utility.cpp

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// Utility.cpp: implementation of the CUtility class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Utility.h"

/*
 * random.c:
 *
 * An improved random number generation package.  In addition to the standard
 * rand()/srand() like interface, this package also has a special state info
 * interface.  The our_initstate() routine is called with a seed, an array of
 * bytes, and a count of how many bytes are being passed in; this array is
 * then initialized to contain information for random number generation with
 * that much state information.  Good sizes for the amount of state
 * information are 32, 64, 128, and 256 bytes.  The state can be switched by
 * calling the our_setstate() routine with the same array as was initiallized
 * with our_initstate().  By default, the package runs with 128 bytes of state
 * information and generates far better random numbers than a linear
 * congruential generator.  If the amount of state information is less than
 * 32 bytes, a simple linear congruential R.N.G. is used.
 *
 * Internally, the state information is treated as an array of longs; the
 * zeroeth element of the array is the type of R.N.G. being used (small
 * integer); the remainder of the array is the state information for the
 * R.N.G.  Thus, 32 bytes of state information will give 7 longs worth of
 * state information, which will allow a degree seven polynomial.  (Note:
 * the zeroeth word of state information also has some other information
 * stored in it -- see our_setstate() for details).
 *
 * The random number generation technique is a linear feedback shift register
 * approach, employing trinomials (since there are fewer terms to sum up that
 * way).  In this approach, the least significant bit of all the numbers in
 * the state table will act as a linear feedback shift register, and will
 * have period 2^deg - 1 (where deg is the degree of the polynomial being
 * used, assuming that the polynomial is irreducible and primitive).  The
 * higher order bits will have longer periods, since their values are also
 * influenced by pseudo-random carries out of the lower bits.  The total
 * period of the generator is approximately deg*(2**deg - 1); thus doubling
 * the amount of state information has a vast influence on the period of the
 * generator.  Note: the deg*(2**deg - 1) is an approximation only good for
 * large deg, when the period of the shift register is the dominant factor.
 * With deg equal to seven, the period is actually much longer than the
 * 7*(2**7 - 1) predicted by this formula.
 */

/*
 * For each of the currently supported random number generators, we have a
 * break value on the amount of state information (you need at least this
 * many bytes of state info to support this random number generator), a degree
 * for the polynomial (actually a trinomial) that the R.N.G. is based on, and
 * the separation between the two lower order coefficients of the trinomial.
 */
#define	TYPE_0		0		/* linear congruential */
#define	BREAK_0		8
#define	DEG_0		0
#define	SEP_0		0

#define	TYPE_1		1		/* x**7 + x**3 + 1 */
#define	BREAK_1		32
#define	DEG_1		7
#define	SEP_1		3

#define	TYPE_2		2		/* x**15 + x + 1 */
#define	BREAK_2		64
#define	DEG_2		15
#define	SEP_2		1

#define	TYPE_3		3		/* x**31 + x**3 + 1 */
#define	BREAK_3		128
#define	DEG_3		31
#define	SEP_3		3

#define	TYPE_4		4		/* x**63 + x + 1 */
#define	BREAK_4		256
#define	DEG_4		63
#define	SEP_4		1

/*
 * Array versions of the above information to make code run faster --
 * relies on fact that TYPE_i == i.
 */
#define	MAX_TYPES	5		/* max number of types above */

static int const degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 };
static int const seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };

/*
 * Initially, everything is set up as if from:
 *
 *	our_initstate(1, &randtbl, 128);
 *
 * Note that this initialization takes advantage of the fact that srandom()
 * advances the front and rear pointers 10*rand_deg times, and hence the
 * rear pointer which starts at 0 will also end up at zero; thus the zeroeth
 * element of the state information, which contains info about the current
 * position of the rear pointer is just
 *
 *	MAX_TYPES * (rptr - state) + TYPE_3 == TYPE_3.
 */

static long randtbl[DEG_3 + 1] = {
	TYPE_3,
	0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 0xde3b81e0, 0xdf0a6fb5,
	0xf103bc02, 0x48f340fb, 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd,
	0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88,
	0xe369735d, 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
	0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, 0x8999220b,
	0x27fb47b9,
};

/*
 * fptr and rptr are two pointers into the state info, a front and a rear
 * pointer.  These two pointers are always rand_sep places aparts, as they
 * cycle cyclically through the state information.  (Yes, this does mean we
 * could get away with just one pointer, but the code for random() is more
 * efficient this way).  The pointers are left positioned as they would be
 * from the call
 *
 *	our_initstate(1, randtbl, 128);
 *
 * (The position of the rear pointer, rptr, is really 0 (as explained above
 * in the initialization of randtbl) because the state table pointer is set
 * to point to randtbl[1] (as explained below).
 */
static long* fptr = &randtbl[SEP_3 + 1];
static long* rptr = &randtbl[1];

/*
 * The following things are the pointer to the state information table, the
 * type of the current generator, the degree of the current polynomial being
 * used, and the separation between the two pointers.  Note that for efficiency
 * of random(), we remember the first location of the state information, not
 * the zeroeth.  Hence it is valid to access state[-1], which is used to
 * store the type of the R.N.G.  Also, we remember the last location, since
 * this is more efficient than indexing every time to find the address of
 * the last element to see if the front and rear pointers have wrapped.
 */
static long *state = &randtbl[1];
static int rand_type = TYPE_3;
static int rand_deg = DEG_3;
static int rand_sep = SEP_3;
static long* end_ptr = &randtbl[DEG_3 + 1];

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CUtility::CUtility()
{

}

CUtility::~CUtility()
{

}

/*
* random:
*
* If we are using the trivial TYPE_0 R.N.G., just do the old linear
* congruential bit.  Otherwise, we do our fancy trinomial stuff, which is
* the same in all the other cases due to all the global variables that have
* been set up.  The basic operation is to add the number at the rear pointer
* into the one at the front pointer.  Then both pointers are advanced to
* the next location cyclically in the table.  The value returned is the sum
* generated, reduced to 31 bits by throwing away the "least random" low bit.
*
* Note: the code takes advantage of the fact that both the front and
* rear pointers can't wrap on the same call by not testing the rear
* pointer if the front one has wrapped.
*
* Returns a 31-bit random number.
*/
long CUtility::our_random()
{
	long i;
	
	if (rand_type == TYPE_0)
		i = state[0] = (state[0] * 1103515245 + 12345) & 0x7fffffff;
	else {
		*fptr += *rptr;
		i = (*fptr >> 1) & 0x7fffffff;	/* chucking least random bit */
		if (++fptr >= end_ptr) {
			fptr = state;
			++rptr;
		} else if (++rptr >= end_ptr)
			rptr = state;
	}
	return(i);
}

unsigned long CUtility::our_random32() {
	// Return a 32-bit random number.
	// Because "our_random()" returns a 31-bit random number, we call it a second
	// time, to generate the high bit:
	long random1 = our_random();
	long random2 = our_random();
	return (u_int32_t)((random2<<31) | random1);
}

int CUtility::gettimeofday(struct timeval* tp, int* /*tz*/) {
	struct timeb tb;
	ftime(&tb);
	tp->tv_sec = tb.time;
	tp->tv_usec = 1000*tb.millitm;
	return 0;
}

void CUtility::setResultMsg(char * msg,...)
{
	return;
}

int CUtility::GetFileSize(char const* fileName, FILE* fid) 
{
	unsigned fileSize = 0; // by default
	
	if (fid != stdin) {
#if !defined(_WIN32_WCE)
		if (fileName == NULL) {
#endif
			if (fseek(fid, 0, SEEK_END) >= 0) {
				fileSize = ftell(fid);
				if (fileSize == (unsigned)-1) fileSize = 0; // ftell() failed
				fseek(fid, 0, SEEK_SET);
			}
#if !defined(_WIN32_WCE)
		} else {
			struct stat sb;
			if (stat(fileName, &sb) == 0) {
				fileSize = sb.st_size;
			}
		}
#endif
	}
	
	return fileSize;
}

void CUtility::setResultErrMsg(char * errmsg,...)
{

}

struct  in_addr CUtility::GetLocalAddr()
{
	char szTmp[256] = {0};
	gethostname(szTmp,sizeof(szTmp));
	struct hostent * pHost = gethostbyname(szTmp);
	char* addrPtr = NULL;
	if(pHost)
	{
		char* addrPtr = pHost->h_addr_list[0];
		return *(struct in_addr *)addrPtr;
	}
	struct in_addr addr = {0};
	return addr;
}