// <param name="pos">Starting position in the byte array</param> | ||
490 | public BitPacker(byte[] data, int pos) | ||
491 | { | ||
492 | Data = data; | ||
493 | bytePos = pos; | ||
494 | } | ||
495 | |||
496 | /// <summary> | ||
497 | /// Pack a floating point value in to the data | ||
498 | /// </summary> | ||
499 | /// <param name="data">Floating point value to pack</param> | ||
500 | public void PackFloat(float data) | ||
501 | { | ||
502 | byte[] input = BitConverter.GetBytes(data); | ||
503 | PackBitArray(input, 32); | ||
504 | } | ||
505 | |||
506 | /// <summary> | ||
507 | /// Pack part or all of an integer in to the data | ||
508 | /// </summary> | ||
509 | /// <param name="data">Integer containing the data to pack</param> | ||
510 | /// <param name="totalCount">Number of bits of the integer to pack</param> | ||
511 | public void PackBits(int data, int totalCount) | ||
512 | { | ||
513 | byte[] input = BitConverter.GetBytes(data); | ||
514 | PackBitArray(input, totalCount); | ||
515 | } | ||
516 | |||
517 | /// <summary> | ||
518 | /// Unpacking a floating point value from the data | ||
519 | /// </summary> | ||
520 | /// <returns>Unpacked floating point value</returns> | ||
521 | public float UnpackFloat() | ||
522 | { | ||
523 | byte[] output = UnpackBitsArray(32); | ||
524 | |||
525 | if (!BitConverter.IsLittleEndian) Array.Reverse(output); | ||
526 | return BitConverter.ToSingle(output, 0); | ||
527 | } | ||
528 | |||
529 | /// <summary> | ||
530 | /// Unpack a variable number of bits from the data in to integer format | ||
531 | /// </summary> | ||
532 | /// <param name="totalCount">Number of bits to unpack</param> | ||
533 | /// <returns>An integer containing the unpacked bits</returns> | ||
534 | /// <remarks>This function is only useful up to 32 bits</remarks> | ||
535 | public int UnpackBits(int totalCount) | ||
536 | { | ||
537 | byte[] output = UnpackBitsArray(totalCount); | ||
538 | |||
539 | if (!BitConverter.IsLittleEndian) Array.Reverse(output); | ||
540 | return BitConverter.ToInt32(output, 0); | ||
541 | } | ||
542 | |||
543 | private void PackBitArray(byte[] data, int totalCount) | ||
544 | { | ||
545 | int count = 0; | ||
546 | int curBytePos = 0; | ||
547 | int curBitPos = 0; | ||
548 | |||
549 | while (totalCount > 0) | ||
550 | { | ||
551 | if (totalCount > (MAX_BITS )) | ||
552 | { | ||
553 | count = MAX_BITS ; | ||
554 | totalCount -= MAX_BITS ; | ||
555 | } | ||
556 | else | ||
557 | { | ||
558 | count = totalCount; | ||
559 | totalCount = 0; | ||
560 | } | ||
561 | |||
562 | while (count > 0) | ||
563 | { | ||
564 | switch(count) | ||
565 | { | ||
566 | case 1: | ||
567 | if ((data[curBytePos] & (0x01)) != 0) | ||
568 | { | ||
569 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
570 | } | ||
571 | break; | ||
572 | case 2: | ||
573 | if ((data[curBytePos] & (0x02)) != 0) | ||
574 | { | ||
575 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
576 | } | ||
577 | break; | ||
578 | case 3: | ||
579 | if ((data[curBytePos] & (0x04)) != 0) | ||
580 | { | ||
581 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
582 | } | ||
583 | break; | ||
584 | case 4: | ||
585 | if ((data[curBytePos] & (0x08)) != 0) | ||
586 | { | ||
587 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
588 | } | ||
589 | break; | ||
590 | case 5: | ||
591 | if ((data[curBytePos] & (0x10)) != 0) | ||
592 | { | ||
593 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
594 | } | ||
595 | break; | ||
596 | case 6: | ||
597 | if ((data[curBytePos] & (0x20)) != 0) | ||
598 | { | ||
599 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
600 | } | ||
601 | break; | ||
602 | case 7: | ||
603 | if ((data[curBytePos] & (0x40)) != 0) | ||
604 | { | ||
605 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
606 | } | ||
607 | break; | ||
608 | case 8: | ||
609 | if ((data[curBytePos] & (0x80)) != 0) | ||
610 | { | ||
611 | Data[bytePos] |= (byte)(0x80 >> bitPos); | ||
612 | } | ||
613 | break; | ||
614 | } | ||
615 | |||
616 | bitPos++; | ||
617 | --count; | ||
618 | ++curBitPos; | ||
619 | |||
620 | if (bitPos >= MAX_BITS) | ||
621 | { | ||
622 | bitPos = 0; | ||
623 | ++bytePos; | ||
624 | } | ||
625 | if (curBitPos >= MAX_BITS) | ||
626 | { | ||
627 | curBitPos = 0; | ||
628 | ++curBytePos; | ||
629 | } | ||
630 | } | ||
631 | } | ||
632 | } | ||
633 | |||
634 | |||
635 | private byte[] UnpackBitsArray(int totalCount) | ||
636 | { | ||
637 | int count = 0; | ||
638 | byte[] output = new byte[4]; | ||
639 | int curBytePos = 0; | ||
640 | int curBitPos = 0; | ||
641 | |||
642 | while (totalCount > 0) | ||
643 | { | ||
644 | if (totalCount > MAX_BITS) | ||
645 | { | ||
646 | count = MAX_BITS; | ||
647 | totalCount -= MAX_BITS; | ||
648 | } | ||
649 | else | ||
650 | { | ||
651 | count = totalCount; | ||
652 | totalCount = 0; | ||
653 | } | ||
654 | |||
655 | while (count > 0) | ||
656 | { | ||
657 | // Shift the previous bits | ||
658 | output[curBytePos] <<= 1; | ||
659 | |||
660 | // Grab one bit | ||
661 | if ((Data[bytePos] & (0x80 >> bitPos++)) != 0) | ||
662 | ++output[curBytePos]; | ||
663 | |||
664 | --count; | ||
665 | ++curBitPos; | ||
666 | |||
667 | if (bitPos >= MAX_BITS) | ||
668 | { | ||
669 | bitPos = 0; | ||
670 | ++bytePos; | ||
671 | } | ||
672 | if (curBitPos >= MAX_BITS) | ||
673 | { | ||
674 | curBitPos = 0; | ||
675 | ++curBytePos; | ||
676 | } | ||
677 | } | ||
678 | } | ||
679 | |||
680 | return output; | ||
681 | } | ||
682 | } | ||
683 | } | ||