compress.cpp

游戏编程的原代码

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 * 这是在LZO的主页(http://wildsau.idv.uni-linz.ac.at/mfx/lzo.html)
 * 上获取的压缩算法,此算法属于GUN软件
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

#include "graphics.h"

#define byte unsigned char

static unsigned _do_compress(byte *in, unsigned in_len, byte *out, unsigned *out_len)
{
	static long wrkmem[16384L];
    register byte *ip;
	byte *op;
	byte *in_end = in + in_len;
	byte *ip_end = in + in_len - 13;
	byte *ii;
	byte **dict = (byte **)wrkmem;
	
	op = out, ip = in, ii = ip;
    ip += 4;

    for (;;)
	{
		register byte *m_pos;
		unsigned m_off;
		unsigned m_len;
		unsigned dindex;

		dindex = ((0x21 * (((((((unsigned)(ip[3]) << 6) ^ ip[2]) << 5) ^ ip[1]) << 5) ^ ip[0])) >> 5) & 0x3fff;
		m_pos = dict[dindex];

		if (((unsigned)m_pos < (unsigned)in) || 
			(m_off = (unsigned)((unsigned)ip - (unsigned)m_pos)) <= 0 ||
			m_off > 0xbfff)  
			goto literal;

		if (m_off <= 0x0800 || m_pos[3] == ip[3])
			goto try_match;
		dindex = (dindex & 0x7ff) ^ 0x201f ;

		m_pos = dict[dindex] ;
		if ((unsigned)(m_pos) < (unsigned)(in) ||
			(m_off = (unsigned)((int)((unsigned)ip - (unsigned)m_pos))) <= 0 ||
			m_off > 0xbfff)
			goto literal;
		if (m_off <= 0x0800 || m_pos[3] == ip[3])
			goto try_match;
		goto literal;

try_match:

		if (*(unsigned short *)m_pos == *(unsigned short *)ip && m_pos[2] == ip[2])
			goto match;

literal:
		dict[dindex] = ip;
		++ip;
		if (ip >= ip_end)
			break;
		continue;

match:
		dict[dindex] = ip;
		if (ip - ii > 0)
		{
			register unsigned t = ip - ii;
			
			if (t <= 3)
				op[-2] |= (byte)t;
			else 
				if (t <= 18)
					*op++ = (byte)(t - 3);
				else 
				{
					register unsigned tt = t - 18;
					*op++ = 0;
					while (tt > 255) 
					{
						tt -= 255;
						*op++ = 0;
					}
					*op++ = (byte)tt;
				}
				do *op++ = *ii++; while(--t > 0);
		}

		ip += 3;

		if (m_pos[3] != *ip++ || m_pos[4] != *ip++ || m_pos[5] != *ip++ ||
			m_pos[6] != *ip++ || m_pos[7] != *ip++ || m_pos[8] != *ip++ ) 
		{
			--ip;
			m_len = ip - ii;
			
			if (m_off <= 0x0800)
			{
				--m_off;
				*op++ = (byte)(((m_len - 1) << 5) | ((m_off & 7) << 2));
				*op++ = (byte)(m_off >> 3);
			}
			else
				if (m_off <= 0x4000)
				{
					-- m_off;
					*op++ = (byte)(32 | (m_len - 2));
					goto m3_m4_offset;
				}
				else
				{
					m_off -= 0x4000;
					*op++ = (byte)(16 | ((m_off & 0x4000) >> 11) | (m_len - 2));
					goto m3_m4_offset;
				}
		}
		else
		{
			{
				byte *end = in_end;
				byte *m = m_pos + 9;
				while (ip < end && *m == *ip)
					m++, ip++;
				m_len = (ip - ii);
			}

			if (m_off <= 0x4000 )  
			{
				--m_off;
				if (m_len <= 33)
					*op++ = (byte)(32 | (m_len - 2));
				else
				{
					m_len -= 33;
					*op++=32;
					goto m3_m4_len;
				}
			}
			else
			{
				m_off -= 0x4000;
				if (m_len <= 9)
					*op++ = (byte)(16 | ((m_off & 0x4000) >> 11) | (m_len - 2));
				else 
				{
					m_len -= 9;
					*op++ = (byte)(16 | ((m_off & 0x4000) >> 11));
m3_m4_len:
					while(m_len > 255)
					{
						m_len -= 255;
						*op++ = 0;
					}
					*op++ = (byte)m_len;
				}
			}

m3_m4_offset:
			*op++ = (byte)((m_off & 63) << 2);
			*op++ = (byte)( m_off >> 6);
		}

		ii = ip;
		if (ip >= ip_end)
			break;
	}
	*out_len = op - out;
	return (unsigned)(in_end - ii);
}

// 压缩内存中的数据块
int compress(void *in, unsigned in_len, void *out)
{
    byte *op = (byte *)out;
    unsigned t, out_len;

    if (in_len <= 13)
		t = in_len;
    else 
	{
		t = _do_compress((unsigned char *)in, in_len, op, &out_len);
		op += out_len;
    }

    if (t > 0)
	{
		byte *ii = (byte *)in + in_len - t;
		if (op == (byte *)out && t <= 238)
			*op++ = (byte)(17 + t);
		else 
			if (t <= 3)
				op[-2] |= (byte)t;
			else if (t <= 18)
				*op++ = (byte)(t - 3);
			else
			{
				unsigned tt = t - 18;

				*op++ = 0;
				while (tt > 255)
				{
					tt -= 255;
					*op++ = 0;
				}
				*op++ = (byte)tt;
			}
			do *op++ = *ii++; while(--t > 0);
	}

	*op++ = 17;
	*op++ = 0;
	*op++ = 0;

	return (op - (byte *)out);
}

// 解压缩内存中的数据块
int decompress(void *in, unsigned in_len, void *out)
{
	register byte *op;
	register byte *ip;
	register unsigned t;
	register byte *m_pos;

	byte *ip_end = (byte *)in + in_len;

	op = (byte *)out;
	ip = (byte *)in;

	if (*ip > 17)
	{
		t = *ip++ - 17;
		if (t < 4)
			goto match_next;
		do *op++ = *ip++; while(--t > 0);
		goto first_literal_run;
    }

    while(1)
	{
		t = *ip++;
		if (t >= 16) goto match;
		if (t == 0)
		{
			while(*ip == 0)
			{
				t += 255;
				ip++;
			}
			t += 15 + *ip++;
		}

		*(unsigned *)op = *( unsigned *)ip;
		op += 4; ip += 4;
		if (--t > 0)	
		{
			if (t >= 4)
			{
				do
				{
					*(unsigned *)op = *(unsigned *)ip;
					op += 4; ip += 4; t -= 4;
				}while(t >= 4);
				if (t > 0) do *op++ = *ip++; while(--t > 0);
			}
			else
				do *op++ = *ip++; while(--t > 0);
		}

first_literal_run:

		t = *ip++;
		if (t >= 16)
			goto match;

		m_pos = op - 0x0801;
		m_pos -= t >> 2;
		m_pos -= *ip++ << 2;

		*op++ = *m_pos++;
		*op++ = *m_pos++;
		*op++ = *m_pos;

		goto match_done;

		while (1)
		{
match:
		if (t >= 64)
		{
			m_pos = op - 1;
			m_pos -= (t >> 2) & 7;
			m_pos -= *ip++ << 3;
			t = (t >> 5) - 1;

			goto copy_match;
		}
		else
			if (t >= 32)
			{
				t &= 31;
				if (t == 0)
				{
					while (*ip == 0)
					{
						t += 255;
						ip++;
					}
					t += 31 + *ip++;
				}

				m_pos = op - 1;
				m_pos -= (*(unsigned short *)ip) >> 2;
				ip += 2;
			}
			else
				if (t >= 16)
				{
					m_pos = op;
					m_pos -= (t & 8) << 11;
					t &= 7;
					if (t == 0) 
					{
						while (*ip == 0) 
						{
							t += 255;
							ip++;
						}
						t += 7 + *ip++;
					}
					m_pos -= (*(unsigned short *)ip) >> 2;
					ip += 2;
					if (m_pos == op)
						goto eof_found;
					m_pos -= 0x4000;
				}
				else 
				{
					m_pos = op - 1;
					m_pos -= t >> 2;
					m_pos -= *ip++ << 2;
					*op++ = *m_pos++; 
					*op++ = *m_pos;
					goto match_done;
				}

				if (t >= 6 && (op - m_pos) >= 4) 
				{
					*(unsigned *)op = *(unsigned *)m_pos;
					op += 4; m_pos += 4; t -= 2;
					do
					{
						*(unsigned *)op = *(unsigned *)m_pos;
						op += 4; m_pos += 4; t -= 4;
					}while(t >= 4);
					if (t > 0) do *op++ = *m_pos++; while(--t > 0);
				}
				else
				{
copy_match:
				*op++ = *m_pos++; *op++ = *m_pos++;
				do *op++ = *m_pos++; while(--t > 0);
			}

match_done:

			t = ip[-2] & 3;
			if (t == 0)	break;

match_next:
			do *op++ = *ip++; while(--t > 0);
			t = *ip++;
		}
   }

eof_found:
   if (ip != ip_end) return -1;
   return (op - (byte*)out);
}

// 压缩指定的文件
BOOL compress_file(char *srcfile, char *destfile)
{
	FILE *fp;
	char *buffer, *cbuffer;
	DWORD fsize, size;
	fp = fopen(srcfile, "rb");
	if (fp == NULL)
		return FALSE;
	fseek(fp, 0, SEEK_END);
	fsize = ftell(fp);
	rewind(fp);
	buffer = new char [fsize];
	cbuffer = new char [fsize];
	if (buffer == NULL || cbuffer == NULL)
	{
		fclose(fp);
		return FALSE;
	}
	fread(buffer, fsize, 1, fp);
	fclose(fp);
	
	size = compress(buffer, fsize, cbuffer);
	fp = fopen(destfile, "wb+");
	if (fp == NULL)
	{
		delete buffer;
		delete cbuffer;
		return FALSE;
	}
	fwrite(&fsize, sizeof(fsize), 1, fp);
	fwrite(cbuffer, size, 1, fp);
	fclose(fp);
	delete buffer;
	delete cbuffer;
	return TRUE;
}

// 解压缩指定的文件
BOOL decompress_file(char *srcfile, char *destfile)
{
	FILE *fp;
	char *buffer, *cbuffer;
	DWORD fsize, size;
	fp = fopen(srcfile, "rb");
	if (fp == NULL)
		return FALSE;
	fseek(fp, 0, SEEK_END);
	fsize = ftell(fp);
	rewind(fp);
	buffer = new char [fsize];
	if (buffer == NULL)
	{
		fclose(fp);
		return FALSE;
	}
	fread(&size, sizeof(size), 1, fp);
	fread(buffer, fsize - sizeof(size), 1, fp);
	fclose(fp);
	
	cbuffer = new char [size];
	if (cbuffer == NULL)
	{
		delete buffer;
		return FALSE;
	}
	decompress(buffer, fsize, cbuffer);
	fp = fopen(destfile, "wb+");
	if (fp == NULL)
	{
		delete buffer;
		delete cbuffer;
		return FALSE;
	}
	fwrite(cbuffer, size, 1, fp);
	fclose(fp);
	delete buffer;
	delete cbuffer;
	return TRUE;
}