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  1. #include <iostream>
  2. #include <string.h>
  3. using namespace std;
  4.  
  5.  
  6. //***************************************************************************
  7. //
  8. // Implementation of DecompressJCALG1 in C++ by Jeffrey Lim
  9. // 
  10. // JCALG1 is copyright (C) Jeremy Collake
  11. //
  12. // Note: This code should work on any little-endian system that supports
  13. //		 mis-aligned reads. To support non-little endian, the functions
  14. //		 CompressionSourceData::GetBit() and CompressionSourceData::GetBits(int)
  15. //		 need to be modified.
  16. //		 If the target system does not support mis-aligned reads, either
  17. //		 the actual decompresssion data has to be made to align to 4-byte 
  18. //		 boundaries [note that there's a 10-byte header on JCALG1], or else 
  19. //		 the CompressionSourceData routines need to be modified.
  20. //
  21. //***************************************************************************
  22.  
  23. //***************************************************************************
  24.  
  25. class CompressionSourceData
  26. {
  27. private:
  28. 	const unsigned *Data;
  29. 	unsigned		BitBuffer;
  30. 	int				BitsRemaining;
  31.  
  32. public:
  33. 	CompressionSourceData(const unsigned *iData);
  34.  
  35. 	int GetBit();
  36. 	int GetBits(int Count);
  37. 	int GetInteger();
  38. };
  39.  
  40. CompressionSourceData::CompressionSourceData(const unsigned *iData)
  41. {
  42. 	Data			= iData;
  43. 	BitBuffer		= 0;
  44. 	BitsRemaining	= 0;
  45. }
  46.  
  47. int CompressionSourceData::GetBit()
  48. {
  49. 	int ReturnValue;
  50.  
  51. 	if(!BitsRemaining)
  52. 	{
  53. 		BitsRemaining = 32;
  54. 		BitBuffer = *Data++;
  55. 	}
  56.  
  57. 	ReturnValue = BitBuffer >> 31;
  58. 	BitBuffer <<= 1;
  59. 	BitsRemaining--;
  60. printf("dbr %d, ", BitBuffer);
  61. 	return ReturnValue;
  62. }
  63.  
  64. int CompressionSourceData::GetBits(int Count)
  65. {
  66. 	if(BitsRemaining >= Count)
  67. 	{
  68. 		int ReturnValue = BitBuffer >> (32-Count);
  69. 		BitBuffer <<= Count;
  70. 		BitsRemaining -= Count;
  71. 		return ReturnValue;
  72. 	}
  73. 	else
  74. 	{
  75. 		int Remainder = Count-BitsRemaining;
  76.  
  77. 		int ReturnValue = BitBuffer >> (32-BitsRemaining) << Remainder;
  78. 		BitBuffer = *Data++;
  79.  
  80. 		ReturnValue |= BitBuffer >> (32-Remainder);
  81. 		BitsRemaining = 32-Remainder;
  82. 		BitBuffer <<= Remainder;
  83.  
  84. 		return ReturnValue;
  85. 	}
  86. }
  87.  
  88. int CompressionSourceData::GetInteger()
  89. {
  90. 	int Value = 1;
  91. 	do
  92. 	{
  93. 		Value = (Value<<1) + GetBit();
  94. 	} while(GetBit());
  95.  
  96. 	return Value;
  97. }
  98.  
  99. //***************************************************************************
  100.  
  101. struct CompressionState
  102. {
  103. 	int		LastIndex;
  104. 	int		IndexBase;
  105. 	int		LiteralBits;
  106. 	int		LiteralOffset;
  107.  
  108. 	CompressionState() { LastIndex = 1; IndexBase = 8; }
  109. };
  110.  
  111. //***************************************************************************
  112.  
  113. void TransferMatch(unsigned char* &Destination, int MatchOffset, int MatchLength)
  114. {
  115. 	unsigned char* p = Destination;
  116. 	unsigned char* s = p-MatchOffset;
  117.  
  118. 	do
  119. 	{
  120. 		*p++ = *s++;
  121. 	} while(--MatchLength);
  122.  
  123. 	Destination = p;
  124. }
  125.  
  126. //***************************************************************************
  127.  
  128. void DecompressJCALG1(void *pDestination, const unsigned *pSource)
  129. {
  130. 	CompressionState		State;
  131. 	CompressionSourceData	Source(pSource+10);		// +10 skips the header of JCALG. A more robust routine would check this
  132. 	unsigned char *Destination = (unsigned char*) pDestination;
  133.  
  134. 	while(1)
  135. 	{
  136. 		if(Source.GetBit())
  137. 		{
  138. 			// Is Literal
  139. 			*Destination++ = Source.GetBits(State.LiteralBits) + State.LiteralOffset;
  140. 		}
  141. 		else
  142. 		{
  143. 			// Isn't literal
  144. 			if(Source.GetBit())
  145. 			{
  146. 				// Normal phrase
  147. 				int HighIndex = Source.GetInteger();
  148.  
  149. 				if(HighIndex == 2) // Use the last index
  150. 				{
  151. 					int PhraseLength = Source.GetInteger();
  152. 					TransferMatch(Destination, State.LastIndex, PhraseLength);
  153. 				}
  154. 				else
  155. 				{
  156. 					State.LastIndex = ((HighIndex-3) << State.IndexBase) + Source.GetBits(State.IndexBase);
  157.  
  158. 					int PhraseLength = Source.GetInteger();
  159.  
  160. 					if(State.LastIndex >= 0x10000)		PhraseLength += 3;
  161. 					else if(State.LastIndex >= 0x37FF)	PhraseLength += 2;
  162. 					else if(State.LastIndex >= 0x27F)	PhraseLength++;
  163. 					else if(State.LastIndex <= 127)		PhraseLength += 4;
  164.  
  165. 					TransferMatch(Destination, State.LastIndex, PhraseLength);
  166. 				}
  167. 			}
  168. 			else
  169. 			{
  170. 				if(Source.GetBit())
  171. 				{
  172. 					// OneBytePhrase or literal size change
  173. 					int OneBytePhraseValue = Source.GetBits(4) - 1;
  174. 					if(OneBytePhraseValue == 0)
  175. 					{
  176. 						*Destination++ = 0;
  177. 					}
  178. 					else if(OneBytePhraseValue > 0)
  179. 					{
  180. 						*Destination = *(Destination-OneBytePhraseValue);
  181. 						Destination++;
  182. 					}
  183. 					else
  184. 					{
  185. 						if(Source.GetBit())
  186. 						{
  187. 							// Next block
  188. 							do
  189. 							{
  190. 								for(int i = 0; i < 256; i++) *Destination++ = Source.GetBits(8);
  191. 							} while(Source.GetBit());
  192. 						}
  193. 						else
  194. 						{
  195. 							// New literal size
  196. 							State.LiteralBits = 7+Source.GetBit();
  197. 							State.LiteralOffset = 0;
  198. 							if(State.LiteralBits != 8)
  199. 							{
  200. 								State.LiteralOffset = Source.GetBits(8);
  201. 							}
  202. 						}
  203. 					}
  204. 				}
  205. 				else
  206. 				{
  207. 					// Short match
  208. 					int NewIndex = Source.GetBits(7);
  209. 					int MatchLength = 2+Source.GetBits(2);
  210. printf("ni %d, ml %d ", NewIndex, MatchLength);
  211. 					if(NewIndex == 0)
  212. 					{
  213. 						// Extended short
  214. 						if(MatchLength == 2) break;	// End of decompression
  215.  
  216. 						State.IndexBase = Source.GetBits(MatchLength+1);
  217. 					}
  218. 					else
  219. 					{
  220. 						State.LastIndex = NewIndex;
  221. 						TransferMatch(Destination, State.LastIndex, MatchLength);
  222. 					}
  223. 				}
  224. 			}
  225. 		}
  226. 	}
  227. }
  228.  
  229. //***************************************************************************
  230.  
  231.  
  232. int main() {
  233. 	// your code goes here
  234.     unsigned int* s = new unsigned int[22]{
  235. 74, 67, 44, 0, 0, 0, 14, 0, 0, 0, 69, 17, 0, 32, 18, 137, 20, 250, 0, 0, 0, 32 };
  236.     unsigned char d[44];
  237.     DecompressJCALG1(&d, s);
  238.     for (int i = 0; i < 44; i++) {
  239.         printf("%d, ", d[i]);
  240.     }
  241. cout << endl;
  242.  
  243. 	return 0;
  244. }
  245.  
Success #stdin #stdout 0s 15240KB
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Standard input is empty
stdout
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dbr 138, dbr 276, dbr 552, ni 0, ml 2 136, 189, 135, 139, 188, 85, 0, 0, 253, 174, 103, 139, 188, 85, 0, 0, 142, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 176, 174, 103, 139, 188, 85, 0, 0, 32, 169, 103, 139,
https://ideone.com/nIOxwv
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
public

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