l_cmd.c

quakeIII源码这个不用我多说吧

	int		pos;
	int		end;

	pos = ftell (f);
	fseek (f, 0, SEEK_END);
	end = ftell (f);
	fseek (f, pos, SEEK_SET);

	return end;
}


FILE *SafeOpenWrite (char *filename)
{
	FILE	*f;

	f = fopen(filename, "wb");

	if (!f)
		Error ("Error opening %s: %s",filename,strerror(errno));

	return f;
}

FILE *SafeOpenRead (char *filename)
{
	FILE	*f;

	f = fopen(filename, "rb");

	if (!f)
		Error ("Error opening %s: %s",filename,strerror(errno));

	return f;
}


void SafeRead (FILE *f, void *buffer, int count)
{
	if ( fread (buffer, 1, count, f) != (size_t)count)
		Error ("File read failure");
}


void SafeWrite (FILE *f, void *buffer, int count)
{
	if (fwrite (buffer, 1, count, f) != (size_t)count)
		Error ("File write failure");
}


/*
==============
FileExists
==============
*/
qboolean	FileExists (char *filename)
{
	FILE	*f;

	f = fopen (filename, "r");
	if (!f)
		return false;
	fclose (f);
	return true;
}

/*
==============
LoadFile
==============
*/
int    LoadFile (char *filename, void **bufferptr, int offset, int length)
{
	FILE	*f;
	void    *buffer;

	f = SafeOpenRead(filename);
	fseek(f, offset, SEEK_SET);
	if (!length) length = Q_filelength(f);
	buffer = GetMemory(length+1);
	((char *)buffer)[length] = 0;
	SafeRead(f, buffer, length);
	fclose(f);

	*bufferptr = buffer;
	return length;
}


/*
==============
TryLoadFile

Allows failure
==============
*/
int    TryLoadFile (char *filename, void **bufferptr)
{
	FILE	*f;
	int    length;
	void    *buffer;

	*bufferptr = NULL;

	f = fopen (filename, "rb");
	if (!f)
		return -1;
	length = Q_filelength (f);
	buffer = GetMemory(length+1);
	((char *)buffer)[length] = 0;
	SafeRead (f, buffer, length);
	fclose (f);

	*bufferptr = buffer;
	return length;
}


/*
==============
SaveFile
==============
*/
void    SaveFile (char *filename, void *buffer, int count)
{
	FILE	*f;

	f = SafeOpenWrite (filename);
	SafeWrite (f, buffer, count);
	fclose (f);
}



void DefaultExtension (char *path, char *extension)
{
	char    *src;
//
// if path doesnt have a .EXT, append extension
// (extension should include the .)
//
	src = path + strlen(path) - 1;

	while (*src != PATHSEPERATOR && src != path)
	{
		if (*src == '.')
			return;                 // it has an extension
		src--;
	}

	strcat (path, extension);
}


void DefaultPath (char *path, char *basepath)
{
	char    temp[128];

	if (path[0] == PATHSEPERATOR)
		return;                   // absolute path location
	strcpy (temp,path);
	strcpy (path,basepath);
	strcat (path,temp);
}


void    StripFilename (char *path)
{
	int             length;

	length = strlen(path)-1;
	while (length > 0 && path[length] != PATHSEPERATOR)
		length--;
	path[length] = 0;
}

void    StripExtension (char *path)
{
	int             length;

	length = strlen(path)-1;
	while (length > 0 && path[length] != '.')
	{
		length--;
		if (path[length] == '/')
			return;		// no extension
	}
	if (length)
		path[length] = 0;
}


/*
====================
Extract file parts
====================
*/
// FIXME: should include the slash, otherwise
// backing to an empty path will be wrong when appending a slash
void ExtractFilePath (char *path, char *dest)
{
	char    *src;

	src = path + strlen(path) - 1;

//
// back up until a \ or the start
//
	while (src != path && *(src-1) != '\\' && *(src-1) != '/')
		src--;

	memcpy (dest, path, src-path);
	dest[src-path] = 0;
}

void ExtractFileBase (char *path, char *dest)
{
	char    *src;

	src = path + strlen(path) - 1;

//
// back up until a \ or the start
//
	while (src != path && *(src-1) != '\\' && *(src-1) != '/')
		src--;

	while (*src && *src != '.')
	{
		*dest++ = *src++;
	}
	*dest = 0;
}

void ExtractFileExtension (char *path, char *dest)
{
	char    *src;

	src = path + strlen(path) - 1;

//
// back up until a . or the start
//
	while (src != path && *(src-1) != '.')
		src--;
	if (src == path)
	{
		*dest = 0;	// no extension
		return;
	}

	strcpy (dest,src);
}


/*
==============
ParseNum / ParseHex
==============
*/
int ParseHex (char *hex)
{
	char    *str;
	int    num;

	num = 0;
	str = hex;

	while (*str)
	{
		num <<= 4;
		if (*str >= '0' && *str <= '9')
			num += *str-'0';
		else if (*str >= 'a' && *str <= 'f')
			num += 10 + *str-'a';
		else if (*str >= 'A' && *str <= 'F')
			num += 10 + *str-'A';
		else
			Error ("Bad hex number: %s",hex);
		str++;
	}

	return num;
}


int ParseNum (char *str)
{
	if (str[0] == '$')
		return ParseHex (str+1);
	if (str[0] == '0' && str[1] == 'x')
		return ParseHex (str+2);
	return atol (str);
}



/*
============================================================================

					BYTE ORDER FUNCTIONS

============================================================================
*/

#ifdef _SGI_SOURCE
#define	__BIG_ENDIAN__
#endif

#ifdef __BIG_ENDIAN__

short   LittleShort (short l)
{
	byte    b1,b2;

	b1 = l&255;
	b2 = (l>>8)&255;

	return (b1<<8) + b2;
}

short   BigShort (short l)
{
	return l;
}


int    LittleLong (int l)
{
	byte    b1,b2,b3,b4;

	b1 = l&255;
	b2 = (l>>8)&255;
	b3 = (l>>16)&255;
	b4 = (l>>24)&255;

	return ((int)b1<<24) + ((int)b2<<16) + ((int)b3<<8) + b4;
}

int    BigLong (int l)
{
	return l;
}


float	LittleFloat (float l)
{
	union {byte b[4]; float f;} in, out;
	
	in.f = l;
	out.b[0] = in.b[3];
	out.b[1] = in.b[2];
	out.b[2] = in.b[1];
	out.b[3] = in.b[0];
	
	return out.f;
}

float	BigFloat (float l)
{
	return l;
}

#ifdef SIN
unsigned short   LittleUnsignedShort (unsigned short l)
{
	byte    b1,b2;

	b1 = l&255;
	b2 = (l>>8)&255;

	return (b1<<8) + b2;
}

unsigned short   BigUnsignedShort (unsigned short l)
{
	return l;
}

unsigned    LittleUnsigned (unsigned l)
{
	byte    b1,b2,b3,b4;

	b1 = l&255;
	b2 = (l>>8)&255;
	b3 = (l>>16)&255;
	b4 = (l>>24)&255;

	return ((unsigned)b1<<24) + ((unsigned)b2<<16) + ((unsigned)b3<<8) + b4;
}

unsigned    BigUnsigned (unsigned l)
{
	return l;
}
#endif


#else


short   BigShort (short l)
{
	byte    b1,b2;

	b1 = l&255;
	b2 = (l>>8)&255;

	return (b1<<8) + b2;
}

short   LittleShort (short l)
{
	return l;
}


int    BigLong (int l)
{
	byte    b1,b2,b3,b4;

	b1 = l&255;
	b2 = (l>>8)&255;
	b3 = (l>>16)&255;
	b4 = (l>>24)&255;

	return ((int)b1<<24) + ((int)b2<<16) + ((int)b3<<8) + b4;
}

int    LittleLong (int l)
{
	return l;
}

float	BigFloat (float l)
{
	union {byte b[4]; float f;} in, out;
	
	in.f = l;
	out.b[0] = in.b[3];
	out.b[1] = in.b[2];
	out.b[2] = in.b[1];
	out.b[3] = in.b[0];
	
	return out.f;
}

float	LittleFloat (float l)
{
	return l;
}

#ifdef SIN
unsigned short   BigUnsignedShort (unsigned short l)
{
	byte    b1,b2;

	b1 = l&255;
	b2 = (l>>8)&255;

	return (b1<<8) + b2;
}

unsigned short   LittleUnsignedShort (unsigned short l)
{
	return l;
}


unsigned    BigUnsigned (unsigned l)
{
	byte    b1,b2,b3,b4;

	b1 = l&255;
	b2 = (l>>8)&255;
	b3 = (l>>16)&255;
	b4 = (l>>24)&255;

	return ((unsigned)b1<<24) + ((unsigned)b2<<16) + ((unsigned)b3<<8) + b4;
}

unsigned    LittleUnsigned (unsigned l)
{
	return l;
}
#endif


#endif


//=======================================================


// FIXME: byte swap?

// this is a 16 bit, non-reflected CRC using the polynomial 0x1021
// and the initial and final xor values shown below...  in other words, the
// CCITT standard CRC used by XMODEM

#define CRC_INIT_VALUE	0xffff
#define CRC_XOR_VALUE	0x0000

static unsigned short crctable[256] =
{
	0x0000,	0x1021,	0x2042,	0x3063,	0x4084,	0x50a5,	0x60c6,	0x70e7,
	0x8108,	0x9129,	0xa14a,	0xb16b,	0xc18c,	0xd1ad,	0xe1ce,	0xf1ef,
	0x1231,	0x0210,	0x3273,	0x2252,	0x52b5,	0x4294,	0x72f7,	0x62d6,
	0x9339,	0x8318,	0xb37b,	0xa35a,	0xd3bd,	0xc39c,	0xf3ff,	0xe3de,
	0x2462,	0x3443,	0x0420,	0x1401,	0x64e6,	0x74c7,	0x44a4,	0x5485,
	0xa56a,	0xb54b,	0x8528,	0x9509,	0xe5ee,	0xf5cf,	0xc5ac,	0xd58d,
	0x3653,	0x2672,	0x1611,	0x0630,	0x76d7,	0x66f6,	0x5695,	0x46b4,
	0xb75b,	0xa77a,	0x9719,	0x8738,	0xf7df,	0xe7fe,	0xd79d,	0xc7bc,
	0x48c4,	0x58e5,	0x6886,	0x78a7,	0x0840,	0x1861,	0x2802,	0x3823,
	0xc9cc,	0xd9ed,	0xe98e,	0xf9af,	0x8948,	0x9969,	0xa90a,	0xb92b,
	0x5af5,	0x4ad4,	0x7ab7,	0x6a96,	0x1a71,	0x0a50,	0x3a33,	0x2a12,
	0xdbfd,	0xcbdc,	0xfbbf,	0xeb9e,	0x9b79,	0x8b58,	0xbb3b,	0xab1a,
	0x6ca6,	0x7c87,	0x4ce4,	0x5cc5,	0x2c22,	0x3c03,	0x0c60,	0x1c41,
	0xedae,	0xfd8f,	0xcdec,	0xddcd,	0xad2a,	0xbd0b,	0x8d68,	0x9d49,
	0x7e97,	0x6eb6,	0x5ed5,	0x4ef4,	0x3e13,	0x2e32,	0x1e51,	0x0e70,
	0xff9f,	0xefbe,	0xdfdd,	0xcffc,	0xbf1b,	0xaf3a,	0x9f59,	0x8f78,
	0x9188,	0x81a9,	0xb1ca,	0xa1eb,	0xd10c,	0xc12d,	0xf14e,	0xe16f,
	0x1080,	0x00a1,	0x30c2,	0x20e3,	0x5004,	0x4025,	0x7046,	0x6067,
	0x83b9,	0x9398,	0xa3fb,	0xb3da,	0xc33d,	0xd31c,	0xe37f,	0xf35e,
	0x02b1,	0x1290,	0x22f3,	0x32d2,	0x4235,	0x5214,	0x6277,	0x7256,
	0xb5ea,	0xa5cb,	0x95a8,	0x8589,	0xf56e,	0xe54f,	0xd52c,	0xc50d,
	0x34e2,	0x24c3,	0x14a0,	0x0481,	0x7466,	0x6447,	0x5424,	0x4405,
	0xa7db,	0xb7fa,	0x8799,	0x97b8,	0xe75f,	0xf77e,	0xc71d,	0xd73c,
	0x26d3,	0x36f2,	0x0691,	0x16b0,	0x6657,	0x7676,	0x4615,	0x5634,
	0xd94c,	0xc96d,	0xf90e,	0xe92f,	0x99c8,	0x89e9,	0xb98a,	0xa9ab,
	0x5844,	0x4865,	0x7806,	0x6827,	0x18c0,	0x08e1,	0x3882,	0x28a3,
	0xcb7d,	0xdb5c,	0xeb3f,	0xfb1e,	0x8bf9,	0x9bd8,	0xabbb,	0xbb9a,
	0x4a75,	0x5a54,	0x6a37,	0x7a16,	0x0af1,	0x1ad0,	0x2ab3,	0x3a92,
	0xfd2e,	0xed0f,	0xdd6c,	0xcd4d,	0xbdaa,	0xad8b,	0x9de8,	0x8dc9,
	0x7c26,	0x6c07,	0x5c64,	0x4c45,	0x3ca2,	0x2c83,	0x1ce0,	0x0cc1,
	0xef1f,	0xff3e,	0xcf5d,	0xdf7c,	0xaf9b,	0xbfba,	0x8fd9,	0x9ff8,
	0x6e17,	0x7e36,	0x4e55,	0x5e74,	0x2e93,	0x3eb2,	0x0ed1,	0x1ef0
};

void CRC_Init(unsigned short *crcvalue)
{
	*crcvalue = CRC_INIT_VALUE;
}

void CRC_ProcessByte(unsigned short *crcvalue, byte data)
{
	*crcvalue = (*crcvalue << 8) ^ crctable[(*crcvalue >> 8) ^ data];
}

unsigned short CRC_Value(unsigned short crcvalue)
{
	return crcvalue ^ CRC_XOR_VALUE;
}
//=============================================================================

/*
============
CreatePath
============
*/
void	CreatePath (char *path)
{
	char	*ofs, c;

	if (path[1] == ':')
		path += 2;

	for (ofs = path+1 ; *ofs ; ofs++)
	{
		c = *ofs;
		if (c == '/' || c == '\\')
		{	// create the directory
			*ofs = 0;
			Q_mkdir (path);
			*ofs = c;
		}
	}
}


/*
============
QCopyFile

  Used to archive source files
============
*/
void QCopyFile (char *from, char *to)
{
	void	*buffer;
	int		length;

	length = LoadFile (from, &buffer, 0, 0);
	CreatePath (to);
	SaveFile (to, buffer, length);
	FreeMemory(buffer);
}

void FS_FreeFile(void *buf)
{
	FreeMemory(buf);
} //end of the function FS_FreeFile

int FS_ReadFileAndCache(const char *qpath, void **buffer)
{
	return LoadFile((char *) qpath, buffer, 0, 0);
} //end of the function FS_ReadFileAndCache

int FS_FOpenFileRead( const char *filename, FILE **file, qboolean uniqueFILE )
{
	*file = fopen(filename, "rb");
	return (*file != NULL);
} //end of the function FS_FOpenFileRead